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 0 0
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 kisutch is a Pacific salmon species distributed in the North Pacific basins from northern Japan through Kamchatka, across the Bering Sea to Alaska, and south through all coastal areas to California. O. kisutch has been introduced into many areas of North America, Asia, Europe, and South America. There are two strains, an anadromous one that migrates and a resident one that stays in freshwater lakes. Within the migratory strain, two morphotypes have been described, an "ocean/coastal" type with small median fins and more streamlined body that lives offshore and an "inshore/interior" type with large median fins and a robust body that remains within inside waters. In anadromous O. kisutch: eggs hatch in streams, juveniles (parr) live in streams for one year and metamorphose into smolts that will migrate to the ocean. In the ocean, smolts grow into adults and might migrate up north. When they are close to maturity, they migrate back to their original streams to spawn. Females create several nests in a defended area called redd. O. kisutch dies after reproduction. In some farms, only females are raised, which are less aggressive. Some farms have an accelerated cycle for maximising growth and reducing the hatchery cycle by 9 months: they rear them in fresh water until parr/smolt, then place them in salt water (during peak of photoperiod - July) until harvest, which occurs at around 19 months of age at 2.5-3.5 kg. Because of their need to migrate as adults, it is unlikely that current farms can provide this welfare need. Further research needs to be done to accommodate this need into farming conditions and on living offshore (home range, aggression, substrate). Currently, the main producer is Chile, with some smaller production in Japan, Canada and the USA. O. kisutch will be affected by climate change.


1. Are minimal farming conditions likely to provide the home range of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
L
Certainty

ALEVINS and FRYWILD: site fidelity [1]-[2] [3]-[2]; at 49 mm: territory size 0.3 m2 [1]-[2]; at 4 months: 0.8 m2 [1]-[2]; smaller territories with high number of intruders or high frequency of benthic food organisms [1]-[2] [3]-[2]. FARM: fibreglass troughs [4]; circulating-water raceways: 137.8 m2 (24.6 x 5.6 m) [4]; indoor oval channels: 6 m2 (0.6 x 10 m) [5]; linear raceways: 25.2 m2 (1.2 x 21 m) [5]; RAS round tanks: 3 m diameter [6].

PARR: WILD: at yearling size (110 mm): territory size 3.7-5.5 m2 [1]-[2]. FARM: RAS round tanks: 3 m diameter [6]; pools: 10-80 m3, 50-250 m2 [7]-[2]; outside rearing ponds [8] [9]; raceways [10].

SMOLTS: WILD: no data found yet. FARM: floating marine net pens (knotless nylon nets): 56.1-92.7 m2 (6.1 x 9.2-15.2 m) [11] [12]; floating hexagonal pen frames of aluminium: 63.3 m2 (edge 4.9 m) [11]; floating marine circular plastic cages: 491-707 m2 (25-30 m) [13]; floating marine steel cages: 500 m2 (25 x 25 m) [13]; land-based closed containment RAS [14]: 28.8 m2 (12 x 2.4 m) [6].

ADULTS: WILD: no data found yet. FARM: floating marine net pens (knotless nylon nets): 56.1-92.7 m2 (6.1 x 9.2-15.2 m) [11] [12]; floating hexagonal pen frames of aluminium: 63.3 m2 (edge 4.9 m) [11]; floating marine circular plastic cages: 491-707 m2 (25-30 m) [13]; floating marine steel cages: 500 m2 (25 x 25 m) [13]; land-based closed containment RAS [14]: 119.1 m2 (24.3 x 4.9 m), 186.1 m2 (30.5 x 6.1 m) [6].

SPAWNERS: WILD: redds: 1.2-2.6 m2 (115-195 x 100-135 cm) [15]-[2] [16]-[2]; inter-redd space: 3 x redd size; total space for 1 spawning pair: 11.7 m2 [16]-[2]. FARM: no data found yet.


2. Are minimal farming conditions likely to provide the depth range of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

ALEVINS and FRYWILD: ≥25 mm [17]. FARM: circulating-water raceways: 900 mm [4]; indoor oval channels: 300 mm [5]; RAS round tanks: 1.5 m [6].

PARR: WILD: shallow water [18]-[2]; >45 cm in December [19]-[2]. FARM: RAS round tanks: 1.5 m [6].

SMOLTS: WILD: 0-20 m at sea [20]. FARM: RAS raceways: 1.5 m [6]; floating marine net pens: 3.7-4.6 m [12], 3-7.6 m [11]; floating marine cages: 16-18 m [13].

ADULTS: WILD: usually 0-30 m [21] [22]-[2], but also ≤90 m [23]-[2]. FARM: RAS raceways: 2.1 m [6]; floating marine net pens: 3.7-4.6 m [12], 3-7.6 m [11]; floating marine cages: 16-18 m [13].

SPAWNERS: WILD: during ocean migration: 18-36 m [21]. Redds: 10.2-20.3 cm [24]-[2], 15-27 cm [15]-[2], 20.7 cm in artificial stream [25]. For nests   crit.7. FARMno data found yet.


3. Are minimal farming conditions compatible with the migrating or habitat-changing behaviour of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

Two strains: one ANADROMOUS [2], the other ("residuals") resident [26]-[2].

Anadromous strain:

ALEVINS and FRYWILD: in streams for 1+ years [27]-[2]. At 38-45 mm, might migrate upstream to reach lakes or similar [28]-[2]. Downstream migration out of river systems at freshets [17]. Threshold size for sea water survival: 7-8 cm [29]-[2]. FARM: fresh water until 30-80 g [13]. For details of holding systems crit. 1 and 2.

PARR: WILD: stay in fresh water for 1-2 years depending on latitude, rarely ≤4 years [30]-[2], mostly in the same area Nov-Feb or move to nearby tributaries [31]. In winter, upstream migration 200-400 m into clear and stable side creeks or small tributary streams [32]-[2]. If displaced downstream by strong currents (up to 38 km [33]-[2]), may migrate back upstream or along the shore into low salinity waters to enter other streams [34]-[2]. FARM:  ALEVINS and FRY.

SMOLTS: WILD: migrate along fresh water to the sea in spring-summer [35] [31] for average 119 days at night [36]-[2]. Several months in near shore areas before migrating further to the sea [37]-[2]. FARM: fresh water until 30-80 g [13], then transferred to salt water [11] until harvest at ca 2.5-3.5 kg [13] [6]; always in fresh water [6]. For details of holding systems crit. 1 and 2.

ADULTS: WILD: migrate northward along the coast in summer, within 150-400 km offshore [38]-[2] [35] [39]. Some follow a counter-clockwise circuit in the Gulf of Alaska in first autumn and winter, few migrate up to 200 km south or remain resident [39]. After 12-18+ months at sea [40]-[2] [22]-[2], migrate southward [22]-[2] at mean 3-55 km/day [41]-[2] [22]-[2] to their freshwater home stream to spawn [40]-[2]. FARM: fresh water [6]. For details of holding systems crit. 1 and 2.

SPAWNERS: WILD: in summer-autumn (depending on latitude) [36]-[2], migrate ≤240 km [28]-[2], rarely 350-2,200 km [42]-[2], for average 106 days [36]-[2] from the sea and through lakes into their streams of origin to spawn [2]. FARM: separation by sex and moved from sea water tanks to freshwater tanks at sexual maturity (March) [43] [13] or in autumn and maturation in freshwater tanks [13]. Sea-ranching hatcheries release SMOLTS into the ocean which home back to the hatchery when mature and are artificially bred [25].

Residual strain:

All age classes: WILD: remain in freshwater lakes, but few reach maturity [26]-[2]. FARM: no data found yet.


4. Is the species likely to reproduce in captivity without manipulation? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
L
Potential
M
Certainty

WILD: mature at 3 years, average 52.7 cm [36]-[2], 3.0-5.5 kg depending on location (4-6 months incubation, 15 months in fresh water, 16 months in seawater) [2]. Some males (called "jacks") mature earlier (30-40 cm), spending only 4-6 months in seawater, and perform sneaky fertilisations near spawning pairs [2]. Other males mature later, staying in fresh water for 2 winters (average 56.6 cm) [36]-[2]. Spawning usually in Nov-Jan, but also mid Aug-March depending on location [35] [2]. Sex ratio: spawn in pairs with extra males attending [26]-[2]. For nest building ➝ crit. 7. Male courts female [2]. Spawning takes 2-3 s [44]-[2]. Females engage in digging behaviour and nest guard until too weak to do so [24]-[2]. Males court until too weak to do so [24]-[2]. After spawning, both male and female have external and internal deterioration and die [45]-[2]. Mean adult survival rate after spawning: 11-15 days (range 4-15 days for females, 4-32 days for males, 3-57 days for jacks) [46]-[2]. FARM: spawn in April-June [43]. Mating by random matrix design (many males with many females) or random single-pair design [47], but males and females might also be separated [43]. Females humanely slaughtered and eggs removed and fertilised by male milt [13] [9] or using mature males [43]. Induced precocious ovulation by hormonal treatment [48] [49] [50]. Further research needed to determine whether this is current practice.


5. Is the aggregation imposed by minimal farming conditions likely to be compatible with the natural behaviour of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

FRYWILD: aggregation after emerging from gravel [35], rarely observed in older FRY [40]-[2], occasionally form groups with large FRY in the front and small ones at the back [51]-[2]. Move in loose aggregates at slow current when food comes from any direction [51]-[2]. 2.9 IND/m2 [17]. FARM: fibreglass troughs: 35,000 IND/m3 [4]; indoor oval channels: 16.7-26.7 IND/m2 [5]; linear raceways: 5.3-47.6 IND/m2 [5]. Excessive crowding in fresh water may lead to furunculosis [11].

PARR: WILD: 0.2-0.7 IND/m2 [31]. In winter, dense aggregation in deep pools with no aggressions [17] [52]-[2], 38-54 IND/m2 [17]. FARM: increasing negative effects when increasing beyond 504-675 IND/m2.

SMOLTS: WILD: migrating in schools of 10-50 IND of similar size [35] [35]; headwater streams: 8.4-8.5 IND/100 m2 [32]-[2]; low flow streams: 19.1 IND/100 m2 [53]-[2]; small streams: 18-67 IND/100 m2 [54]-[2]; streams rich in insect fauna: 125-141 IND/100 m2 [55]-[2]. Streams produce 7-10 times more SMOLTS than lakes [26]-[2]. More gregarious than PARR [2]. FARM: marine net pens: 12 kg/m3 [12], 13.9-15.5 kg/m3 [11].

ADULTS: WILD: schools of 20-30 IND in inshore areas [15]-[2]. No evidence of schooling in offshore areas [28]-[2]. FARM:  SMOLTS.

SPAWNERS: WILD and FARMno data found yet.


6. Is the species likely to be non-aggressive and non-territorial? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

ALEVINS and FRYWILD: territorial [17] [35] [40]-[2]. Larger FRY establish dominance through aggression (harass, chase, nip), smaller FRY may not defend territories [17]. Aggressiveness positively correlated with number of IND, size, and light intensity and negatively correlated with available food [54]-[2] [18]-[2]. Aggression more frequent in groups of FRY with similar size than different size [17]. FARM: aggressive when competing for food, females less aggressive in general [6].

PARR: WILD: territorial [56]. Antagonistic behaviour when in high current streams [51]-[2], no aggression in dense groups in deep pools [52]-[2]. FARM ALEVINS. LAB: territorial and aggressive in groups of 6 [56].

SMOLTS: WILD: less territorial than PARR [2]. FARM ALEVINS.

ADULTS: WILDno data found yet. FARM ALEVINS.

SPAWNERS: WILD: chase or bite other attending males or females [35] [25]. Wild-caught IND in artificial stream: larger IND more aggressive than smaller ones [25]. FARM: hatchery-reared IND in artificial stream: males less aggressive than wild ones [25].


7. Are minimal farming conditions likely to match the natural substrate and shelter needs of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

Eggs, ALEVINS, and FRYWILD: eggs in clean, loose gravel [35]. Higher egg survival with 3.4-26.9 mm gravel size [57]-[2]. Gravel ≤3.2 cm diameter: ALEVINS move 5-10 cm down through gravel, gravel 3.2-6.3 cm diameter: ALEVINS move >20 cm down through gravel [58]-[2]. FRY hide in gravel and under large stones during daylight [15]-[2]. Quiet waters close to the banks with shady areas with overhanging branches [15]-[2]FRY in open shorelines or on stream margins of structurally complex streams, with logs, bushes, and stones [59]-[2]. Habitat preference order: back eddies, log jams, undercuts or open bank areas, fast water [60]-[2]. Settle at the bottom during darkness and stay near rocks or logs during daylight [1]-[2]. FARM: artificial substrate increased growth of ALEVINS and consequently survival of PARR [61]. Preference for and higher growth rate in clear vs. turbid water [5]. RAS: neither substrate nor environmental enrichment [6]. For details of holding systems crit. 1 and 2. LAB: higher egg survival in gravel (3-32 mm diameter) with no sand [62].

PARR: WILD: spring-fed ponds adjacent to main stream [63]-[2]; deeper pools of streams with logs, exposed roots, and undercut banks, especially important when temperature approaches 2 °C [19]-[2]. Preference for side pools with cover [17] [64]-[2] and clear rubble vs. silted rubble [64]-[2]. Higher survival in complex habitat with large woody debris [65] and riparian canopy and low % of bedrock [31]. Uniformly distributed and close to gravel bottom when at high current streams [18]-[2]. Can handle sediments in water of 4,000 mg/L, but will cease feeding at >300 mg/L [66]-[2]. Can survive in residual pools of streams that dry out during the summer [67]. FARM: pools with streamside vegetation for shading [7]-[2]; biomass is reduced if canopy is very dense [68]-[2]. RAS: neither substrate nor environmental enrichment [6]. LAB: avoidance of turbid water >70 nephelometric turbidity units, which induces fright behaviour [69].

SMOLTS: WILD: at sea [37]-[2]. FARM: black plastic cover to inhibit marine plant growth [11]. RAS: neither substrate nor environmental enrichment [6]. For details of holding systems crit. 1 and 2.

ADULTS:  SMOLTS.

SPAWNERS: WILD: fine gravel to coarse rubble [70]-[2] (≤15 cm diameter), sometimes mud, fine sand, silt [16]-[2]. Female digs 3-4 real nests in succession without males' participation and several fake nests before and after spawning [24]-[2]. Nests: 17.8-39.1 cm gravel depth in well oxygenated water [24]-[2]. Clear to heavily silted water [70]-[2]. Females displace silt and sand when digging [24]-[2]. After spawning, female buries eggs within 1 min and creates a new nest for next spawning event [24]-[2]. FARMno data found yet.


8. Are minimal farming conditions (handling, confinement etc.) likely not to stress the individuals of the species? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

ALEVINS: FARM: stressed by turbid water [5], grading and moving, changes in water quality, changes in feeding regime or even feed type [6]. Following protocols and routines prevents stress [6].

PARR: FARM: stressed by transport [71] [72], removal from water (30 s) or confinement [73], grading and moving, changes in water quality, changes in feeding regime or even feed type [6]. Following protocols and routines prevents stress [6]. LAB: stressed by social isolation, stressed when subordinate in a group of 6 [56].

SMOLTSFARM: stressed by transport [71] [72], removal from water (30 s) or confinement [73], grading and moving, changes in water quality, changes in feeding regime or even feed type [6]. Following protocols and routines prevents stress [6]. Pens with rigid polyethylene plastic screening cause scarring of the eyes and eventual blindness [11]. Stress is more severe in SMOLTS than in PARR [74].

ADULTS: FARM: stressed by handling (6.5% deaths) [11], grading and moving, changes in water quality, changes in feeding regime or even feed type [6]. Following protocols and routines prevents stress [6]. Rounded caudal fins due to abrasion form the net [11].

SPAWNERS: FARM: in artificial streams: hatchery-reared IND less active than wild conspecifics [25].


9. Are malformations of this species likely to be rare under farming conditions? What overall welfare potential can be achieved? How certain are these findings?

?
Likelihood
?
Potential
L
Certainty

ALEVINS and FRY: WILD: no data found yet. FARM: spinal issues [6].

PARR: WILD: for salmonids inlcuding O. kisutch, rarely blindness [35], rarely missing fins (pectoral, ventral, adipose, caudal partially) due to injuries or birth defect [35]. Occasional twisted snouts, deformed upper/lower jaws, spine curvature in S shape, abnormal shortness [35]. FARM: for salmonids inlcuding O. kisutch, twisted snouts, deformed upper/lower jaws, spine curvature in S shape, abnormal shortness [35]. Spinal issues [6].

SMOLTS: WILD: for salmonids including O. kisutch, one or both opercula turned under [35]. FARM: for salmonids including O. kisutch, opercula that do not fully cover the gills, probably due to inappropriate diet [35]. Spinal issues [6].

ADULTS: WILD: for salmonids including O. kisutch, common full or partial blindness [35], occasionally missing fins (pectoral, ventral, adipose, caudal partially) due to injuries or birth defect [35]. Occasional twisted snouts, deformed upper/lower jaws, spine curvature in S shape, abnormal shortness [35]. FARM: for salmonids inlcuding O. kisutch, twisted snouts, deformed upper/lower jaws, spine curvature in S shape, abnormal shortness [35]. Spinal issues [6].


10. Is a humane slaughter protocol likely to be applied under minimal farming conditions? What overall welfare potential can be achieved? How certain are these findings?

L
Likelihood
M
Potential
M
Certainty

Common slaughter method: FARM: anaesthetised with high CO2 or iced water [13], then bled by cutting gill arches and immersing in iced water [13] [6]. LAB: anaesthetised with high CO2 and bled by cutting gill arches [75]. High-standard slaughter method: for O. mykiss, indications that electrical stunning before killing by chilling or bleeding is most effective [76] [77] [78] [79]. Percussive stunning before killing by chilling or bleeding is most effective in larger trout sizes [78]. Further research needed to determine whether this applies to O. kisutch as well [80].


Side note: Domestication

DOMESTICATION LEVEL 5 [81], fully domesticated.


Side note: Feeding without components of forage fishery

All age classes: WILD: carnivorous [35] [82] [83] [84] [85]. FARM: for PARR in fresh water [86] and for SMOLTS in sea water [87], fish meal may be partly* replaced by sustainable sources; for PARR in fresh water, fish oil may be partly* [88] to mostly* replaced [89].

* 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 [81]
FARM = setting in farm environment
FRY = larvae from external feeding on, for details Findings 10.1 Ontogenetic development
IND = individuals
LAB = setting in laboratory environment
PARR = juvenile stage in rivers, for details Findings 10.1 Ontogenetic development
SMOLTS = 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


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