Authors: Jenny Volstorf, Vighnesh Samel

Katsuwonus pelamis is an OCEANODROMOUS PELAGIC fish species with a cosmopolitan distribution in offshore tropical waters. It tends to form large schools near the surface, often associated with floating objects, birds, sharks, and cetaceans, and is mixed with other species of tuna. Consumed globally both freshly and as a processed product (canned, dried, salted, etc.), it is one of the most heavily exploited fish species (in terms of tonnage), mainly targeted commercially by purse seining but also by other fishing methods such as longlines, troll fishing, and hand lines and pole-and-lines.

Hand lines and pole-and-lines impose a relatively short time of contact with the gear and emersion, along with a rapid and efficient release from the gear. Important welfare hazards include hooking and jerking causing mouth injuries, manual unhooking the barbless hook in the case of hand lines, hard dropping, lack of oxygen resulting in floundering on the deck, and the lack of immediate sorting, stunning, and slaughter facilities on most vessels. This results in IND suffering due to physical injuries, asphyxiation, experiencing their own weight and a stressful mortality, and getting crushed in crowded conditions on the deck and in the storage unit.

Whilst the injuries due to hooking and jerking in pole-and-lines are inevitable, the use of barbless hooks is recommended. Furthermore, measures such as cushioning the deck, keeping it moist, and having a slope, ramps, or conveyor belts leading to the opening of the catch storage chamber can be used to avoid a delay in the storage of IND. Likewise, we recommend immediate stunning of IND after sorting, followed by immediate killing when the IND are in an unconscious state. To the best of our knowledge, this has not yet been implemented in a commercial context. Future focus should be on determining optimum stunning and slaughter procedures and disincentivising fishing around FADs to reduce the rate of bycatch. Live bait FISHES are an indispensable part of pole-and-line fishing, but they suffer from poor welfare through the process of catching, transfer to the main vessel, on-board storage in live bait tanks, and throwing during the fishing process. It is, therefore, imminent to make efficient use of the live bait FISHES to minimise the quantity used or preferably, find methods to replace their use altogether.

Pole-and-lines is considered to be the most welfare-friendly fishing technique. Even though our WelfareScore is low, it is better than all for WelfareChecks assessed so far. Applying the outlined mitigation measures will potentially succeed in making pole-and-lines the least welfare deteriorating catching method for K. pelamis.

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

Likelihood

Potential

Certainty

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?

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?

• target species: hand lines in South Sulawesi, Indonesia, with a bigger average catch size than pole-and-lines (60 versus 45 cm) and shorter catch time (5 versus 7 months) 28 and thus probably lower risk for overexploitation 0.
  With pole-and-lines, off Maumere, Indonesia, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to replace purse seine with pole-and-lines in spawning areas (where K. pelamis is bycatch in purse seines) 12.
  Hand line bycatch-avoidance management: recommended to regulate fishing times to reduce the proportion of undersized IND 17.
  Pole-and-lines bycatch-avoidance management: closure of spawning and nursing grounds during spawning season in October 49↶6. With pole-and-lines, off Lakshadweep, India, fishing ban in the Indian Exclusive Economic Zone prior to or during the onset of the South West monsoon for the conservation and management of fishing resources and for sea safety reasons 50.
  • How to improve: closure of spawning and nursing grounds, seasonal fishing bans
• non-target species: usable bycatch: given that K. pelamis schools with Thunnus albacares (Yellowfin tuna) when these are JUVENILES 51 32 and with pole-and-lines, T. albacares JUVENILES get attracted to FADs, they may potentially get caught, causing concerns 51. With pole-and-lines, off Brazil, 5.8% bycatch: mainly T. albacares, followed by Coryphaena hippurus (Mahi-mahi), rarely Thunnus atlanticus (Blackfin tuna), Thunnus obesus (Bigeye tuna), Auxis thazard (Frigate tuna), Acanthocybium solandri (Wahoo), Euthynnus alletteratus (Little tunny), Seriola lalandi (Yellowtail amberjack) 27; in Lakshadweep, India, 74.2% of catch contained K. pelamis, another 22.6% commercially relevant T. albacares and neritic tunas - especially when catching took place near anchored FADs 11; in Seram and Halmahera Sea, Indonesia, bycatch included T. albacares and Auxis rochei (Bullet tuna) 32; off Maumere, Eastern Indonesia, accidental catch of T. albacares when mistaken for school of K. pelamis 6; (also targeting T. albacares), off Bitung City, Indonesia, caught C. hippurus and Elagatis bipinnulata (Rainbow runner) retained by the fishers 33; off Japan, main target K. pelamis, also targeted: T. albacares, Thunnus alalunga (Albacore), T. obesus, other commercially relevant species: Euthynnus affinis (Mackerel tuna), A. thazard, S. lalandi, and E. bipinnulata 20. Alternatively to FADs, fishers caught free-swimming schools with a similar catch rate as using FADs but with lower rates of T. albacares bycatch 12.
  Hand lines in South Sulawesi, Indonesia, more selective than pole-and-lines (catch one instead of <3 species with relative uniform size) 28 and thus probably lower risk for non-target bycatch 0. Hand lines, off Karakelang Island, Indonesia, included 29.8% E. affinis, 15.8% C. hippurus 13.
  With pole-and-lines, in Lakshadweep, India, 2.9% usable bycatch - especially when catching took place near flotsams: E. bipinnulata, C. hippurus, sharks (mainly Carcharhinus falciformis [Silky shark], followed by Carcharhinus amblyrhynchos [Grey reef shark], Galeocerdo cuvier [Tiger shark], Alopias pelagicus [Pelagic thresher], Negaprion acutidens [Sicklefin lemon shark], and Sphyrna lewini [Scalloped hammerhead]), A. solandri, bill fishes 11. Please note, G. cuvier is near threatened (decreasing) 52, C. falciformis is vulnerable (decreasing) 53, and A. pelagicus 54, C. amblyrhynchos 55, N. acutidens 56, and S. lewini 57 are endangered (decreasing) according to IUCN.
  With pole-and-lines, off Sri Lanka, ca 4% bycatch of neritic tuna species, A. rochei, A. thazard, and E. affinis 29.
  With hand lines and pole-and-lines, in the Maldives, 2 small trevallies (unspecified species 0) and 3 E. affinis were caught and consumed locally 58.
  Troll lines, off Palabuhanratu, Indonesia, included T. albacares and T. obesus in category of target catch 59, 18% bycatch included mainly Kajikia audax (Striped marlin), to much smaller degree C. hippurus and Loligo sp, rarely Scomberomorus commerson (Narrow-barred Spanish mackerel), Istiophorus platypterus (Indio-Pacific sailfish), E. bipinnulata 59.
  
  • How to improve: prefer free-swimming schools over FAD-associated IND to reduce bycatch of Thunnus albacares
• non-target species: for pole-and-lines, fishers throw live bait FISHES 27 23 using small scoop nets to attract IND to the bow 18 2 6 9, bow and the port side 3 19 20, or to the stern of the vessel and start a feeding frenzy 7 4 25 26. Then, catching with pole-and-lines starts 6. With troll lines, off Palabuhanratu, Indonesia, fishers threw live bait FISHES to test appetite of target IND, caught them over FADs 59. Given catch of live bait FISHES, hazard consequences to those FISHES are probable:
  usable bycatch: with pole-and-lines, off Brazil, open-circulation water tanks for live bait FISHES (usually Sardinella brasiliensis [Brazilian sardinella]) 27.
  With hand lines and pole-and-lines, in the Maldives, live bait FISHES were mostly Spratelloides gracilis (Silver-stripe round herring), but also Spratelloides delicatulus (Blue sprat), Encrasicholina heteroloba (Shorthead anchovy), Caesionidae (Fusiliers), juvenile Apogonidae (Cardinalfishes), Chromis viridis (Blue-green damselfish), Lepidozygous tapeinosoma (Fusilier damselfish), Atherinidae (Silversides) 60 58. S. gracilis, S. delicatulus, E. heteroloba, C. viridis, Selar crumenophthalmus (Bigeye scad), Decapterus macarellus (Mackerel scad), Odonus niger (Redtoothed triggerfish), Herklotsichthys quadrimaculatus (Bluestripe herring), Atherinomorus lacunosus (Hardyhead silverside), and species from family Apogonidae and Caesionidae 61.
  PELAGIC FISHES like sprats and anchovies were caught with rectangular lift nets 60 58, e.g., the net is attached to two long poles and dipped into the water and then lifted, trapping the caught FISHES 61. Catching takes place during the day 61 within the atolls 60 58 8 or – most frequently – at night 62 58 7 61 (with or without SCUBA) using artificial lights to attract the FISHES 61. This procedure causes significant mortality of the live bait FISHES due to poor handling techniques 62.
  For DEMERSAL species like cardinalfishes and fusiliers, weighted nets are lowered close to the sea floor, and opened with the help of divers 61. The FISHES are attracted towards the net using chum or various other techniques such as chasing with coconut frond, plastic pipes, or making a sound with chains attached to the end of a rope 61. The FISHES are quickly transferred to the live bait tank using dry scooping or wet scooping 61 with big (50 cm) and small (ca 35 cm) ∅ scoop nets 58. Recommended to use 35 cm instead of 50 cm scoop nets, as the latter scoop large quantities of FISHES at once and cause higher mortality 58. Alternatively, prefer buckets with sea water over dry scooping to transfer live bait FISHES to the vessels 62. Live bait FISHES were kept in tanks ("bait wells") 60 7 in water 60 on vessel 60 7. During catching, transferring, and storing, live bait FISHES are subjected to hauling from large depths (45-60 m), crowding, contact with the gear, lack of oxygen, dry scooping at high densities, and hypoxic conditions in the storage tanks 61. This will lead to barotrauma, scale and mucous loss, other injuries, hypoxia 61. Most resilient species: for pole-and-lines, Apogonids followed by E. heteroloba and Caesionids; for hand lines, A. lacunosus, followed by Caesionids and H. quadrimaculatus 61. H. quadrimaculatus is chosen by most fishers as the second-best bait to keep, followed by A. lacunosus and Caesionids 61. The excess live bait FISHES at the end of the fishing day are a) retained in the live bait tank for the following day, b) discarded into the sea, reef/inner atoll (pole-and-lines), c) sold (hand lines), d) consumed 61. Rather than releasing excess live bait FISHES back to the atoll, recommended to keep for later use 62.
  With pole-and-lines, in Lakshadweep, India, live bait FISHES: mostly S. gracilis, S. delicatulus, to a lesser degree Ceasio spp., Ptero ceasio spp., C. viridis, L. tapeinosoma, fusiliers, cardinalfishes 11.
  With pole-and-lines, off Sri Lanka, fishers look for bait FISHES Dipterygonotus balteatus (Mottled fusilier) by diving, catch with lift net at 20-100 m 29.
  For pole-and-lines, off Bitung City, Indonesia, used live bait FISHES: scads, Selaroides leptolepis (Yellowstripe trevally), anchovies, fusiliers, Dussumieria acuta (Rainbow sardine) 33; off Maumere, Eastern Indonesia, live bait FISHES mostly anchovies 12, Stolephorus zollingeri (Japanese anchovy), but also E. heteroloba, 5.7-7.2 cm 6. In Seram and Halmahera Sea, Indonesia, fishers bought live bait FISHES from specialised bait fishers who caught them with lift nets or similar means 32. Live bait FISHES were caught at midnight, swiftly transferred from lift nets to 5-8 buckets of 50 L each which are washed to get rid of debris and equipped with water circulation 6.
  With hand lines and pole-and-lines, off Bitung, North Sulawesi, Indonesia, the live bait FISHES are first crowded using a small-meshed lift net 63 and then dry scooped from the tank into small buckets on the port and the starboard side of the vessel using large scoop nets 18 63. The live bait tank is present in the centre of the deck 18 63. Excess live bait FISHES may be discarded - instead of throwing live bait FISHES into the open sea, recommended to throw them overboard when the vessel returns back to the atoll to ensure higher survival of the FISHES 60.
  For pole-and-lines, off Japan, live bait FISHES were collected from aquaculture facilities using surrounding nets: FISHES were gradually crowded and first transferred into buckets using wet scoop nets and then into the baitfish tank from the starboard side of the vessel 19. Live bait FISHES (anchovies, sardines 5 2, small scads, silversides) were kept alive in live bait tanks with seawater circulation 2. With pole-and-line, in distant-water areas in the Western Central Pacific, low temperature live bait tanks with cooling, filtering, purifying, bubbling system yielding >85% survival after 30 days 5.
  With hand lines and pole-and-lines, in Indonesia, recommendations: training courses for fishers on best practices in handling, storage 16.
  With pole-and-lines, recommended to divide big bait schools to decrease crowding density and lack of oxygen and avoid mortality 4. Recommended to release predators accidentally caught in the same net as live bait FISHES to avoid stress and mortality 4. Recommended to use low wattage light before transfer of live bait to vessel and allow for the FISHES to settle down (ideally until daylight) to avoid stress and abrasions 4. Recommended to transfer from net to bait wells quickly but gently using buckets with sea water and avoiding high densities 4. Recommended to keep live bait FISHES in tanks with smooth surfaces, low lights, and circulation 62. Circulating sea water in holding tank for live bait FISHES through openings in the hull of the vessel allows for water renewal but requires the vessel to move 4. Alternatively, oxygen can be supplied through a) bamboo poles inserted through hull openings, b) pumping through air stones, c) mechanical pumps 4. For more recommendations on holding live bait, see 4.
  
  • How to improve: take care to treat live bait FISHES quickly and gently using wet scooping and hold them in well-oxygenated and circulating bait wells or low temperature live bait tanks (see entry for details)
• non-target species: with hand lines, fishers use live bait FISHES on hooks 13, so hazard consequences are probable:
  usable bycatch: with hand lines, off Karakelang Island, Indonesia, using live bait FISHES did not yield higher catch of K. pelamis than silk cloth or chicken feathers 13 - given the low sample size, further research is needed 0.
  With pole-and-lines, in the Maldives, no live bait is used on barbless hooks 7; in Indonesia, no live bait is used but barbless hook covered in raffia rope and chicken feathers (lure) 6.
  
  • How to improve: with hand lines, replace live bait FISHES on the hook with raffia rope or chicken feathers (further research needed)
• non-target species: given quantities of live bait FISHES used, overexploitation is possible:
  usable bycatch: with hand lines and pole-and-lines, in the Maldives, annual live bait FISHES catch of ca 12,100 tonnes between 2017 and 2022 (IPNLF data) 61. Catches fluctuated from 34 kg/trip targeting S. gracilis during the day to 296 kg/trip targeting cardinalfishes at night using artificial light 60, average catch ranging at 20-515 kg/trip 58. The catch per haul is highly variable, ranging at 7.2-78.6 kg 61. Live bait FISHES catch: 208 kg/trip (standard deviation = 322 kg) for pole-and-lines and 347 kg/trip (standard deviation = 526 kg) for hand lines 61. Utilisation ratio: 11.8 kg tuna per kg live bait FISHES 58. Ca 325 kg/d/trip live bait FISHES used, utilisation ratio: 7.3-13 kg of tuna per kg of live bait FISHES which is inefficient compared to other pole-and-lines fisheries because the fishers throw generous quantities of live bait FISHES and also due to the large scale mortality of commonly used species like sprats 61. Recommended to employ master fishers from the Pacific to improve bait holding conditions and catching efficiency 60. The excess live bait FISHES at the end of the fishing day are a) retained in the live bait tank for the following day 61, b) discarded into the open sea 60 61 causing inevitable mortality by predation 60, reef/inner atoll (pole-and-lines), c) sold (hand lines), d) consumed 61. Rather than releasing excess live bait FISHES back to the atoll, recommended to keep for later use 62. Excess live bait FISHES may be discarded – instead of throwing live bait FISHES into the open sea, recommended to throw them overboard when the vessel returns back to the atoll to ensure higher survival of the FISHES 60 or to the place where they were caught 4. As larger vessels require larger quantities of bait FISHES and fishing takes place on the same fishing grounds, this can cause local depletions 60. With hand lines and pole-and-lines, in the Maldives, anchovies and sprats were the most commonly used live bait species because they get easily attracted to light, but they have low resilience, implying early and large-scale mortality and a high frequency of bait fishing 60. Catching live bait FISHES in these huge numbers using artificial lights to attract as many FISHES as possible may make the fishery unsustainable in the future 61. If bait fish populations decline, recommendations: larger closure zone, limitation in attracting lights and net sizes 62. For more details, see 62. With pole-and-lines, in the Maldives, occasional complaints about the shortage of live bait FISHES, especially in the southern atolls, indicating potential overexploitation and leading to a ban on live bait export 62. To avoid overexploitation of live bait populations, recommendations: raise awareness and educate fishers on sustainability 60 62 4 and welfare 60 to ensure compliance with regulations which include: monitoring live bait populations 62 4, ban on SCUBA gear, ban to export live bait FISHES or sell for human consumption 62. Recommended to employ boat-associated fishing, a method in which the boat itself is used as an FAD to eliminate the need for live bait FISHES 60.
  With pole-and-lines, in Seram and Halmahera Sea, Indonesia, fishers used 3,504-8,844 kg live bait of Stolephorus spp. during 3-5 trips to catch 27,317-97,345 kg target species, giving 5.8-10.7 kg catch per kg bait 32. Fluctuations in catch:live bait ratio due to ocean conditions and expertise of fishers 32. With pole-and-lines, off Maumere, Eastern Indonesia, ratio of 16.7-181.3 kg catch per kg live bait FISHES (mostly anchovies) 12. With hand lines and pole-and-lines, in Indonesia, recommendations: training courses for fishers on utilisation of bait FISHES to optimise the bait to catch ratios 16. Where applicable, support initiatives like artificial bait or live bait FISHES procured from aquaculture facilities 16, although this is arguable 64. Self reporting by the fishers and automated data reporting system (community based fisheries monitoring). If live bait FISHES are procured from third parties, the third parties should be legal operators 16.
  With pole-and-lines, off Japan, live bait FISHES were collected from aquaculture facilities 19. For pole-and-lines, off Japan, 10 kg tuna per kg of live bait FISHES (anchovies, sardines 5 2, small scads, silversides) 2.
  With pole-and-lines, live bait management recommended to impose rules or regulations as well as a code of conduct (to avoid waste) 4. This should include collaboration with fishers (reports on species, amount used, mortality) 4 64. Recommended to use live bait FISHES at low ratio to target species by stopping to throw live bait FISHES if schools do not react properly 4. Live bait FISHES reared in aquaculture can relieve pressure on wild-caught FISHES 4: Chanos chanos (Milkfish) 11 4 could be ideal bait fish for its attractiveness to tuna, easy reproduction in captivity, omnivorous diet 4.
  Recommended to identify the location and the time of spawning for the live bait fishery and demarcate spawning grounds for protection 64. For live bait, recommended to prohibit the use of spawners by appropriate spatial and temporal closures 64. Stock enhancement programmes recommended to maintain most popular live bait populations 64.
  
  • How to improve: use the vessel as FAD instead of throwing live bait FISHES (further research needed); if not possible, explore the possibility and efficacy of using hatchery-reared live bait (e.g., Chanos chanos) or maintain wild populations through stock enhancement programmes; raise awareness with fishers on sustainability, monitor live bait FISHES populations, improve utilisation ratio (catch:live bait), reduce waste by retaining excess live bait FISHES at the end of the day (for more details, see entry)
• non-target species: given that pole-and-lines can catch K. pelamis at FADs which attract other species, there is the risk to also catch co-existing, preyed-on, and predating species 0; given extensive live bait fishery, there is the risk to also catch co-existing, preyed-on, and predating species of the live bait FISHES 0:
  non-usable bycatch: with pole-and-lines, off the Azores, Portugal, encounters with cetaceans in 9.9% of fishing events, mostly Delphinus delphis (Common dolphin), more rarely Stenella frontalis (Atlantic spotted dolphin) and Tursiops truncatus (Common bottlenose dolphin), seldomly Balaenoptera physalus (Fin whale), Balaenoptera borealis (Sei whale), Balaenoptera acutorostrata (Common minke whale), Stenella coeruleoalba (Striped dolphin), Grampus griseus (Risso's dolphin), Pseudorca crassidens (False killer whale), Physeter macrocephalus (Sperm whale), which for the most part arrived after fishing started. Of the 9.9%, in 44%, tuna schools dived down in reaction to cetaceans being present, in 41%, cetaceans (mostly D. delphis, to a lesser degree S. frontalis, T. truncatus) fed on live bait FISHES 65.
  With pole-and-lines, in the Maldives, occasional bycatch of small species and fish larvae with a high mortality during bait fishing 60.
  With pole-and-lines, in Lakshadweep, India, 0.3% non-usable bycatch - especially when catching took place near flotsams - discarded alive: triggerfishes, miscellaneous 11. FADs tend to attract smaller-sized IND and FISHES towards them - thus, fishing around FADs increases bycatch, causing a negative impact on the pelagic fish community 66. With live bait fishery for pole-and-lines, in Lakshadweep, India: 5-6% bycatch independent of catch in outer reefs or lagoons, which are mostly discarded alive (triggerfishes, Anthias spp., Atherinids) or consumed by the crew (wrasses, half beaks) 11.
  
  • How to improve: prefer free-swimming schools over FAD-associated IND
• non-target species: given that pole-and-lines can catch K. pelamis at FADs and by throwing live bait FISHES which both attract ETP species, there is the risk to also catch co-existing, preyed-on, and predating species 0. Even though ETP species should be released ("non-usable"; listed here), in some regions, they are consumed ("usable") – see above:
  with pole-and-lines, of 87 fishing trips in the Maldives, accidental bycatch of ETP species: 7 sharks alive and non injured or slightly injured (C. falciformis; representing 4.6% fishing trips), 2 sharks dead (2.3% of fishing trips), 3 birds alive and non injured or slightly injured (Anous tenuirostris [Lesser noddy], Anous stolidus [Brown noddy]; one bird affected during trolling; 2.3% fishing trips) 7. Given the size and the strength, accidental catch of adult C. falciformis, Carcharhinus longimanus (Oceanic whitetip), etc. is unlikely 7. Given the short lines used, turtles are unlikely to be caught, but can get entangled in FADs 7.
  With live bait fishery for pole-and-lines, in the Maldives, anecdotal mentions of interactions between live bait fishing and ETP species 62. Recommended to raise awareness to also avoid the catch of ETP species during bait fishing 62.
  With live bait fishery for hand lines and pole-and-lines, in the Maldives, occasional bycatch of sharks and rays, which get caught in the lift nets and can suffer from injuries 58. 1 Carcharhinus melanopterus (Blacktip reef shark) returned dead 58.
  With pole-and-lines, in Lakshadweep, India, 0.001% ETP species caught and safely released: Onychoprion fuscatus (Sooty tern) when feeding on live bait FISHES 11.
  With live bait fishery for pole-and-lines, in Lakshadweep, India: in 35% of fishing trips, turtles (Eretmochelys imbricata [Hawksbill sea turtle] and Chelonia mydas [Green sea turtle]) entered the net (dip nets and encircling boat seines), in 7% sharks - all were released unharmed 11. Sightings of dolphins, sting rays, birds nearby 11.
  With hand lines and pole-and-lines, in Indonesia, code of conduct includes several rules: binding to minimise catching marine megafauna and ETP species, all the retained sharks should be landed with their fins still attached to the carcass, it is prohibited to remove the shark fins on board vessels, prohibited to land, retain, or trans ship shark fins, train the captain and the crew members on best practices of handling and releasing marine megafauna and ETP species 16. Given ETP species could collide with or get entangled in FADs, hazard consequences are probable 0. With hand lines and pole-and-lines, in Indonesia, FADs are required to use non-entangling and easily biodegradable material, ensuring that the main parts of the FAD are non-trapping and they do not unravel to prevent ghost fishing 16.
  
  • How to improve: use non-entangling FADs; raise awareness to avoid the catch of ETP species; if caught, train crew how to handle and release ETP species
• non-target species: given the principle of hand lines and pole-and-lines to catch at or close to the surface 7 28 e.g., 23 18 2 25 up to 10 m 29 (=avoid the bottom), seabed damage or impact on benthos respectively is unlikely 7. Hand lines and pole-and-lines in South Sulawesi, Indonesia, assessed to be more environmentally friendly fishing gear than seine nets 28.
  Given that for hand lines and pole-and-lines, in the Maldives, live bait fishing for the DEMERSAL FISHES takes place in the atolls and that the vessels might need to anchor 60 62 61 – to use sticks to scare the live bait FISHES out of the corals 62 – potential damage to the corals are probable 60 62. Damage to the coral reef structures whilst trying to drive out reef-associated live bait FISHES out of the crevices 64. Usually no anchoring to catch PELAGIC live bait FISHES 61.
  With live bait fishery for pole-and-lines, in Lakshadweep, India, in 2.8% of 25 fishing trips: damages to corals by nets, fishers (swimming to support fishing), anchoring in lagoons and outer reefs 11.
  Globally, estimated 23% of hand lines and 65% of pole-and-lines get abandoned, lost, or discarded 67 as well as 9.9% drifting FADs in the Indian and Atlantic Ocean 68 and ca 88.7% anchored FADs off Samoa 69↶70 or ca 80.7% off the Maldives 71. Given the small sample size, further research is needed as well as whether this applies to K. pelamis and hand lines or pole-and-lines 0. With hand lines and pole-and-lines, in Indonesia, FADs are required to use non-entangling and easily biodegradable material, ensuring that the main parts of the FAD are non-trapping and they do not unravel to prevent ghost fishing 16. Recommended to record and report the loss and/or recovery of fishing gear and retain old fishing gear on board 16.
  With live bait fishery for pole-and-lines, recommended to a) avoid contact of gear with coral reefs, b) instead of anchoring in reefs, use moored buoys 4. Recommended ban on fishing practices that can disrupt coral reefs 62 64. Continuous monitoring of live bait FISHES habitats for physical, chemical, and biological changes 64.
  
  • How to improve: impact on benthos from hand lines and pole-and-lines unlikely, but probable in case of live bait fishery of BENTHIC species – avoid sticks and anchoring in reefs as well as fishing gear that damages corals, prefer mooring buoys, prevent ghost fishing by retaining old gear on board and using biodegradable material for FADs

How much is this species targeted annually?

Authors: Jenny Volstorf, Vighnesh Samel

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 may occur most frequently through contact with the gear, handling, decreasing distance to neighbours during storage, and exposure to the storing medium. To avoid or decrease it during prospection, prefer free-swimming schools over FAD-associated IND; if not possible, use non-entangling FADs. To avoid it during catching/hauling, prefer shallow catching depth or – if catching at larger depths – prefer slow hauling speed. Further research needed on hooking injuries. To avoid it for JUVENILES that might be released, prefer free-schwimming schools over FAD-associated IND, prefer large hook sizes (=smaller number), stop catching process when catching JUVENILES, avoid accidental discards to not scare IND away (that are still in the water), but discard JUVENILES as soon as possible – further research needed on the way to do that efficiently; with hand lines, prefer catching in deeper waters (>200 m). To avoid it during release from gear and sorting, keep the landing deck smooth, cover it with suitable cushioning (e.g., tarpaulin), keep the surface moist, avoid crowding, and prefer non-manual handling (e.g., conveyor belt), prefer barbless hooks over barbed hooks (further research needed) and gently over forced unhooking. To avoid it during sorting, prefer below-deck system of sloped chutes to carry IND to the storage units; if not possible or available, find alternatives to cushion the fall from deck to storage. Post sorting, prefer immediate stunning followed by slaughter while still unconscious, continue with cleaning IND before putting them in storage. Further research needed.

1.1 Barotrauma

Extruded eyes/guts: no data found yet.

Ruptured swim bladder: no data found yet.

Bleeding: no data found yet.

• Given catching depth with hand lines at 10-100 m 17, 100 m 28 and unknown speed of hauling, barotrauma is possible 0.
  Given catching depth with pole-and-lines at the surface 7 28 (e.g., 23 18 2 25) up to 10 m 29, barotrauma is unlikely 0.
  • Catching step:  Catching
  • How to improve: prefer shallow catching depth or – if catching at larger depths – prefer slow hauling speed

1.2 Damages/abrasions/lacerations/wounds

Eye damage: no data found yet.

• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)
• With pole-and-lines, after catching, rinsing with sea water 47 46 6 35 to remove blood when the IND are on deck 46 or to get rid of bacteria when the IND are in the storage area 6. Spraying IND with seawater and not properly cleaning them will result in fish blood collecting in the storage 46.
  Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46. IND with injuries will spoil quicker and transmit bacteria to intact IND 46. Other fishers sort out IND with scratches, wounds, burst bellies, other damages and sort large from small IND 6. Manually handling IND by grabbing them and assuming IND are not already dead, hazard consequences are probable 0. Further research needed on types of consequences and on how to avoid them. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching steps:  Sorting Discarding
  • How to improve: post sorting, prefer immediate stunning followed by slaughter while still unconscious, continue with cleaning IND before putting them in storage
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

• With hand lines, fishers lower line down to the FAD and pull up and backwards when they feel an IND bite 14 leading to injuries to the mouth 14.
  With pole-and-lines, as soon as IND bite the hook, fishers pull up and backwards. Given that fishers in Japan use barbed hooks with live bait if the IND are not biting actively 20, injuries to the mouth, gills, oesophagus, and gut are probable 0. Most frequently, fishers use barbless hooks 7 20 2 12 6 which will probably cause injuries to the mouth 0. Further research needed on types of hazard consequences.
  • Catching steps:  Catching Bycatch avoidance Emersion

Opercular/gill damage: no data found yet.

Scale loss: no data found yet.

Broken spine: no data found yet.

• Fishers fish around FADs to locate IND 10 7 11 12 13 14 2. They either install FADs 10 6 or use existing FADs 7 13 14, called "rumpon" 10 14 to specify a traditional type of FAD in Indonesia 15, anchored at 500-1,000 m depth consisting of 3-4 layers of 6 m long bamboo poles, building a raft from which fishers hang coconut leaves as attractor for small FISHES to take shelter and for larger FISHES to find prey 6. FADs can also float and consist of naturally occurring logs 7 or flotsams 11. Given the risk of colliding with or entangling in the FADs during prey pursuit, hazard consequences are probable 0. Further research needed on types of hazard consequences.
  With hand lines and pole-and-lines, in Indonesia, FADs are required to use non-entangling and easily biodegradable material, ensuring that the main parts of the FAD are non-trapping 16. Alternatively to FADs, fishers catch free-schwimming schools 12 11 with a similar catch rate as using FADs 12 but with higher percentage of catchable size than in non-FAD associated schools (90% versus 48.4% IND) 17 and with lower rates of Yellowfin tuna Thunnus albacares bycatch 12. Recommended to target free swimming schools as opposed to FAD-associated fishing 12 17.
  • Catching step:  Prospection
  • How to improve: prefer free-swimming schools over FAD-associated IND; if not possible, use non-entangling FADs
• With hand lines, fishers lower line down to the FAD and pull up and backwards when they feel an IND bite 14 leading to injuries to the mouth 14.
  With pole-and-lines, as soon as IND bite the hook, fishers pull up and backwards. Given that fishers in Japan use barbed hooks with live bait if the IND are not biting actively 20, injuries to the mouth, gills, oesophagus, and gut are probable 0. Most frequently, fishers use barbless hooks 7 20 2 12 6 which will probably cause injuries to the mouth 0. Further research needed on types of hazard consequences.
  • Catching steps:  Catching Bycatch avoidance Emersion
• With hand lines and pole-and-lines, fishers immediately pull when IND bite 23 2 6 14.
  Given catching at the surface with pole-and-lines 7 28 (e.g., 23 18 2 25) up to 10 m 29 compared to depth of 10-100 m with hand lines 28 17, catch duration and therefore time hooked – resulting in hazard consequences – will probably be shorter with pole-and-lines 0.
  • Catching step:  Catching
• With hand lines, IND of 23-42 cm FORK LENGTH caught around shallow water FADs (<200 m deep) versus 29-52 cm around deep-water FADs (>200 m deep) 30, indicating larger catch size at larger depth 0. Recommended to regulate fishing gear depth to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: with hand lines, prefer catching in deeper waters (>200 m) to decrease the catch of JUVENILES
• With hand lines, 48.4% IND of catchable size (dominating size class 31-40 cm) when operated around FADs versus 90% IND of catchable size in non-FAD associated schools. Recommended to avoid FADs to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer free-schwimming schools over FAD-associated IND to avoid catching JUVENILES
• With hand lines, hook sizes 5 and 7 caught IND 23-52 cm FORK LENGTH 30, hook size 9 14. Recommended to regulate hook sizes to reduce the proportion of undersized IND 17.
  With pole-and-lines, hook sizes 2.5-2.8 (probably measured in cm 0) caught IND of <10-60+ cm TOTAL LENGTH 6, hook size 2.5-4 (probably measured in cm 0) caught IND of average 45 cm 28, catch size 21-72 cm 32, hook sizes 2.8-4.8 (probably measured in cm 0) 33, hook sizes 5-7 caught IND of range 25-69 cm FORK LENGTH (mean 40.5 cm FORK LENGTH) 12, hooks 13-15 caught IND of 39-87 cm FORK LENGTH (mean 55.8 cm FORK LENGTH) 27, hook size 16 caught IND of 38-61 cm FORK LENGTH 29.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7 to decrease the number of JUVENILES 12.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer large hook sizes (=smaller number) to avoid catching JUVENILES
• With pole-and-lines, recommended to stop the catching process when catching JUVENILES (<1.5 kg) 34.
  • Catching step:  Bycatch avoidance
  • How to improve: stop catching process when catching JUVENILES
• With pole-and-lines, given that IND are brought on deck with a swinging action at an obtuse angle 3 18 2 37 35 25 26 and drop heavily on the flying deck 20 18 6, the front deck 3 2 37 19, or the back deck 7 23 24 21 35 22 25 26, hazard consequences are probable 0. With pole-and-lines in general, dropping from considerable height onto hard deck surface led to physical damage (e.g., broken skull and stomach) in 25.5-28.6% of IND caught 38. Further research needed to determine whether this applies to K. pelamis as well.
  Fishers can manually unhook IND by gently catching them under the left arm and removing the hook from the mouth using their right hand before placing them on the deck of the fishing vessel 24 or when the IND are less active 6 or caught with baited barbed hooks 20. Dropping from under the arm or swinging the IND at a relatively acute angle results in a reduced drop height 23.
  With pole-and-lines, recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching step:  Release from gear
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), and keep surface moist; if not available or possible, swing IND at acute angle or catch under the arm to gently unhook and reduce drop height
• With hand lines, IND have to be unhooked manually 14.
  With pole-and-lines, given that fishers in Japan use barbed hooks with live bait if the IND are not biting actively 20, during release from these hooks, injuries to the mouth, gills, oesophagus, and gut are probable 0. Most frequently, fishers use barbless hooks 7 2 12 6 20 which will cause injuries to the mouth during unhooking – at times tearing or dislocating bones in the upper jaw 40 – but generally of small extent 40. Given forced manual unhooking in case the IND was hooked deeply 35, mouth injuries are probable 0. Further research needed on types of hazard consequences.
  With pole-and-lines, IND have to be unhooked either by a jerk mid-air or after the IND land on the deck 3 23 18 2 35 or manually after being brought on to the vessel 23 24 6. In the case of manual unhooking, the fishers pull up the IND into one arm and gently unhook them using the other hand before dropping them on the deck of the fishing vessel 24 20.
  In recreational angling of some species ≤35 cm, longer mean unhooking time for barbed than barbless hooks, especially in larger FISHES 41 42, but no difference in other species of mean 34.6 cm TOTAL LENGTH 43. No difference in rate of deep hooking (=oesophagus or stomach, sometimes also gills) between barbed and barbless hooks 41 43. Higher incidence of moderate to severe injuries in barbed than barbless hooks in some species 42, but no difference between mild, moderate, and severe injuries in other species, probably due to appropriate hook size:fish size ratio 43. Further research needed to determine which of these results apply to hand lines or pole-and-lines and K. pelamis as well.
  • Catching step:  Release from gear
  • How to improve: prefer barbless hooks over barbed hooks (further research needed) and gently over forced unhooking
• With hand lines and pole-and-lines, given that fishers lift IND out of the water onto the deck (e.g., 7 23 20 2 6 35 22 9 36), given that water is a relatively denser medium, and given no evolutionary adaptation to experiencing own weight in air 44, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Release from gear Storing
• With pole-and-lines, after catching, rinsing with sea water 47 46 6 35 to remove blood when the IND are on deck 46 or to get rid of bacteria when the IND are in the storage area 6. Spraying IND with seawater and not properly cleaning them will result in fish blood collecting in the storage 46.
  Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46. IND with injuries will spoil quicker and transmit bacteria to intact IND 46. Other fishers sort out IND with scratches, wounds, burst bellies, other damages and sort large from small IND 6. Manually handling IND by grabbing them and assuming IND are not already dead, hazard consequences are probable 0. Further research needed on types of consequences and on how to avoid them. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching steps:  Sorting Discarding
  • How to improve: post sorting, prefer immediate stunning followed by slaughter while still unconscious, continue with cleaning IND before putting them in storage
• With pole-and-lines, given that after sorting, fishers throw IND into storage 46 6 and given IND are not already dead 45, hazard consequences are probable 0. Further research needed on types of hazard consequences and how to avoid them. Alternatively, fishers use conveyor belts on deck leading to the entry of the underdeck 3 19 2 which reduces drop height by a number of sloped chutes that carry IND to available storage units 3.
  • Catching step:  Sorting
  • How to improve: prefer below-deck system of sloped chutes to carry IND to the storage units; if not possible or available, find alternatives to cushion the fall from deck to storage (further research needed)
• With pole-and-lines, IND occasionally get unhooked before or right after being landed too close to the edge of the vessel, resulting in them getting inadvertently released back into the sea 26. As long as catching takes place, fishers take care not to accidentally throw caught IND back into the water, as this can scare others away 6.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7, release immature IND immediately after boarding 12.
  • Catching step:  Discarding
  • How to improve: avoid accidental discards to not scare IND away (that are still in the water), but discard JUVENILES as soon as possible – further research needed on the way to do that efficiently
• With pole-and-lines, given that after sorting, fishers place IND in a way to maximise storage capacity 6 45 22, piling IND and ice in multiple layers 47 46 and given IND are not already dead, crowding stress is probable 0. If storing a large quantity of IND, use horizontal bulkheads to hold the second and the third layers so that the IND at the bottom layer/level are not crushed 47.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

1.3 Ecchymosis

• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, given that after sorting, fishers place IND in a way to maximise storage capacity 6 45 22, piling IND and ice in multiple layers 47 46 and given IND are not already dead, crowding stress is probable 0. If storing a large quantity of IND, use horizontal bulkheads to hold the second and the third layers so that the IND at the bottom layer/level are not crushed 47.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

1.4 Desiccation (surface issue)

• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

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 contact with the gear, lack of oxygen, and handling/dropping. To avoid it during prospection, use remote sensing for detecting potential fishing zones (NOAA meteorological satellite image receiver) and approach school from left or right instead of from behind and prevent running into the school to avoid scaring IND away. To avoid it for JUVENILES that might be released, prefer free-schwimming schools over FAD-associated IND, prefer large hook sizes (=smaller number), stop catching process when catching JUVENILES, avoid accidental discards to not scare IND away (that are still in the water), but discard JUVENILES as soon as possible – further research needed on the way to do that efficiently; with hand lines, prefer catching in deeper waters (>200 m). To avoid it during release from gear and sorting, keep the landing deck smooth, cover it with suitable cushioning (e.g., tarpaulin), keep the surface moist, avoid crowding, and prefer non-manual handling (e.g., conveyor belt). To avoid it during sorting, prefer below-deck system of sloped chutes to carry IND to the storage units; if not possible or available, find alternatives to cushion the fall from deck to storage. Post sorting, prefer immediate stunning followed by slaughter while still unconscious, continue with cleaning IND before putting them in storage. Further research needed. Stress is probably not an issue during setting, as fishers use water spraying to not invoke fear of the boat and as fishers cover the hook with raffia rope and chicken feathers, add shiny lead weight, and perform jerking movements with the line to not invoke fear of the hook.

Cortisol, glucose, lactate, other physiological stress parameters: no data found yet.

Opercular movement: no data found yet.

• With pole-and-lines, fishers use echosound/sonar devices to locate IND 2 3 4. Fishers use low frequency sonar with a range of 1,500 m with low resolution and 500m with high resolution to locate schools of IND and observe their behaviour 5. They also use high frequency and tilt-scanning sonars 5. Further research needed on types of hazard consequences. Fishers use NOAA meteorological satellite image receiver (NOAA receiver) to locate fishing grounds near the Japanese shore 5.
  • Catching step:  Prospection
  • How to improve: use remote sensing for detecting potential fishing zones (NOAA meteorological satellite image receiver)
• With pole-and-lines, fishers spot fishing grounds by observing the sea surface (ripples/splashes, jumping IND) 4 6, flying 7 4 2 or diving birds 6, or dolphins 8 9. Approaching school from left or right instead of from behind does not scare IND away 6. Recommended to avoid directing vessel directly into the school, as IND will dive away and resurface at a distance 4. When fishing starts and the boat is stopped, fishers keep engines on to be able to chase school should it move away 6.
  • Catching step:  Prospection
  • How to improve: approach school from left or right instead of from behind and prevent running into the school to avoid scaring IND away
• With pole-and-lines, once boat is adjacent to school, water spraying with pump system from bow 18 12 2 6 9, the bow and the port side 3 19 20 the bow, the port, and the starboard sides 21 22, the stern 7 23 24 25 26, or the stern and starboard sides 27 of the vessel to hide sight of boat 4 6 and to simulate a school of prey 4. Fishers throw live bait 27 23 to attract IND to the bow 18 2 6 9, bow and the port side 3 19 20, or to the stern and start a feeding frenzy 7 4 25 26. When fishing starts and the boat is stopped, fishers keep engines on to be able to chase school should it move away 6. Fishers throw line with barbless hook 7 20 2 12 6 covered by raffia rope 6 or chicken feathers 12 6 in spraying water – both measures to hide sight of hook 6.
  • Catching step:  Setting
  • How to improve: distract IND with water spraying and cover hook with raffia rope and chicken feathers to not invoke fear of boat and hook
• With hand lines, upon reaching the fishing ground, the line was deployed near the FAD 14. Dependent on the type of bait, fishers used trolling with artificial baits like chicken feathers and silk cloth and threw live bait FISHES in the water 13.
  With pole-and-lines, fishers throw live bait 27 23 to attract IND 3 18 19 2 6 9 and start a feeding frenzy 7 4 25 26. Hook has lead weight covered in shiny nickel to attract IND 6. Fishers jerk the line to simulate live bait 6.
  • Catching step:  Setting
  • How to improve: attract IND with shiny lead weight and jerking movements with the line to not invoke fear of hook
• With hand lines, fishers lower line down to the FAD and pull up and backwards when they feel an IND bite 14 leading to injuries to the mouth 14.
  With pole-and-lines, as soon as IND bite the hook, fishers pull up and backwards. Given that fishers in Japan use barbed hooks with live bait if the IND are not biting actively 20, injuries to the mouth, gills, oesophagus, and gut are probable 0. Most frequently, fishers use barbless hooks 7 20 2 12 6 which will probably cause injuries to the mouth 0. Further research needed on types of hazard consequences.
  • Catching steps:  Catching Bycatch avoidance Emersion
• With hand lines and pole-and-lines, fishers immediately pull when IND bite 23 2 6 14.
  Given catching at the surface with pole-and-lines 7 28 (e.g., 23 18 2 25) up to 10 m 29 compared to depth of 10-100 m with hand lines 28 17, catch duration and therefore time hooked – resulting in hazard consequences – will probably be shorter with pole-and-lines 0.
  • Catching step:  Catching
• With hand lines, IND of 23-42 cm FORK LENGTH caught around shallow water FADs (<200 m deep) versus 29-52 cm around deep-water FADs (>200 m deep) 30, indicating larger catch size at larger depth 0. Recommended to regulate fishing gear depth to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: with hand lines, prefer catching in deeper waters (>200 m) to decrease the catch of JUVENILES
• With hand lines, 48.4% IND of catchable size (dominating size class 31-40 cm) when operated around FADs versus 90% IND of catchable size in non-FAD associated schools. Recommended to avoid FADs to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer free-schwimming schools over FAD-associated IND to avoid catching JUVENILES
• With hand lines, hook sizes 5 and 7 caught IND 23-52 cm FORK LENGTH 30, hook size 9 14. Recommended to regulate hook sizes to reduce the proportion of undersized IND 17.
  With pole-and-lines, hook sizes 2.5-2.8 (probably measured in cm 0) caught IND of <10-60+ cm TOTAL LENGTH 6, hook size 2.5-4 (probably measured in cm 0) caught IND of average 45 cm 28, catch size 21-72 cm 32, hook sizes 2.8-4.8 (probably measured in cm 0) 33, hook sizes 5-7 caught IND of range 25-69 cm FORK LENGTH (mean 40.5 cm FORK LENGTH) 12, hooks 13-15 caught IND of 39-87 cm FORK LENGTH (mean 55.8 cm FORK LENGTH) 27, hook size 16 caught IND of 38-61 cm FORK LENGTH 29.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7 to decrease the number of JUVENILES 12.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer large hook sizes (=smaller number) to avoid catching JUVENILES
• With pole-and-lines, recommended to stop the catching process when catching JUVENILES (<1.5 kg) 34.
  • Catching step:  Bycatch avoidance
  • How to improve: stop catching process when catching JUVENILES
• With hand lines and pole-and-lines, given that fishers lift IND out of the water onto the deck (e.g., 7 23 20 2 6 35 22 9 36) and given that IND emerge out of water with a high metabolic rate, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Emersion Release from gear Discarding
• With hand lines and pole-and-lines, given that fishers lift IND out of the water onto the deck (e.g., 7 23 20 2 6 35 22 9 36), given that water is a relatively denser medium, and given no evolutionary adaptation to experiencing own weight in air 44, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Release from gear Storing
• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)
• With pole-and-lines, after catching, rinsing with sea water 47 46 6 35 to remove blood when the IND are on deck 46 or to get rid of bacteria when the IND are in the storage area 6. Spraying IND with seawater and not properly cleaning them will result in fish blood collecting in the storage 46.
  Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46. IND with injuries will spoil quicker and transmit bacteria to intact IND 46. Other fishers sort out IND with scratches, wounds, burst bellies, other damages and sort large from small IND 6. Manually handling IND by grabbing them and assuming IND are not already dead, hazard consequences are probable 0. Further research needed on types of consequences and on how to avoid them. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching steps:  Sorting Discarding
  • How to improve: post sorting, prefer immediate stunning followed by slaughter while still unconscious, continue with cleaning IND before putting them in storage
• With pole-and-lines, given that after sorting, fishers throw IND into storage 46 6 and given IND are not already dead 45, hazard consequences are probable 0. Further research needed on types of hazard consequences and how to avoid them. Alternatively, fishers use conveyor belts on deck leading to the entry of the underdeck 3 19 2 which reduces drop height by a number of sloped chutes that carry IND to available storage units 3.
  • Catching step:  Sorting
  • How to improve: prefer below-deck system of sloped chutes to carry IND to the storage units; if not possible or available, find alternatives to cushion the fall from deck to storage (further research needed)
• With pole-and-lines, sharks that follow the fishing vessel specifically target IND that have fallen off the hook 7. Given that IND are probably stressed by hooking and potential emersion, there is a higher probability of falling prey to sharks 0.
  • Catching step:  Discarding
• With pole-and-lines, IND occasionally get unhooked before or right after being landed too close to the edge of the vessel, resulting in them getting inadvertently released back into the sea 26. As long as catching takes place, fishers take care not to accidentally throw caught IND back into the water, as this can scare others away 6.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7, release immature IND immediately after boarding 12.
  • Catching step:  Discarding
  • How to improve: avoid accidental discards to not scare IND away (that are still in the water), but discard JUVENILES as soon as possible – further research needed on the way to do that efficiently
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, given that after sorting, fishers place IND in a way to maximise storage capacity 6 45 22, piling IND and ice in multiple layers 47 46 and given IND are not already dead, crowding stress is probable 0. If storing a large quantity of IND, use horizontal bulkheads to hold the second and the third layers so that the IND at the bottom layer/level are not crushed 47.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, after catching, rinsing with sea water 47 46 6 35 to remove blood when the IND are on deck 46 or to get rid of bacteria when the IND are in the storage area 6. Spraying IND with seawater and not properly cleaning them will result in fish blood collecting in the storage 46. Assuming that IND are not already dead, hazard consequences are probable 0.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• LAB: spiking in two places (hind brain and before tail) led to immediate loss of motion (except a short time of trembling) and higher bleeding rate than individually spiking heart, behind pectoral fin, or before tail, and combining spiking hind brain and behind pectoral fin 48. Higher scores in preference survey for meat colour and taste in IND spiking (hind brain + 1 min) and placed in ice water than just placed in ice water 48.
  • Catching step:  Slaughter

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) water. To avoid it during storing, prefer immediate stunning followed by slaughter while still unconscious. Temperature shock during catching is probably not an issue in pole-and-lines, as catching takes place at the surface. To avoid it in hand lines, prefer shallow catching depth. Further research needed.

• Given catching depth with hand lines at 10-100 m 17, 100 m 28, temperature shock is possible 0.
  Given catching depth with pole-and-lines at the surface 7 28 (e.g., 23 18 2 25) up to 10 m 29, temperature shock is unlikely 0.
  • Catching step:  Catching
  • How to improve: prefer shallow catching depth
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

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?

There is no conclusion yet.

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?

There is no conclusion yet.

Unspecified: no data found yet.

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 from emersion on. To avoid it, prefer immediate stunning followed by slaughter while still unconscious. Further research needed.

• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)

• With hand lines and pole-and-lines, given that fishers lift IND out of the water onto the deck (e.g., 7 23 20 2 6 35 22 9 36) and given that IND emerge out of water with a high metabolic rate, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Emersion Release from gear Discarding
• With hand lines and pole-and-lines, given that fishers lift IND out of the water onto the deck (e.g., 7 23 20 2 6 35 22 9 36), given that water is a relatively denser medium, and given no evolutionary adaptation to experiencing own weight in air 44, hazard consequences are probable 0. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Release from gear Storing
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, given that after sorting, fishers place IND in ice-water mix and seal storage to avoid exposure to air 6, given that storage holds are sealed with insulating agents 10, and assuming IND are not already dead, hazard consequences are probable 0. Further research needed on types of hazard consequences.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious
• With pole-and-lines, fishers leave IND to flounder on deck 23 18 37 21 35 45 22 26 until whole catch has been taken in resulting in asphyxia in air 46 36.
  With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, probably no stunning and slaughter but asphyxia or hypothermia or both 0.
  With pole-and-lines, given that after sorting, fishers place IND on ice and dilute with sea water, then seal storage to avoid exposure to air 6 and given that storage holds are sealed with insulating agents 10, probably no stunning and slaughter but hypoxia or hypothermia or both 0.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  LAB: percussive stunning or piercing hind brain both followed by deep freezing at -60 °C resulted in higher pH, lower metmyoglobin ratio, and higher organoleptic value than IND percussively stunned and placed in ice water 48.
  • Catching step:  Slaughter
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious; LAB: percussion of head+gutting or percussion of head/spiking of brain+deep freeze

Unspecified: no data found yet.

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?

There is no conclusion yet.

Unspecified: no data found yet.

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?

There is no conclusion yet.

Inactivity/low vitality: no data found yet.

Oxidative stress: no data found yet.

Unspecified: no data found yet.

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?

IND may be scared during prospection and setting. To avoid it, approach school from left or right instead of from behind and prevent running into the school, distract IND with water spraying and cover hook with raffia rope and chicken feathers to not invoke fear of boat and hook, attract IND with shiny lead weight and jerking movements with the line to not invoke fear of hook. IND that are still in the water may be scared during discarding. Try to avoid accidental discards.

9.1 Fear (continuum up to panic)

Freeze: no data found yet.

• LAB: for the Bluefin tuna Thunnus thynnus, exposure to boat engine sound caused a potential avoidance behaviour in FISHES, where they swam vertically to the water surface and occasionally to the bottom of a semi-enclosed area 1. Further research needed to determine whether this applies to K. pelamis as well.
  • Catching step:  Prospection
• With pole-and-lines, IND occasionally get unhooked before or right after being landed too close to the edge of the vessel, resulting in them getting inadvertently released back into the sea 26. As long as catching takes place, fishers take care not to accidentally throw caught IND back into the water, as this can scare others away 6.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7, release immature IND immediately after boarding 12.
  • Catching step:  Discarding
  • How to improve: avoid accidental discards to not scare IND away (that are still in the water), but discard JUVENILES as soon as possible – further research needed on the way to do that efficiently

• With pole-and-lines, fishers spot fishing grounds by observing the sea surface (ripples/splashes, jumping IND) 4 6, flying 7 4 2 or diving birds 6, or dolphins 8 9. Approaching school from left or right instead of from behind does not scare IND away 6. Recommended to avoid directing vessel directly into the school, as IND will dive away and resurface at a distance 4. When fishing starts and the boat is stopped, fishers keep engines on to be able to chase school should it move away 6.
  • Catching step:  Prospection
  • How to improve: approach school from left or right instead of from behind and prevent running into the school to avoid scaring IND away
• With pole-and-lines, once boat is adjacent to school, water spraying with pump system from bow 18 12 2 6 9, the bow and the port side 3 19 20 the bow, the port, and the starboard sides 21 22, the stern 7 23 24 25 26, or the stern and starboard sides 27 of the vessel to hide sight of boat 4 6 and to simulate a school of prey 4. Fishers throw live bait 27 23 to attract IND to the bow 18 2 6 9, bow and the port side 3 19 20, or to the stern and start a feeding frenzy 7 4 25 26. When fishing starts and the boat is stopped, fishers keep engines on to be able to chase school should it move away 6. Fishers throw line with barbless hook 7 20 2 12 6 covered by raffia rope 6 or chicken feathers 12 6 in spraying water – both measures to hide sight of hook 6.
  • Catching step:  Setting
  • How to improve: distract IND with water spraying and cover hook with raffia rope and chicken feathers to not invoke fear of boat and hook
• With hand lines, upon reaching the fishing ground, the line was deployed near the FAD 14. Dependent on the type of bait, fishers used trolling with artificial baits like chicken feathers and silk cloth and threw live bait FISHES in the water 13.
  With pole-and-lines, fishers throw live bait 27 23 to attract IND 3 18 19 2 6 9 and start a feeding frenzy 7 4 25 26. Hook has lead weight covered in shiny nickel to attract IND 6. Fishers jerk the line to simulate live bait 6.
  • Catching step:  Setting
  • How to improve: attract IND with shiny lead weight and jerking movements with the line to not invoke fear of hook

Startling behaviour: no data found yet.

Unspecified: no data found yet.

9.2 Other

Unspecified: no data found yet.

Although killing 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 lack of oxygen and handling/dropping. To avoid it for JUVENILES that might be released, prefer free-schwimming schools over FAD-associated IND, prefer large hook sizes (=smaller number), stop catching process when catching JUVENILES; with hand lines, prefer catching in deeper waters (>200 m). To avoid it during release from gear and sorting, keep the landing deck smooth, cover it with suitable cushioning (e.g., tarpaulin), keep the surface moist, avoid crowding, and prefer non-manual handling (e.g., conveyor belt). To avoid it during storing, prefer immediate stunning followed by slaughter while still unconscious. Further research needed.

• With hand lines, IND of 23-42 cm FORK LENGTH caught around shallow water FADs (<200 m deep) versus 29-52 cm around deep-water FADs (>200 m deep) 30, indicating larger catch size at larger depth 0. Recommended to regulate fishing gear depth to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: with hand lines, prefer catching in deeper waters (>200 m) to decrease the catch of JUVENILES
• With hand lines, 48.4% IND of catchable size (dominating size class 31-40 cm) when operated around FADs versus 90% IND of catchable size in non-FAD associated schools. Recommended to avoid FADs to reduce the proportion of undersized IND 17.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer free-schwimming schools over FAD-associated IND to avoid catching JUVENILES
• With hand lines, hook sizes 5 and 7 caught IND 23-52 cm FORK LENGTH 30, hook size 9 14. Recommended to regulate hook sizes to reduce the proportion of undersized IND 17.
  With pole-and-lines, hook sizes 2.5-2.8 (probably measured in cm 0) caught IND of <10-60+ cm TOTAL LENGTH 6, hook size 2.5-4 (probably measured in cm 0) caught IND of average 45 cm 28, catch size 21-72 cm 32, hook sizes 2.8-4.8 (probably measured in cm 0) 33, hook sizes 5-7 caught IND of range 25-69 cm FORK LENGTH (mean 40.5 cm FORK LENGTH) 12, hooks 13-15 caught IND of 39-87 cm FORK LENGTH (mean 55.8 cm FORK LENGTH) 27, hook size 16 caught IND of 38-61 cm FORK LENGTH 29.
  With pole-and-lines, of IND 25-69 cm FORK LENGTH caught, 53% immature – not so different from size range caught in purse seine and challenging the future of the population 12. Recommended to use larger hooks (=smaller number) than 5-7 to decrease the number of JUVENILES 12.
  • Catching step:  Bycatch avoidance
  • How to improve: prefer large hook sizes (=smaller number) to avoid catching JUVENILES
• With pole-and-lines, recommended to stop the catching process when catching JUVENILES (<1.5 kg) 34.
  • Catching step:  Bycatch avoidance
  • How to improve: stop catching process when catching JUVENILES
• With pole-and-lines, given that IND are brought on deck with a swinging action at an obtuse angle 3 18 2 37 35 25 26 and drop heavily on the flying deck 20 18 6, the front deck 3 2 37 19, or the back deck 7 23 24 21 35 22 25 26, hazard consequences are probable 0. With pole-and-lines in general, dropping from considerable height onto hard deck surface led to physical damage (e.g., broken skull and stomach) in 25.5-28.6% of IND caught 38. Further research needed to determine whether this applies to K. pelamis as well.
  Fishers can manually unhook IND by gently catching them under the left arm and removing the hook from the mouth using their right hand before placing them on the deck of the fishing vessel 24 or when the IND are less active 6 or caught with baited barbed hooks 20. Dropping from under the arm or swinging the IND at a relatively acute angle results in a reduced drop height 23.
  With pole-and-lines, recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching step:  Release from gear
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), and keep surface moist; if not available or possible, swing IND at acute angle or catch under the arm to gently unhook and reduce drop height
• With pole-and-lines, no sorting while catching is ongoing: fishers let IND flounder on deck 23 18 37 21 35 45 22 26 often in crowded conditions – resulting in cuts and bruises – and only sort IND manually after the whole catch has been taken in 46 36 45, which in the Maldives can take 5 min to >4 h 7 and thus might already be after death 46 36. Given that IND are crowded on the deck 38 during the sorting process 37 and get kicked on or stood upon by the fishers 37, hazard consequences are probable 0. Some fishers do not sort out IND with injuries and bruises or sort large from small IND 46, but wait until they are immobile 45 to put all IND into storage by grabbing them with hands 46 45 (large-sized IND: 2-5 with one grab, small-sized IND: 8+ with one grab) 46.
  Given that IND – that were dropped on the sloping flying deck 18 6 9 or a sloped ramp on the main deck 2 and released from hook – slide down onto the main deck 18 6 9 or directly to the storage unit 20 22 or on to a crowded conveyor belt leading to the storage unit 3 19 2, physical injuries are probable 0. Further research needed on types of hazard consequences and on how to avoid them. Recommended to keep landing deck smooth and free of obstructions to avoid bruises and damages 4. Recommended to cover landing deck with tarpaulin or another sheet and keep those wet to avoid scratches, skin abrasions, bruises 4 (see here for unidentified tunas caught with pole-and-lines 39).
  • Catching steps:  Sorting Discarding
  • How to improve: keep landing deck smooth, cover with suitable cushioning (e.g., tarpaulin), keep surface moist, avoid crowding, prefer non-manual handling (e.g., conveyor belt)
• With pole-and-lines, sharks that follow the fishing vessel specifically target IND that have fallen off the hook 7. Given that IND are probably stressed by hooking and potential emersion, there is a higher probability of falling prey to sharks 0.
  • Catching step:  Discarding
• With pole-and-lines, given storing on board with ice 7 47 46 36 or without ice 36, in ice-water mix (vessels 20-200 gross tonnage) 5 3 2 6 9, mixture of sea and cold fresh water 20, in refrigerated seawater 8, or in deep freeze (vessels >200 gross tonnage) 5 and given that in some cases, the IND are not already dead 45 22, hazard consequences are probable 0. Further research needed on types of hazard consequences. Layering IND and ice in storage kept organoleptic quality, microbial count, and histamine levels below safety threshold 47 if stacked evenly 47 46 and not too high 47. Putting in ice-water mix immediately after arriving on deck improved quality over keeping in air 36. Mixing ice with sea water reduced pressure from ice to skin and avoids skin damage 6.
  LAB: immediately killing the IND after arriving on board (percussive stunning followed by gutting) and then storing in ice at ice:IND ratio 1:1 is recommended for better quality 10.
  • Catching step:  Storing
  • How to improve: prefer immediate stunning followed by slaughter while still unconscious

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?

There is no conclusion yet.

Unspecified: no data found yet.