Information
Authors: Vighnesh Samel, María J. Cabrera-Álvarez
Version: A | 1.0Published: 2026-07-03
WelfareScore | catch
Legend
The score card gives our welfare assessments for aquatic species in 10 criteria.
For each criterion, we score the probability to experience good welfare under minimal catching conditions ("Likelihood") and under high-standard catching conditions ("Potential") representing the worst and best case scenario. The third dimension scores how certain we are of our assessments based on the number and quality of sources we found ("Certainty").
The WelfareScore sums just the "High" scores in each dimension. Although good welfare ("High") seems not possible in some criteria, there could be at least a potential improvement from low to medium welfare (indicated by ➚ and the number of criteria).
- Li = Likelihood that the individuals of the species experience good welfare under minimal catching conditions
- Po = Potential of the individuals of the species to experience good welfare under high-standard catching conditions
➚ = potential improvements not reaching "High" - Ce = Certainty of our findings in Likelihood and Potential
WelfareScore = Sum of criteria scoring "High" (max. 10 per dimension)
High
Medium
Low
Unclear
No findings
General remarks
Sardina pilchardus (European pilchard) is a small, schooling pelagic fish found in coastal waters of the north-east Atlantic Ocean, the Mediterranean Sea, and the Black Sea. Sold fresh, frozen, dried, smoked, or canned, it is extensively targeted by fisheries throughout its range and is also caught as a secondary species in fisheries targeting Engraulis encrasicolus (European anchovy), Scomber colias (Atlantic chub mackerel), Scomber scombrus (Atlantic mackerel), and Trachurus trachurus (Horse mackerel). It is captured using commercial methods such as purse seines, pelagic trawls, and bottom trawls as well as several small-scale gears.
During purse seine capture, the pilchards endure various welfare hazards, including exposure to loud engine noise, intense crowding in the net for extended periods, transfer to onboard storage units via crowded brail nets, exposure to air and tight packing (leading to flopping on plastic crates or in boxes while being crushed by the weight of their con-specifics), an agonising death without prior humane stunning and slaughter, and a high probability of being preyed upon by marine mammals and seabirds during encirclement, hauling, slipping, and discarding. These hazards lead to consequences such as physical injuries, asphyxia, temperature shock, physiological stress, and exhaustion, among others.
Important mitigation measures include, but are not limited to, targeting smaller schools of fishes, reducing crowding duration, slipping excess or unwanted catch rather than discarding it, using relatively lower-stress slipping methods, pumping individuals to storage units instead of brailing, using marine megafauna deterrent devices, such as Dolphin Deterrent Devices for marine mammals and visual deterrents like the Scarybird device for seabirds throughout the fishing process, and the immediate humane stunning and slaughter of the caught fishes. Given that there is currently no viable solution to humanely stun and slaughter the caught fishes, there is an urgent need for further research to develop such technologies.
1 Prospection
To find the fishes in their habitat, there are different techniques to localise them (e.g., echosound/sonar, chasing).
What is the probability of avoiding a decrease in welfare during the process of searching for the species?
It is low for minimal catching conditions, as engine noises possibly affect the IND. It is high for high-standard catching conditions, given fishers keep vessel engines off. Our conclusion is based on a medium amount of evidence, as further research is needed.Likelihood
Potential
Certainty
2 Setting
Catching methods differ in the way they are set up and consequently in the time it takes for setting them.
What is the probability of avoiding a decrease in welfare during the process of setting the catching method?
It is low for minimal catching conditions given predation pressure. It is high for high-standard catching conditions, given fishers a) abort net setting if they spot cetaceans, b) use DDD to reduce interactions with dolphins during setting, c) catch IND at dusk, night, or dawn, when the visibility of the net is low – the latter needs to be verified for the target species. Our conclusion is based on a medium amount of evidence, as further research is needed.Likelihood
Potential
Certainty
3 Catching
Given the principle of the catching method, the gear (with the fishes caught) may be hauled vertically or horizontally in the water for a certain amount of time and distance.
What is the probability of avoiding a decrease in welfare during catching?
It is low for minimal catching conditions given contact with the gear, crowding duration, decreasing distance to neighbours, and predation pressure as the purse seine is hauled close to the vessel. It is medium for high-standard catching conditions given a) that barotrauma is improbable and fishers b) prefer catching IND in calm waters, c) minimise crowding duration, d) use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds, e) avoid catching Sardina pilchardus schools when mixed with other species. Our conclusion is based on a high amount of evidence, as it seems clear that crowding – and the related hazard consequences – cannot be avoided.Likelihood
Potential
Certainty
4 Bycatch avoidance
Not all specimens of the target species are equally sought after, e.g., when they are undersized, of wrong sex, wrong age, damaged, over quota, or mixed with a high proportion of undersized or unwanted non-target fishes. Measures to prevent this bycatch still in the water may include slipping in purse seine, window in net, opening in trap, etc.
What is the probability of avoiding a decrease in welfare with the help of bycatch-avoiding measures?
It is low for minimal catching conditions, because once in the purse seine, IND experience lack of oxygen, contact with the gear, decreasing distance to neighbours, and handling as well as predation pressure inside and outside the net. It is high for high-standard catching conditions, given fishers a) interpret sonar/echo-sounder, b) target small schools, c) prefer catching IND in calm waters, d) refrain from using light to attract schools in seasons where the schools contain high frequency of undersized IND, e) use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds, f) prefer sampling to detect bycatch during the early stages of fishing and abort fishing to let the IND escape, g) prefer slipping unwanted catch (still in the water) over discarding (from deck to water), h) prefer modified over standard slipping. Our conclusion is based on a high amount of evidence.Likelihood
Potential
Certainty
5 Emersion
The process of bringing the fishes out of the water also depends on the catching method and may, thus, differ in duration and impact (e.g., netting, brailing, pumping, lifting).
What is the probability of avoiding a decrease in welfare during emersion?
It is low for minimal catching conditions given crowding, predation pressure, exposure to air (during brailing), contact with the gear, experiencing its own weight, and decreasing distance to neighbours. It is medium for high-standard catching conditions given a) that attacks by con-specifics are improbable and fishers b) avoid catching IND in rough seas, c) catch IND at dusk, night, or dawn, when the chances of solar exposure are low, d) use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds, e) minimise crowding duration, e) prefer pumps over brails to transfer IND to the vessel; with pumps, ensure that IND are not mixed with other species. Our conclusion is based on a medium amount of evidence, as further research is needed on technology or techniques to better mitigate crowding and decreasing distance to neighbours.Likelihood
Potential
Certainty
6 Release from gear
There are different ways to remove the fishes from the gear (e.g., unhooking, disentangling, dropping).
What is the probability of avoiding a decrease in welfare during release from the gear?
It is low for minimal catching conditions given lack of oxygen, dropping, handling, and a lack of care for good welfare (e.g., kicking IND). It is medium for high-standard catching conditions given fishers prefer pumps over brails to transfer IND to the vessel which can theoretically avoid lack of oxygen, but dropping and handling might still occur depending on the velocity with which IND arrive on deck, whether they are catapulted away from storage, and kicked or stood upon by fishers as well as the height from which they fall. Our conclusion is based on a medium amount of evidence, as further research is needed on mitigation measures.Likelihood
Potential
Certainty
7 Sorting
Given the species specificity of the method, sorting might be necessary once the catch arrives on deck.
What is the probability of avoiding a decrease in welfare during sorting?
It is low for minimal catching conditions given lack of oxygen, handling, dropping, and a lack of care for good welfare (e.g., kicking IND). It is medium for high-standard catching conditions given fishers prefer slipping unwanted catch (still in the water) over discarding (from deck to water) which will mitigate the welfare hazards but probably not sort out all unwanted catch. Our conclusion is based on a high amount of evidence.Likelihood
Potential
Certainty
8 Discarding
If bycatch of the target species could not be prevented, the individuals could still be returned from the gear/deck to the water.
What is the probability of avoiding a decrease in welfare during discarding?
It is low for minimal catching conditions, as discards happen to varying degrees (given season and region) and given lack of oxygen and handling before as well as displacement and predation pressure after discarding. It is medium for high-standard catching conditions, given fishers a) prefer slipping unwanted catch (still in the water) over discarding (from deck to water) which will mitigate most welfare hazards but probably not sort out all unwanted catch, b) discard IND as soon as possible at the fishing location/on the fishing grounds, c) use DDD to reduce interactions with dolphins and use a Scarybird device (visual bird deterrent) to reduce interactions with seabirds. Our conclusion is based on a high amount of evidence.Likelihood
Potential
Certainty
9 Storing
Given how long it takes the vessel to return to the harbour, the caught fishes have to be stored for a certain amount of time. This storing happens most frequently with the fishes still being alive, but differing in the type of storage containers and medium (ice, brine, air, etc.).
What is the probability of avoiding a decrease in welfare during storing?
It is low for minimal and high-standard catching conditions given storing of IND that are not dead (which subjects them to lack of oxygen, decreasing distance to neighbours, contact with the storing container, and exposure to the storing medium) and no established methods of improving this (by immediate stunning followed by slaughter while still insensible and unconscious). Our conclusion is based on a medium amount of evidence, as further research is needed.Likelihood
Potential
Certainty
10 Slaughter
Ideally, slaughter a) immediately follows stunning (i.e., while the individual is unconscious), b) happens according to a clear and reproducible set of instructions verified under catching conditions, and c) avoids pain, suffering, and distress.
What is the probability of avoiding a decrease in welfare during stunning/slaughter?
It is low for minimal and high-standard catching conditions given asphyxia and/or hypothermia and as there is no protocol for immediate humane stunning – followed by slaughter while still insensible and unconscious – reported in the literature. Our conclusion is based on a medium amount of evidence, as further research is needed.Likelihood
Potential
Certainty
Side note: Uncategorised catching step
Sometimes the literature does not specify the welfare hazards and the catching step that lead to hazard consequences.
What are consequences that decrease welfare during uncategorised steps of the catching process?
No data found yet.Side note: General improvements of the method
The focus of this WelfareCheck | catch is the welfare of the target species. There could be improvements to the catching method that are not covered by the criteria and could include prevention of overexploitation, prevention of bycatch of non-target species, e.g., pingers to deter cetaceans, and avoiding damage to the environment, though.
What are these improvements?
To decrease suffering, the best is to avoid catching animals – that would be discarded – in the first place which could mean for the target species (besides the more practical measures given in 2.4. Predation pressure, 4.4. Handling (unhooking/touching/disentangling), 4.7. Other) to set up spatio-temporal closures, apply local management and government measures, and define a minimum mesh size. For non-target species, it could mean interpreting sonar/echo-sounder, creating risk maps to decrease interactions with cetaceans, using DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds, aborting net setting if you spot cetaceans, targeting small schools, prefering sampling to detect bycatch during the early stages of fishing and aborting fishing to let the species escape, prefering modified over standard slipping, and prefering slipping unwanted catch (still in the water) over discarding (from deck to water). Impact on benthos is improbable, as the net is not dragged along the seafloor.- Target species: in Portugal, annual catch of Sardina pilchardus in the 1960s peaked at 150,000 t but declined constantly since then 15, reaching 64,000 t in 2008, then decreased by 20% until 2011, after which it dropped sharply 4, averaging at 46,000 t in 2008-2013 15 due to a decline in the stock biomass 4.
Measures to manage population besides interpreting sonar/echo-sounder, targeting small schools, using DDD to reduce interactions with dolphins during catching and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds, refraining from using light to attract schools in seasons where the schools contain high frequency of undersized IND, preferring sampling to detect bycatch during the early stages of fishing and abort fishing to let the IND escape, preferring modified over standard slipping, and prefering slipping unwanted catch (still in the water) over discarding (from deck to water) (→ 4.7. Other):
In the Mediterranean, prohibited to operate purse seines at a distance <300 m from the shore line or in areas shallower than 50 m for the sustainable exploitation of fisheries resources and the protection of protected habitats such as seagrass beds 49.
In Greece, closure of the fishery between 15 December and the end of February alongside prohibition of fishing two days before and after a full moon. Minimum mesh size for the night purse seine: 14 mm, maximum length of the seine: 800 m, and maximum height of seine: 120 m 6, EU minimum landing size of 110 mm TOTAL LENGTH 49↶6. To reduce discards, recommended to implement stricter measures and inspection by authorities to encourage fishers to target bigger IND, increase the mesh size in the upper part of the net to improve selectivity, and establish temporal fishing closures depending on the spawning periods of the targeted species 6.
In Portugal, purse seine fishery can only be conducted outside the 50 m isobath 7. Fishing effort reduces November-April due to voluntary area closures in northern and central Portugal, wherein fishing usually stops in February and March or because of bad weather 4.
Since 1997, landing limits for the purse seine fleet have been set annually in Portugal and distributed among Producer Organisations (POs) as well as the few non-associated vessels 1. Since 1999, POs in northern Portugal voluntarily introduced daily landing limits on their vessels to manage the annual quota of the PO as a function of local market-price fluctuations 1. Before 2009, there were no limits on catch of IND in Portuguese waters by the administration, although management measures like maximum number of fishing days per year and weekend fishing bans time and area closures, and daily landing limits (North of Peniche) were in place 51↶4. Post 2011, however, to recover from the low level of Sardina pilchardus biomass, strict regulations were implemented by the Portuguese and the Spanish administrations as a multi-annual management plan for the Atlantic Iberian sardine stock with restrictions on annual catches 51↶4. These management measures include limits on fishing effort, time and area closures, daily landing limits, and annual catch limits 15. The nets should have a minimum mesh size of 16 mm 7.
In Spain, purse seine fishing was traditionally stopped during winters for about two months (mid-December-mid-February), but the closure now extends to November-May 52. The minimum mesh size of nets is 14 mm 52. In the Bay of Biscay, Spain, purse seine fisheries targeting IND were initially certified by the Marine Stewardship Council in 2017, but has been suspended due to the relatively poor status of the sardine stock 46. Likewise, the Portuguese fleet has been initially certified, but was suspended in 2014 52. However, both Spanish and Portuguese fleets have been re-certified after joint management efforts such as setting annual catches, closed season periods, and limits on juvenile fishing, among other measures under the multi-annual management plan, 2021 52.
The landing obligation (Article 15 of the EU Common Fisheries Policy) probably does not apply for the Atlantic stocks of Sardina pilchardus stocks such as the Iberian stock, because its catch limits are set as a bilateral agreement between Portugal and Spain, and not by the EU commission. However, the fishery itself falls under the obligation, implying it is obliged to limit the discard of primary species like E. encrasicolus, T. trachurus, and Scomber scombrus 52 52 52. In the Mediterranean, the landing obligation applies to Sardina pilchardus and purse seine fisheries obliged to discard less than 5% of the total annual catch 53. - How to improve: spatio-temporal closures, local management and government measures, minimum mesh size
- Non-target species: given the principle of purse seine to catch whole schools 16 9 11, there is the risk to also include co-existing, preyed-on, and predating species 0.
Usable bycatch: in Portugal, Sardina pilchardus usually caught with other commercially relevant species like Scomber colias (Atlantic chub mackerel; Scomber japonicus in the original paper replaced with Scomber colias, because it has ceased being considered a subspecies of S. japonicus) 1 18, Scomber colias 28 29, Trachurus picturatus (Blue jay mackerel) 18, Trachurus trachurus (Atlantic horse mackerel) 1 18 29, Engraulis encrasicolus (European anchovy) 1 18, Trisopterus luscus (Pouting), and Balistes carolinensis (Grey triggerfish) 1. Moreover, fishers target Scomber colias and T. trachurus during restrictive management measures on catching Sardina pilchardus 28.
In Greece, important usable bycatch species include Sparus aurata (Gilthead seabream), Boops boops (Bogue bream), and Scomber colias (S. japonicus in the original paper). In the Aegaen Sea, 3% other marketable species comprising 47 FISHES (Auxis rochei [Bullet tuna], Belone belone gracilis [Garfish], Caranx crysos [Blue runner], Caranx rhonchus [False scad], Citharus linguatula [Spotted flounder], Coryphaena hippurus [Mahi-mahi], Dactylopterus volitans [Flying gurnard], Dentex dentex [Common dentex], Diplodus annularis [Annular seabream], Diplodus vulgaris [Common two-banded seabream], Euthynnus alletteratus [Little tunny], Lithognathus mormyrus [Sand steenbras], Liza saliens [Leaping mullet], Lophius budegassa [Blackbellied angler], Merluccius merluccius [European hake], Mugil cephalus [Striped mullet], Mullus barbatus [Red mullet], Mullus surmuletus [Striped red mullet], Oblada melanura [Saddled seabream], Pagellus erythrinus [Common pandora], Pagrus pagrus [Red porgy], Pomatomus saltator [Bluefish], Sarda sarda [Atlantic bonito], Sarpa salpa [Salema porgy], Sciaena umbra [Brown meagre], Scomber scombrus [Atlantic mackerel], Scorpaena scrofa [Red scorpionfish], Solea kleini [Klein's sole], Solea lascaris [Sand sole], Solea vulgaris [Common sole], S. aurata, Sphyraena sphyraena [European barracuda], Spicara maena [Blotched picarel], Spicara smaris [Picarel], Spondyliosoma cantharus [Black seabream], Sprattus sprattus [European sprat], Trachinotus ovatus [Pompano], Trachinus draco [Greater weever], Trachurus mediterraneus [Mediterranean horse mackerel], Trachurus picturatus, Trachurus trachurus, Trigla lucerna [Tub gurnard], Triglophorus lastoviza [Streaked gurnard], Trisopterus minutus capelanus, Uranoscopus scaber [Atlantic stargazer], Xiphias gladius [Swordfish], and Zeus faber [John Dory]), 6 molluscs (Illex coindetii [Southern shortfin squid], Loligo vulgaris [European squid], Octopus vulgaris [Common octopus], Sepia officinalis [Common cuttlefish], Sepiolidae, and Todarodes sagittatus [European flying squid]), and 2 crustaceans (Parapenaeus longirostris [Deep-water rose shrimp] and Penaeus kerathurus [Striped prawn]). In the Ionian Sea, 1.9% other marketable species comprised 10 FISHES (Centracanthus cirrus [Curled picarel], D. annularis, Lepidopus caudatus [Silver scabbardfish], Scomber scombrus, Scomber colias [S. japonicus in the original paper], S. aurata, Sphyraena sphyraena, Thunnus alalunga [Albacore], T. mediterraneus, and T. trachurus) and 2 molluscs (I. coindetii and L. vulgaris) 6.
Off the coast of Türkiye, bycatch and use of 26 species, which includes FISHES (mostly: Boops boops, Sardinella aurita [Round sardinella], Sarda sarda, Mugilidae, Sarpa salpa, Scomber scombrus, to a smaller degree: Trachurus sp., Thunnus thynnus [Atlantic bluefin tuna], Sparus aurata, Scomber colias, and rarely: Dicentrarchus labrax [European seabass], Belone belone, Sphyraena sphyraena, Pomatomus saltatrix [Bluefish], Argyrosomus regius [Meagre], Xiphias gladius, Pagellus erythrinus, Auxis rochei, Coryphaena hippurus, Mullus surmuletus, Serranus cabrilla [Comber], Diplodus puntazzo, Scomberomorus commerson [Narrow-barred Spanish mackerel], and Pleuronectes flesus [European flounder]), crustaceans (mostly Penaeus sp.), and to a smaller degree the mollusc Loligo vulgaris 10.
Non-usable bycatch: in Spain, in métiers targeting Sardina pilchardus, Scomber scombrus and Trachurus sp. formed 48% and 36% of the discards, alongside a few discards of other FISHES like mackerel, Trachurus sp., Garfish, Sunfish, Anglerfish, Atlantic bonito, Hake, Small-spotted catshark, Common sole, Greater weever, Anchovy, Wedge sole, and family Triglidae 46.
In Greece, in the Aegean Sea, ~4.6% discard rate comprising 60 bony FISHES (Arnoglossus laterna [Mediterraenean scaldfish], Arnoglossus rueppelli [Rüppell's scaldback], Arnoglossus thori [Thor's scaldfish], Aspitrigla cuculus [Red gurnard], Atherina boyeri [Big-scale sand smelt], Atherina hepsetus [Mediterranean sand smelt], Blennius ocellaris [Butterfly blenny], Capros aper [Boarfish], Cepola rubescens [Red bandfish], Chlorotocus crassicornis, Chromis chromis [Damselfish], Conger conger [European conger], Coris julis [Mediterranean rainbow wrasse], Deltentosteus quadrimaculatus [Four-spotted goby], Diplodus puntazzo, Diplodus sargus [Sargo], Echelus myrus [Painted eel], Echeneis naucrates [Live sharksucker], Etrumeus teres [Red-eye round herring], Eutrigla gurnardus [Grey gurnard], Gaidropsarus mediterraneus [Shore rockling], Glossanodon leioglossus [Small-toothed argentine], Gobius niger [Black gober], Gobius sp., Gymnammodytes cicerelus [Mediterranean sand eel], Hippocampus hippocampus [Short-snouted sea horse], Hirundichthys rondeletii [Black wing flyingfish], L. caudatus, Lepidotrigla cavillone [Large-scaled gurnard], Lesueurigobius friesii [Fries's goby], Lesueurigobius suerii [Lesueur's goby], Lophius piscatorius [Angler], Merlangius merlangus euxinus [Whiting], Microchirus ocellatus [Four-eyed sole], Microchirus variegatus [Thickback sole], Micromesistius poutassou [Blue whiting], Monochirus hispidus [Whiskered sole], Myctophidae, Ophidion barbatum [Snake blenny], Pagellus acarne [Axillary seabream], Pagellus bogaraveo [Blackspot seabream], Scorpaena notata [Small red scorpionfish], Scorpaena porcus [Black scorpionfish], Scorpaena spp., Seriola dumerili [Greater amberjack], Serranus cabrilla [Comber], Serranus hepatus [Brown comber], Serranus scriba [Painted comber], Stephanolepis diaspros [Reticulated filefish], Symphodus cinereus [Grey wrasse], Symphodus mediterraneus [Axillary wrasse], Symphodus ocellatus [Ocellated wrasse], Symphodus rostratus [Pointed-snout wrasse], Symphodus tinca [East Atlantic peacock wrasse], Symphodus sp., Syngnathus acus [Greater pipefish], Syngnathus typhle [Broadnosed pipefish], Synodus saurus [Atlantic lizardfish], T. alalunga, and Xyrichthys novacula [Pearly razorfish]), 6 cartilaginous FISHES (Dasyatis pastinaca [Common stingray], Raja montagui [Spotted ray], Raja naevus [Cuckoo skate], Raja polystigma [Speckled skate], Scyliorhinus canicula [Small-spotted catshark], and Torpedo nobiliana [Atlantic torpedo]), 5 molluscs (Alloteuthis media [Midsize squid], Eledone cirrhosa [Curled octopus], Eledone moschata [Musky octopus], Sepia elegans [Elegant cuttlefish], and Sepietta spp.), and 5 crustaceans (Goneplax rhomboides [Angular crab], Liocarcinus depurator [Harbour crab], Majidae, Scyllarus arctus [Small European locust lobster], and Squilla mantis [Spot-tail mantis shrimp]). In the Ionian Sea, 2.2% discard rate, comprising 14 FISHES (A. hepsetus, B. belone gracilis, C. crysos, C. chromis, C. julis, Labrus viridis [Green wrasse], Mullus surmuletus, P. acarne, S. scriba, S. scrofa, S. hepatus, S. vulgaris, S. cantharus, and S. saurus) and the mollusc A. media. Furthermore, commercially valuable species such as L. piscatorius, T. alalunga, and S. scrofa were often discarded because catches of undersized individuals were very low 6.
Please note, Leucoraja naevus (Raja naevus in [Tsagarakis et al. 2012]; decreasing), S. commerson (decreasing), S. umbra (decreasing; vulnerable in the Mediterranean) are near threatened, D. dentex (Decreasing), D. pastinaca (decreasing), H. hippocampus (decreasing) are vulnerable according to IUCN.
For methods of bycatch prevention in the target species that might also work on non-target species → 4.7. Other. Further research needed on co-existing, preyed-on, and predating species. - How to improve: interpret sonar/echo-sounder, target small schools, prefer sampling to detect bycatch during the early stages of fishing and abort fishing to let the species escape, prefer modified over standard slipping, prefer slipping unwanted catch (still in the water) over discarding (from deck to water)
- Non-target species: given the principle of purse seine to catch whole schools 16 9 11, given that Sardina pilchardus is the primary prey of Delphinus delphis (Common dolphin) 30 31 32, and given that fishing operations are carried out from sunset to sunrise which coincides with the feeding period of dolphins 54 55 56↶17, there is the risk of cetacean bycatch 0.
Four cetacean species, D. delphis, Tursiops truncatus (Common bottlenose dolphin), Phocoena phocoena (Harbour porpoise), and Balaenoptera acutorostrata (Common minke whale) show a spatial overlap with the Portuguese purse seine fishery 14.
Cetaceans present in 16.9% of the fishing events, with D. delphis accounting for ~95% of the sightings, mostly at night in summer and early autumn 15.
D. delphis, T. truncatus, P. phocoena, and unidentified Delphinids observed at mean sighting rates of 0.72, 0.03, 0.01, and 0.03 groups/hour 17. Cetaceans present in 21% of the fishing trips (n = 115), with 27% (n = 31) of the sightings during navigation, 14% (n = 16) during searching, and 59% (n = 68) during the fishing operation, with D. delphis being the most frequently sighted (83.5%) during the fishing trips, followed by T. truncatus (5.2%), P. phocoena (2.6%), unidentified small cetaceans (7.8%) and a single observation of B. acutorostrata 29.
Sighting rate/purse seine set of 9.7% for D. delphis in Alboran sea, off the Spanish coast 24.
Encirclement of three cetacean species at a rate of 0.023 encirclements/set with deaths of 3 D. delphis, with an estimated fleet-level mortality of approximately 69 and 91 in northern and southern Portugal for 2010 and 78 in southern Portugal for 2011 15.
Three events of small cetacean bycatch corresponding to 8 individuals, 7 of which were released and 1 died in the net 17, D. delphis interactions in 18% of sets, resulting in an accidental capture and death of one dolphin 14, accidental captures in ~1.6%, leading to deaths of cetaceans in ~0.8% of the sets 29, and bycatch of D. delphis with 38 animals bycaught, 29 of which were released alive whilst the rest were already dead 22. The dead dolphins were not detected until the end of the fishing operation when the net was brought close to the vessel 15 22.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
For methods of bycatch prevention in the target species that might also work on non-target species → 2.4. Predation pressure 4.4. Handling (unhooking/touching/disentangling) 4.7. Other.
Recommended to create models based on data obtained from vessel monitoring systems, cetacean distributions, and cetacean occurrence to produce maps of the probability of interactions to identify problematic areas and seasons 15. - How to improve: create risk maps to decrease interactions with cetaceans, use DDD to reduce interactions with dolphins during catching, abort net setting if you spot cetaceans, make observations to detect bycatch during the early stages of fishing and abort fishing to let species escape, prefer modified over standard slipping
- Non-target species: given the principle of purse seine to catch whole schools along with the predator species 16 9 11, given that different species of seabirds, including sea gulls, prey on Sardina pilchardus 34 35 36, there is the risk of bycatch of birds 0.
In a survey conducted 2010-2012: reported bycatch rate of ~1.7 birds/trip in interview surveys and an observed bycatch rate of ~0.2 birds/trip, corresponding to ~0.11 birds/set during on-board observations 57. The main affected species were Puffinus mauretanicus (Balearic shearwater), Morus bassanus (Northern gannet), Calonectris borealis (Cory’s shearwater), and Phalacrocorax carbo (Great cormorant) 57. Bycatch of three immature gulls, L. michahellis and L. fuscus in the net, resulting in a bycatch rate of 3 birds/100 trips 33. The critically endangered P. mauretanicus, due to its gregariousness and close association to fishing vessels 58↶57, was especially vulnerable to bycatch when purse seine nets were set near its flock, with a mean ~7.7 birds caught per set 57. In Spain, entanglement of a single Larus michahellis (Yellow-legged gull) in the purse seine net, which was eventually released alive 46.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33. - How to improve: use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- Non-target species: given the principle of purse seine to catch at the surface (avoid the bottom) 23, seabed damage or impact on benthos respectively is improbable 0. When fishing takes place over the shelf or in shallower water, the bottom may be touched 0. The net is not dragged along the seafloor 23, though, so huge impact on benthos is improbable 0.
- How to improve: impact on benthos improbable
Side note: Commercial relevance
How much is this species targeted annually?
1,217,319 t/year 2003-2022 59 (across catching methods like purse seine, pelagic trawl, bottom trawl, and others 60 amounting to 61,000,000,000 IND/year 2003-2022 59.Glossary
FISHES = using "fishes" instead of "fish" for more than one individual - whether of the same species or not - is inspired by Jonathan Balcombe who proposed this usage in his book "What a fish knows". By referring to a group as "fishes", we acknowledge the individuals with their personalities and needs instead of an anonymous mass of "fish".
IND = individuals
JUVENILES = fully developed but immature individuals
LAB = setting in laboratory environment
TOTAL LENGTH = from snout to tip of caudal fin as compared to fork length (from snout to fork of caudal fin) 45 or standard length (from head to base of tail fin) or body length (from the base of the eye notch to the posterior end of the telson)
Bibliography
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Information
Authors: Vighnesh Samel, María J. Cabrera-Álvarez
Version: A | 1.0Published: 2026-07-03
Please note: This view of the WelfareCheck was generated automatically from the default view.
1 Physical damage
As a consequence of welfare hazards, fishes may suffer from physical damage (e.g., barotrauma, abrasions/lacerations/wounds, ecchymosis, desiccation).
Where in the catching process does physical damage occur and how to avoid it?
Physical damage (like skin damage and scale loss) may occur most frequently through contact with the gear, crowding (in the water) and decreasing distance to neighbours (inside and outside the water), handling, and dropping.
To avoid or decrease it during catching and emersion, prefer catching IND in calm waters, minimise crowding duration.
To avoid or decrease it for target bycatch that will be released, interpret sonar/echo-sounder, target small schools, prefer catching IND in calm waters, refrain from using light to attract schools in seasons where the schools contain high frequency of undersized IND, prefer sampling to detect bycatch during the early stages of fishing and abort fishing to let the IND escape, prefer slipping unwanted catch (still in the water) over discarding (from deck to water), prefer modified over standard slipping.
To avoid or decrease it during emersion, catch IND at dusk, night, or dawn, when the chances of solar exposure are low.
To avoid or decrease it during emersion and release from gear, prefer pumps over brails to transfer IND to the vessel; with pumps, ensure that the IND are not mixed with other species.
To avoid or decrease it during discarding, discard IND as soon as possible at the fishing location/on the fishing grounds.
To avoid it during sorting and storing, prefer immediate stunning followed by slaughter while still insensible and unconscious.
Further research needed. Barotrauma and attacks by con-specifics are improbable.
1.1 Barotrauma
Extruded eyes/guts: no data found yet.
Ruptured swim bladder: no data found yet.
Bleeding: no data found yet.
Unspecified- Given catching depths of 18-117 m 6, 19.8-51.2 m 13, 25-68 m 10, ~32 m 22, 35-73 m 18, 39 m 28, or 41.4-49.6 m 4, 50-100 m 24 with unknown hauling speed and given luring IND to the surface using artificial light 6 7 8 9 10 11, barotrauma is improbable 0.
1.2 Damages/abrasions/lacerations/wounds
Eye damage: no data found yet.
Skin damage- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
- IND transferred from the purse seine net to the on-board storage unit with traditionally used brail nets 16 7 9 25 11 with a capacity of 100 kg 25 or with pumps (Pescamotion 6 plus) with loading capacities of 6.7 kg/min (400 kg/h) 26, 83.6-97.4 kg/min, 165.5-189.5 kg/min 25.
With brails, given that the transfer to the storage space of the vessel takes ~36 min 13 or ~40 min 12 and given the force with which the net is dipped into the purse seine, exposure to air, and the crowding density, hazard consequences are probable 0. Damages in 10-16% IND like indentations and irregular body shapes because IND in the lower level were crushed by the weight of the IND above them 25.
With pumps, given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 0. 7% IND damaged with light cuts in one sample and in another sample, 17% IND damaged with scratches and deep cuts in the skin as a result of IND being mixed with T. trachurus, whose sharp scales along the lateral line damaged the IND 25. Probably no difference in stress between brailing and pumping (relatively low muscle pH in all the caught IND) 25.
Mouth damage: no data found yet.
Opercular/gill damage: no data found yet.
Scale loss- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
Broken spine: no data found yet.
Unspecified- Given the principle of purse seine to encircle the IND, haul the net close to the vessel taking average 45 min 1 or 52 min 13, and partially haul the net up (called “drying up” 12), thereby crowding the IND 23 in a net pouch at the bunt end 16 9 11, hazard consequences are probable 0.
IND get gilled or snared in the net 9 24. - Varying wave height (<0.5-2+ m) can probably cause stress during hauling and fish transfer to the vessel by increasing the probability of fish collision with the net 13 and probably with con-specifics 0, causing abrasion 13. ~40% IND survived after being caught in rough seas (wave height 1.5-2 m), whilst >80% survived when caught in good sea conditions (wave height 0-0.5 m) 18.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
- In multi-species fishery, purse seine was not set in 56 of 179 trips (~31%) 4 – possibly after interpreting sonar/echo-sounder or judgment of the fishers 0 – due to schools being too small, mixed with other species, or containing JUVENILES or due to bad weather 4 – effectively avoiding bycatch before it can happen 0.
- In some cases, fishers attract schools of IND using lights 6 7 8 9 10 11. Given that in spring to summer this potentially attracts undersized IND that would need to be discarded, recommended not to use light during this season 26.
- Given that the mean TOTAL LENGTH of maturity for 50% of the population of 10.1 cm (2 years observation period) 37, 11.4-12.6 cm for females, 10.2-12.2 cm for males (9 years observation period) 38, 11.7 cm for females, 11.4 cm for males (2 years observation period) 39, 12.2-16.4 cm (60 years observation period) 40, 14.3-15.6 cm (estimated over 15 years observation period) 41, 15.8 cm (3 years observation period) 42 (outlier: 7.9 cm in the Adriatic sea over 3 years observation period 43) overlaps with mean TOTAL LENGTH at catching of 11.2-13.1 cm 10, 14-14.1 cm 28, 15.9-17.9 cm 13, and given that IND school and the principle of purse seine is to catch whole schools 16 9 11, there is a risk of bycatch (accidental catch of undersized, wrong sex, wrong age, damaged, over quota IND, and mixture with undersized or unwanted non-target FISHES) of the target species 18 0.
After setting the net and in the initial stages of hauling, skippers or captains can get an impression of the catch by looking at a sample of FISHES that come to the surface. At that point, they can abort the process if the catch contains a high proportion of bycatch 44. - In multi-species fishery, out of 30 trips, 23 had a slipping event with ca 366.9 t slipped against 177.4 t landed. At the local fleet level during the same time period as the study (11 weeks), ca 4,979 t were slipped corresponding to 69% of the total catch out of which >95% were Sardina pilchardus 1.
In multi-species fishery, total catch 1-17 t/set, mostly (95% in weight) Sardina pilchardus, versus actual landings <1-13 t, indicating that the difference was slipped 12.
Slipping: ~1 t/trip 14, 0-7 t/set from a catch of 1-17 t/set 13. During 15 months, ca 25 t slipped corresponding to 16% of the total catch 7.
Reasons for slipping included reaching the daily quota 1 12 14 4 7, catch exceeding the storage capacity of the vessel 7, undersized IND in the catch 1 12, mixture with undersized or unwanted non-target bycatch 1 12 14 4, such as the pelagic crab Polybius henslowi 1 12.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - Given that IND school 47, aggression between con-specifics is improbable 0.
- IND transferred from the purse seine net to the on-board storage unit with traditionally used brail nets 16 7 9 25 11 with a capacity of 100 kg 25 or with pumps (Pescamotion 6 plus) with loading capacities of 6.7 kg/min (400 kg/h) 26, 83.6-97.4 kg/min, 165.5-189.5 kg/min 25.
With brails, given that the transfer to the storage space of the vessel takes ~36 min 13 or ~40 min 12 and given the force with which the net is dipped into the purse seine, exposure to air, and the crowding density, hazard consequences are probable 0. Damages in 10-16% IND like indentations and irregular body shapes because IND in the lower level were crushed by the weight of the IND above them 25.
With pumps, given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 0. 7% IND damaged with light cuts in one sample and in another sample, 17% IND damaged with scratches and deep cuts in the skin as a result of IND being mixed with T. trachurus, whose sharp scales along the lateral line damaged the IND 25. Probably no difference in stress between brailing and pumping (relatively low muscle pH in all the caught IND) 25. - After scooping the IND out of the purse seine, the scoop net is released above the storage space of the vessel 16 9 11. Given exposure to air, dropping from a certain height, landing hard in plastic containers 16 9 11 or boxes 7, being catapulted away from the containers, and kicked or stood upon by the fishers 16 9 11, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Some IND may be entangled in the net 9. Given exposure to air, dropping from a certain height, landing hard on deck, being kicked or stood upon by fishers 9, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - After transferring on board, catch with no commercial value discarded 4. Given that IND have a high value 14, discarding improbable 4. Value depends on region: Sardina pilchardus commercially important along Portuguese mainland 21, Greece 6, and the Bay of Biscay 46, but not on the Madeira archipelago 7.
IND discarded at an average discard rate of 0.91-14.85 kg/trip and 1.74-5.2 kg/trip in mixed métiers and in métiers targeting Engraulis encrasicolus; in métiers targeting Sardina pilchardus, discarding rate of 0.34-31.22 kg/trip 46.
IND comprised 32.7% of the total discards; 60% of the caught IND were discarded back into the sea due to their low commercial value 7.
In the Aegean sea, 63.06 mt of IND discarded annually compared to <0.01 mt in the Ionian sea 6. At 55.7 mm, 76.6 mm, and 97.5 mm TOTAL LENGTH – 75%, 50%, and 25% of the IND are discarded. Discarding sizes greater in summer, which is the spawning season, than in spring 6. Given EU minimum landing size of 110 mm TOTAL LENGTH 49↶6, catching and discarding of JUVENILES evident 0.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Given that fishers manually discard IND after emersion, release from gear, sorting – including all welfare hazards outlined there – and after transport to shore, given pressure by boxes put on top of each other (with the IND inside), contact with ice, and exposure to air, and given IND are not already dead 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.- Catching step:
- How to improve: prefer slipping unwanted catch (still in the water) over discarding (from deck to water) (for management measures → 12. Side note: General improvements of the method)
- Given that fishers manually discard IND after transport to shore and given that IND are not already dead 11, hazard consequences are probable 0. Recommended to discard IND as soon as possible at the fishing location/on the fishing grounds 0. For recommended methods to avoid bycatch still in the water →4.2. Contact with the gear and 4.7. Other.
- Given storing on board in plastic crates 9 11 or isothermic boxes 16, pressure by boxes put on top of each other (with the IND inside), getting crushed by con-specifics, and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
1.3 Ecchymosis
Bruising and discoloration of the skin due to squeezing1.4 Desiccation (surface issue)
Unspecified- Given that fishing takes place before sunrise 1 12 13 18 19 16 or at both sunrise and sunset 17 6 9 11, when solar exposure is limited 0, hazard consequences arising from solar exposure are improbable 0.
- Given storing on board in plastic crates 9 11 or isothermic boxes 16, pressure by boxes put on top of each other (with the IND inside), getting crushed by con-specifics, and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
2 Stress
Stress is a likely consequence of various welfare hazards. It may be measured via physiological parameters (cortisol, glucose, lactate, etc.) or behavioural observations (e.g., opercular movement).
Where in the catching process does stress occur and how to avoid it?
Stress may occur most frequently through noise, predation pressure (inside and outside the net), contact with the gear, crowding (in the water) and decreasing distance to neighbours (inside and outside the water), exposure to air, handling, and dropping.
To avoid or decrease it during prospection, keep vessel engines off.
To avoid or decrease it during setting, abort net setting if you spot cetaceans.
To avoid or decrease it during setting, catching, emersion, and for target bycatch that will be released, use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds.
To avoid or decrease it during catching and emersion, prefer catching IND in calm waters and minimise crowding duration.
To avoid or decrease it for target bycatch that will be released, interpret sonar/echo-sounder, target small schools, prefer catching IND in calm waters, refrain from using light to attract schools in seasons where the schools contain high frequency of undersized IND, prefer sampling to detect bycatch during the early stages of fishing and abort fishing to let the IND escape, prefer slipping unwanted catch (still in the water) over discarding (from deck to water), prefer modified over standard slipping.
To avoid or decrease it during emersion and release from gear, prefer pumps over brails to transfer IND to the vessel; with pumps, ensure that the IND are not mixed with other species.
To avoid or decrease it during discarding, prefer slipping unwanted catch (still in the water) over discarding (from deck to water), discard IND as soon as possible at the fishing location/on the fishing grounds, use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds.
To avoid it during storing and slaughter, prefer immediate stunning followed by slaughter while still insensible and unconscious.
Further research needed.
- LAB: exposing IND to the sound of dolphin pingers producing ultrasonic sound (70 kHz) at a source level of 145 dB re 1 lPa @ 1 m and producing constant pulses at a pulse duration of 300 ms at and an inter-pulse duration of 4 s modestly increased plasma cortisol at a rate of 0.56 µg/dl per hour and reduced average school height which the authors did not view as stressful behaviour 20. Further research needed to determine the extent of stress experienced by the IND and on how to avoid or decrease it.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - LAB: highest survival of IND in waters at <16 °C 18. 20% lower survival at higher than at lower water temperatures (23 °C versus 16 or 18 °C), but temperature had no effect on cortisol or haematocrit levels, indicating the absence of acute stress 27.
- Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
Opercular movement: no data found yet.
Unspecified- Fishers leave for the fishing grounds from the harbour at the same time 1, fish in close proximity to other vessels 1, and get information about the fishing grounds from other fishers 2 3↶4. Given the potential accumulated sound caused by the engines of all the vessels and an aversive horizontal movement away from the vessel shown by a similar species, Clupea harengus 5, hazard consequences are probable 0. Further research needed on types of hazard consequences.
In some cases, fishers attract schools of IND using lights 6 7 8 9 10 11 as well as turn the engine off and passively attract IND with light and chum 6 7. - Fishers use fish finding devices (sonars and echo-sounders) of frequencies 50-200 kHz 8 10 to detect schools of IND 1 12 13 14 15 16 9 11 4 7, to estimate their abundance 1 13, or to observe IND behaviour 17 before initiating the fishing operation usually before sunrise 1 12 13 18 19 16 or at both sunrise and sunset 17 6 9 11. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Most of the cetacean sightings and interactions occurred during setting 15, causing Sardina pilchardus schools to sink (4 cases) or scatter (1 case), and damaged the fishing gear (1 case), leading to abortion of fishing 17. Occasionally, unsuccessful fishing events due to fish behavior 4, probably indicating IND trying to escape 21. But they also caused the IND to cluster into a school, wherein the fishing process was not aborted 17.
- A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with Delphinus delphis compared to an interaction rate of 5.6% in net sets without dolphin deterrent devices 22.
- Given the principle of purse seine to encircle the IND, haul the net close to the vessel taking average 45 min 1 or 52 min 13, and partially haul the net up (called “drying up” 12), thereby crowding the IND 23 in a net pouch at the bunt end 16 9 11, hazard consequences are probable 0.
IND get gilled or snared in the net 9 24. - Varying wave height (<0.5-2+ m) can probably cause stress during hauling and fish transfer to the vessel by increasing the probability of fish collision with the net 13 and probably with con-specifics 0, causing abrasion 13. ~40% IND survived after being caught in rough seas (wave height 1.5-2 m), whilst >80% survived when caught in good sea conditions (wave height 0-0.5 m) 18.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Higher probability of cetacean presence and interaction, mostly Delphinus delphis, at higher catch density of Sardina pilchardus 14 15 29, because Sardina pilchardus is the primary prey of D. delphis 30 31 32. E.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29.
Three cetacean species, D. delphis, Tursiops truncatus, and Phocoena phocoena, got encircled in the net 15 29.
~60% 29, 82% 15 of cetacean interactions were recorded outside the net after encirclement, towards the end of fishing operations 14 15, during net hauling 14 29 22 and transfer 14 29.
D. delphis fed in surface waters around the purse seine set (e.g., on IND escaping the net) and caught IND that were gilled or snared in the net 24.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.- Catching steps:
- How to improve:
- use DDD to reduce interactions with dolphins during catching, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- use DDD to reduce interactions with dolphins during emersion, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
- In multi-species fishery, purse seine was not set in 56 of 179 trips (~31%) 4 – possibly after interpreting sonar/echo-sounder or judgment of the fishers 0 – due to schools being too small, mixed with other species, or containing JUVENILES or due to bad weather 4 – effectively avoiding bycatch before it can happen 0.
- In some cases, fishers attract schools of IND using lights 6 7 8 9 10 11. Given that in spring to summer this potentially attracts undersized IND that would need to be discarded, recommended not to use light during this season 26.
- Given that the mean TOTAL LENGTH of maturity for 50% of the population of 10.1 cm (2 years observation period) 37, 11.4-12.6 cm for females, 10.2-12.2 cm for males (9 years observation period) 38, 11.7 cm for females, 11.4 cm for males (2 years observation period) 39, 12.2-16.4 cm (60 years observation period) 40, 14.3-15.6 cm (estimated over 15 years observation period) 41, 15.8 cm (3 years observation period) 42 (outlier: 7.9 cm in the Adriatic sea over 3 years observation period 43) overlaps with mean TOTAL LENGTH at catching of 11.2-13.1 cm 10, 14-14.1 cm 28, 15.9-17.9 cm 13, and given that IND school and the principle of purse seine is to catch whole schools 16 9 11, there is a risk of bycatch (accidental catch of undersized, wrong sex, wrong age, damaged, over quota IND, and mixture with undersized or unwanted non-target FISHES) of the target species 18 0.
After setting the net and in the initial stages of hauling, skippers or captains can get an impression of the catch by looking at a sample of FISHES that come to the surface. At that point, they can abort the process if the catch contains a high proportion of bycatch 44. - In multi-species fishery, out of 30 trips, 23 had a slipping event with ca 366.9 t slipped against 177.4 t landed. At the local fleet level during the same time period as the study (11 weeks), ca 4,979 t were slipped corresponding to 69% of the total catch out of which >95% were Sardina pilchardus 1.
In multi-species fishery, total catch 1-17 t/set, mostly (95% in weight) Sardina pilchardus, versus actual landings <1-13 t, indicating that the difference was slipped 12.
Slipping: ~1 t/trip 14, 0-7 t/set from a catch of 1-17 t/set 13. During 15 months, ca 25 t slipped corresponding to 16% of the total catch 7.
Reasons for slipping included reaching the daily quota 1 12 14 4 7, catch exceeding the storage capacity of the vessel 7, undersized IND in the catch 1 12, mixture with undersized or unwanted non-target bycatch 1 12 14 4, such as the pelagic crab Polybius henslowi 1 12.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - IND transferred from the purse seine net to the on-board storage unit with traditionally used brail nets 16 7 9 25 11 with a capacity of 100 kg 25 or with pumps (Pescamotion 6 plus) with loading capacities of 6.7 kg/min (400 kg/h) 26, 83.6-97.4 kg/min, 165.5-189.5 kg/min 25.
With brails, given that the transfer to the storage space of the vessel takes ~36 min 13 or ~40 min 12 and given the force with which the net is dipped into the purse seine, exposure to air, and the crowding density, hazard consequences are probable 0. Damages in 10-16% IND like indentations and irregular body shapes because IND in the lower level were crushed by the weight of the IND above them 25.
With pumps, given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 0. 7% IND damaged with light cuts in one sample and in another sample, 17% IND damaged with scratches and deep cuts in the skin as a result of IND being mixed with T. trachurus, whose sharp scales along the lateral line damaged the IND 25. Probably no difference in stress between brailing and pumping (relatively low muscle pH in all the caught IND) 25. - Given no evolutionary adaptation to experiencing own weight in air 48, hazard consequences following emersion are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- After scooping the IND out of the purse seine, the scoop net is released above the storage space of the vessel 16 9 11. Given exposure to air, dropping from a certain height, landing hard in plastic containers 16 9 11 or boxes 7, being catapulted away from the containers, and kicked or stood upon by the fishers 16 9 11, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Some IND may be entangled in the net 9. Given exposure to air, dropping from a certain height, landing hard on deck, being kicked or stood upon by fishers 9, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - After transferring on board, catch with no commercial value discarded 4. Given that IND have a high value 14, discarding improbable 4. Value depends on region: Sardina pilchardus commercially important along Portuguese mainland 21, Greece 6, and the Bay of Biscay 46, but not on the Madeira archipelago 7.
IND discarded at an average discard rate of 0.91-14.85 kg/trip and 1.74-5.2 kg/trip in mixed métiers and in métiers targeting Engraulis encrasicolus; in métiers targeting Sardina pilchardus, discarding rate of 0.34-31.22 kg/trip 46.
IND comprised 32.7% of the total discards; 60% of the caught IND were discarded back into the sea due to their low commercial value 7.
In the Aegean sea, 63.06 mt of IND discarded annually compared to <0.01 mt in the Ionian sea 6. At 55.7 mm, 76.6 mm, and 97.5 mm TOTAL LENGTH – 75%, 50%, and 25% of the IND are discarded. Discarding sizes greater in summer, which is the spawning season, than in spring 6. Given EU minimum landing size of 110 mm TOTAL LENGTH 49↶6, catching and discarding of JUVENILES evident 0.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Given that fishers manually discard IND after emersion, release from gear, sorting – including all welfare hazards outlined there – and after transport to shore, given pressure by boxes put on top of each other (with the IND inside), contact with ice, and exposure to air, and given IND are not already dead 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.- Catching step:
- How to improve: prefer slipping unwanted catch (still in the water) over discarding (from deck to water) (for management measures → 12. Side note: General improvements of the method)
- Given that fishers manually discard IND after transport to shore and given that IND are not already dead 11, hazard consequences are probable 0. Recommended to discard IND as soon as possible at the fishing location/on the fishing grounds 0. For recommended methods to avoid bycatch still in the water →4.2. Contact with the gear and 4.7. Other.
- Higher probability of cetacean presence and interaction, mostly D. delphis, at higher catch density of Sardina pilchardus 14 15 29, e.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29. Given this cetacean presence, considering that Sardina pilchardus is the primary prey of D. delphis 30 31 32, and given that D. delphis fed in surface waters around the purse seine set and preyed on escaping IND that were gilled or snared in the net 24, predation on discarded IND is probable 0.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation on discarded IND is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.
LAB: in simulated predation experiments with exposure to a natural predator, Dicentrarchus labrax, IND stressed by crowding allowed closer predator approach distance, avoided forming a tight ball formation due to an increased average distance to neighbour, and had lower swimming velocities compared to IND that were not crowded. This temporary behavioural impairment lasted ~2 days, indicating higher susceptibility to post release predation of IND for several hours or days 19. - Given storing on board with little ice 16 9 11 25, much ice 14 – implying exposure to air – or in ice-water mix (probably for stunning) 25 and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
- Given storing on board in plastic crates 9 11 or isothermic boxes 16, pressure by boxes put on top of each other (with the IND inside), getting crushed by con-specifics, and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
- Given storing on ice 16 9 11 and given that IND are not already dead 16 9 11 50, probably asphyxia and/or hypothermia 0. Given storing in ice-water mix without prior humane stunning 25, probably asphyxia and/or hypothermia 0. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
3 Temperature shock
The difference between temperature in water and air may induce a thermal shock.
Where in the catching process does temperature shock occur and how to avoid it?
Temperature shock may occur during exposure to ice.
To avoid it during sorting and discarding, prefer slipping unwanted catch (still in the water) over discarding (from deck to water).
To avoid or decrease it during discarding, discard IND as soon as possible at the fishing location/on the fishing grounds.
To avoid it during storing and slaughter, prefer immediate stunning followed by slaughter while still insensible and unconscious.
Further research needed.
- Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - After transferring on board, catch with no commercial value discarded 4. Given that IND have a high value 14, discarding improbable 4. Value depends on region: Sardina pilchardus commercially important along Portuguese mainland 21, Greece 6, and the Bay of Biscay 46, but not on the Madeira archipelago 7.
IND discarded at an average discard rate of 0.91-14.85 kg/trip and 1.74-5.2 kg/trip in mixed métiers and in métiers targeting Engraulis encrasicolus; in métiers targeting Sardina pilchardus, discarding rate of 0.34-31.22 kg/trip 46.
IND comprised 32.7% of the total discards; 60% of the caught IND were discarded back into the sea due to their low commercial value 7.
In the Aegean sea, 63.06 mt of IND discarded annually compared to <0.01 mt in the Ionian sea 6. At 55.7 mm, 76.6 mm, and 97.5 mm TOTAL LENGTH – 75%, 50%, and 25% of the IND are discarded. Discarding sizes greater in summer, which is the spawning season, than in spring 6. Given EU minimum landing size of 110 mm TOTAL LENGTH 49↶6, catching and discarding of JUVENILES evident 0.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Given that fishers manually discard IND after emersion, release from gear, sorting – including all welfare hazards outlined there – and after transport to shore, given pressure by boxes put on top of each other (with the IND inside), contact with ice, and exposure to air, and given IND are not already dead 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.- Catching step:
- How to improve: prefer slipping unwanted catch (still in the water) over discarding (from deck to water) (for management measures → 12. Side note: General improvements of the method)
- Given that fishers manually discard IND after transport to shore and given that IND are not already dead 11, hazard consequences are probable 0. Recommended to discard IND as soon as possible at the fishing location/on the fishing grounds 0. For recommended methods to avoid bycatch still in the water →4.2. Contact with the gear and 4.7. Other.
- Given storing on board with little ice 16 9 11 25, much ice 14 – implying exposure to air – or in ice-water mix (probably for stunning) 25 and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
- Given storing on ice 16 9 11 and given that IND are not already dead 16 9 11 50, probably asphyxia and/or hypothermia 0. Given storing in ice-water mix without prior humane stunning 25, probably asphyxia and/or hypothermia 0. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
4 Osmoregulatory distress
The quick transition from one salinity level to another may lead to osmoregulatory distress.
Where in the catching process does osmoregulatory distress occur and how to avoid it?
Osmoregulatory distress may occur during handling and displacement.
To avoid or decrease it during discarding, prefer slipping unwanted catch (still in the water) over discarding (from deck to water), discard IND as soon as possible at the fishing location/on the fishing grounds.
Further research needed.
- After transferring on board, catch with no commercial value discarded 4. Given that IND have a high value 14, discarding improbable 4. Value depends on region: Sardina pilchardus commercially important along Portuguese mainland 21, Greece 6, and the Bay of Biscay 46, but not on the Madeira archipelago 7.
IND discarded at an average discard rate of 0.91-14.85 kg/trip and 1.74-5.2 kg/trip in mixed métiers and in métiers targeting Engraulis encrasicolus; in métiers targeting Sardina pilchardus, discarding rate of 0.34-31.22 kg/trip 46.
IND comprised 32.7% of the total discards; 60% of the caught IND were discarded back into the sea due to their low commercial value 7.
In the Aegean sea, 63.06 mt of IND discarded annually compared to <0.01 mt in the Ionian sea 6. At 55.7 mm, 76.6 mm, and 97.5 mm TOTAL LENGTH – 75%, 50%, and 25% of the IND are discarded. Discarding sizes greater in summer, which is the spawning season, than in spring 6. Given EU minimum landing size of 110 mm TOTAL LENGTH 49↶6, catching and discarding of JUVENILES evident 0.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Given that fishers manually discard IND after emersion, release from gear, sorting – including all welfare hazards outlined there – and after transport to shore, given pressure by boxes put on top of each other (with the IND inside), contact with ice, and exposure to air, and given IND are not already dead 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.- Catching step:
- How to improve: prefer slipping unwanted catch (still in the water) over discarding (from deck to water) (for management measures → 12. Side note: General improvements of the method)
- Given that fishers manually discard IND after transport to shore and given that IND are not already dead 11, hazard consequences are probable 0. Recommended to discard IND as soon as possible at the fishing location/on the fishing grounds 0. For recommended methods to avoid bycatch still in the water →4.2. Contact with the gear and 4.7. Other.
5 Disorientation
Removing an individual from its home ground and social group and subjecting it to a potentially stressful catching event may result in disorientation.
Where in the catching process does disorientation occur and how to avoid it?
Disorientation may occur during displacement.
To avoid or decrease it during discarding, discard IND as soon as possible at the fishing location/on the fishing grounds.
Further research needed.
- Given that fishers manually discard IND after transport to shore and given that IND are not already dead 11, hazard consequences are probable 0. Recommended to discard IND as soon as possible at the fishing location/on the fishing grounds 0. For recommended methods to avoid bycatch still in the water →4.2. Contact with the gear and 4.7. Other.
6 Asphyxia
Lack of oxygen is a likely consequence for aquatic species facing removal from the water.
Where in the catching process does asphyxia occur and how to avoid it?
Asphyxia may occur most frequently through crowding (in the water), decreasing distance to neighbours (inside and outside the water), and lack of oxygen.
To avoid or decrease it during catching and emersion, minimise crowding duration.
To avoid or decrease it for target bycatch that will be released, target small schools.
To avoid or decrease it during emersion and release from gear, prefer pumps over brails to transfer IND to the vessel; with pumps, ensure that the IND are not mixed with other species.
To avoid or decrease it during sorting, prefer slipping unwanted catch (still in the water) over discarding (from deck to water).
To avoid it during storing and slaughter, prefer immediate stunning followed by slaughter while still insensible and unconscious.
Further research needed.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0.
- Given the principle of purse seine to encircle the IND, haul the net close to the vessel taking average 45 min 1 or 52 min 13, and partially haul the net up (called “drying up” 12), thereby crowding the IND 23 in a net pouch at the bunt end 16 9 11, hazard consequences are probable 0.
IND get gilled or snared in the net 9 24. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - IND transferred from the purse seine net to the on-board storage unit with traditionally used brail nets 16 7 9 25 11 with a capacity of 100 kg 25 or with pumps (Pescamotion 6 plus) with loading capacities of 6.7 kg/min (400 kg/h) 26, 83.6-97.4 kg/min, 165.5-189.5 kg/min 25.
With brails, given that the transfer to the storage space of the vessel takes ~36 min 13 or ~40 min 12 and given the force with which the net is dipped into the purse seine, exposure to air, and the crowding density, hazard consequences are probable 0. Damages in 10-16% IND like indentations and irregular body shapes because IND in the lower level were crushed by the weight of the IND above them 25.
With pumps, given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 0. 7% IND damaged with light cuts in one sample and in another sample, 17% IND damaged with scratches and deep cuts in the skin as a result of IND being mixed with T. trachurus, whose sharp scales along the lateral line damaged the IND 25. Probably no difference in stress between brailing and pumping (relatively low muscle pH in all the caught IND) 25. - After scooping the IND out of the purse seine, the scoop net is released above the storage space of the vessel 16 9 11. Given exposure to air, dropping from a certain height, landing hard in plastic containers 16 9 11 or boxes 7, being catapulted away from the containers, and kicked or stood upon by the fishers 16 9 11, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Some IND may be entangled in the net 9. Given exposure to air, dropping from a certain height, landing hard on deck, being kicked or stood upon by fishers 9, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid or decrease them.
- Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - Given storing on board with little ice 16 9 11 25, much ice 14 – implying exposure to air – or in ice-water mix (probably for stunning) 25 and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
- Given storing on ice 16 9 11 and given that IND are not already dead 16 9 11 50, probably asphyxia and/or hypothermia 0. Given storing in ice-water mix without prior humane stunning 25, probably asphyxia and/or hypothermia 0. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
7 Dehydration (internal issue)
Loss of water is another likely consequence of exposing aquatic species to air.
Where in the catching process does dehydration occur and how to avoid it?
Unspecified8 Fatigue/exhaustion
In an attempt to escape the situation of being caught, many individuals struggle and resist until they are exhausted.
Where in the catching process does fatigue/exhaustion occur and how to avoid it?
Fatigue/exhaustion may occur through crowding (in the water), decreasing distance to neighbours (inside and outside the water), handling, and lack of oxygen.
To avoid or decrease it during catching and emersion, minimise crowding duration.
To avoid or decrease it during sorting, prefer slipping unwanted catch (still in the water) over discarding (from deck to water).
Further research needed.
Inactivity/low vitality: no data found yet.
Oxidative stress: no data found yet.
Unspecified- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.
9 Emotion-like states
The process of being caught probably induces states not unlike emotions.
Where in the catching process do emotion-like states occur and how to avoid them?
Emotion-like states (like avoidance or startling behaviour, escape manoeuvres) may occur through noise, predation pressure, crowding (in the water), and decreasing distance to neighbours (inside and outside the water).
To avoid or decrease it during prospection, keep vessel engines off.
To avoid or decrease it during setting, catch IND at dusk, night, or dawn, when the visibility of the net is low, abort net setting if you spot cetaceans.
To avoid or decrease it during catching and emersion, minimise crowding duration.
To avoid or decrease it for target bycatch that will be released, target small schools.
To avoid or decrease it for target bycatch that will be released or during discarding, use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds.
Further research needed.
9.1 Fear (continuum up to panic)
Freeze: no data found yet.
Avoidance behaviour- Fishers leave for the fishing grounds from the harbour at the same time 1, fish in close proximity to other vessels 1, and get information about the fishing grounds from other fishers 2 3↶4. Given the potential accumulated sound caused by the engines of all the vessels and an aversive horizontal movement away from the vessel shown by a similar species, Clupea harengus 5, hazard consequences are probable 0. Further research needed on types of hazard consequences.
In some cases, fishers attract schools of IND using lights 6 7 8 9 10 11 as well as turn the engine off and passively attract IND with light and chum 6 7. - Most of the cetacean sightings and interactions occurred during setting 15, causing Sardina pilchardus schools to sink (4 cases) or scatter (1 case), and damaged the fishing gear (1 case), leading to abortion of fishing 17. Occasionally, unsuccessful fishing events due to fish behavior 4, probably indicating IND trying to escape 21. But they also caused the IND to cluster into a school, wherein the fishing process was not aborted 17.
- Most of the cetacean sightings and interactions occurred during setting 15, causing Sardina pilchardus schools to sink (4 cases) or scatter (1 case), and damaged the fishing gear (1 case), leading to abortion of fishing 17. Occasionally, unsuccessful fishing events due to fish behavior 4, probably indicating IND trying to escape 21. But they also caused the IND to cluster into a school, wherein the fishing process was not aborted 17.
- Most of the cetacean sightings and interactions occurred during setting 15, causing Sardina pilchardus schools to sink (4 cases) or scatter (1 case), and damaged the fishing gear (1 case), leading to abortion of fishing 17. Occasionally, unsuccessful fishing events due to fish behavior 4, probably indicating IND trying to escape 21. But they also caused the IND to cluster into a school, wherein the fishing process was not aborted 17.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0.
- Given that fishing takes place before sunrise 1 12 13 18 19 16 or at both sunrise and sunset 17 6 9 11, when the visibility of net for the IND is probably relatively low, based on observations from other small pelagic species like Clupea harengus and Scomber scombrus 5, panic behaviour is improbable 0.
- Higher probability of cetacean presence and interaction, mostly Delphinus delphis, at higher catch density of Sardina pilchardus 14 15 29, because Sardina pilchardus is the primary prey of D. delphis 30 31 32. E.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29.
Three cetacean species, D. delphis, Tursiops truncatus, and Phocoena phocoena, got encircled in the net 15 29.
~60% 29, 82% 15 of cetacean interactions were recorded outside the net after encirclement, towards the end of fishing operations 14 15, during net hauling 14 29 22 and transfer 14 29.
D. delphis fed in surface waters around the purse seine set (e.g., on IND escaping the net) and caught IND that were gilled or snared in the net 24.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.- Catching steps:
- How to improve:
- use DDD to reduce interactions with dolphins during catching, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- use DDD to reduce interactions with dolphins during emersion, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- Higher probability of cetacean presence and interaction, mostly D. delphis, at higher catch density of Sardina pilchardus 14 15 29, e.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29. Given this cetacean presence, considering that Sardina pilchardus is the primary prey of D. delphis 30 31 32, and given that D. delphis fed in surface waters around the purse seine set and preyed on escaping IND that were gilled or snared in the net 24, predation on discarded IND is probable 0.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation on discarded IND is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.
LAB: in simulated predation experiments with exposure to a natural predator, Dicentrarchus labrax, IND stressed by crowding allowed closer predator approach distance, avoided forming a tight ball formation due to an increased average distance to neighbour, and had lower swimming velocities compared to IND that were not crowded. This temporary behavioural impairment lasted ~2 days, indicating higher susceptibility to post release predation of IND for several hours or days 19.
9.2 Other
Unspecified: no data found yet.
10 Mortality
Although death is the ultimate goal of fisheries, many mortalities happen unwanted - even resulting in discards - and unregulated, without avoiding prolonged suffering.
Where in the catching process does mortality occur and how to avoid it?
Mortality may occur most frequently through contact with the gear, crowding (in the water), decreasing distance to neighbours (inside and outside the water), predation pressure, handling, and dropping.
To avoid or decrease it during catching, avoid catching Sardina pilchardus schools when mixed with other species.
To avoid or decrease it during catching and emersion, prefer catching IND in calm waters, minimise crowding duration.
To avoid or decrease it during catching, emersion, and for JUVENILES that might be released, use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds.
To avoid or decrease it for JUVENILES that might be released, interpret sonar/echo-sounder, target small schools, prefer catching IND in calm waters, refrain from using light to attract schools in seasons where the schools contain high frequency of undersized IND, prefer sampling to detect bycatch during the early stages of fishing and abort fishing to let the IND escape, prefer slipping unwanted catch (still in the water) over discarding (from deck to water), prefer modified over standard slipping.
To avoid or decrease it during emersion and release from gear, prefer pumps over brails to transfer IND to the vessel; with pumps, ensure that the IND are not mixed with other species.
To avoid or decrease it during sorting and discarding, prefer slipping unwanted catch (still in the water) over discarding (from deck to water).
To avoid or decrease it during discarding, use DDD to reduce interactions with dolphins and a Scarybird device (visual bird deterrent) to reduce interactions with seabirds.
To avoid it during storing, prefer immediate stunning followed by slaughter while still insensible and unconscious.
Further research needed.
Attacks by con-specifics are improbable.
- Given the principle of purse seine to encircle the IND, haul the net close to the vessel taking average 45 min 1 or 52 min 13, and partially haul the net up (called “drying up” 12), thereby crowding the IND 23 in a net pouch at the bunt end 16 9 11, hazard consequences are probable 0.
IND get gilled or snared in the net 9 24. - Varying wave height (<0.5-2+ m) can probably cause stress during hauling and fish transfer to the vessel by increasing the probability of fish collision with the net 13 and probably with con-specifics 0, causing abrasion 13. ~40% IND survived after being caught in rough seas (wave height 1.5-2 m), whilst >80% survived when caught in good sea conditions (wave height 0-0.5 m) 18.
- In multi-species fishery, total catch 1-17 t/set corresponding to 20,000-320,000 FISHES/set, mostly (95% in weight) Sardina pilchardus 12. 0.3-1.5 t/trial corresponding to 9.8-16.3 kg/m3 18, average catch ~3.8-5.1 t/haul 4, 1.2-2.6 t/set (1,170-3,610 kg/set) 25.
Higher levels of nutrients (ammonia, urea, organic nitrogen, phosphate) in surface seawater at end of hauling net close to the vessel and partially up (“drying up”) than in phase before or after potentially indicates stress from exhaustion, crowding, and confinement especially in IND with contact with the net 12. Setting, hauling, and crowding caused wide range of scale loss: 21% IND with complete scale loss to 32% IND without scale loss 12. Extremely high densities during crowding (≥1,000 IND/m3) caused chaotic swimming, leaps out of the water, gasps for air 12.
Increasing stress (elevated cortisol and glucose levels), osmotic imbalance (elevated chloride and sodium levels, reduced potassium levels), and exhaustion (reduced adenosine tri-phosphate, adenosine di-phosphate) with increasing duration of fishing, especially time in the net during crowding 13.
Higher mortality in crowded IND than those at the beginning of the catching process (range 65.7-100% versus 34.5-100%) – more prominent in spring (mean 87% versus 67%) than in autumn (56.6% versus 76.6%) – and massive scale loss and injuries of head, abdomen, and fins in dead IND, so recommended to avoid high density in bunt end of the net during hauling 26.
LAB: simulated fishing increased scale loss (pre fishing: 1%, post fishing: 5%) which potentially increased mortality. After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min). Simulated fishing increased stress (elevated cortisol), created osmotic imbalance (reduced haematocrit), and increased scale loss (pre fishing: mean 1%, post fishing: mean 5%), the latter potentially increasing mortality (mean ≤27% scale loss in dead IND). After long fishing simulations (40 or 60 min), 30% IND survived after 10 days compared to >70% IND surviving after short fishing simulations (10 or 20 min) 27.
LAB: with simulated crowding, higher mortality (42.6-69.6%) in high density for a longer duration (40 min) compared to 3-7.3% mortality in low density for a short duration (20 min). Mortality did not just increase with increasing crowding density but also with increasing pre-crowding school size 19.
LAB: peak cortisol, glucose, and chloride concentrations in IND immediately post transfer to the storage tanks and then decreased throughout time in captivity, indicating acute stress. Furthermore, significantly higher proportion of scale loss and caudal fin damage in dead IND as compared to live IND, alongside faster mortality of IND with more scale loss due to a cumulative effect of catching and live transport 18. - Higher probability of cetacean presence and interaction, mostly Delphinus delphis, at higher catch density of Sardina pilchardus 14 15 29, because Sardina pilchardus is the primary prey of D. delphis 30 31 32. E.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29.
Three cetacean species, D. delphis, Tursiops truncatus, and Phocoena phocoena, got encircled in the net 15 29.
~60% 29, 82% 15 of cetacean interactions were recorded outside the net after encirclement, towards the end of fishing operations 14 15, during net hauling 14 29 22 and transfer 14 29.
D. delphis fed in surface waters around the purse seine set (e.g., on IND escaping the net) and caught IND that were gilled or snared in the net 24.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.- Catching steps:
- How to improve:
- use DDD to reduce interactions with dolphins during catching, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- use DDD to reduce interactions with dolphins during emersion, use Scarybird device (visual bird deterrent) to reduce interactions with seabirds
- LAB: higher survival of IND when caught not mixed with any other species 18.
- Estimated higher amount of catch slipped when fishers targeted dense echo sounder marks to set the net than when they targeted low to moderate marks 1.
At the beginning of slipping through lowering the head line, some IND dead, many stressed (chaotic swimming, gasps for air), high amount of detached scales in the water 1.
In some cases, vessels receive a part of catch from other vessels in the vicinity 4 9, which is probably excess catch caught by the latter 0. Given that sharing excess catch with another vessel 1 4 will probably prolong crowding duration and contact with the gear, we cannot endorse it 0. - Standard slipping involves partially hauling the net up to the vessel (“drying up”) and letting IND escape over the head line and resulted in estimated 11.7% survival, 70.6% median scale loss within two days of slipping, and 16.6% mortality after 90 min sea and land transport. Higher survival (44.7%), lower rate of scale loss (48.8%), and lower transport mortality (3.9%) with modified slipping technique that created net opening below water. No difference between modified slipping technique and control IND from non-crowded time in the net for survival, scale loss, transport mortality, and stress (cortisol, glucose, lactate, plasma osmolality) indicating no additional hazard consequences through modified slipping 28.
- In multi-species fishery, purse seine was not set in 56 of 179 trips (~31%) 4 – possibly after interpreting sonar/echo-sounder or judgment of the fishers 0 – due to schools being too small, mixed with other species, or containing JUVENILES or due to bad weather 4 – effectively avoiding bycatch before it can happen 0.
- In some cases, fishers attract schools of IND using lights 6 7 8 9 10 11. Given that in spring to summer this potentially attracts undersized IND that would need to be discarded, recommended not to use light during this season 26.
- Given that the mean TOTAL LENGTH of maturity for 50% of the population of 10.1 cm (2 years observation period) 37, 11.4-12.6 cm for females, 10.2-12.2 cm for males (9 years observation period) 38, 11.7 cm for females, 11.4 cm for males (2 years observation period) 39, 12.2-16.4 cm (60 years observation period) 40, 14.3-15.6 cm (estimated over 15 years observation period) 41, 15.8 cm (3 years observation period) 42 (outlier: 7.9 cm in the Adriatic sea over 3 years observation period 43) overlaps with mean TOTAL LENGTH at catching of 11.2-13.1 cm 10, 14-14.1 cm 28, 15.9-17.9 cm 13, and given that IND school and the principle of purse seine is to catch whole schools 16 9 11, there is a risk of bycatch (accidental catch of undersized, wrong sex, wrong age, damaged, over quota IND, and mixture with undersized or unwanted non-target FISHES) of the target species 18 0.
After setting the net and in the initial stages of hauling, skippers or captains can get an impression of the catch by looking at a sample of FISHES that come to the surface. At that point, they can abort the process if the catch contains a high proportion of bycatch 44. - In multi-species fishery, out of 30 trips, 23 had a slipping event with ca 366.9 t slipped against 177.4 t landed. At the local fleet level during the same time period as the study (11 weeks), ca 4,979 t were slipped corresponding to 69% of the total catch out of which >95% were Sardina pilchardus 1.
In multi-species fishery, total catch 1-17 t/set, mostly (95% in weight) Sardina pilchardus, versus actual landings <1-13 t, indicating that the difference was slipped 12.
Slipping: ~1 t/trip 14, 0-7 t/set from a catch of 1-17 t/set 13. During 15 months, ca 25 t slipped corresponding to 16% of the total catch 7.
Reasons for slipping included reaching the daily quota 1 12 14 4 7, catch exceeding the storage capacity of the vessel 7, undersized IND in the catch 1 12, mixture with undersized or unwanted non-target bycatch 1 12 14 4, such as the pelagic crab Polybius henslowi 1 12.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - Given that IND school 47, aggression between con-specifics is improbable 0.
- IND transferred from the purse seine net to the on-board storage unit with traditionally used brail nets 16 7 9 25 11 with a capacity of 100 kg 25 or with pumps (Pescamotion 6 plus) with loading capacities of 6.7 kg/min (400 kg/h) 26, 83.6-97.4 kg/min, 165.5-189.5 kg/min 25.
With brails, given that the transfer to the storage space of the vessel takes ~36 min 13 or ~40 min 12 and given the force with which the net is dipped into the purse seine, exposure to air, and the crowding density, hazard consequences are probable 0. Damages in 10-16% IND like indentations and irregular body shapes because IND in the lower level were crushed by the weight of the IND above them 25.
With pumps, given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 0. 7% IND damaged with light cuts in one sample and in another sample, 17% IND damaged with scratches and deep cuts in the skin as a result of IND being mixed with T. trachurus, whose sharp scales along the lateral line damaged the IND 25. Probably no difference in stress between brailing and pumping (relatively low muscle pH in all the caught IND) 25. - Usually no sorting but direct release into the storage space of the vessel 16 9 25 and manually distributing equally across the boxes 16 9.
If sorting takes place, then after lifting IND out of the purse seine onto deck, manually sorting by species and size into boxes 7 11. Given exposure to air, throwing into boxes, landing hard in plastic containers, being catapulted away from the containers, kicked or stood upon by fishers, pressure by boxes put on top of each other (with the IND inside), and contact with ice 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46. - After transferring on board, catch with no commercial value discarded 4. Given that IND have a high value 14, discarding improbable 4. Value depends on region: Sardina pilchardus commercially important along Portuguese mainland 21, Greece 6, and the Bay of Biscay 46, but not on the Madeira archipelago 7.
IND discarded at an average discard rate of 0.91-14.85 kg/trip and 1.74-5.2 kg/trip in mixed métiers and in métiers targeting Engraulis encrasicolus; in métiers targeting Sardina pilchardus, discarding rate of 0.34-31.22 kg/trip 46.
IND comprised 32.7% of the total discards; 60% of the caught IND were discarded back into the sea due to their low commercial value 7.
In the Aegean sea, 63.06 mt of IND discarded annually compared to <0.01 mt in the Ionian sea 6. At 55.7 mm, 76.6 mm, and 97.5 mm TOTAL LENGTH – 75%, 50%, and 25% of the IND are discarded. Discarding sizes greater in summer, which is the spawning season, than in spring 6. Given EU minimum landing size of 110 mm TOTAL LENGTH 49↶6, catching and discarding of JUVENILES evident 0.
After pumping FISHES from the net on deck, automated sorting by size and species with a two grid system of sizes 13-14 mm and 8-9 mm. 70.4-100% mortality range after discarding from the grid system using a fish pump to release IND back in the sea. Higher mortality rate within the first 48 h and lower mortality in spring (88.2%) than in autumn (100%). To reduce mortality, recommended to submerge the flexible hose of the pump whilst discarding the IND and increasing the surface area of the sieve 26.
Given that fishers manually discard IND after emersion, release from gear, sorting – including all welfare hazards outlined there – and after transport to shore, given pressure by boxes put on top of each other (with the IND inside), contact with ice, and exposure to air, and given IND are not already dead 11, hazard consequences are probable 0. Further research needed on types of hazard consequences.
Automatic pumping systems that pump IND from the net directly into storage holds have potentially discouraged sorting and discarding, favouring slipping over discarding 46.- Catching step:
- How to improve: prefer slipping unwanted catch (still in the water) over discarding (from deck to water) (for management measures → 12. Side note: General improvements of the method)
- Higher probability of cetacean presence and interaction, mostly D. delphis, at higher catch density of Sardina pilchardus 14 15 29, e.g., increase in interactions with D. delphis (0.04 →0.23) with an increase in catch per unit effort (0 →64 kg/h), increase in predicted number of dolphin interactions in 2010-2011 (0.7 →6.2) with an increase in catch per unit effort (0 →75 kg/h) 29. Given this cetacean presence, considering that Sardina pilchardus is the primary prey of D. delphis 30 31 32, and given that D. delphis fed in surface waters around the purse seine set and preyed on escaping IND that were gilled or snared in the net 24, predation on discarded IND is probable 0.
A dolphin deterrent device emitting random sound frequencies at 5-5,000 kHz and a potency of emission <165 dB deployed during net setting for ~5 min eliminated the risk of interactions with D. delphis compared to an interaction rate of 5.6% in net sets without DDD 22. Given the effectiveness at net setting, a similar effectiveness at later stages of capture (catching [hauling, crowding], emersion, discarding) is probable, so we recommend using DDD throughout the whole process 0.
Given the presence of and interaction with seabird species 11 like Larus michahellis (Yellow-legged gull), Larus fuscus (Lesser black-headed gull), Calonectris borealis (Cory's shearwater), Puffinus mauretanicus (Balearic shearwater), and Morus bassanus (Northern gannet) 33 and given that Sardina pilchardus is preyed on by different species of sea gulls 34 35 36, predation on discarded IND is probable 0.
A raptor-shaped Scarybird device attached on the top of a vessel using a 6 m pole and a 1.5 m line significantly reduced the number of gulls, L. michahellis and L. fuscus (Lesser black-headed gull) by ~44% and C. borealis by ~53% around the vessel, while also non-significantly reducing the number of M. bassanus (Northern gannet) by ~60% and all shearwaters in general, by 33%. It also successfully reduced the rate of interaction for all the observed bird species 33.
LAB: in simulated predation experiments with exposure to a natural predator, Dicentrarchus labrax, IND stressed by crowding allowed closer predator approach distance, avoided forming a tight ball formation due to an increased average distance to neighbour, and had lower swimming velocities compared to IND that were not crowded. This temporary behavioural impairment lasted ~2 days, indicating higher susceptibility to post release predation of IND for several hours or days 19. - Given storing on board with little ice 16 9 11 25, much ice 14 – implying exposure to air – or in ice-water mix (probably for stunning) 25 and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
- Given storing on board in plastic crates 9 11 or isothermic boxes 16, pressure by boxes put on top of each other (with the IND inside), getting crushed by con-specifics, and given that IND are not already dead 16 9 11 50, hazard consequences are probable 0. Further research needed on types of hazard consequences. Recommended to stun IND immediately humanely and slaughter while still insensible and unconscious 0.
11 Uncategorised behavioural changes
When it is difficult to assign an observed behaviour to one of the above categories, we report it here.
Where in the catching process do uncategorised behavioural changes occur and how to avoid them?
UnspecifiedGlossary
FISHES = using "fishes" instead of "fish" for more than one individual - whether of the same species or not - is inspired by Jonathan Balcombe who proposed this usage in his book "What a fish knows". By referring to a group as "fishes", we acknowledge the individuals with their personalities and needs instead of an anonymous mass of "fish".
IND = individuals
JUVENILES = fully developed but immature individuals
LAB = setting in laboratory environment
TOTAL LENGTH = from snout to tip of caudal fin as compared to fork length (from snout to fork of caudal fin) 45 or standard length (from head to base of tail fin) or body length (from the base of the eye notch to the posterior end of the telson)
Bibliography
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2 Carvalho, Joao Paulo, Laura Wise, and Alberto Murta. 2008. Fuzzy modeling and simulation of purse-seine fishing skippers behavior. In NAFIPS 2008 - 2008 Annual Meeting of the North American Fuzzy Information Processing Society, 1–6. New York City, NY, USA: IEEE. https://doi.org/10.1109/NAFIPS.2008.4531325.
3 Diana Oliveira Feijó. 2013. Caracterização da pesca do Cerco na Costa Portuguesa. Master thesis, Porto: Universidade do Porto.
4 Feijó, D., A. Marçalo, T. Bento, J. Barra, D. Marujo, M. Correia, and A. Silva. 2018. Trends in the activity pattern, fishing yields, catch and landing composition between 2009 and 2013 from onboard observations in the Portuguese purse seine fleet. Regional Studies in Marine Science 23: 97–106. https://doi.org/10.1016/j.rsma.2017.12.007.
5 Misund, O. A. 1993. Avoidance behaviour of herring (Clupea harengus) and mackerel (Scomber scombrus) in purse seine capture situations. Fisheries Research 16: 179–194. https://doi.org/10.1016/0165-7836(93)90051-8.
6 Tsagarakis, Konstantinos, Vassiliki Vassilopoulou, Argyris Kallianiotis, and Athanassios Machias. 2012. Discards of the purse seine fishery targeting small pelagic fish in the eastern Mediterranean Sea. Scientia Marina 76: 561–572. https://doi.org/10.3989/scimar.03452.02B.
7 Tejerina, R, M Hermida, G Faria, and J Delgado. 2019. The purse-seine fishery for small pelagic fishes off the Madeira Archipelago. African Journal of Marine Science 41. Taylor & Francis: 373–383. https://doi.org/10.2989/1814232X.2019.1678520.
8 Tosunoglu, Zafer, Tevfik Ceyhan, Ozlem Gulec, Faik Ozan Duzbastilar, Muharrem Hakan Kaykac, Celalettin Aydin, and Gulnur Metin. 2021. Effects of Lunar Phases and Other Variables on CPUE of European Pilchard, Sardina pilchardus, Caught by Purse Seine in the Eastern Mediterranean. Turkish Journal of Fisheries and Aquatic Sciences 21: 283–290. https://doi.org/10.4194/1303-2712-v21_6_03.
9 Carlos C. 2021. sardinas pesca del cerco galicia costa da morte (YouTube).
10 Ceyhan, Tevfik, and Zafer Tosunoğlu. 2021. Relationship Between by Catch Ratio of Sardine-Anchovy Targeted Purse Seine and Some Environmental Factors Based on a General Addictive Model in the Aegean Sea. Aquatic Sciences and Engineering 37: 1–7. https://doi.org/10.26650/ASE2021963166.
11 Pardo, Ignacio. 2023. Pesca de Cerco - Playa Astilleru (YouTube).
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13 Marçalo, Ana, Luísa Mateus, José Henrique Duarte Correia, Pedro Serra, Rob Fryer, and Yorgos Stratoudakis. 2006. Sardine (Sardina pilchardus) stress reactions to purse seine fishing. Marine Biology 149: 1509–1518. https://doi.org/10.1007/s00227-006-0277-5.
14 Feijó, D., A Marçalo, J Vingada, and Silva, A. 2011. Observações a bordo da pescaria do cerco: padrão de actividade, composição das capturas, rendimentos de pesca e interacções com cetáceos em 2010 [Translated from Portuguese to English using Chat GPT- GPT 5.2]. In , 381–396.
15 Marçalo, Ana, Isidora Katara, Diana Feijó, Helder Araújo, Isabel Oliveira, Jorge Santos, Marisa Ferreira, et al. 2015. Quantification of interactions between the Portuguese sardine purse-seine fishery and cetaceans. ICES Journal of Marine Science 72: 2438–2449. https://doi.org/10.1093/icesjms/fsv076.
16 Pepe Serrat. 2016. Pesca cerco sardina (YouTube).
17 Wise, Laura, Alexandra Silva, Marisa Ferreira, Mónica A. Silva, and Marina Sequeira. 2007. Interactions between small cetaceans and the purse-seine fishery in western Portuguese waters. Scientia Marina 71: 405–412. https://doi.org/10.3989/scimar.2007.71n2405.
18 Marçalo, A., P. Pousão-Ferreira, L. Mateus, J. H. Duarte Correia, and Y. Stratoudakis. 2008. Sardine early survival, physical condition and stress after introduction to captivity. Journal of Fish Biology 72: 103–120. https://doi.org/10.1111/j.1095-8649.2007.01660.x.
19 Marçalo, A., J. Araújo, P. Pousão-Ferreira, G. J. Pierce, Y. Stratoudakis, and K. Erzini. 2013. Behavioural responses of sardines Sardina pilchardus to simulated purse-seine capture and slipping. Journal of Fish Biology 83: 480–500. https://doi.org/10.1111/jfb.12184.
20 Goetz, Sabine, M. Begoña Santos, José Vingada, Damián Costas Costas, Antonio González Villanueva, and Graham John Pierce. 2015. Do pingers cause stress in fish? An experimental tank study with European sardine, Sardina pilchardus (Walbaum, 1792) (Actinopterygii, Clupeidae), exposed to a 70 kHz dolphin pinger. Hydrobiologia 749: 83–96. https://doi.org/10.1007/s10750-014-2147-3.
21 Marçalo, Ana. 2026. Personal communication.
22 Marçalo, Ana, Flávia Carvalho, Magda Frade, Luís Bentes, Pedro Monteiro, João Pontes, Sofia Alexandre, et al. 2025. Reducing Cetacean Interactions With Bottom Set‐Nets and Purse Seining Using Acoustic Deterrent Devices in Southern Iberia. Aquatic Conservation: Marine and Freshwater Ecosystems 35: e70061. https://doi.org/10.1002/aqc.70061.
23 He, Pingguo, Frank Chopin, Petri Suuronen, Richard S.T. Ferro, and Jon Lansley. 2021. Classification and illustrated definition of fishing gears. FAO Fisheries and Aquaculture Technical Papers 672. Rome, Italy: Food and Agriculture Organization of the United Nations (FAO). https://doi.org/10.4060/cb4966en.
24 Giménez, Joan, Matthieu Authier, Julio Valeiras, Esther Abad, Ana Marçalo, Marta Coll, Pauline Gauffier, M. Begoña Santos, and Renaud De Stephanis. 2021. Consumption rates and interaction with fisheries of Mediterranean common dolphins in the Alboran Sea. Regional Studies in Marine Science 45: 101826. https://doi.org/10.1016/j.rsma.2021.101826.
25 Janči, Tibor, Tonka Gauta, Predrag Putnik, Danijel Kanski, and Mario Lovrinov. 2023. Influence of Fish Handling Practices Onboard Purse Seiners on Quality Parameters of Sardines (Sardina pilchardus) during Cold Storage. Biomolecules 13: 192. https://doi.org/10.3390/biom13020192.
26 Duzbastilar, Faik Ozan, Zafer Tosunoglu, Tevfik Ceyhan, Muharrem Hakan Kaykac, Celalettin Aydin, Ozlem Gulec, and Gulnur Metin. 2022. A Variation in the Mortality of European Anchovy and European Pilchard After Sieving and Discarding from a Purse Seine Fishery in the Eastern Mediterranean. Turkish Journal of Fisheries and Aquatic Sciences 23. https://doi.org/10.4194/TRJFAS21516.
27 Marçalo, Ana, Tiago A. Marques, João Araújo, Pedro Pousão-Ferreira, Karim Erzini, and Yorgos Stratoudakis. 2010. Fishing simulation experiments for predicting the effects of purse-seine capture on sardine (Sardina pilchardus). ICES Journal of Marine Science 67: 334–344. https://doi.org/10.1093/icesjms/fsp244.
28 Marçalo, Ana, Pedro M. Guerreiro, Luís Bentes, Mafalda Rangel, Pedro Monteiro, Frederico Oliveira, Carlos M. L. Afonso, et al. 2018. Effects of different slipping methods on the mortality of sardine, Sardina pilchardus, after purse-seine capture off the Portuguese Southern coast (Algarve). PLOS ONE 13. Public Library of Science: e0195433. https://doi.org/10.1371/journal.pone.0195433.
29 Dias, Inês C., Ana Marçalo, Diana Feijó, Isabel Domingos, and Alexandra A. Silva. 2022. Interactions between the common dolphin, Delphinus delphis, and the Portuguese purse seine fishery over a period of 15 years (2003–2018). Aquatic Conservation: Marine and Freshwater Ecosystems 32: 1351–1364. https://doi.org/10.1002/aqc.3828.
30 Silva, M.A. 1999. Diet of common dolphins, Delphinus delphis , off the Portuguese continental coast. Journal of the Marine Biological Association of the United Kingdom 79: 531–540. https://doi.org/10.1017/S0025315498000654.
31 Marçalo, Ana, Lídia Nicolau, Joan Giménez, Marisa Ferreira, Jorge Santos, Hélder Araújo, Alexandra Silva, José Vingada, and Graham J. Pierce. 2018. Feeding ecology of the common dolphin (Delphinus delphis) in Western Iberian waters: has the decline in sardine (Sardina pilchardus) affected dolphin diet? Marine Biology 165: 44. https://doi.org/10.1007/s00227-018-3285-3.
32 Milani, Cristina B., Adriana Vella, Pavlos Vidoris, Aristidis Christidis, Nikolaos Kamidis, and Eygenia Leykaditou. 2019. Interactions between fisheries and cetaceans in the Thracian sea (Greece) and management proposals. Fisheries Management and Ecology 26: 374–388. https://doi.org/10.1111/fme.12370.
33 Oliveira, Nuno, Ana Almeida, Hany Alonso, Emanuel Constantino, André Ferreira, Iván Gutiérrez, Ana Santos, Elisabete Silva, and Joana Andrade. 2021. A contribution to reducing bycatch in a high priority area for seabird conservation in Portugal. Bird Conservation International 31: 553–572. https://doi.org/10.1017/S0959270920000489.
34 Pedrocchi, V., D. Oro, and J. Gonzáles-Solís. 1996. Differences between diet of adult and chick Audouin’s Gulls Larus audouinii at the Chafarinas Islands, SW Mediterranean. Ornis Fennica 73: 124–130.
35 Cardona, Luis, Laura Martínez-Iñigo, Rafael Mateo, and Jacob González-Solís. 2015. The role of sardine as prey for pelagic predators in the western Mediterranean Sea assessed using stable isotopes and fatty acids. Marine Ecology Progress Series 531: 1–14. https://doi.org/10.3354/meps11353.
36 Calado, J. G., D. M. Matos, J. A. Ramos, F. Moniz, F. R. Ceia, J. P. Granadeiro, and V. H. Paiva. 2018. Seasonal and annual differences in the foraging ecology of two gull species breeding in sympatry and their use of fishery discards. Journal of Avian Biology 49. https://doi.org/10.1111/jav.01463.
37 Badreldin, Mohab, Reda M. Fahim, Lafi Al Solami, and Hatem H. Mahmoud. 2025. Biological aspects and population dynamics of the European pilchard Sardina pilchardus (Walbaum, 1792) in the southeastern Mediterranean waters. Journal of Fish Biology n/a: 15. https://doi.org/10.1111/jfb.70285.
38 Basilone, Gualtiero, Rosalia Ferreri, Salvatore Aronica, Salvatore Mazzola, Angelo Bonanno, Antonella Gargano, Maurizio Pulizzi, et al. 2021. Reproduction and Sexual Maturity of European Sardine (Sardina pilchardus) in the Central Mediterranean Sea. Frontiers in Marine Science 8. Frontiers. https://doi.org/10.3389/fmars.2021.715846.
39 Tsikliras, Athanassios C, and Emmanuil T Koutrakis. 2013. Growth and reproduction of European sardine, Sardina pilchardus (Pisces: Clupeidae), in northeastern Mediterranean. Cah. Biol. Mar. 54: 365–374.
40 Silva, Alexandra, Sara Faria, and Cristina Nunes. 2013. Long-term changes in maturation of sardine, Sardina pilchardus, in Portuguese waters. Scientia Marina 77. CSIC, Consejo Superior de Investigaciones Científicas: 429–438. https://doi.org/10.3989/scimar.03852.03A.
41 Véron, Matthieu, Erwan Duhamel, Michel Bertignac, Lionel Pawlowski, Martin Huret, and Loïc Baulier. 2020. Determinism of Temporal Variability in Size at Maturation of Sardine Sardina pilchardus in the Bay of Biscay. Frontiers in Marine Science 7. Frontiers: 17. https://doi.org/10.3389/fmars.2020.567841.
42 Amenzoui, Khadija, Fatima Ferhan-Tachinante, Ahmed Yahyaoui, Souad Kifani, and Abdel Hakim Mesfioui. 2006. Analysis of the cycle of reproduction of Sardina pilchardus (Walbaum, 1792) off the Moroccan Atlantic coast. Comptes Rendus Biologies 329. Les Défis de La Microbiologie et Des Maladies Infectieuses: 892–901. https://doi.org/10.1016/j.crvi.2006.08.002.
43 Sinovčić, Gorenka, Vanja Čikeš Keč, and Barbara Zorica. 2008. Population structure, size at maturity and condition of sardine, Sardina pilchardus (Walb., 1792), in the nursery ground of the eastern Adriatic Sea (Krka River Estuary, Croatia). Estuarine, Coastal and Shelf Science 76: 739–744. https://doi.org/10.1016/j.ecss.2007.07.037.
44 Marçalo, Ana. 2023. Personal communication.
45 Pawson, M.G., and G.D. Pickett. 1996. The Annual Pattern of Condition and Maturity in Bass, Dicentrarchus Labrax, in Waters Around England and Wales. Journal of the Marine Biological Association of the United Kingdom 76: 107. https://doi.org/10.1017/S0025315400029040.
46 Ruiz, Jon, Maite Louzao, Iñaki Oyarzabal, Luis Arregi, Estanis Mugerza, and Andres Uriarte. 2021. The Spanish purse-seine fishery targeting small pelagic species in the Bay of Biscay: Landings, discards and interactions with protected species. Fisheries Research 239: 105951. https://doi.org/10.1016/j.fishres.2021.105951.
47 Zwolinski, Juan, Alexandre Morais, Vitor Marques, Yorgos Stratoudakis, and Paul G. Fernandes. 2007. Diel variation in the vertical distribution and schooling behaviour of sardine (Sardina pilchardus) off Portugal. ICES Journal of Marine Science 64: 963–972. https://doi.org/10.1093/icesjms/fsm075.
48 Breen, Mike, Neil Anders, Odd-Børre Humborstad, Jonatan Nilsson, Maria Tenningen, and Aud Vold. 2020. Catch Welfare in Commercial Fisheries. In The Welfare of Fish, ed. Tore S. Kristiansen, Anders Fernö, Michail A. Pavlidis, and Hans van de Vis, 401–437. Animal Welfare. Cham: Springer International Publishing. https://doi.org/10.1007/978-3-030-41675-1_17.
49 Council regulation (EC) No 1967/2006 of 21 December 2006 concerning management measures for the sustainable exploitation of fishery resources in the Mediterranean Sea, amending Regulation (EEC) No 2847/93 and repealing Regulation (EC) No 1626/94. 2006. European Council.
50 Carefish/catch consortium. 2023. Carefish report - welfare assessment in purse seine fisheries.
51 DGRM. 2012. Plano de Gestão para a pesca da sardinha (2012-2015). Lisboa.
52 Scarcella, Giuseppe, José Ríos, and Diego Solé. 2025. Iberian Sardine Purse Seine Fishery- Public Certification Report. Initial assessment. Marine Stewardship Council Fisheries Assessments. Bureau Veritas Certification Holding SAS.
53 Comission delegated regulation (EU) 2023/2460 of 22 August 2023 supplementing Regulation (EU) No 1380/2013 of the European Parliament and of the Council as regards the establishment of a de minimis exemption to the landing obligation for certain small pelagic fisheries in the Mediterranean Sea. 2023. Official Journal of the European Union.
54 Waring, Gordon T., Patricia Gerrior, P. Michael Payne, Betsy L. Parry, and John R. Nicolas. Incidental Take of Marine Mammals in Foreign Fishery Activities Off the Northeast United States, 1977-88. Fishery Bulletin, US 88: 347–360.
55 Crespo, E A, S N Pedraza, S L Dans, M Koen Alonso, L M Reyes, N A García, M Coscarella, and A C M Schiavini. 1997. Direct and Indirect Effects of the Highseas Fisheries on the Marine Mammal Populations in the Northern and Central Patagonian Coast. Journal of Northwest Atlantic Fishery Science 22: 189–207. https://doi.org/10.2960/J.v22.a15.
56 Vila, Àlex Aguilar, Jaume Forcada i Nogués, Anna Arderiu i Bofill, Assumpció Borrell i Thió, Àlex Monnà Cano, José Aramburu Galeano, Teresa Pastor Ramos, and Gemma Cantos i Font. 1997. Inventario de los cetáceos de las aguas atlánticas peninsulares: aplicación de la directiva 92/43/CEE. Barcelona: Universitat de Barcelona.
57 Oliveira, Nuno, Ana Henriques, Joana Miodonski, Joana Pereira, Débora Marujo, Ana Almeida, Nuno Barros, et al. 2015. Seabird bycatch in Portuguese mainland coastal fisheries: An assessment through on-board observations and fishermen interviews. Global Ecology and Conservation 3: 51–61. https://doi.org/10.1016/j.gecco.2014.11.006.
58 Arcos, José Manuel, Maite Louzao, and Daniel Oro. Fisheries Ecosystem Impacts and Management in the Mediterranean: Seabirds Point of View.
59 Mood, A., and P. Brooke. 2025. Fishcount.org.uk.
60 Pauly, Daniel, Dirk Zeller, and M. L. D. Palomares. 2020. Sea Around Us - Concepts, Design, and Data. Sea Around Us | Fisheries, Ecosystems and Biodiversity.
Sardina pilchardus
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Sardina pilchardus photographed in Ligurian sea (Italy) by Alessandro Duci.
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good point from country record
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WelfareCheck
How do you score?
The legend next to the WelfareScore card gives the definitions of the three dimensions we score the welfare of aquatic species on. You will also find the score options and how we arrive at the overall WelfareScore. If you scroll down to the criteria, you will find the explanations for the scores for each criterion for many species already. We are in the process of inserting these for all WelfareChecks we update. If your species of interest is missing these score justifications or if you are interested to know more details about the scoring procedure, please consult our scoring rationale.
For WelfareChecks we have not managed to update yet, previous scoring rationales may apply:
- before 2022: scoring rationale
- before 2018: scoring rationale
What are side notes? Why are they not scored?
The criteria cover the main focus of the WelfareChecks – an assessment of the welfare of aquatic species. When selecting the criteria, though, we were aware of the importance of some topics so that we wanted to include them and collect data but not score them. For WelfareChecks | farm, these topics are "domestication level", "feed replacement", and "commercial relevance". The domestication and commercial relevance aspects allow us to analyse the questions whether increasing rate of domestication or relevance in farming worldwide goes hand in hand with better welfare; the feed replacement rather goes in the direction of added suffering for all those species which end up as feed. For a carnivorous species, to gain 1 kg of meat, you do not just kill this one individual but you have to take into account the meat that it was fed during its life in the form of fish meal and fish oil. In other words, carnivorous species (and to a degree also omnivorous ones) have a larger "fish in:fish out" ratio.
Profile
Why does it look different than the last time I was here?
Probably, we updated the profile. Check the version number in the head of the page. For more information on the version, see the FAQ about this. Why do we update profiles? Not just do we want to include new research that has come out, but we are continuously developing the database itself. For example, we changed the structure of entries in criteria or we added explanations for scores in the WelfareCheck | farm. And we are always refining our scoring rules.
What does "not investigated by us yet" mean?
The centre of the Overview is an array of criteria covering basic features and behaviours of the species. Each of this information comes from our literature search on the species. If we researched a full Dossier on the species, probably all criteria in the Overview will be covered and thus filled. This was our way to go when we first set up the database.
Because Dossiers are time consuming to research, we switched to focusing on WelfareChecks. These are much shorter profiles covering just 10 criteria we deemed important when it comes to behaviour and welfare in aquaculture (and lately fisheries, too). Also, WelfareChecks contain the assessment of the welfare potential of a species which has become the main feature of the fair-fish database over time. Because WelfareChecks do not cover as many criteria as a Dossier, we don't have the information to fill all blanks in the Overview, as this information is "not investigated by us yet".
Our long-term goal is to go back to researching Dossiers for all species covered in the fair-fish database once we set up WelfareChecks for each of them. If you would like to support us financially with this, please get in touch at ffdb@fair-fish.net
What is the difference between "not investigated by us yet" and "no data found yet"?
See the question "What does "not investigated by us yet" mean?". In short, if we have not had a look in the literature - or in other words, if we have not investigated a criterion - we cannot know the data. If we have already checked the literature on a criterion and could not find anything, it is "no data found yet". You spotted a "no data found yet" where you know data exists? Get in touch with us at ffdb@fair-fish.net!
Behind an entry, what does "[x]↶[y]" mean?
Once you have clicked on "show details", the entry for a criterion will unfold and display the summarised information we collected from the scientific literature – complete with the reference(s).
As reference style we chose "Springer Humanities (numeric, brackets)" which presents itself in the database as a number in a grey box. Mouse over the box to see the reference; click on it to jump to the bibliography at the bottom of the page. But what does "[x]↶[y]" refer to?
This is the way we mark secondary citations. In this case, we read reference "y", but not reference "x", and cite "x" as mentioned in "y". We try to avoid citing secondary references as best as possible and instead read the original source ourselves. Sometimes we have to resort to citing secondarily, though, when the original source is: a) very old or not (digitally) available for other reasons, b) in a language no one in the team understands. Seldomly, it also happens that we are running out of time on a profile and cannot afford to read the original. As mentioned, though, we try to avoid it, as citing mistakes may always happen (and we don't want to copy the mistake) and as misunderstandings may occur by interpreting the secondarily cited information incorrectly.
If you spot a secondary reference and would like to send us the original work, please contact us at ffdb@fair-fish.net
Why don't you cite paper xyz?
In general, we aim at giving a good representation of the literature published on the respective species and read as much as we can. We do have a time budget on each profile, though. This is around 80-100 hours for a WelfareCheck and around 300 hours for a Dossier. It might thus be that we simply did not come around to reading the paper.
It is also possible, though, that we did have to make a decision between several papers on the same topic. If there are too many papers on one issue than we manage to read in time, we have to select a sample. On certain topics that currently attract a lot of attention, it might be beneficial to opt for the more recent papers; on other topics, especially in basic research on behaviour in the wild, the older papers might be the go-to source.
And speaking of time: the paper you are missing from the profile might have come out after the profile was published. For the publication date, please check the head of the profile at "cite this profile". We currently update profiles every 6-7 years.
If your paper slipped through the cracks and you would like us to consider it, please get in touch at ffdb@fair-fish.net
What does the version number/appearance/major update/minor update mean?
This number, for example "C | 2.1 (2022-11-02)", contains 4 parts:
- "C" marks the appearance – the design level – of the profile part. In WelfareChecks | farm, appearance "C" is our most recent one with consistent age class and label (WILD, FARM, LAB) structure across all criteria.
- "2." marks the number of major releases within this appearance. Here, it is major release 2. Major releases include e.g. changes of the WelfareScore. Even if we just add one paper – if it changes the score for one or several criteria, we will mark this as a major update for the profile. With a change to a new appearance, the major release will be re-set to 1.
- ".1" marks the number of minor updates within this appearance. Here, it is minor update 1. With minor updates, we mean changes in formatting, grammar, orthography. It can also mean adding new papers, but if these papers only confirm the score and don't change it, it will be "minor" in our book. With a change to a new appearance, the minor update will be re-set to 0.
- "(2022-11-02)" is the date of the last change – be it the initial release of the part, a minor, or a major update. The nature of the changes you may find out in the changelog next to the version number.
If an Advice, for example, has an initial release date and then just a minor update date due to link corrections, it means that – apart from correcting links – the Advice has not been updated in a major way since its initial release. Please take this into account when consulting any part of the database.
General
How to use the FAQ?
First up, you will find answers to questions for the specific page you are on. Scrolling down in the FAQ window, there are also answers to more general questions. Explore our website and the other sub pages and find there the answers to questions relevant for those pages.
How do I navigate in the fair-fish database?
In the fair-fish database, when you have chosen a species (either by searching in the search bar or in the species tree), the landing page is an Overview, introducing the most important information to know about the species that we have come across during our literatures search, including common names, images, distribution, habitat and growth characteristics, swimming aspects, reproduction, social behaviour but also handling details. To dive deeper, visit the Dossier where we collect all available ethological findings (and more) on the most important aspects during the life course, both biologically and concerning the habitat. In contrast to the Overview, we present the findings in more detail citing the scientific references.
Depending on whether the species is farmed or wild caught, you will be interested in different branches of the database.
Farm branch
Founded in 2013, the farm branch of the fair-fish database focuses on farmed aquatic species.
Catch branch
Founded in 2022, the catch branch of the fair-fish database focuses on wild-caught aquatic species.
What is the farm branch?
The heart of the farm branch of the fair-fish database is the welfare assessment – or WelfareCheck | farm – resulting in the WelfareScore | farm for each species. The WelfareCheck | farm is a condensed assessment of the species' likelihood and potential for good welfare in aquaculture, based on welfare-related findings for 10 crucial criteria (home range, depth range, migration, reproduction, aggregation, aggression, substrate, stress, malformations, slaughter).
For those species with a Dossier, we conclude to-be-preferred farming conditions in the Advice | farm. They are not meant to be as detailed as a rearing manual but instead, challenge current farming standards and often take the form of what not to do.
What is the catch branch?
In parallel to farm, the main element of the catch branch of the fair-fish database is the welfare assessment – or WelfareCheck | catch – with the WelfareScore | catch for each species caught with a specific catching method. The WelfareCheck | catch, too, is a condensed assessment of the species' likelihood and potential for good welfare – or better yet avoidance of decrease of good welfare – this time in fisheries. We base this on findings on welfare hazards in 10 steps along the catching process (prospection, setting, catching, emersion, release from gear, bycatch avoidance, sorting, discarding, storing, slaughter).
In contrast to the farm profiles, in the catch branch we assess the welfare separately for each method that the focus species is caught with. In the case of a species exclusively caught with one method, there will be one WelfareCheck, whereas in other species, there will be as many WelfareChecks as there are methods to catch the species with.
Summarising our findings of all WelfareChecks | catch for one species in Advice | catch, we conclude which catching method is the least welfare threatening for this species and which changes to the gear or the catching process will potentially result in improvements of welfare.
What do we mean by "welfare"?
Welfare of aquatic species is at the heart of the fair-fish database. In our definition of welfare, we follow Broom (1986): “The welfare of an individual is its state as regards its attempts to cope with its environment.” Thus, welfare may be perceived as a continuum on which an individual rates “good” or “poor” or everything in between.
We pursue what could be called a combination of not only a) valuing the freedom from injuries and stress (function-based approach) but b) supporting attempts to provide rewarding experiences and cognitive challenges (feelings-based approach) as well as c) arguing for enclosures that mimic the wild habitat as best as possible and allow for natural behaviour (nature-based approach).
What if I have a question?
Try mousing over the element you are interested in - oftentimes you will find explanations this way. If not, there will be FAQ on many of the sub-pages with answers to questions that apply to the respective sub-page. If your question is not among those, contact us at ffdb@fair-fish.net.
Where is the FishEthoBase?
It's right here! We decided to re-name it to fair-fish database for several reasons. The database has grown beyond dealing purely with ethology, more towards welfare in general – and so much more. Also, the partners fair-fish and FishEthoGroup decided to re-organise their partnership. While maintaining our friendship, we also desire for greater independence. So, the name "fair-fish database" establishes it as a fair-fish endeavour.
Frequently asked questions
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