Version: B | 1.1 (2022-06-23)
Please note: This part of the profile is currently being revised.
Condensed assessment of the species' likelihood and potential for good fish welfare in aquaculture, based on ethological findings for 10 crucial criteria.
Li = Likelihood that the individuals of the species experience good welfare under minimal farming conditions
Po = Potential of the individuals of the species to experience good welfare under high-standard farming conditions
Ce = Certainty of our findings in Likelihood and Potential
FishEthoScore = Sum of criteria scoring "High" (max. 10)
Gadus morhua is one of the most important commercial fish species in Northern Europe and North America’s eastern coast. Cods stocks were heavily reduced during the 1980s, and today the fishery is very low compared to historical levels. Stock collapses increased the investments in cod aquaculture enterprises, both hatcheries and on-growing farms began to accelerate. Within a few years an annual production capacity in the order of 60 million juveniles and around 400 on-growing sites was built up in Norway alone. However, the financial market crisis in 2008, together with recover of natural stocks decreased aquaculture production. Despite the big investment in cod aquaculture, the living conditions and the husbandry systems that maximise the welfare of this species are still to be defined, developed and improved. This lack is quite incomprehensible, given the background and the availability of research performed on this species. To optimise fish welfare of this species, improvements are mainly needed to meet home range and depth range needs, reproduction without manipulation, deformation rate, aggression and stress reduction.
1 Home range
Many species traverse in a limited horizontal space (even if just for a certain period of time per year); the home range may be described as a species' understanding of its environment (i.e., its cognitive map) for the most important resources it needs access to. What is the probability of providing the species' whole home range in captivity?It is low for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Larvae: WILD: no data found yet. FARM: intensive system: tanks: 1.5 m3 1 2; extensive system: 5-200,000 m3 1 2.
Juveniles: WILD: 0.5-15 km 3 4 5 6 7, or about 27 ha 8. FARM: circular tanks: 5,000-9,000 L 9. Sea cages: 15 x 15 m Meager et al. 2010, adapted from salmon, max 35x35 m or 90 m diameter 10.
Adults ➝ Juveniles.
Spawners: WILD: home range 3-26 km 7, spawning arena range: 1.7-50.8 ha Meager et al. 2010. FARM: tanks: >25 m3 11.
2 Depth range
Given the availability of resources (food, shelter) or the need to avoid predators, species spend their time within a certain depth range. What is the probability of providing the species' whole depth range in captivity?It is low for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Larvae: WILD and FARM: no data found yet.
Juveniles: WILD: 15-165 m depth 12 6 7. FARM: sea cages: 12 m Meager et al. 2010, adapted from salmon, max 50 m depth 10.
Adults: ➝ Juveniles.
Spawners: WILD: 50–200 m depth 13 14, mostly at 20-40 m on spawning arena of 30-68 m Meager et al. 2010. FARM: no data found yet.
Some species undergo seasonal changes of environments for different purposes (feeding, spawning, etc.) and with them, environmental parameters (photoperiod, temperature, salinity) may change, too. What is the probability of providing farming conditions that are compatible with the migrating or habitat-changing behaviour of the species?It is low for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
A species reproduces at a certain age, season, and sex ratio and possibly involving courtship rituals. What is the probability of the species reproducing naturally in captivity without manipulation of theses circumstances?It is low for minimal and high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Species differ in the way they co-exist with conspecifics or other species from being solitary to aggregating unstructured, casually roaming in shoals or closely coordinating in schools of varying densities. What is the probability of providing farming conditions that are compatible with the aggregation behaviour of the species?There are unclear findings for minimal farming conditions. It is high for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Larvae: WILD: no data found yet. FARM: intensive conditions 150-300 larvae/L 22 FAO).
Juveniles: WILD: schooling and shoaling 23 Fahay et al.1999 24. FARM: tanks: 35-95 kg/m3 25; offshore cages: 15-35 kg/m3 26, 3-6 IND/m3 Meager et al. 2010; usually 20 kg/m3 27 the same used for the Salmo salar.
Adults: ➝ Juveniles.
Spawners: WILD: form spawning aggregations 28 13. FARM: no data found yet.
There is a range of adverse reactions in species, spanning from being relatively indifferent towards others to defending valuable resources (e.g., food, territory, mates) to actively attacking opponents. What is the probability of the species being non-aggressive and non-territorial in captivity?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Larvae: WILD: no data found yet. LAB: cannibalistic 2 29. FARM: no data found yet.
Juveniles: WILD and FARM: cannibalistic 30. LAB: aggressive behaviour 31 32 33 9; cannibalistic 34 29. Appropriate feed and feeding strategies reduce aggression and cannibalism 34 31 33 9.
Adults: ➝ Juveniles.
Spawners: WILD: mate competition 35. FARM: no data found yet.
Depending on where in the water column the species lives, it differs in interacting with or relying on various substrates for feeding or covering purposes (e.g., plants, rocks and stones, sand and mud). What is the probability of providing the species' substrate and shelter needs in captivity?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Larvae: WILD: use substrate 36. FARM: no data found yet.
Juveniles: WILD: use substrate 3 37 37 36. FARM: no data found yet. LAB: net pens: lower frequency of interaction with the net wall (biting the net may result in escapes) with enrichment (mainly PVC pipes on the bottom) compared to plain compartment Zimmermann et al. 2012.
Adults: WILD and FARM: ➝ Juveniles.
Spawners: WILD: use substrate 38 39 13. FARM: no data found yet.
Farming involves subjecting the species to diverse procedures (e.g., handling, air exposure, short-term confinement, short-term crowding, transport), sudden parameter changes or repeated disturbances (e.g., husbandry, size-grading). What is the probability of the species not being stressed?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Larvae: stressed by grading, netting and transporting 40.
Juveniles: stressed by grading 40, netting 40 41, transporting 40, anthropogenic noise 42, hypoxia 43, and air exposure 41. For stress and temperature ➝ crit. 3.
Adults: stressed by netting 41, anthropogenic noise 42, hypoxia 43, and air exposure 41. For stress and temperature ➝ crit. 3.
Spawners: stressed by anthropogenic noise 42.
Deformities that – in contrast to diseases – are commonly irreversible may indicate sub-optimal rearing conditions (e.g., mechanical stress during hatching and rearing, environmental factors unless mentioned in crit. 3, aquatic pollutants, nutritional deficiencies) or a general incompatibility of the species with being farmed. What is the probability of the species being malformed rarely?It is low for minimal farming conditions. It is medium for high-standard farming conditions. Our conclusion is based on a medium amount of evidence.
Larvae: malformations of the vertebral column 44. Further research needed on the percentage rate.
Juveniles: malformations of the vertebral column in 4.1% fed with zooplankton and 14.2% fed with rotifers during larvae stage 45; malformations of the vertebral column in >20% of individuals 46 47.
Adults: ➝ Juveniles.
The cornerstone for a humane treatment is that 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 farming conditions, and c) avoids pain, suffering, and distress. What is the probability of the species being slaughtered according to a humane slaughter protocol?It is high for minimal and high-standard farming conditions. Our conclusion is based on a high amount of evidence.
Common and high-standard slaughter method: a protocol for electrical stunning and killing by bleeding is available. Most effective when stunned at 107 Vrms 0.5+0.2 Arms for 15 s and exsanguination immediately after stunning 48 49. Stunning in a bath containing AQUI-STM anaesthesia induces unconsciousness without recovery and permits to reduce the stunning time to 5 s without avoidance behaviour or distress 49.
Side note: Domestication
Teletchea and Fontaine introduced 5 domestication levels illustrating how far species are from having their life cycle closed in captivity without wild input, how long they have been reared in captivity, and whether breeding programmes are in place. What is the species’ domestication level?
DOMESTICATION LEVEL 4 50 Jorstad et al. 2013, level 5 being fully domesticated.
Side note: Forage fish in the feed
450-1,000 milliard wild-caught fishes end up being processed into fish meal and fish oil each year which contributes to overfishing and represents enormous suffering. There is a broad range of feeding types within species reared in captivity. To what degree may fish meal and fish oil based on forage fish be replaced by non-forage fishery components (e.g., poultry blood meal) or sustainable sources (e.g., soybean cake)?
All age classes: WILD: omnivorous 51. FARM: fish meal and fish oil may be partly* replaced by non-forage fishery components 52 53 54 55.
*partly = <51% – mostly = 51-99% – completely = 100%
DOMESTICATION LEVEL 4 = entire life cycle closed in captivity without wild inputs 50
FARM = setting in farming environment or under conditions simulating farming environment in terms of size of facility or number of individuals
IND = individuals
LAB = setting in laboratory environment
PHOTOPERIOD = duration of daylight
WILD = setting in the wild
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32 NOT FOUND
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