Author: Jenny Volstorf

Engraulis ringens is the most heavily targeted single fish species in the oceans. It is distributed along the coasts of Peru and Chile in the immensely productive Humboldt current system, a stream carrying cold water from the Antarctic and upwelling deep and nutrient-rich water to the surface. Here, E. ringens finds the preferred cold water and the preferred prey zooplankton. In years of El Nino and in summer, when warm water spreads, E. ringens migrates closer to the coast to stay in cold water layers. Because E. ringens lives in schools, fishing folks predominantly use purse seining to catch it, which imposes the risk of catching under-sized IND. In fact, the target size entails JUVENILES as well as ADULTS. What concerns bycatch of non-target species, E. ringens is the main prey for some penguins, dolphins, boobies, birds, sea lions, and seals among others. These species are in danger of being accidentally caught by the E. ringens fishery, especially by the wooden (32.6-110 m³ holding capacity) or steel industrial fleet (90-870 m³) which catches E. ringens for fish meal production. The wooden small- (<10 m³) and medium-scale fleet (10-32.6 m³) catches E. ringens for direct human consumption and seldomly causes bycatch of larger species than jellyfish.

Besides the high density inside the purse seine during hauling and especially during crowding causing injuries and stress, E. ringens will be easy prey for adjacent predators. Transfer to the vessel mainly happens via pumps which avoids contact with air, but the arrival on deck or in the storage containers is most likely stressful and may lead to injuries. Further research is needed on welfare hazards and their consequences. E. ringens is brought to land without prior stunning or slaughter. A protocol for both, stunning and slaughter, is urgently needed.

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

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

Not all specimens of the target species are equally sought after, e.g., when they are undersized, of wrong sex, wrong age, damaged or over quota. 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

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: in 2000-2008, employing a spawning-related closure of fishing season protected 57% eggs spawned (10.0-14.0 cm females: 67% eggs protected, >14 cm females: 50% eggs protected) 24. Correlation of egg production with recruits into schools indicates effectiveness of closing season for ensuring good recruitment and preventing overexploitation 24. Closure of fishing season continues to be applied and depends on reaching total allowable catch or a fixed date 25 26.
  • How to improve: spawning-related closure of fishing seasons
• target and non-target species: in 2005-2010, in small-scale (holding capacity <10 m³) and medium-scale fleet (10-32.6 m³), fuel consumption/t FISHES increased with size of vessel (from 14.7 kg fuel/t FISHES to 17.2-29.0 kg fuel/t FISHES), in wooden industrial fleet (32.6-110 m³), fuel consumption decreased (from 15.3 to 10.1 kg fuel/t FISHES), similar trend in factors climate change, terrestrial acidification, natural land transformation, freshwater eutrophication, human and ecotoxicity, still: small- and medium-scale fleet amounted to 11,000 t fuel/year, industrial fleet to 84,000 t fuel/year 14. Given the amount of fuel consumption per year, there is the risk of fuel leaks that could potentially have a large impact on local fauna 10.
  • How to improve: industrial fleet with lower fuel consumption/t FISHES, but larger overall fuel consumption than small- to medium-scale fisheries
• target and non-target species: for purse seine fishery in Western and Central Pacific, in 2003-2015, >10,000 pollution incidents including 71% dumped waste (mainly plastics), 16% oil spillages and leakages, 13% abandoned, lost or dumped fishing gear 27. Further research needed to determine whether this applies to E. ringens and purse seine fishery off Peru and Chile as well. Lost fishing gear could potentially have a large impact on local fauna through ghost fishing. In survey among experts from Peru artisanal fishery, anchovy purse seine was voted among active fishing gear with most impact on local fauna 28.
• non-target species: given the principle of purse seine to catch whole schools 6 7, there is the risks to also include co-existing, preyed-on, and predating species 10.
  Usable bycatch: In industrial fleet, bycatch of scyphomedusa Chrysaora plocamia fluctuates in frequency seasonally (5.3% of catching weight in austral summer 2008-2009) and may inflict large economic losses by having bycatch weight subtracted from catching weight (from ca 13% proportion C. plocamia on) and by discarding catch when containing >40% C. plocamia 13. In 1997-2010, catch of small-scale fleet consisted of 11% Scomber japonicus, 7% Trachurus murphyi, 2% Odontesthes regia regia, all used for direct human consumption; industrial fleet with limited bycatch; bycatch of Anchoa nasus by small- and medium-scale fleets sold as fish meal 14.
  Non-usable bycatch: bycatch of Delphinus delphis at rate of 58/19 hauls and of Otaria flavescens at 1/19 hauls 4. In industrial company in 2012, Delphinus delphis at ca 640 IND/year 14. In industrial and artisanal fishery off Chile in 2015-2017, 1,500+ Ardenna creatopus (IUCN: vulnerable) 29-30 31-30. This non-target species bycatch may be reduced (but not completely avoided) through various methods → 6.7. Other. Of 58 accidentally caught Delphinus delphis, 75.7% escaped unharmed by fishermen lowering or raising the net, 19% escaped with lesions 4. Of 58 accidentally caught Delphinus delphis in 19 hauls, 3 died (death rate 0.16/haul, 0.38/fishing trip), of 1 Otaria flavescens in 19 hauls, 1 died (0.05/haul, 0.13/trip) 4. In 2005-2019 off Chilean coast (18-53°S), 13,548 beached Ardenna grisea, 2,115 Spheniscus magellanicus, 1,639 Phalacrocorax bougainvilli, of which A. grisea and S. magellanicus showed high spatial overlap (93% and 72%) and A. grisea showed high temporal correlation (0.6) with combined industrial and artisanal fishery of E. ringens and Strangomera bentincki 32. Welfare hazards including mortality are best avoided by preventing bycatch. Further research needed on gear settings and on other co-existing, preyed-on, and predating species. 
  • How to improve: hydroacoustic scanning, sampling, gentle slipping, landing obligation, bycatch limit
• non-target species: given the principle of purse seine to catch at the surface (avoid the bottom) 6 7, seabed damage or impact on benthos respectively is unlikely 10. When fishing takes place over the shelf or in shallower water, the bottom may be touched 10. The net is not dragged along the seafloor 6 7 8, though, so huge impact on benthos is unlikely 10.

How much is this species targeted annually?

Author: Jenny Volstorf

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 occurs most frequently during contact with the gear and a decreasing distance to neighbours and given lack of care for good welfare. To avoid it, prefer mesh size that avoids catching JUVENILES given body diameter in season and region and take more care to increase welfare. 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 the principle of purse seine to catch at the surface 6 7, there is no risk of barotrauma 11 12.
  • Catching step:  Catching

1.2 Damages/abrasions/lacerations/wounds

Eye damage: no data found yet.

Skin damage: no data found yet.

Scale loss: no data found yet.

Broken spine: no data found yet.

• Given body diameter of ~1.3 cm 2↶3 and mesh size of 1.6 cm 4 or 1.3 cm 5, JUVENILES getting stuck in the net is probable 6 7.
  • Catching steps:  Catching Emersion Release from gear Bycatch avoidance
  • How to improve: prefer mesh size that avoids catching JUVENILES given body diameter in season and region
• Given the principle of purse seine to haul the net close to the ship and crowd the IND before suctioning them into the storage space of the ship 6 7 8, taking 2-3 h/haul 9, average 90 min/haul 4, hazard consequences are probable 10. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Catching Emersion
• E. ringens is mostly processed into fish meal 13 14, so there probably is no non-usable bycatch of the target species, meaning it could increase the risk of lack of care during the catching process leading to injuries 10.
  • Catching steps:  Catching Emersion Release from gear Storing
• Given that JUVENILES aggregate with ADULTS in schools 15 16 17, aggression between conspecifics is unlikely 10.
  • Catching step:  Emersion
• Probably no sorting but direct pumping into the storage space of the ship 13 18 6 7 8. Given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 10. Further research needed on gear settings, on types of hazard consequences, and on how to avoid a decrease in welfare.
  • Catching steps:  Emersion Sorting

1.3 Ecchymosis

Bruising and discoloration of the skin due to squeezing: no data found yet.

1.4 Desiccation (surface issue)

Unspecified: no data found yet.

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 occurs most frequently during contact with the gear and a decreasing distance to neighbour (incl. crowding). Further research needed for ways to avoid it. When it comes to bycatch of the target species, to decrease suffering, the best is to avoid catching IND in the first place by hydroacoustic scanning, sampling, gentle slipping, landing obligations, and bycatch limits.

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

Opercular movement: no data found yet.

• Given the principle of purse seine to haul the net close to the ship and crowd the IND before suctioning them into the storage space of the ship 6 7 8, taking 2-3 h/haul 9, average 90 min/haul 4, hazard consequences are probable 10. Further research needed on types of hazard consequences and on how to avoid them.
  • Catching steps:  Catching Emersion
• Given the principle of purse seine to catch IND at the surface and slowly haul the seine close to the ship 6 7 8 and thus no way of fleeing predators, there is the risk of stress by predators being present in or close to the net 10.
  • Catching step:  Emersion
  • How to improve: for ways to avoid predators in the net → 6.7. Other.
• Probably no sorting but direct pumping into the storage space of the ship 13 18 6 7 8. Given the speed with which IND arrive on deck or slide down chutes respectively and based on the crowding density, hazard consequences are probable 10. Further research needed on gear settings, on types of hazard consequences, and on how to avoid a decrease in welfare.
  • Catching steps:  Emersion Sorting
• After setting the net and in the initial stages of hauling, skippers or captains can get an impression of the catch by looking at a sample of fishes that come to the surface. At that point, they can abort the process if the catch does not include the target species and before the school is crowded 11.
  • Catching step:  Bycatch avoidance
  • How to improve: sampling
• Given that the TOTAL LENGTH of JUVENILES of 7.4-12.3 cm 19 overlaps with the size at catching of 6.3-19.3 cm 20 and as JUVENILES aggregate with ADULTS in schools 15 16 17 and the principle of purse seine is to catch whole schools 6 7, there is a risk of bycatch (accidental catch of undersized, wrong sex, wrong age, damaged, over quota IND) of the target species 10. Bycatch and discards may be reduced by hydroacoustic electronic scanning for identification of school in terms of species and size composition, sampling of individuals within the purse seine, gentle slipping of unwanted catch through modifications of the purse seine, landing obligation for the whole catch plus compliance incentives 5. Peruvian law’s bycatch limit: 5% of total catch 21.
  • Catching step:  Bycatch avoidance
  • How to improve: hydroacoustic scanning, sampling, gentle slipping, landing obligation, bycatch limit
• 2-4 hauls/trip before returning to shore 4, 1 trip of 12-24 h per day 23. Given this duration in live storage, hazard consequences are probable 10.
  • Catching step:  Storing

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 storing, but is prefereable over asphyxia. Further research needed.

• Storage space of the ship usually without refrigeration: ca 10% of small- and medium-scale vessels provide ice, industrial fleet seldomly has refrigerating system installed 14. Given ice, temperature shock is probable, but prefereable over asphyxia 10.
  • Catching step:  Storing

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.

Unspecified: no data found 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 most likely occurs instead of a proper stunning/slaughter protocol. To avoid it, prefer immediate stunning followed by slaughter while the IND is still unconscious. Further research needed

Behaviour indicating lack of oxygen (gulping, tail beating, etc.): no data found yet.

Intolerance towards lower concentrations of oxygen: no data found yet.

• Direct pumping into the storage space of the ship 13 18 6 7 8, so probably no stunning and slaughter but asphyxia 10.
  • Catching step:  Slaughter

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?

Fear may occur during prospection. Further research needed for ways to avoid it.

9.1 Fear (continuum up to panic)

Freeze: no data found yet.

• Within 40 m from 43.6 m long scientific trawler, no horizontal avoidance behaviour from schools when acoustically surveyed with vertical echosounder and multi-beam sonar, but within 5-10 m from the vessel, vertical avoidance by diving to 5 m compared to usual 2 m 1. Behaviour is probably rather due to making room for the vessel volume than "predator" avoidance 1.
  • Catching step:  Prospection

Escape manoeuvres: no data found yet.

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 occurs most frequently during handling. (Mortality due to attacks by con-specifics and due to discards are unlikely.) To avoid it, take more care to increase welfare. Further research needed.

• Given that JUVENILES aggregate with ADULTS in schools 15 16 17, aggression between conspecifics is unlikely 10.
  • Catching step:  Emersion
• Some IND are catapulted away from the chute and lie on deck, some IND are kicked or stood on by fishing folks 18 6 7 8. Further research needed on gear settings, on mortality rate, and on how to avoid mortality.
  • Catching steps:  Release from gear Sorting
• E. ringens is mostly processed into fish meal 13 14, so there probably is no non-usable bycatch of the target species, meaning also accidentally caught undersized, wrong sex, wrong age, damaged IND may be used which reduces discards (and thus mortality) 10.
  • Catching step:  Discarding
  • How to improve: use as fish meal

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.