Age and Method of Release Affect Migratory Performance of Hatchery Steelhead

Tatara, Christopher P.; Cooper, Matt R.; Gale, William L.; Kennedy, Benjamen M.; Pasley, Chris R.; Berejikian, Barry A.

doi:10.1080/02755947.2017.1317676

Cited by 10 publications

(24 citation statements)

References 34 publications

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“…; Tatara et al. ). After a period of volitional emigration, the raceway gates are closed, and non‐migrants can be either euthanized or released into closed bodies of water where they will not present a risk to native stocks.…”

Section: Discussionmentioning

confidence: 96%

“…Lower daily rations and rearing temperatures were implemented for the S2 group than for the S1 group (Tatara et al. : their supplement). Both S1 and S2 juveniles were reared in Methow River water during the month(s) prior to their release in mid‐April in order to facilitate homing to the Methow River.…”

Section: Methodsmentioning

confidence: 99%

“…A minimal number of PIT‐tagged fish released from the WNFH are detected as migrants at PIT tag interrogation sites in the Columbia River after June 30 of their RY (Tatara et al. ). We defined migratory steelhead as fish that left the Methow River and were detected at least once at any of the four main‐stem Columbia River hydroelectric dams equipped with PIT tag interrogation systems (Rocky Reach, McNary, John Day, or Bonneville Dam; Figure ) by June 30 of each RY.…”

Section: Methodsmentioning

confidence: 99%

“…Each model included prerelease FL (mm) and a quadratic term for FL as continuous covariates because previous results (Tatara et al. ) found that models including the quadratic term best estimated survival during out‐migration. The goodness‐of‐fit tests indicated that the data fit the logistic regression models (Pearson and Hosmer–Lemeshow tests: all P ≥ 0.05).…”

Section: Methodsmentioning

confidence: 99%

“…Migration rates of S2 steelhead from the WNFH to the Columbia River were equivalent or better than those of S1 steelhead, and fish size at release largely explained significant migration and survival differences between S1 and S2 fish in some RYs (Tatara et al. ). In this study, we evaluated how age at release affects residualism in hatchery steelhead.…”

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confidence: 99%

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Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

Tatara

Larsen

Cooper

et al. 2019

N American J Fish Manag

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Steelhead Oncorhynchus mykiss that fail to emigrate seaward after release from hatcheries, commonly referred to as “residuals,” can have negative impacts on natural populations ranging from competition and predation to interbreeding with returning anadromous adults. We investigated how age at release, size, and maturation status influenced the rate of residual production in hatchery summer‐run steelhead released from the Winthrop National Fish Hatchery (Methow River, Washington) between 2010 and 2015. Migration data from 21,598 individuals implanted with PIT tags identified 1,783 residual steelhead expressing two distinct phenotypes: immature male and female parr; and precociously mature males. We found that age at release significantly affected the predominant residual phenotype. Age‐1 steelhead residuals (S1 rearing strategy) were dominated by smaller parr of both sexes (fish < 146 mm FL), while age‐2 residuals (S2 rearing strategy) were dominated by mature males, although both phenotypes were present in both S1 and S2 residual groups. Collections of residual steelhead in the Methow River indicated that parr phenotype residuals grew as well as natural‐origin juvenile O. mykiss, suggesting potential competition for food resources and habitat. Detections of PIT tags within the Methow River basin indicated that precocious male residuals may overlap both spatially and temporally with previously documented spawning anadromous adults, posing a potential genetic management risk. Both residual phenotypes had poor overwinter survival, and only 1 of the 1,783 residual fish eventually returned to the Methow River as an anadromous adult. We conclude that the ecological and genetic consequences of residual steelhead far outweigh their potential contribution to anadromous production, and measures should be taken to reduce their production by changing hatchery rearing practices.

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Section: Discussionmentioning

confidence: 96%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

Tatara

Larsen

Cooper

et al. 2019

N American J Fish Manag

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Plasticity of Behavioral and Growth Responses to Two Feeding Regimes and Implications for the Domestication of Steelhead Trout

et al. 2021

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The effects of domestication selection on fitness are of serious concern in hatchery‐reared anadromous salmonids, which often experience selection for rapid growth and associated deviations from natural agonistic and feeding behaviors. The high rations that are used to raise age‐1 smolts and the reduced rations that are used to produce age‐2 smolts potentially result in very different behavioral tactics and social dynamics of competition in hatchery tanks. Consequently, steelhead Oncorhynchus mykiss hatchery programs with recovery or conservation goals may need to change their aquaculture practices to minimize domestication selection. This study investigated how the feeding rate (proportion of presented food items that were successfully captured) and relative competitive ability (ability to monopolize food items in small groups) of age‐1 and age‐2 steelhead corresponded to feeding location (surface or bottom) and growth rate in hatchery rearing tanks. We raised steelhead from a common broodstock to smolt at age 1 or age 2 by manipulating their rations (age‐1 fish received the high ration, age‐2 the low ration). The fish in the age‐1 treatment had a lower feeding rate than did those in the age‐2 treatment. Feeding rate was positively correlated with both body size and with growth rate in the rearing tanks at both rations. The age‐2 steelhead were more likely to be detected at a single feeding location than were the age‐1 fish, which were more frequently detected at both locations. The more competitive age‐1 fish were more frequently detected at both feeding locations, and the less competitive fish were detected at only one location. Relative competitive ability was not associated with feeding location in the age‐2 treatment, nor was it associated with growth rate in either treatment. Age‐2 steelhead that were detected only at the bottom or at both feeding locations had higher growth rates than those that were detected only at the surface, suggesting greater scramble competition near the point of food delivery under the restricted ration. Feeding location was not associated with growth rate in the age‐1 treatment. The results indicate that ration directly affects feeding rate and that ration and relative competitive ability interact to influence feeding rate. Because feeding rate was positively associated with growth rate at both ration levels in the hatchery tanks, behaviors that are associated with feeding motivation may be an important trait under selection in salmonid hatcheries.

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Parallel epigenetic modifications induced by hatchery rearing in a Pacific salmon

Luyer

Laporte

Beacham

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

187

184

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Wild stocks of Pacific salmonids have experienced sharp declines in abundance over the past century. Consequently, billions of fish are released each year for enhancing abundance and sustaining fisheries. However, the beneficial role of this widely used management practice is highly debated since fitness decrease of hatchery-origin fish in the wild has been documented. Artificial selection in hatcheries has often been invoked as the most likely explanation for reduced fitness, and most studies to date have focused on finding signatures of hatchery-induced selection at the DNA level. We tested an alternative hypothesis, that captive rearing induces epigenetic reprogramming, by comparing genome-wide patterns of methylation and variation at the DNA level in hatchery-reared coho salmon (Oncorhynchus kisutch) with those of their wild counterparts in two geographically distant rivers. We found a highly significant proportion of epigenetic variation explained by the rearing environment that was as high as the one explained by the river of origin. The differentially methylated regions show enrichment for biological functions that may affect the capacity of hatchery-born smolts to migrate successfully in the ocean. Shared epigenetic variation between hatchery-reared salmon provides evidence for parallel epigenetic modifications induced by hatchery rearing in the absence of genetic differentiation between hatchery and natural-origin fish for each river. This study highlights epigenetic modifications induced by captive rearing as a potential explanatory mechanism for reduced fitness in hatchery-reared salmon.

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Age and Method of Release Affect Migratory Performance of Hatchery Steelhead

Cited by 10 publications

References 34 publications

Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

Age at Release, Size, and Maturation Status Influence Residualism in Hatchery Steelhead

Plasticity of Behavioral and Growth Responses to Two Feeding Regimes and Implications for the Domestication of Steelhead Trout

Parallel epigenetic modifications induced by hatchery rearing in a Pacific salmon

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