CONSERVATION AND SCIENCE REPORT

 

Issue 4, 2018

Bill Bakke

Director of Science and Conservation 

The Conservation Angler

www.theconservationangler.org

_____________________________

From Brian Morrison, Ontario, Canada

I found this quote from the ‘father’ of fish culture in Canada about his efforts to sustain a landlocked population of Atlantic Salmon in Lake Ontario circa 1870’s:

 

Fish Culture - Lake Ontario Atlantic Salmon

 

Samuel Wilmot who initiated fish culture in Canada, wrote in 1870: “A repetition of this process (planting artificially hatched salmon in streams emptying into Lake Ontario) for a few years, aided by judicious enactments for their preservation and protection, would undoubtedly soon replenish and restock the waters of Lake Ontario with salmon.”

 

Within a comparatively few years after this prediction, the salmon was extinct in Lake Ontario.  It is possible that if artificial propagation had never been discovered we would be further ahead than we are today in fish conservation, because then such complete dependence would not have been placed on hatcheries as the cure-all for the maintenance of fish populations.  It would probably have been learned much sooner that, unless natural conditions favorable for a species are maintained, a body of water cannot be made to produce it in numbers.

 

Hatcheries have a place in fisheries management, but it is not as large as was once believed.  A carefully considered opinion of the place of fish culture in fisheries management is contained in a fish policy adopted by the American Fisheries Society in 1954.  This is the organization through which those engaged in research or administration meet to consider problems in fisheries management.  Their pronouncement contained the following statements: “Periodic replanting is desirable of lakes that winterkill infrequently or of waters which are occasionally depleted by pollution; otherwise; the stocking of the young of any species in waters having adequate spawning conditions is considered of doubtful value.”

 

Harkness and Dymond (1961) Atlantic Salmon were extirpated from Lake Ontario by the late 1800’s, and functionally gone by the mid 1880’s.

Genetic Differences Between Wild and Hatchery Brown Trout

Linløkken, Arne N., Thrond O. Haugen, Matthew P. Kent, Sigbjørn Lien. 2017. Genetic differences between wild and hatchery-bred brown trout (Salmo trutta L.) in single nucleotide polymorphisms linked to selective traits. Ecology and Evolution .  DOI: 10.1002/ece3.3070.

 

Brown trout are present in streams and lakes of different environmental conditions and are adapted to local environments through phenotypic plasticity and genetic modification due to natural selection. An important trait of animals is individual growth… growth shows high variability due to the ultimate environmental factors, among which temperature is crucial in monitoring populations from a conservation perspective.

This study includes three groups of brown trout, from the same population, of which two groups comprise wild specimens and one is composed of F1-generation individuals reared in a hatchery. The two wild fish groups were sampled in order to study effects of over-winter size-selective survival (selective sweeps) among loci of SNP markers. The hatchery-reared fish are used for annual supportive stocking in a downstream lake and are bred from a mixture of two local strains to maintain locally adapted genotypes. One of those is the wild fish strain of the two former groups. The hatchery group was included to explore the differing effects of selective forces in wild compared with hatchery fish bred from a limited number of randomly picked wild fish subject to forced mating, and with offspring living in a protected environment. Body size, which is shown to correlate positively with survival of young fish (Lorenzen, 1996), is used as a selective trait in the comparisons.

Results

“Artificial spawning and breeding in hatchery will, due to the lack of sexual selection and natural selection by the environment, result in a “hatchery genepool” differing from that of their pristine relatives.”

“The lack of natural selection under hatchery conditions may also lead to survival of maladapted behavior types that normally would not survive in nature. For instance bold behavior types may be beneficial in a hatchery environment as food is not limited and predation risk nonexistent (Sundström et al., 2004). Individuals with such risk-prone behavior are probably likely to be subject to predation in the wild.”

“Our results suggest that winter and spring conditions in the rearing stream Sagbekken favor genotypes coding for expressions of phenotypic values of a combination of physiological and behavioral traits (possibly linked to feeding activity) at low temperatures, and through this affects the mean body size of the cohort. This differs from the even larger hatchery fish…”

“…differentiation may result from the absence of sexual selection and/or differentiating selection mechanisms imposed under artificial spawning compared to what occurs under natural spawning.” 

“The genepool of the resulting offspring therefor may be very different from what results from natural spawning (Araki et al., 2008; Lamaze, Garant, & Bernatchez, 2013; Wedekind, Rudolfsen, Jacob, Urbach, & Muller, 2007). With a mortality of <5% in the hatchery, there was hardly any post fertilization selection affecting the H/1+ group, that is, phenotypic misfits in the wild, could survive well in the hatchery.”

“…growth capacity [was] expressed differentially between wild and hatchery-reared brown trout. This finding agrees with other studies demonstrating highly differentiated selection regimes in salmonid hatcheries compared with the wild, with possible negative long-term introgression consequences for wild populations exposed to repeated stocking of hatchery-reared individuals.”

“The lack of natural selection under hatchery conditions may also lead to survival of maladapted behavior types that normally would not survive in nature. For instance bold behavior types may be beneficial in a hatchery environment as food is not limited and predation risk nonexistent.  Individuals with such risk-prone behavior are probably likely to be subject to predation in the wild.

Climate Change and Synchrony Changes in Predator- Prey Life History

Bell, Donovan A., Ryan P. Kovach, Scott C. Vulstek, John E. Joyce,, David A. Tallmon. 2017. Climate-induced trends in predator–prey synchrony differ across life-history stages of an anadromous salmonid. Canadian Journal of Fisheries and Aquatic Sciences, 10.1139/cjfas-2016-0309

Abstract

Differential climate-induced shifts in phenology can create mismatches between predators and prey, but few studies have examined predator–prey mismatch across multiple life-history stages. We used long-term data from a warming stream with shifting salmonid migration timings to quantify intra-annual migration synchrony between predatory Dolly Varden (Salvelinus malma) and Pacific salmon prey and examined how predator–prey synchrony has been influenced by climate change. We demonstrate that Dolly Varden have become increasingly mismatched with spring downstream migrations of abundant pink salmon (Oncorhynchus gorbuscha) juveniles. However, Dolly Varden have remained matched with fall upstream migrations of spawning Pacific salmon, including coho (Oncorhynchus kisutch), sockeye (Oncorhynchus nerka), and pink salmon. Downstream predator–prey migration synchrony decreased over time and with higher temperatures, particularly with pink salmon. In contrast, upstream migration synchrony was temporally stable and increased with rising temperatures. Differing trends in Dolly Varden predator–prey synchrony may be explained by the direct use of salmon to cue upstream migration, but not downstream migration. Overall, we show that climate change can have differing impacts on predator–prey synchrony across life-history stages. 

Climate Change and Steelhead

 

Alisa A. Wade, Timothy J. Beechie, Erica Fleishman, Nathan J. Mantua, Huan Wu,

John S. Kimball, David M. Stoms and Jack A. Stanford. 2013. Steelhead vulnerability to climate change in the Pacific Northwest. Journal of Applied Ecology 2013, 50, 1093–1104. doi: 10.1111/1365-2664.12137

 

http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12137/epdf

This study points out that steelhead are at risk due to changing climate conditions in their spawning and rearing habitats that are already modified by development of watersheds and impacts such as dams, water diversions, agriculture and forestry, urban development and pollution etc. Those impacts create a legacy of depletion for wild steelhead that will expand and become more severe with climate change.  It is mentioned that harvest and hatcheries have an impact on wild steelhead recognizing that fishery management does not secure spawner abundance (escapement from fisheries) and egg deposition criteria by watershed for wild populations. In addition naturally spawning hatchery steelhead with wild fish causes reduced survival and spawning success of wild steelhead in most watersheds. The principle changes due to fishery and habitat management is reduced life history diversity represented by genetic and trait diversity impacts affecting resiliency.   Consequently, current management of wild steelhead populations and the productivity of their habitats have set these animals up for even larger impacts from climate change because wild steelhead have reduced ability to cope with changes to their freshwater environment. Changes in their ocean habitat from climate warming are causing survival reduction for potential spawners.   

Summary

1. Steelhead (Oncorhynchus mykiss) and other Pacific salmon are threatened by unsustainable levels of harvest, genetic introgression from hatchery stocks and degradation or loss of freshwater habitat. Projected climate change is expected to further stress salmon through increases in stream temperatures and altered stream flows.

2. We demonstrate a spatially explicit method for assessing salmon vulnerability to projected climatic changes  (scenario for the years 2030–2059), applied here to steelhead salmon across the entire Pacific Northwest (PNW). We considered steelhead exposure to increased temperatures and more extreme high and low flows during four of their primary freshwater life stages: adult migration, spawning, incubation and rearing. Steelhead sensitivity to climate change was estimated on the basis of their regulatory status and the condition of their habitat. We assessed combinations of exposure and sensitivity to suggest actions that may be most effective for reducing steelhead vulnerability to climate change.

3. Our relative ranking of locations suggested that steelhead exposure to increases in temperature will be most widespread in the southern Pacific Northwest, whereas exposure to substantial flow changes will be most widespread in the interior and northern Pacific Northwest. There were few locations where we projected that steelhead had both relatively low exposure and sensitivity to climate change.

4. Synthesis and applications. There are few areas where habitat protection alone is likely to be sufficient to conserve steelhead under the scenario of climate change considered here. Instead, our results suggest the need for coordinated, landscape-scale actions that both increase salmon resilience and ameliorate climate change impacts, such as restoring connectivity of floodplains and high-elevation habitats.

“Stream temperatures, a critical control on salmon growth (Magnuson, Crowder & Medvick 1979) and distribution (Brannon et al. 2004), are projected to increase in the PNW in the coming decades.”

“Stream flow regimes, which also control abundance and distributions of freshwater fishes (Stanford et al. 1996; Poff et al. 1997), are also projected to change.”

“Shifts in stream temperature and flow regimes therefore pose additional threats to populations of steelhead and other salmonids (Waples, Beechie & Pess 2009) as a result of climate change.”

“We compared steelhead populations’ exposure and sensitivity to climate change to suggest optimal adaptation measures (actions to reduce either exposure or sensitivity to climate stressors) to maintain or increase probabilities of population persistence.”

“Our assessment of climatic threats to the freshwater portion of the steelhead life cycle is novel in three primary ways. First, we considered the effects of climate change–driven projected changes in both stream temperature and flow rather than solely air temperatures, stream temperatures or stream flow.”

“Secondly, we considered the effects of climate stress at multiple life stages, an important element of steelhead response to stressors that is not addressed in many studies that consider both temperature and flow.”

“Thirdly, we accounted for the multiple dimensions of exposure: duration, intensity and likelihood of effects. Our general approach could be adapted for other Pacific salmon and fishes with freshwater life stages and could be applied at finer resolutions with more detailed data.”

 “…exposure of steelhead to high temperatures will be greatest in the southern coastal and interior Columbia River Basin.”

“In general, steelhead populations in low-elevation rivers at the southern periphery of their range are expected to be most exposed to temperature stress during all life stages.”

“We projected that the most extreme reductions in low flow magnitudes would occur primarily in the western Cascade, Lower Snake and Upper Columbia; consequently, we estimated that steelhead in these areas also had high exposure to more extreme low flows because of both increased duration and reduced magnitude of summer low flows.”

“We estimated that steelhead exposure to extreme high flows was greatest in the west Cascade region where   duration, intensity and timing of high flow changes were all unfavourable to steelhead incubation and migration life stages.”

“Our analysis provides the first relative ranking of estimated steelhead vulnerability to climate change across the entire PNW. We did not aim to prioritize specific areas for conservation because realistic prioritization requires finer-resolution assessments.”

“All modelling methods have limitations, from computational requirements to reliability of projections to clarity of underlying assumptions.”

“…habitat protection alone is likely insufficient for steelhead conservation given our projected changes in climate. Most steelhead populations in the PNW have poor status because they already have experienced unprecedented changes in stream temperature and flow patterns as a result of land- and water use practices, and climate change is projected to exacerbate these changes (NRC 1996).”

“Effective measures for increasing the quality of steelhead habitat include improving water quality, increasing water quantity, restoring connectivity of steelhead habitat and floodplains and improving instream habitat structure and nutrients (Roni et al. 2002; Roni, Hanson & Beechie 2008).

“Similarly, altering hatchery and harvest management practices might improve population status by decreasing hatchery introgression and increasing the abundance and diversity of wild fish (Schindler et al. 2010).

“Given the potential importance of stream temperature changes to steelhead persistence, it may be important to focus local restoration efforts on groundwater contributions to stream flow and creation of thermal refugia via hyporheic exchange.”

“Restoring connectivity of floodplains and high-elevation habitats will provide greater habitat diversity, increase resilience of salmon populations and decrease both temperature and peak flow effects by restoring physical processes that create refugia from both high temperatures and high flows (Waples, Beechie & Pess 2009”

“Maintaining diverse, connected habitats through each life stage (Crozier, Zabel & Hamlett 2008) and across the entire PNW can provide a partial buffer against future climate change effects and is likely to be necessary if steelhead are to persist throughout much of their range in the future. Steelhead and salmon have evolved for millions of years and have long thrived under changing climatic conditions when provided access to a connected array of varied habitats that support genetic and life-history diversity.”

 

Factors Influencing Hatchery Steelhead Residualization

Tatara et al. 2017. Age and Method of Release Affect Migratory Performance of Hatchery Steelhead. North American Journal of Fisheries Management 37:700–713,

“Regardless of the duration of hatchery rearing, an important goal of hatchery programs for anadromous salmonids is to produce smolts with high survival, rapid migration to the ocean, and low rates of residualism. Hatchery programs with high survival and efficient migration rates should be more likely to produce greater returns of anadromous adults. Steelhead that do not smolt prior to release often residualize (i.e., fail to out-migrate; Viola and Schuck 1995). In S1 (one year hatchery rearing) steelhead programs, residual fish are often small individuals that failed to attain thresholds for smoltification.

“In contrast, residuals from S2 (two year hatchery rearing) hatchery programs are often male fish that have exceeded thresholds for maturation during the extended rearing period (Berejikian et al. 2012). In either case, residual hatchery steelhead are less likely to survive, migrate, and contribute to the production of anadromous adults (Snow et al. 2013). Solutions to curtail residualism include size grading (Tipping et al. 2003), growth modulation (Sharpe et al. 2007), and volitional release with retention of non-migratory fish (Viola and Schuck 1995; Gale et al. 2009; Snow et al. 2013).

“The fate of steelhead that failed to transition (i.e., residual fish) was unknown but modeled as a mortality, because residual individuals are extremely unlikely to contribute to the anadromous adult population. Residual steelhead may die, may remain in the Methow River to spawn (e.g., as precocious males; Sharpe et al. 2007; Snow et al. 2013), or may survive to smolt in a subsequent year.

“The percentage of undetected fish from a given RY (return year) that were later detected as migrating during the year after release was low suggesting that few would return as anadromous adults.

“Both S1 and S2 steelhead that left the hatchery volitionally were larger and had higher survival than steelhead that were forced from the hatchery at the end of the volitional release period. Volitional release strategies have been used to remove nonmigratory hatchery steelhead so as to reduce residualism and the associated ecological and genetic risks to natural populations (Viola and Schuck 1995; Snow et al. 2013).

“Differences in overall survival between S1 and S2 steelhead were only significant in one RY, suggesting that residualism may be responsible for observed differences in survival between S1 and S2 steelhead and that this occurs closer to the point of release. However, volitional release appears to be an effective practice for removing these nonmigratory fish in both S1 and S2 hatchery populations. Finally, out-migration travel times of S2 smolts were consistently shorter than the travel times of S1 smolts, suggesting that an S2 rearing strategy might also reduce ecological interaction by reducing the amount of time for which hatchery smolts reside in freshwater after release (Tatara and Berejikian 2012).

“A common-garden experiment with S1 and S2 steelhead produced using NOR (natural origin) broodstock from the Methow River (i.e., same broodstock as the fish reported here) found that the S1 steelhead were smaller than S2 fish at the time of smoltification and that 24% of S1 steelhead did not survive a seawater challenge versus less than 1% of the S2 steelhead (Berejikian et al. 2017).

“Beyond technical solutions (i.e., engineering) or logistical solutions (e.g., fish transfers between hatcheries), adoption of an S2 strategy might be the only way to capitalize on the increased genetic and ecological benefits of using a local NOR broodstock at some geographic locations.

“Production of S2 smolts will require more resources than S1 smolts, and management strategies will have to consider the trade-off between those costs versus improvements in postrelease survival and potential reduction of ecological and genetic risks posed by residual hatchery steelhead.

I was unable to find an estimate of residualism in native broodstock hatchery steelhead reared for 2 years.  Residuals did occur but it was assumed to be less than for NOR hatchery brood reared for one year.  The study ends with a statement that two year old hatchery smolts migrate faster to the ocean and have higher survival than one year old smolts, but the decision to change the hatchery rearing program from a one year smolt to a two year smolt is a cost trade-off for managers.  This means that economic concerns trump ecological, conservation, and return rate for mitigation hatchery fish.  I suspect that managers compensate for poor performance of one year old hatchery smolts (cheaper) by releasing more fish.  This likely runs counter to conservation and recovery goals for steelhead threatened with extinction because more hatchery adults return than wild adults causing ecological and genetic impacts for the wild steelhead. (BMB)

 

Are Hatchery Juveniles from Wild Brood Stock Similar to Wild Juveniles

Salvanes, A.G.V. 2017.  Are antipredator behaviours of hatchery Salmo salar juveniles similar to wild juveniles? John Wiley and Sons.

Abstract

This study explores how antipredator behaviour of juvenile Atlantic salmon Salmo salar developed during conventional hatchery rearing of eggs from wild brood stock, compared with the behaviour of wild-caught juveniles from the same population. Juveniles aged 1+ years were tested in two unfamiliar environments; in one S. salar were presented with simulated predator attacks and in the other they were given the opportunity to explore an open-field arena. No difference was found in their spontaneous escape responses or ventilation rate (reflex responses) after simulated predator attacks. Hatchery-reared juveniles were more risk-prone in their behaviours than wild-caught individuals. Hatchery juveniles stayed less time in association with shelter. In the open-field arena, hatchery juveniles were more active than wild juveniles. Hatchery juveniles were also immobile for less time and spent a shorter amount of time than wild juveniles in the fringe of the open-field arena. Salmo salar size had no effect on the observed behaviour. Overall, this study provides empirical evidence that one generation of hatchery rearing does not change reflex responses associated with threats, whereas antipredator behaviour, typically associated with prior experience, was less developed in hatchery-reared than in wild individuals.

Introduction

“Release of captive-reared animals into the wild has a long history and is a common and accepted tool for enhancing and improving populations. For anadromous salmonids, major release programmes started in 1860–1880 both in the Pacific (Oncorhynchus spp.) and in the North Atlantic Oceans.

“Basic assumptions underlying release programmes, although not necessarily explicitly stated, are that hatchery-reared released individuals have the same biological and genetic characteristics as wild conspecifics. There are many examples of studies that challenge these assumptions and few, if any, release programmes of fishes can be regarded successful.

“Previous studies on salmonids have shown that hatcheries produce fishes characterized by antipredator behaviours that differ from behaviours of wild conspecifics.

“Prior experiences are important in shaping antipredator behaviour in fishes, but some behavioural traits can also be inherited.

“In hatcheries, rearing environments are very different from natural habitats with respect to density, predation risk, current velocities, shelter opportunities, food and feeding regimes. All these contribute to selection in hatcheries being different from selection in nature. Behavioural, morphological and physiological differences may therefore occur in hatchery-reared fishes because of differences in learning, expression of phenotypic traits and genotype selection.

“In hatcheries, there is plenty of food, habitats are more or less constant and the fishes can feed without themselves experiencing any risk of becoming prey for a larger predator. In nature, predation risk is an unavoidable part of life. Here bold fish will expose themselves to higher mortality risk than shy fish. To survive, prey species in natural populations will continuously need to modify behavior as predation risk changes.  In nature, there is seldom room for trial and error learning when predators are encountered. In order to survive, the prey have to recognize threats based on their prior experience and then respond appropriately.

“Due to their different background, it is therefore expected that hatchery and wild fishes differ in the way they respond to unfamiliar environments and to predation risk. Prior experience from threats will help in developing behavioural repertoires that give survival advantages. These issues are of particular interest for enhancement programmes where fishes are released.

“Instantaneous escape responses from threats are regulated by the autonomous nervous system that control involuntary actions (reflexes) such as heart rate and ventilation rate, but can also be a result of previous learned avoidance behaviours. Reflex responses allow the fish to make rapid escape responses at close range and this will give survival advantages.

“Increased ventilation means increased oxygen consumption and supply for metabolism under acute stress which together with increased heart rate will prepare the body’s motor system for immediate escape.  Hence, physiological responses to stress appear to be associated with escape reflex responses.

“In addition to appropriate reflex responses, prior experience will be crucial for prey survival in novel risky environments. Previous work on fishes, birds and mammals has shown that experience in early life affects behavioural phenotype.  Expression of behaviour developed prior to the experimental situation can be quantified using open field tests. Expressed behaviours depend on how individuals trade-off the benefit against costs of exploration. Risk can be reduced by avoiding dangerous places, or by changing activity pattern if a threat is encountered. Prey can escape from attacks and hide if shelter is present and they can reduce visibility through cryptic coloration or by freezing.

Findings

“Predator avoidance, possibly one of the most important skills to learn in most environments, is partly innate and partly dependent on experience. Reflex responses will generate rapid and appropriate responses at close range  and prior experience from threats will help in developing behavioural repertoires that give survival advantages. The data presented here demonstrate that wild caught juvenile S. salar and hatchery-reared juveniles spontaneously escaped simulated predator attacks and increased their ventilation rates, but they did not differ in characteristic reflex responses.

“Differences between hatchery and wild juveniles were, however, found in behaviours considered to be associated with prior experience. Wild juveniles stayed longer in association with shelter than hatchery juveniles did. Furthermore, in the open-field arena the wild juveniles were less active and stayed longer in the fringe than hatchery juveniles did and they were immobile (froze) for a longer time than hatchery juveniles.

“Despite the fact that wild juveniles in this study were smaller than hatchery juveniles, size had no effects on the observed behavioural differences. That wild juveniles were smaller suggests that behavioural trade-offs between growth and mortality favour growth in hatcheries, but result in submaximal growth due to the cost of predation risk in nature.

“Irrespective of being wild-caught from the Vosso River or being reared at Voss hatchery, juvenile S. salar studied here increased ventilation rates when exposed to simulated predator attacks and both groups escaped spontaneously from the attack. This suggests that first generation of hatchery-reared S. salar juveniles did not alter typical reflex responses to threats.

“Survival probability for a S. salar juvenile is different in a natural stream than in a hatchery environment. In nature there is seldom room for trial and error learning when predators are encountered and in order to survive the prey have to recognize threats based on their prior experience and then respond appropriately. Prey in natural populations would be faced with the continual need to modify their behaviours under the risk of predation since the activity patterns of predators are highly variable over space and time and wild individuals still alive in their natural habitat have survived due to appropriate behaviours.

“In hatcheries, those alive have survived because of good rearing conditions: plenty of food, no predators and the animals will have experienced a relatively constant and non-challenging environment. Hence, hatchery fishes will be deprived of experiences such as unpredictability, unfamiliar environments and threats. If hatchery fishes are released into natural habitats, it is therefore expected that they will have a narrower behavioural repertoire to tackle predation risk in their new environment. That wild juvenile S. salar in this study stayed longer in association with shelter than hatchery juveniles suggests that wild juveniles took fewer risks than hatchery juveniles.

“The behaviours measured in open-field tests typically express behavioural differences gained prior to the experimental situation. Individuals that have high activity and exploration rates are regarded as taking more risks than those that are less active and explore less. The costs for high exploration is high mortality as shown in studies across taxa.

“The data presented in this study show that hatchery juveniles explored more, were immobile for shorter time and stayed less time in the fringe of the open-field test arena than wild caught juveniles from the same S. salar population.

“In conclusion, hatchery juveniles expressed a riskier behaviour than wild juveniles with higher activity and exploration and by associating very little with shelter.

“In conclusion, hatchery juveniles expressed a riskier behaviour than wild juveniles with higher activity and exploration and by associating very little with shelter. Despite that this is believed to be caused by different prior experience it cannot not be ruled out that an alternative (non-mutually exclusive) explanation could have been selection and differential survival in both hatchery and wild environments leading to a non-random composition of phenotypes and genotypes surviving to testing in both groups. For example, not all individuals have survived in the wild to the juvenile stage and many individuals without the appropriate antipredator responses have died along the way. Thus, the individuals who have survived to this stage (and been captured) may have a non-random set of behaviours, phenotypes and genotypes. A higher proportion of risk-taking individuals of the wild than of hatchery S. salar may have been dead already at the time they were captured from the river (as a consequence of being too bold). Thus, without controlling for survival differences, it cannot be firmly concluded that the differences between the groups shown in this study are only due to plasticity and prior experiences.

“Nevertheless, despite that different selection occurs in hatcheries and the wild, there is empirical evidence that fishes and other animals can learn from experience and adapt their behaviour to fit local environments. For example, animals from high and low-predation sites develop different behavioural strategies that help promote survival in their respective environments. Other work on salmonids has shown that different kinds of early life experience can improve antipredator behaviours (Berejikian et al., 2003; Vilhunen, 2006; Roberts et al., 2011), as well as neural plasticity and spatial learning.

“Overall, this study provides empirical evidence that one generation hatchery rearing did not change reflex responses assumed to be associated with threats in juvenile Vosso S. salar, whereas antipredator behaviours associated with prior experience were more pronounced in wild than in hatchery-reared individuals. Fishes that grow and develop in a natural environment have the advantage that direct experience helps to refine and adapt behaviour so that it fits the demands of local environments. In this way, a fish learns the adaptive value of being wary of predators, or it learns how to most efficiently move between different resources. By contrast, fishes that are reared in hatcheries and subsequently released are at a considerable disadvantage because they are behaviourally ill-equipped to deal with the novel environment. It is an important step to ensure that proper antipredator behaviour is developed in hatcheries if fishes are released into the wild to enhance and improve populations. 

Additional Observations:

James Mullan 1990:

James Mullan (1990) reported on Mid-Columbia River chinook and compared the behavior of hatchery and wild chinook salmon. “We can spend the next 30 years on IHN virus or genetics and it wouldn’t change a thing. The problem is in chinook salmon behavior.  Wild fish and hatchery fish behave very differently.  Hatchery fish cannot be raised to act like wild fish.”

“Low returns of hatchery chinook salmon (Mullan 1987) seem to lie outside the purview of fish health and genetics…the behavior of chinook salmon in hatcheries is conditions – like that of Pavlov’s famous dogs – differently from that of wild fish.  For example, large age-0 and yearling spring chinook salmon released to Icicle Creek do not orient to cover, remain at the water surface, and drift downstream in the channel regardless of the season.  Recently-hatched fry released to Icicle Creek, by contrast, quickly remove themselves from strong currents and mimic the behaviour of naturally-produced chinook.  Exceptions to low hatchery returns almost invariably involve chinook salmon least exposed to hatchery life (Heard 1987).

Nathaniel Reed, 2018:

"I asked the hatchery manager about the quality of his parr and smolts.  He replied that his product was the finest of any hatchery in the country.  After a pause, I asked him: "Why do only 1% make it back to the rivers where they are stocked?" 

 

He replied: "Mr. Reed, my duty is to produce thousands of parr and smolts.  It is not in my jurisdiction to discover why so few of my superbly grown parr and smolts do not return to the rivers in which they have been stocked!"

 

"Ted Williams's recitation of the disastrous results of the West Coast federal, state and tribal hatcheries is accurate and should be compelling, but the political forces that continue to produce millions of Pacific salmon and steelhead have a lobby as forceful as the sugar cane lobby."

 

References

 

Heard, W.R. (editor) 1987. Report of the 1987 Alaska chinook salmon workshop. NWAFC Processed Rep. 88-06, 244p. Alaska Fish. Cent., Ned. Mar. Fish. Ser., NOAA, P.O. Box 210155, Auke Bay, AK 99821.

Mullan, James. 1990.  Status and Future of Spring Chinook Salmon in the Columbia River Basin – Conservation and Enhancement. Donn L. Park (Convenor).  Session II Stock Status and Carrying Capacity, Don Chapman Consultants, Inc. Boise, Idaho. NOAA Technical Memorandum NMFS-F/NWC-187.

Mullan, James 1987. Status and propagation of chinook salmon in the mid-Columbia River through 1985. U.S. Fish and Wildlife Service Biol. Rep. 89(3): 1-111.

Reed, N. Atlantic Salmon Journal, Summer 2018.