Short profile


FishEthoScore of the species

Abbreviated assessment of the species' likelihood and potential for fish welfare in aquaculture, based on ethological findings for 10 crucial criteria.

Criteria Li Po Ce
1 Home range
2 Depth range ?
3 Migration ?
4 Reproduction
5 Aggregation
6 Aggression
7 Substrate ?
8 Stress
9 Malformation
10 Slaughter
FishEthoScore 0 1 4
Li = Likelihood that the individuals of the species experience welfare under minimal farming conditions
Po = Potential overall potential of the individuals of the species to experience welfare under improved farming conditions
Ce = Certainty of our findings in Likelihood and Potential
 
                    ?     /  
  High    Medium     Low     Unclear  No findings
 
FishEthoScore = Sum of criteria scoring "High" (max. 10)



General remarks

Oncorhynchus mykiss is one of the dominant freshwater salmonids farmed in Europe and North America. In addition, it is one of the most widely studied model fish species in the wild and in captivity. Yet, 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. The low FishEthoScore is mainly due to the dependence of fish in the diet, need of space, high levels of aggression, needs of substrate, stress under farming conditions and high levels of deformations. In addition, anadromous fish experience changes in morphology, behaviour and environmental requirements through their life history. Thus, husbandry systems and practices need to take such differences into account in order to achieve and maintain higher welfare standards throughout the life cycle of the cultured fishes. The development of new rearing strategies to optimise the husbandry practices, handling with special care and the establishment of a slaughter protocol would be a step forward to solve some specific welfare concerns. Finally, providing feed which does not contain any fish components from wild catch has proven feasible for this species in lab studies, so a protocol for application in farming conditions has to be developed.


1. Are minimal farming conditions likely to provide the home range of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
H
Certainty

Eggs: WILD: deposited in redds [1]. FARM: trays, tanks: 40-50 cm x 4 m [2], 10,000 eggs/0.2 m2 [3].

ALEVINS and FRYWILD: salmonids move short distances from the redd [4]. Further research needed to determine whether this applies to Oncorhynchus mykiss as well. FARM: round tanks: 2 m in diameter [2]; tanks: 2 x 2 m [2], 0.5-1.4 m[5].

PARR and SMOLT: WILD: usually 0-3 km [6] [7] [8] [9]. FARM: raceways and ponds: 2-3 m x 12-30 m [2]; 4-25 m3 [5]; cages: 6 x 6 m [2], 16,000-130,000 m3 [10].

ADULTS: usually 1-15 km [6] [11] [12] [13] [8]FARM PARR and SMOLT.

SPAWNERS: usually 1-15 km [14]FARM tanks: 1m[3].


2. Are minimal farming conditions likely to provide the depth range of the species? Is there potential for improvement? How certain are these findings?

?
Likelihood
M
Potential
M
Certainty

Eggs: WILD: deposited in redds [1]. FARM: trays, tanks: 20 cm [2], 50 cm [3].

ALEVINS and FRY: WILD: salmonids move short distances [15] [16]. Further research needed to determine whether this applies to Oncorhynchus mykiss as well. FARM: tanks: 50-60 cm [2], 0.8-1m [3] [5].

PARR and SMOLT: WILD: usually swim 0-5 m deep [17] [18] [19]. FARM: raceways and ponds: 1-1.2 m [3] [2]; cages: 4-5 m [2], 40 m [20],10-50 m [10].

ADULTS: WILD: usually swim 0-20 m deep [17] [11] [18]. FARM PARR and SMOLT.

SPAWNERSWILD and FARM: no data found yet.


3. Are minimal farming conditions compatible with the migrating or habitat-changing behaviour of the species? Is there potential for improvement? How certain are these findings?

?
Likelihood
M
Potential
M
Certainty

Two populations: steelhead trout ANADROMOUS [13] [21] [14] move from fresh water to seawater. Rainbow trout POTAMODROMOUS [13] stationary, stay permanently in fresh water, 

Steelhead trout population:

ALEVINSFRY and PARRWILD: stationary [2] [1], remain in steams and rivers [22] [23]

SMOLTWILD: migration to sea [24]FARMEURYHALINE > 50g, 70-100g good survival rate at the sea [25]. Brackish and saltwater cages 20-34 ppm [10].

ADULTSWILD: return as GRILSE to natal streams to spawn [24] [23]SPAWNERSFARM: 10-17 ‰ [26].

KELTWILD: return to sea and spawn again in streams [24] [23]

Rainbow trout population:

WILD: All age classes stationary, except adults move upstream to spawn [11].

All age classes: further research needed on welfare parameters to determine whether presenting species with conditions of different migratory phases indeed satisfies their urge to migrate or whether they need to experience the transition.


4. Is the species likely to reproduce in captivity without manipulation? Is there potential to allow for it under farming conditions? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

WILD: spawning occurs from November until May in the Northern hemisphere and from August to November on the Southern hemisphere [27] [2]Males perform aggressive courtship displays [28] [3]. Female builds redd [29] [17] [30]. FARM: do not spawn naturally, eggs and milt are stripped [2] [3].

 


5. Is the aggregation imposed by minimal farming conditions likely to be compatible with the natural behaviour of the species? Is there potential to allow for it under farming conditions? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

ALEVINS and FRY: WILD: territorial, establish social hierarchies [31]. LAB: territorial, establish social hierarchies [32] [33] [34] [35]FARMFRY: 2,000 to 5,000 fry/m[3].

PARR and SMOLT: WILD: territorial, establish social hierarchies [36]. FARM: stocking densities: tanks: 40-265 kg/m[37] [38]; raceways: 8-160 kg/m[38]; cages: 30-40 kg/m[2]. Low and high stocking densities affect welfare [37] [38] LAB: stocking densities 10-80 kg/m3, low and high stocking densities affect welfare [39].

ADULTS: WILD: salmonids live in schools during migration [40] [41] [42]. Further research needed to determine whether this applies to Oncorhynchus mykiss as well. FARM PARR and SMOLT.

SPAWNERS: WILD:  ADULTS. FARM: rearing at low densities with unknown extension [2]

All age classes: FARM: wide variation in recommended stocking densities 2-80 kg/m3, in Europe and North America commercial farmers use normally 15-40 kg/m3, maximum observed at 60 kg/m[38] [10].


6. Is the species likely to be non-aggressive and non-territorial? Is there potential for improvement? How certain are these findings?

L
Likelihood
L
Potential
H
Certainty

ALEVINS and FRY: higher levels of aggression in wild than under farming conditions [31] [33]. FARM: no food competition at stocking density 9.9-37.6 kg/m3 [32]. LAB: individuals with larger yolk sacs [34] and quick emergence from spawning gravel are more aggressive [35] [43].

PARR and SMOLT: FARM: more aggressive with feeding schedule compared to free access regime [44] [45]LAB: aggressive when establishing dominant-subordinate relationships [46] [47] [48] [49] [50] [51].

ADULTS: LAB: aggressive when establishing dominant-subordinate relationships [48].

SPAWNERS: FARM: males performs aggressive courtship [3].

For all age classes, no data found yet on aggression behaviour in the wild.


7. Are minimal farming conditions likely to match the natural substrate and shelter needs of the species? Is there potential for improvement? How certain are these findings?

?
Likelihood
M
Potential
M
Certainty

Eggs, ALEVINS and FRY: WILD: successful incubation and emergence dependent on gravel characteristics [52] [30]FARM: use artificial hatching substrate [3] [5]LAB: emergence from spawning gravel used to distinguish distinct stress coping styles and growth performances [35] [43]. The use of gravel reduce fin erosions [53]

PARR and SMOLT: WILD: use gravel, stones and boulders as shelters [17] [22] [54] [55]FARM: rearing in earthen-bottom ponds enhances physiology [56] and increase survival when transferred to seawater [57]LAB: cobble substrate reduce fins erosions [58].

ADULTS: ➝ PARR and SMOLTFARM: rearing in earthen-bottom ponds increase survival when transferred to seawater [57]

SPAWNERS: WILD: use substrate to build redds [17] [30]FARM: no data found yet. 

 


8. Are minimal farming conditions (handling, confinement etc.) likely not to stress the individuals of the species? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
H
Certainty

ALEVINS and FRY: stressed by acute handling [59] and confinment [60].

PARR and SMOLT: stressed by repeated handling [61] [62] [63] [64], confinement, crowding [65] [66], group hierarchies [67] [48] [49] and transport [68].                                     

ADULTS: stressed by confinement [69] [65], repeated handling [70] [48] [71], group hierarchies [69] and transport [68].

SPAWNERS: stressed by handling [72]; identified quantitative trait loci (QTL) when stressed by crowding [73].


9. Are malformations of this species likely to be rare under farming conditions? Is there potential for improvement? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

ALEVINS and FRY: malformations of spine [74] in >15% of individuals.

PARR and SMOLT: malformations of spine [75] [76] [77] [78] [79] in >10% of individuals.

ADULTS: malformations of spine [76] [77] [79] in >10% of individuals.

SPAWNERS: no data found yet

For all age classes, no data found yet on frequency of malformations in the wild.

 


10. Is a humane slaughter protocol likely to be applied under minimal farming conditions? Is there potential for improvement? How certain are these findings?

L
Likelihood
H
Potential
H
Certainty

Indications that electrical stunning before killing by chilling/bleeding are most effective [80] [81] [82] [83]. Percussive stunning before killing by chilling/bleeding are most effective in larger trout sizes [82].


Side note: Domestication

DOMESTICATION LEVEL 5 [84] [85], fully domesticated. Cultured since late 19th century [2].


Side note: Feeding without components of forage fishery

ALEVINS and FRY: WILD: carnivorous [2] [1]. FARM: fish meal and fish oil may be completely* replaced by plant protein [86] [87].

PARR and SMOLT: WILD: carnivorous [2] [1]. FARM: fish meal and fish oil may be mostly* replaced by plant protein [88] [89] [90] [91]. Further research needed to clarify the feasability of complete* replacement.

ADULTS PARR and SMOLT.

SPAWNERSWILD: carnivorous [2] [1]. FARM: fish meal and fish oil may be completely* replaced by plant protein [87] [92].

*partly = <51% – mostly = 51-99% – completely = 100%


Glossary

ADULTS = mature individuals, for details Findings 10.1 Ontogenetic development
ALEVINS = larvae until the end of yolk sac absorption, for details Findings 10.1 Ontogenetic development
ANADROMOUS = migrating from the sea into fresh water to spawn
DOMESTICATION LEVEL 5 = selective breeding programmes are used focusing on specific goals [84]
EURYHALINE = tolerant of a wide range of salinities
FARM = setting in farm environment
FRY = larvae from external feeding on, for details Findings 10.1 Ontogenetic development
GRILSE = adults returning from sea to home river to spawn, for details Findings 10.1 Ontogenetic development
KELT = adults surviving spawning, for details Findings 10.1 Ontogenetic development
LAB = setting in laboratory environment
PARR = juvenile stage in rivers, for details Findings 10.1 Ontogenetic development
POTAMODROMOUS = migrating within fresh water
SMOLT = juvenile stage migrating to the sea, for details Findings 10.1 Ontogenetic development
SPAWNERS = adults that are kept as broodstock
WILD = setting in the wild


Bibliography

[1] Froese, R., and D. Pauly. 2014. FishBase. World Wide Web electronic publication. www.fishbase.org.
[2] Cowx, I. G. 2005. Cultured Aquatic Species Information Programme. Oncorhynchus mykiss. Rome: FAO Fisheries and Aquaculture Department.
[3] Hoitsy, György, Woynarovich Andras, and Moth-Poulsen Thomas. 2012. Guide to the small scale artificial propagation of trout. FAO Fisheries and Aquaculture: 22.
[4] Gustafson-Greenwood, Karla I., and John R. Moring. 1990. Territory size and distribution of newly-emerged Atlantic salmon (Salmo salar). Hydrobiologia 206: 125–131. https://doi.org/10.1007/BF00018638.
[5] Woynarovich, András, György Hoitsy, and Thomas Moth-Poulsen. 2011. Small-scale rainbow trout farming. FAO Fisheries and Aquaculture Technical Paper 561. Rome: Food and Agriculture Organization of the United Nations.
[6] Erman, Don C., and George R. Leidy. 1975. Downstream Movement of Rainbow Trout Fry in a Tributary Sagehen Creek, under Permanent and Intermittent Flow. Transactions of the American Fisheries Society 104: 467–473. https://doi.org/10.1577/1548-8659(1975)104467:DMORTF2.0.CO;2.
[7] Mitro, Matthew G., and Alexander V. Zale. 2002. Seasonal Survival, Movement, and Habitat Use of Age-0 Rainbow Trout in the Henrys Fork of the Snake River, Idaho. Transactions of the American Fisheries Society 131: 271–286. https://doi.org/10.1577/1548-8659(2002)1310271:SSMAHU2.0.CO;2.
[8] Mellina, Eric, Scott G. Hinch, Kirsten D. MacKenzie, and Greg Pearson. 2005. Seasonal Movement Patterns of Stream-Dwelling Rainbow Trout in North-Central British Columbia, Canada. Transactions of the American Fisheries Society 134: 1021–1037. https://doi.org/10.1577/T03-188.1.
[9] Cocherell, Sarah A., Gardner J. Jones, Javier B. Miranda, Dennis E. Cocherell, Joseph J. Cech, Lisa C. Thompson, and A. Peter Klimley. 2010. Distribution and movement of domestic rainbow trout, Oncorhynchus mykiss, during pulsed flows in the South Fork American River, California. Environmental Biology of Fishes 89: 105–116. https://doi.org/10.1007/s10641-010-9701-2.
[10] Noble, C., K. Gismervik, M.H. Iversen, J. Kolarevic, J. Nilsson, and L.H. Stien. 2020. Welfare Indicators for farmed rainbow trout: tools for assessing fish welfare.
[11] James, G. D., and J. R. M. Kelso. 1995. Movements and habitat preference of adult rainbow trout (Oncorhynchus mykiss) in a New Zealand montane lake. New Zealand Journal of Marine and Freshwater Research 29: 493–503. https://doi.org/10.1080/00288330.1995.9516682.
[12] Gido, Keith B., Robert D. Larson, and Lief A. Ahlm. 2000. Stream-Channel Position of Adult Rainbow Trout Downstream of Navajo Reservoir, New Mexico, Following Changes inReservoir Release. North American Journal of Fisheries Management 20: 250–258. https://doi.org/10.1577/1548-8675(2000)0200250:SCPOAR2.0.CO;2.
[13] Meka, J, E. Knudsen, D. Douglas, and R. Benter. 2003. Variable migratory patterns of different adult rainbow trout life history types in a southwest Alaska watershed. Journal Articles 132.
[14] Venman, Mark R., and Michel Dedual. 2005. Migratory behaviour of spawning rainbow trout (Oncorhynchus mykiss) in the Tongariro River, New Zealand, after habitat alteration. New Zealand Journal of Marine and Freshwater Research 39: 951–961. https://doi.org/10.1080/00288330.2005.9517365.
[15] Heggenes, Jan. 1990. Habitat utilization and preferences in juvenile atlantic salmon (salmo salar) in streams. Regulated Rivers: Research Management 5: 341–354. https://doi.org/10.1002/rrr.3450050406.
[16] Crisp, D. Trevor. 1993. The environmental requirements of salmon and trout in fresh water. Freshwater Forum 3: 176–202.
[17] Vondracek, B., and D. R. Longanecker. 1993. Habitat selection by rainbow trout Oncorhynchus mykiss in a California stream: implications for the Instream Flow Incremental Methodology. Ecology of Freshwater Fish 2: 173–186. https://doi.org/10.1111/j.1600-0633.1993.tb00100.x.
[18] Matthews, K. R., and N. H. Berg. 1997. Rainbow trout responses to water temperature and dissolved oxygen stress in two southern California stream pools. Journal of Fish Biology 50: 50–67. https://doi.org/10.1111/j.1095-8649.1997.tb01339.x.
[19] Ebersole, J. L., W. J. Liss, and C. A. Frissell. 2001. Relationship between stream temperature, thermal refugia and rainbow trout Oncorhynchus mykiss abundance in arid-land streams in the northwestern United States. Ecology of Freshwater Fish 10: 1–10. https://doi.org/10.1034/j.1600-0633.2001.100101.x.
[20] Cardia, Francesco, Alessandro Lovatelli, and Food and Agriculture Organization of the United Nations. 2015. Aquaculture operations in floating HDPE cages: a field handbook. Rome: Food and Agriculture Organization of the United States.
[21] Riva Rossi, Carla, Milagros Arguimbau, and Miguel Pascual. 2003. The spawning migration of anadromous rainbow trout in the Santa Cruz River, Patagonia (Argentina) through radio-tracking. Ecología austral 13: 151–159.
[22] Bradford, Michael J, and Paul S Higgins. 2001. Habitat-, season-, and size-specific variation in diel activity patterns of juvenile chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Oncorhynchus mykiss). Canadian Journal of Fisheries and Aquatic Sciences 58: 365–374. https://doi.org/10.1139/f00-253.
[23] Shapovalov, Leo, and Alan C. Taft. 1954. The Life Histories of the Steelhead Rainbow Trout (Salmo gairdneri gairdneri) and Silver Salmon (Oncorhynchus kisutch) With Special Reference to Waddell Creek, California, and Recommendations Regarding Their Management. Fish Bulletin 98. State of California Department of Fish and Game.
[24] Light, Jeffrey T, Cohn K Harris, and Robert L Burgner. 1989. Ocean distribution and migration of steelhead (Oncorhynchus mykiss, formerly Salmo gairdneri). Document submitted to the International North Pacific Fisheries Commission. FRI-UW-8912. Seattle: FisheriesResearch Institute, University of Washington.
[25] European Food Safety Authority (EFSA). 2008. Animal welfare aspects of husbandry systems for farmed trout ‐ Scientific Opinion of the Panel on Animal Health and Welfare. EFSA Journal 6. https://doi.org/10.2903/j.efsa.2008.796.
[26] Albrektsen, S., and O. Torrissen. 1988. Physiological changes in blood and seminal plasma during the spawning period of maturing rainbow trout held under different temperature and salinity regimes, and the effect on survival of the broodstock and the eyed eggs. Nofima.
[27] Froese, R., and D. Pauly. 2020. Oncorhynchus mykiss, Rainbow trout : fisheries, aquaculture, gamefish. www.fishbase.org. https://www.fishbase.de/summary/Oncorhynchus-mykiss.html. Accessed August 12.
[28] Tautz, A. F., and C. Groot. 1975. Spawning Behavior of Chum Salmon (Oncorhynchus keta) and Rainbow Trout (Salmo gairdneri). Journal of the Fisheries Research Board of Canada 32: 633–642. https://doi.org/10.1139/f75-081.
[29] Greeley, John R. 1932. The Spawning Habits of Brook, Brown and Rainbow Trout, and the Problem of Egg Predators. Transactions of the American Fisheries Society 62: 239–248. https://doi.org/10.1577/1548-8659(1932)62[239:TSHOBB]2.0.CO;2.
[30] Workman, R. D., Daniel B. Hayes, and Thomas G. Coon. 2004. Spawning Habitat Selection by Rainbow Trout in the Pere Marquette River, Michigan. Journal of Great Lakes Research 30: 397–406. https://doi.org/10.1016/S0380-1330(04)70357-3.
[31] Berejikian, B A, S B Mathews, and T P Quinn. 1996. Effects of hatchery and wild ancestry and rearing environments on the development of agonistic behavior in steelhead trout (Oncorhynchus mykiss) fry. Canadian Journal of Fisheries and Aquatic Sciences 53: 2004–2014. https://doi.org/10.1139/f96-133.
[32] Wagner, Eric J., Steven S. Intelmann, and M. Douglas Routledge. 1996. The Effects of Fry Rearing Density on Hatchery Performance, Fin Condition, and Agonistic Behavior of Rainbow Trout Oncorhynchus mykiss Fry. Journal of the World Aquaculture Society 27: 264–274. https://doi.org/10.1111/j.1749-7345.1996.tb00608.x.
[33] Berejikian, Barry A, E Paul Tezak, Thomas A Flagg, Anita L LaRae, Eric Kummerow, and Conrad VW Mahnken. 2000. Social dominance, growth, and habitat use of age-0 steelhead (Oncorhynchus mykiss) grown in enriched and conventional hatchery rearing environments. Canadian Journal of Fisheries and Aquatic Sciences 57: 628–636. https://doi.org/10.1139/f99-288.
[34] Andersson, Madelene Åberg, and Erik Höglund. 2012. Linking Personality to Larval Energy Reserves in Rainbow Trout (Oncorhynchus mykiss). PLOS ONE 7: e49247. https://doi.org/10.1371/journal.pone.0049247.
[35] Andersson, Madelene Åberg, Uniza Wahid Khan, Oyvind Overli, Hans Magnus Gjøen, and Erik Höglund. 2013. Coupling between stress coping style and time of emergence from spawning nests in salmonid fishes: evidence from selected rainbow trout strains (Oncorhynchus mykiss). Physiology Behavior 116–117: 30–34. https://doi.org/10.1016/j.physbeh.2013.03.019.
[36] Jenkins, Thomas M. 1969. Social Structure, Position Choice and Micro-distribution of Two Trout Species (Salmo trutta and Salmo gairdneri) Resident in Mountain Streams. Animal Behaviour Monographs 2: 55–123. https://doi.org/10.1016/S0066-1856(69)80002-6.
[37] Mäkinen, T., and K. Ruohonen. 1990. The effect of rearing density on the growth of Finnish rainbow trout (Oncorhynchus my kiss Walbaum 1792). Journal of Applied Ichthyology 6: 193–203. https://doi.org/10.1111/j.1439-0426.1990.tb00579.x.
[38] Ellis, T., B. North, A. P. Scott, N.r. Bromage, M. Porter, and D. Gadd. 2002. The relationships between stocking density and welfare in farmed rainbow trout. Journal of Fish Biology 61: 493–531. https://doi.org/10.1111/j.1095-8649.2002.tb00893.x.
[39] North, B. P., J. F. Turnbull, T. Ellis, M. J. Porter, H. Migaud, J. Bron, and N. R. Bromage. 2006. The impact of stocking density on the welfare of rainbow trout (Oncorhynchus mykiss). Aquaculture 255: 466–479. https://doi.org/10.1016/j.aquaculture.2006.01.004.
[40] Fried, Stephen M., James D. McCleave, and George W. LaBar. 1978. Seaward Migration of Hatchery-Reared Atlantic Salmon, Salmo salar, Smolts in the Penobscot River Estuary, Maine: Riverine Movements. Journal of the Fisheries Research Board of Canada 35: 76–87. https://doi.org/10.1139/f78-011.
[41] McCormick, Stephen D, Lars P Hansen, Thomas P Quinn, and Richard L Saunders. 1998. Movement, migration, and smolting of Atlantic salmon (Salmo salar). Canadian Journal of Fisheries and Aquatic Sciences 55: 77–92. https://doi.org/10.1139/d98-011.
[42] Riley, W. D., A. T. Ibbotson, D. L. Maxwell, P. I. Davison, W. R. C. Beaumont, and M. J. Ives. 2014. Development of schooling behaviour during the downstream migration of Atlantic salmon Salmo salar smolts in a chalk stream. Journal of Fish Biology 85: 1042–1059. https://doi.org/10.1111/jfb.12457.
[43] Andersson, M. Å, D. C. Laursen, P. I. M. Silva, and E. Höglund. 2013. The relationship between emergence from spawning gravel and growth in farmed rainbow trout Oncorhynchus mykiss. Journal of Fish Biology 83: 214–219. https://doi.org/10.1111/jfb.12153.
[44] Moutou, K. A., I. D. McCarthy, and D. F. Houlihan. 1998. The effect of ration level and social rank on the development of fin damage in juvenile rainbow trout. Journal of Fish Biology 52: 756–770. https://doi.org/10.1111/j.1095-8649.1998.tb00818.x.
[45] Noble, C., K. Mizusawa, K. Suzuki, and M. Tabata. 2007. The effect of differing self-feeding regimes on the growth, behaviour and fin damage of rainbow trout held in groups. Aquaculture 264: 214–222. https://doi.org/10.1016/j.aquaculture.2006.12.028.
[46] Gregory, J. S., and J. S. Griffith. 1996. Aggressive behaviour of underyearling rainbow trout in simulated winter concealment habitat. Journal of Fish Biology 49: 237–245. https://doi.org/10.1111/j.1095-8649.1996.tb00020.x.
[47] Johnsson, Jörgen I. 1997. Individual Recognition Affects Aggression and Dominance Relations in Rainbow Trout, Oncorhynchus mykiss. Ethology 103: 267–282. https://doi.org/10.1111/j.1439-0310.1997.tb00017.x.
[48] Sloman, K. A., N. B. Metcalfe, A. C. Taylor, and K. M. Gilmour. 2001. Plasma cortisol concentrations before and after social stress in rainbow trout and brown trout. Physiological and biochemical zoology: PBZ 74: 383–389. https://doi.org/10.1086/320426.
[49] Øverli, Øyvind, Susann Kotzian, and Svante Winberg. 2002. Effects of cortisol on aggression and locomotor activity in rainbow trout. Hormones and Behavior 42: 53–61. https://doi.org/10.1006/hbeh.2002.1796.
[50] Fernandes-de-Castilho, Marisa, Tom G. Pottinger, and Gilson Luiz Volpato. 2008. Chronic social stress in rainbow trout: Does it promote physiological habituation? General and Comparative Endocrinology 155: 141–147. https://doi.org/10.1016/j.ygcen.2007.04.008.
[51] Grobler, Josias M. B., and Chris M. Wood. 2013. The physiology of rainbow trout in social hierarchies: two ways of looking at the same data. Journal of Comparative Physiology. B, Biochemical, Systemic, and Environmental Physiology 183: 787–799. https://doi.org/10.1007/s00360-013-0752-5.
[52] Sowden, Terry K., and G. Power. 1985. Prediction of Rainbow Trout Embryo Survival in Relation to Groundwater Seepage and Particle Size of Spawning Substrates. Transactions of the American Fisheries Society 114: 804–812. https://doi.org/10.1577/1548-8659(1985)114804:PORTES2.0.CO;2.
[53] Arndt, Ronney E., M. Douglas Routledge, Eric J. Wagner, and Roger F. Mellenthin. 2001. Influence of Raceway Substrate and Design on Fin Erosion and Hatchery Performance of Rainbow Trout. North American Journal of Aquaculture 63: 312–320. https://doi.org/10.1577/1548-8454(2001)0630312:IORSAD2.0.CO;2.
[54] Reeves, Gordon H., Jon B. Grunbaum, and Dirk W. Lang. 2010. Seasonal variation in diel behaviour and habitat use by age 1+ Steelhead (Oncorhynchus mykiss) in Coast and Cascade Range streams in Oregon, U.S.A. Environmental Biology of Fishes 87: 101–111. https://doi.org/10.1007/s10641-009-9569-1.
[55] Ligon, F. K., R. J. Nakamoto, B. C. Harvey, and P. F. Baker. 2016. Use of streambed substrate as refuge by steelhead or rainbow trout Oncorhynchus mykiss during simulated freshets. Journal of Fish Biology 88: 1475–1485. https://doi.org/10.1111/jfb.12925.
[56] Zydlewski, Gayle B., J. Scott Foott, Kenneth Nichols, Scott Hamelberg, Joseph Zydlewski, and Björn Thrandur Björnsson. 2003. Enhanced smolt characteristics of steelhead trout exposed to alternative hatchery conditions during the final months of rearing. Aquaculture 222. Salmonid Smoltification: 101–117. https://doi.org/10.1016/S0044-8486(03)00105-4.
[57] Tipping, Jack M. 2008. Adult Returns of Hatchery Steelhead Juveniles Reared in Earthen- and Asphalt-Bottom Ponds. North American Journal of Aquaculture 70: 115–117. https://doi.org/10.1577/A07-017.1.
[58] Bosakowski, Thomas, and Eric J. Wagner. 1994. Assessment of Fin Erosion by Comparison of Relative Fin Length in Hatchery and Wild Trout in Utah. Canadian Journal of Fisheries and Aquatic Sciences 51: 636–641. https://doi.org/10.1139/f94-064.
[59] Barry, T. P., J. A. Malison, J. A. Held, and J. J. Parrish. 1995. Ontogeny of the cortisol stress response in larval rainbow trout. General and Comparative Endocrinology 97: 57–65. https://doi.org/10.1006/gcen.1995.1006.
[60] Sadoul, Bastien, Isabelle Leguen, Violaine Colson, Nicolas C. Friggens, and Patrick Prunet. 2015. A multivariate analysis using physiology and behavior to characterize robustness in two isogenic lines of rainbow trout exposed to a confinement stress. Physiology Behavior 140: 139–147. https://doi.org/10.1016/j.physbeh.2014.12.006.
[61] Vijayan, M. M., and T. W. Moon. 1992. Acute Handling Stress Alters Hepatic Glycogen Metabolism in Food-Deprived Rainbow Trout (Oncorhynchus mykiss). Canadian Journal of Fisheries and Aquatic Sciences 49: 2260–2266. https://doi.org/10.1139/f92-247.
[62] Ellis, T., J. D. James, C. Stewart, and A. P. Scott. 2004. A non-invasive stress assay based upon measurement of free cortisol released into the water by rainbow trout. Journal of Fish Biology 65: 1233–1252. https://doi.org/10.1111/j.0022-1112.2004.00499.x.
[63] Jentoft, Sissel, Are H. Aastveit, Peter A. Torjesen, and Øivind Andersen. 2005. Effects of stress on growth, cortisol and glucose levels in non-domesticated Eurasian perch (Perca fluviatilis) and domesticated rainbow trout (Oncorhynchus mykiss). Comparative Biochemistry and Physiology Part A: Molecular Integrative Physiology 141: 353–358. https://doi.org/10.1016/j.cbpb.2005.06.006.
[64] Hoskonen, Petri, and Juhani Pirhonen. 2006. Effects of repeated handling, with or without anaesthesia, on feed intake and growth in juvenile rainbow trout, Oncorhynchus mykiss (Walbaum). Aquaculture Research 37: 409–415. https://doi.org/10.1111/j.1365-2109.2005.01448.x.
[65] Pottinger, T. G. 2006. Context dependent differences in growth of two rainbow trout (Oncorhynchus mykiss) lines selected for divergent stress responsiveness. Aquaculture.
[66] Laursen, Danielle Caroline, Madelene Åberg Andersson, Patricia Isabel Mota Silva, Erik Petersson, and Erik Höglund. 2013. Utilising spatial distribution in two-tank systems to investigate the level of aversiveness to crowding in farmed rainbow trout Oncorhynchus mykiss. Applied Animal Behaviour Science 144: 163–170. https://doi.org/10.1016/j.applanim.2013.01.010.
[67] Øverli, Øyvind, Charmaine A. Harris, and Svante Winberg. 1999. Short-term effects of fights for social dominance and the establishment of dominant-subordinate relationships on brain monoamines and cortisol in rainbow trout. Brain, Behavior and Evolution 54: 263–275. https://doi.org/10.1159/000006627.
[68] Shabani, Fazli, Ulf Erikson, Elvira Beli, and Agim Rexhepi. 2016. Live transport of rainbow trout (Onchorhynchus mykiss) and subsequent live storage in market: Water quality, stress and welfare considerations. Aquaculture 453: 110–115. https://doi.org/10.1016/j.aquaculture.2015.11.040.
[69] Øverli, Øyvind, Christina Sørensen, and Göran E. Nilsson. 2006. Behavioral indicators of stress-coping style in rainbow trout: Do males and females react differently to novelty? Physiology Behavior 87: 506–512. https://doi.org/10.1016/j.physbeh.2005.11.012.
[70] Pickering, A. D., T. G. Pottinger, J. P. Sumpter, J. F. Carragher, and P. Y. Le Bail. 1991. Effects of acute and chronic stress on the levels of circulating growth hormone in the rainbow trout, Oncorhynchus mykiss. General and Comparative Endocrinology 83: 86–93. https://doi.org/10.1016/0016-6480(91)90108-I.
[71] Lepage, Olivier, Olof Tottmar, and Svante Winberg. 2002. Elevated dietary intake of L-tryptophan counteracts the stress-induced elevation of plasma cortisol in rainbow trout (Oncorhynchus mykiss). The Journal of Experimental Biology 205: 3679–3687.
[72] Wagner, Eric, Ronney Arndt, and Blaine Hilton. 2002. Physiological stress responses, egg survival and sperm motility for rainbow trout broodstock anesthetized with clove oil, tricaine methanesulfonate or carbon dioxide. Aquaculture 211: 353–366. https://doi.org/10.1016/S0044-8486(01)00878-X.
[73] Rexroad, Caird E, Roger L Vallejo, Sixin Liu, Yniv Palti, and Gregory M Weber. 2012. QTL affecting stress response to crowding in a rainbow trout broodstock population. BMC Genetics 13: 97. https://doi.org/10.1186/1471-2156-13-97.
[74] Bonnet, Emilie, Alexis Fostier, and Julien Bobe. 2007. Characterization of rainbow trout egg quality: A case study using four different breeding protocols, with emphasis on the incidence of embryonic malformations. Theriogenology 67: 786–794. https://doi.org/10.1016/j.theriogenology.2006.10.008.
[75] Madsen, Lone, and Inger Dalsgaard. 1999. Vertebral column deformities in farmed rainbow trout ( Oncorhynchus mykiss ). Aquaculture 171: 41–48.
[76] Deschamps, M. -H., A. Kacem, R. Ventura, G. Courty, P. Haffray, F. J. Meunier, and J. -Y. Sire. 2008. Assessment of “discreet” vertebral abnormalities, bone mineralization and bone compactness in farmed rainbow trout. Aquaculture 279: 11–17. https://doi.org/10.1016/j.aquaculture.2008.03.036.
[77] Pulcini, D., C. Boglione, E. Palamara, and S. Cataudella. 2010. Use of meristic counts and skeletal anomalies to assess developmental plasticity of farmed rainbow trout (Oncorhynchus mykiss, Walbaum 1792): a preliminary study. Journal of Applied Ichthyology 26: 298–302. https://doi.org/10.1111/j.1439-0426.2010.01425.x.
[78] Davidson, John, Christopher Good, Carla Welsh, and Steven T. Summerfelt. 2011. Abnormal swimming behavior and increased deformities in rainbow trout Oncorhynchus mykiss cultured in low exchange water recirculating aquaculture systems. Aquacultural Engineering 45: 109–117. https://doi.org/10.1016/j.aquaeng.2011.08.005.
[79] Boglione, Clara, Domitilla Pulcini, Michele Scardi, Elisa Palamara, Tommaso Russo, and Stefano Cataudella. 2014. Skeletal Anomaly Monitoring in Rainbow Trout (Oncorhynchus mykiss , Walbaum 1792) Reared under Different Conditions. PLOS ONE 9: e96983. https://doi.org/10.1371/journal.pone.0096983.
[80] Robb, D H F, and S C Kestin. 2002. Methods Used to Kill Fish: Field Observations and Literature Reviewed. Animal Welfare 11: 269–282.
[81] Lines, J. A., D. H. Robb, S. C. Kestin, S. C. Crook, and T. Benson. 2003. Electric stunning: a humane slaughter method for trout. Aquacultural Engineering 28: 141–154. https://doi.org/10.1016/S0144-8609(03)00021-9.
[82] European Food Safety Authority (EFSA). 2009. Species-specific welfare aspects of the main systems of stunning and killing of farmed fish: Rainbow Trout. EFSA Journal 7: 1012. https://doi.org/10.2903/j.efsa.2009.1012.
[83] Concollato, Anna, Rolf Erik Olsen, Sheyla Cristina Vargas, Antonio Bonelli, Marco Cullere, and Giuliana Parisi. 2016. Effects of stunning/slaughtering methods in rainbow trout (Oncorhynchus mykiss) from death until rigor mortis resolution. Aquaculture 464: 74–79. https://doi.org/10.1016/j.aquaculture.2016.06.009.
[84] 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.
[85] Teletchea, Fabrice. 2015. Domestication of Marine Fish Species: Update and Perspectives. Journal of Marine Science and Engineering 3: 1227–1243. https://doi.org/10.3390/jmse3041227.
[86] Le Boucher, Richard, Edwige Quillet, Marc Vandeputte, Jean Michel Lecalvez, Lionel Goardon, Béatrice Chatain, Françoise Médale, and Mathilde Dupont-Nivet. 2011. Plant-based diet in rainbow trout (Oncorhynchus mykiss Walbaum): Are there genotype-diet interactions for main production traits when fish are fed marine vs. plant-based diets from the first meal? Aquaculture 321: 41–48. https://doi.org/10.1016/j.aquaculture.2011.08.010.
[87] Geurden, Inge, Peter Borchert, Mukundh N. Balasubramanian, Johan W. Schrama, Mathilde Dupont-Nivet, Edwige Quillet, Sadasivam J. Kaushik, Stéphane Panserat, and Françoise Médale. 2013. The Positive Impact of the Early-Feeding of a Plant-Based Diet on Its Future Acceptance and Utilisation in Rainbow Trout. PLOS ONE 8: e83162. https://doi.org/10.1371/journal.pone.0083162.
[88] Pongmaneerat, Juadee, and Takeshi Watanabe. 1992. Utilization of Soybean Meal as Protein Source in Diets for Rainbow Trout. Nippon Suisan Gakkaishi 58: 1983–1990. https://doi.org/10.2331/suisan.58.1983.
[89] Gomes, Emídio F., Paulo Rema, and Sadasivam J. Kaushik. 1995. Replacement of fish meal by plant proteins in the diet of rainbow trout (Oncorhynchus mykiss): digestibility and growth performance. Aquaculture 130: 177–186. https://doi.org/10.1016/0044-8486(94)00211-6.
[90] Refstie, Ståle, Ståle J. Helland, and Trond Storebakken. 1997. Adaptation to soybean meal in diets for rainbow trout, Oncorhynchus mykiss. Aquaculture 153: 263–272. https://doi.org/10.1016/S0044-8486(97)00025-2.
[91] Pettersson, A., L. Johnsson, E. Brännäs, and J. Pickova. 2009. Effects of rapeseed oil replacement in fish feed on lipid composition and self-selection by rainbow trout (Oncorhynchus mykiss). Aquaculture Nutrition 15: 577–586. https://doi.org/10.1111/j.1365-2095.2008.00625.x.
[92] Lazzarotto, Viviana, Geneviève Corraze, Amandine Leprevost, Edwige Quillet, Mathilde Dupont-Nivet, and Françoise Médale. 2015. Three-Year Breeding Cycle of Rainbow Trout ( Oncorhynchus mykiss ) Fed a Plant-Based Diet, Totally Free of Marine Resources: Consequences for Reproduction, Fatty Acid Composition and Progeny Survival. PLOS ONE 10: e0117609. https://doi.org/10.1371/journal.pone.0117609.