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.
Adults ➝ Juveniles.
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.
Adults: ➝ Juveniles.
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?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.
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.
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.
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.
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.
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)?
*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
2 Brown, Joseph A., Gidon Minkoff, and V. Puvanendran. 2003. Larviculture of Atlantic cod (Gadus morhua): progress, protocols and problems. Aquaculture 227. 3rd Fish and Shellfish Larviculture Symposium: 357–372. https://doi.org/10.1016/S0044-8486(03)00514-3.
3 Clark, Donald S., and John M. Green. 1990. Activity and movement patterns of juvenile Atlantic cod, Gadus morhua, in Conception Bay, Newfoundland, as determined by sonic telemetry. Canadian Journal of Zoology 68: 1434–1442. https://doi.org/10.1139/z90-214.
4 Pihl, Leif, and Mats Ulmestrand. 1993. Migration pattern of juvenile cod (Gadus morhua) on the Swedish west coast. ICES Journal of Marine Science 50: 63–70. https://doi.org/10.1006/jmsc.1993.1007.
5 Neat, Francis C., Peter J. Wright, Alain F. Zuur, Iain M. Gibb, Fiona M. Gibb, David Tulett, David A. Righton, and Robert J. Turner. 2006. Residency and depth movements of a coastal group of Atlantic cod (Gadus morhua L.). Marine Biology 148: 643–654. https://doi.org/10.1007/s00227-005-0110-6.
6 Aalvik, I.M. 2013. Life history and spatial ecology of Skagerrak coastal cod (Gadus morhua). Master, Oslo, Norway: Centre for Ecological and Evolutionary Synthesis Department of Biology University of Oslo.
7 Neat, Francis C., Victoria Bendall, Barbara Berx, Peter John Wright, Macdara Ó Cuaig, Bryony Townhill, Pieter-Jan Schön, Janette Lee, and David Righton. 2014. Movement of Atlantic cod around the British Isles: implications for finer scale stock management. Journal of Applied Ecology 51: 1564–1574. https://doi.org/10.1111/1365-2664.12343.
8 Espeland, S.H., A.F. Gundersen, E.M. Olsen, H. Knutsen, J. Gjøsæter, and N.C. Stenseth. 2007. Home range and elevated egg densities within an inshore spawning ground of coastal cod. International Council for the Exploration of the Sea - Oxford Journals.: 920–928.
9 Rosenlund, Grethe, and Ólafur Halldórsson. 2007. Cod juvenile production: Research and commercial developments. Aquaculture 268. Larvi 2005: 188–194. https://doi.org/10.1016/j.aquaculture.2007.04.040.
10 Otterå, Håkon. 2004. Cultured Aquatic Species Information Programme. Gadus morhua. Rome: FAO Fisheries and Aquaculture Department.
11 Björnsson, Björn, Hjalti Karlsson, and Vilhjálmur Thorsteinsson. 2010. Effects of anthropogenic feeding on the migratory behaviour of coastal cod (Gadus morhua) in Northwest Iceland. Fisheries Research 106: 81–92. https://doi.org/10.1016/j.fishres.2010.07.007.
12 Pálsson, Ólafur K, and Vilhjálmur Thorsteinsson. 2003. Migration patterns, ambient temperature, and growth of Icelandic cod (Gadus morhua): evidence from storage tag data. Canadian Journal of Fisheries and Aquatic Sciences 60: 1409–1423. https://doi.org/10.1139/f03-117.
13 Grabowski, Timothy B., Kevin M. Boswell, Bruce J. McAdam, R. J. David Wells, and Guđrún Marteinsdóttir. 2012. Characterization of Atlantic Cod Spawning Habitat and Behavior in Icelandic Coastal Waters. PLOS ONE 7: e51321. https://doi.org/10.1371/journal.pone.0051321.
14 Meager, Justin J., Jon Egil Skjæraasen, Ørjan Karlsen, Svein Løkkeborg, Ian Mayer, Kathrine Michalsen, Trygve Nilsen, and Anders Fernö. 2012. Environmental regulation of individual depth on a cod spawning ground. Aquatic Biology 17: 211–221. https://doi.org/10.3354/ab00469.
15 Godø, Olav Rune. 1984. Migration, mingling and homing of North-East Arctic cod from two separated spawning grounds. s. 289-302.
16 Svedäng, H., D. Righton, and P. Jonsson. 2007. Migratory behaviour of Atlantic cod Gadus morhua: natal homing is the prime stock-separating mechanism. Marine Ecology Progress Series 345: 1–12. https://doi.org/10.3354/meps07140.
17 Neuenfeldt, S., D. Righton, F. Neat, P. J. Wright, H. Svedäng, K. Michalsen, S. Subbey, et al. 2013. Analysing migrations of Atlantic cod Gadus morhua in the north-east Atlantic Ocean: then, now and the future. Journal of Fish Biology 82: 741–763. https://doi.org/10.1111/jfb.12043.
18 Pérez-Casanova, J. C., M. L. Rise, B. Dixon, L. O. B. Afonso, J. R. Hall, S. C. Johnson, and A. K. Gamperl. 2008. The immune and stress responses of Atlantic cod to long-term increases in water temperature. Fish & Shellfish Immunology 24: 600–609. https://doi.org/10.1016/j.fsi.2008.01.012.
19 Fahay, MP, PL Berrien, DL Johnson, and WW Morse. 1999. Essential fish habitat source document: Atlantic cod, Gadus morhua, life history and habitat characteristics. NOAA Tech Memo NMFS- NE.
20 Kjesbu, O. S. 1989. The spawning activity of cod, Gadus morhua L. Journal of Fish Biology 34: 195–206. https://doi.org/10.1111/j.1095-8649.1989.tb03302.x.
21 Hansen, Tom, Ørjan Karlsen, Geir Lasse Taranger, Gro-Ingunn Hemre, Jens Christian Holm, and Olav Sigurd Kjesbu. 2001. Growth, gonadal development and spawning time of Atlantic cod (Gadus morhua) reared under different photoperiods. Aquaculture 203: 51–67. https://doi.org/10.1016/S0044-8486(01)00610-X.
22 Baskerville-Bridges, B, and L. J Kling. 2000. Larval culture of Atlantic cod (Gadus morhua) at high stocking densities. Aquaculture 181: 61–69. https://doi.org/10.1016/S0044-8486(99)00220-3.
23 DeBlois, E. M., and G. A. Rose. 1995. Effect of foraging activity on the shoal structure of cod (Gadus morhua). Canadian Journal of Fisheries and Aquatic Sciences 52: 2377–2387. https://doi.org/10.1139/f95-830.
24 Wroblewski, J. S., Bruce G. Nolan, George A. Rose, and Brad deYoung. 2000. Response of individual shoaling Atlantic cod to ocean currents on the northeast Newfoundland Shelf. Fisheries Research 45: 51–59. https://doi.org/10.1016/S0165-7836(99)00096-X.
25 Björnsson, Björn, Agnar Steinarsson, Matthías Oddgeirsson, and Sólveig R. Ólafsdóttir. 2012. Optimal stocking density of juvenile Atlantic cod (Gadus morhua L.) reared in a land-based farm. Aquaculture 356–357: 342–350. https://doi.org/10.1016/j.aquaculture.2012.04.047.
26 Dempster, Tim, Jon-Erik Juell, Jan Erik Fosseidengen, Arne Fredheim, and Pål Lader. 2008. Behaviour and growth of Atlantic salmon (Salmo salar L.) subjected to short-term submergence in commercial scale sea-cages. Aquaculture 276: 103–111. https://doi.org/10.1016/j.aquaculture.2008.01.018.
27 Jones, M. 2004. Cultured Aquatic Species Information Programme. Salmo salar. Rome: FAO Fisheries and Aquaculture Department.
28 Skjæraasen, Jon Egil, Justin J. Meager, Ørjan Karlsen, Jeffrey A. Hutchings, and Anders Fernö. 2011. Extreme spawning-site fidelity in Atlantic cod. ICES Journal of Marine Science 68: 1472–1477. https://doi.org/10.1093/icesjms/fsr055.
29 Puvanendran, V., B.J. Laurel, and J.A. Brown. 2008. Cannibalism of Atlantic cod Gadus morhua larvae and juveniles on first-week larvae. Aquatic Biology 2: 113–118.
30 Blom, G., and A. Folkvord. 1997. A snapshot of cannibalism in 0-group Atlantic cod (Gadus morhua) in a marine pond. Journal of Applied Ichthyology 13: 177–181. https://doi.org/10.1111/j.1439-0426.1997.tb00118.x.
31 Höglund, Erik, Marit Jørgensen Bakke, Øyvind Øverli, Svante Winberg, and Göran E. Nilsson. 2005. Suppression of aggressive behaviour in juvenile Atlantic cod (Gadus morhua) by l-tryptophan supplementation. Aquaculture 249: 525–531. https://doi.org/10.1016/j.aquaculture.2005.04.028.
32 NOT FOUND
33 Hatlen, Bjarne, Barbara Grisdale-Helland, and Ståle J. Helland. 2006. Growth variation and fin damage in Atlantic cod (Gadus morhua L.) fed at graded levels of feed restriction. Aquaculture 261: 1212–1221. https://doi.org/10.1016/j.aquaculture.2006.09.027.
34 Folkvord, Arild, and Håkon Otterå. 1993. Effects of initial size distribution, day length, and feeding frequency on growth, survival, and cannibalism in juvenile Atlantic cod (Gadus morhua L.). Aquaculture 114: 243–260. https://doi.org/10.1016/0044-8486(93)90300-N.
35 Hutchings, Jeffrey A, Todd D Bishop, and Carolyn R McGregor-Shaw. 1999. Spawning behaviour of Atlantic cod, Gadus morhua: evidence of mate competition and mate choice in a broadcast spawner. Canadian Journal of Fisheries and Aquatic Sciences 56: 97–104. https://doi.org/10.1139/f98-216.
36 Tupper, M., and R.G. Boutilier. 1995. Effects of habitat on settlement, growth, and postsettlement surviva antic cod Gadus morhua. Can. J. Fish. Aquat. Sci. 52: 1834–1841.
37 Gotceitas, Vytenis, Sandra Fraser, and Joseph A Brown. 1997. Use of eelgrass beds (Zostera marina) by juvenile Atlantic cod (Gadus morhua). Canadian Journal of Fisheries and Aquatic Sciences 54: 1306–1319. https://doi.org/10.1139/f97-033.
38 Robichaud, D, and G A Rose. 2001. Multiyear homing of Atlantic cod to a spawning ground. Canadian Journal of Fisheries and Aquatic Sciences 58: 2325–2329. https://doi.org/10.1139/f01-190.
39 Wright, P. J., E. Galley, I. M. Gibb, and F. C. Neat. 2006. Fidelity of adult cod to spawning grounds in Scottish waters. Fisheries Research 77: 148–158. https://doi.org/10.1016/j.fishres.2005.10.008.
40 King, William, and David L Berlinsky. 2006. Whole-body corticosteroid and plasma cortisol concentrations in larval and juvenile Atlantic cod Gadus morhua L. following acute stress. Aquaculture Research 37: 1282–1289. https://doi.org/10.1111/j.1365-2109.2006.01558.x.
41 King, William, Lawrence J Buckley, and David L Berlinsky. 2006. Effect of acclimation temperature on the acute stress response in juvenile Atlantic cod, Gadus morhua L., and haddock, Melanogrammus aeglefinus L. Aquaculture Research 37: 1685–1693. https://doi.org/10.1111/j.1365-2109.2006.01623.x.
42 Sierra-Flores, Rogelio, Tim Atack, Hervé Migaud, and Andrew Davie. 2015. Stress response to anthropogenic noise in Atlantic cod Gadus morhua L. Aquacultural Engineering 67: 67–76. https://doi.org/10.1016/j.aquaeng.2015.06.003.
43 Herbert, N. A., and J. F. Steffensen. 2005. The response of Atlantic cod, Gadus morhua, to progressive hypoxia: fish swimming speed and physiological stress. Marine Biology 147: 1403–1412. https://doi.org/10.1007/s00227-005-0003-8.
44 Grotmol, Sindre, Harald Kryvi, and Geir K. Totland. 2005. Deformation of the notochord by pressure from the swim bladder may cause malformation of the vertebral column in cultured Atlantic cod Gadus morhua larvae: a case study. Diseases of Aquatic Organisms 65: 121–128. https://doi.org/10.3354/dao065121.
45 Imsland, Albert K, Atle Foss, Roland Koedijk, Arild Folkvord, Sigurd O Stefansson, and Thor M Jonassen. 2006. Short- and long-term differences in growth, feed conversion efficiency and deformities in juvenile Atlantic cod (Gadus morhua) startfed on rotifers or zooplankton. Aquaculture Research 37: 1015–1027. https://doi.org/10.1111/j.1365-2109.2006.01523.x.
46 Fjelldal, Per Gunnar, Terje van der Meeren, Knut E. Jørstad, and Tom Johnny Hansen. 2009. A radiological study on vertebral deformities in cultured and wild Atlantic cod (Gadus morhua, L.). Aquaculture 289: 6–12. https://doi.org/10.1016/j.aquaculture.2008.12.025.
47 Uglem, Ingebrigt, Marius Berg, Rebecca Varne, Rune Nilsen, Jarle Mork, and Pål Arne Bjørn. 2011. Discrimination of wild and farmed Atlantic cod (Gadus morhua) based on morphology and scale-circuli pattern. ICES Journal of Marine Science 68: 1928–1936. https://doi.org/10.1093/icesjms/fsr120.
48 Digre, Hanne, Ulf Erikson, Ekrem Misimi, Bert Lambooij, and Hans Van De Vis. 2010. Electrical stunning of farmed Atlantic cod Gadus morhua L.: a comparison of an industrial and experimental method. Aquaculture Research 41: 1190–1202. https://doi.org/10.1111/j.1365-2109.2009.02406.x.
49 Erikson, U., B. Lambooij, H. Digre, H. G. M. Reimert, M. Bondø, and H. van der Vis. 2012. Conditions for instant electrical stunning of farmed Atlantic cod after de-watering, maintenance of unconsciousness, effects of stress, and fillet quality — A comparison with AQUI-STM. Aquaculture 324–325: 135–144. https://doi.org/10.1016/j.aquaculture.2011.10.011.
50 Teletchea, Fabrice, and Pascal Fontaine. 2012. Levels of domestication in fish: implications for the sustainable future of aquaculture. Fish and Fisheries 15: 181–195. https://doi.org/10.1111/faf.12006.
51 Magnussen, Eyðfinn. 2011. Food and feeding habits of cod (Gadus morhua) on the Faroe Bank. ICES Journal of Marine Science 68: 1909–1917. https://doi.org/10.1093/icesjms/fsr104.
52 Hansen, A.-C., Ø. Karlsen, G. Rosenlund, M. Rimbach, and G.-I. Hemre. 2007. Dietary plant protein utilization in Atlantic cod, Gadus morhua L. Aquaculture Nutrition 13: 200–215. https://doi.org/10.1111/j.1365-2095.2007.00486.x.
53 Hansen, Ann-Cecilie, Grethe Rosenlund, Ørjan Karlsen, Wolfgang Koppe, and Gro-Ingunn Hemre. 2007. Total replacement of fish meal with plant proteins in diets for Atlantic cod (Gadus morhua L.) I — Effects on growth and protein retention. Aquaculture 272: 599–611. https://doi.org/10.1016/j.aquaculture.2007.08.034.
54 Olsen, Rolf Erik, Ann-Cecilie Hansen, Grethe Rosenlund, Gro-Ingunn Hemre, Terry M. Mayhew, David L. Knudsen, Orhan Tufan Eroldoğan, Reidar Myklebust, and Ørjan Karlsen. 2007. Total replacement of fish meal with plant proteins in diets for Atlantic cod (Gadus morhua L.) II — Health aspects. Aquaculture 272: 612–624. https://doi.org/10.1016/j.aquaculture.2007.05.010.
55 Tibbetts, S.m., R.e. Olsen, and S.p. Lall. 2011. Effects of partial or total replacement of fish meal with freeze-dried krill (Euphausia superba) on growth and nutrient utilization of juvenile Atlantic cod (Gadus morhua) and Atlantic halibut (Hippoglossus hippoglossus) fed the same practical diets. Aquaculture Nutrition 17: 287–303. https://doi.org/10.1111/j.1365-2095.2010.00753.x.