Effects of smolt release timing and size on the survival of hatchery-origin coho salmon in the Strait of Georgia

Irvine, James R.; O'Neill, M. H. B.; Godbout, Lyse; Schnute, Jon T.

doi:10.1016/j.pocean.2013.05.014

Cited by 29 publications

(33 citation statements)

References 19 publications

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“…In conclusion, the hatchery practice of delayed release tended to increase resident behavior of Puget Sound Coho Salmon but residents still made up only a small fraction of the recoveries. Residency is apparently related to environmental factors that vary with year; the interannual variation and general downward trend in survival of Coho Salmon in the Salish Sea (Beamish et al 1999Irvine et al 2013) also suggest strong marine influences on Coho Salmon ecology. The environmental variation in Puget Sound seems to influence resident behavior in Chinook Salmon as well, though it is unclear how biotic and abiotic factors interact with each fish's internal condition and genotype to determine whether they display resident or migratory behavior once they enter marine waters.…”

Section: Discussionmentioning

confidence: 99%

Factors Affecting Partial Migration in Puget Sound Coho Salmon

Rohde

Fresh

Quinn

2014

N American J Fish Manag

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Partial migration, the behavior pattern in which a portion of a population migrates while others do not, is a widespread phenomenon with ecological and evolutionary consequences. Most Coho Salmon Oncorhynchus kisutch from Puget Sound, Washington, migrate to feed over the continental shelf or offshore in the North Pacific Ocean, but some remain in the semiestuarine waters of Puget Sound and are termed residents. The objective of this study was to determine which of several factors influenced residency in Puget Sound Coho Salmon. Coded wire tag recovery data showed that resident Coho Salmon were smaller than their migratory counterparts, and we used this size difference and the relative catch patterns along the coast and in Puget Sound to classify Coho Salmon caught in Puget Sound between November and August as residents. We then analyzed the effects of location of origin, day of release, weight at release, hatchery or wild rearing, and year on the proportion of fish caught as residents. Based on 268 release groups between 1975 and 1992, we classified 3.4% of fish recovered as residents, 61.3% as migrants, and 35.3% as ambiguous because they were recovered in Puget Sound in September and October, when residents and migrants were mixed. The proportion of residents varied as a function of year, basin, and day of the year. Releases into south Puget Sound produced the highest proportion of residents, and resident fish tended to be recovered in the basin where they entered Puget Sound. While other factors may influence residency in Coho Salmon, the effects of day of release and location of origin may be useful for management of these populations, as the tendency to remain in Puget Sound or migrate to the coast affects the fisheries in which the fish are taken and their growth rate, their uptake of contaminants, and their role in food webs. Received August 15, 2013; accepted February 3, 2014

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Section: Discussionmentioning

confidence: 99%

Factors Affecting Partial Migration in Puget Sound Coho Salmon

Rohde

Fresh

Quinn

2014

N American J Fish Manag

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“…These potential interactions will likely vary regionally and/or locally, as suggested by previous studies of juvenile Chinook in the Salish Sea (Chamberlin et al 2017). However, like previous studies have suggested (Beamish et al 1992, Irvine et al 2013), more diverse release strategies that resemble natural stocks could be explored as a means to promote a more balanced, natural marine food web that is less influenced by pulsed, high-density subsidies of hatchery fish. The intent of this study is not to argue in favor of releasing smaller Chinook or claim that altering release dates will result in increases in marine survival of either natural or hatchery populations.…”

Section: Discussionmentioning

confidence: 96%

“…The intent of this study is not to argue in favor of releasing smaller Chinook or claim that altering release dates will result in increases in marine survival of either natural or hatchery populations. However, like previous studies have suggested (Beamish et al 1992, Irvine et al 2013), more diverse release strategies that resemble natural stocks could be explored as a means to promote a more balanced, natural marine food web that is less influenced by pulsed, high-density subsidies of hatchery fish. Staggering releases over several months, and coordinating releases among hatchery operations to reduce homogenization across sub-basins, could dampen numerical responses from predators and could also hedge against poor environmental conditions via increased portfolio effects (Satterthwaite and Carlson 2015).…”

Section: Discussionmentioning

confidence: 99%

Ecological implications of changing hatchery practices for Chinook salmon in the Salish Sea

et al. 2019

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For over a century, hatchery programs have been used to subsidize natural salmon populations in order to increase fisheries opportunities and, more recently, to conserve declining natural populations. While an extensive literature has described the impacts of large-scale hatchery operations on freshwater ecosystems, less attention has been given to ecosystem interactions within the marine environment. We analyzed records of hatchery-released Chinook salmon in the Salish Sea to assess temporal and spatial changes in hatchery practices since 1950, with the goal of identifying potential implications for ecosystem dynamics and conservation efforts in the region. Over the past 65 yr, we found significant changes in the size and time at which juvenile salmon are released, resulting in decreased diversity of these traits. Research suggests that predation on juvenile salmon by other fish, avian, and marine mammal species could be size-dependent, and our results indicate that current hatchery practices are releasing Chinook salmon in the size range preferred by these predators. With current marine survival rates at chronically low levels, and increasing demand for hatchery subsidies, it is important to consider how modifying existing hatchery programs intended to reduce homogenization may promote more natural marine food web dynamics, with potential benefits to both hatchery and natural Chinook populations.

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“…[31,32]) showed that survival was affected more by release date than release size. However, Irvine et al [33], based on 25-27 years of data, concluded more recently that the declining trend in survival of Strait of Georgia coho could not be reversed by manipulating release time and/or size as suggested by the results of the aforementioned short-term experiments. These authors also reported mixed effects of time and size at release among the five hatchery populations they examined.…”

Section: Discussionmentioning

confidence: 99%

“…These authors also reported mixed effects of time and size at release among the five hatchery populations they examined. The results presented in [33] are unique because studies of hatchery effects on return are generally short term ones. Mathews and Ishida [34] using experiments conducted at a Columbia River hatchery for one brood year and a southern Oregon hatchery in the next brood year, found that the effect release size on coho survival were mixed.…”

Section: Discussionmentioning

confidence: 99%

Exploring the Biological Basis of Age-Specific Return Variability of Chinook Salmon (Oncorhynchus tshawytscha) From the Robertson Creek Hatchery, British Columbia Using Biological or Physical Oceanographic Explanatory Variables

Tanasichuk¹,

Emmonds²

2016

TOFISHSJ

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Abstract:We used information about hatchery rearing and release practices for 173 releases of age 0+ smolts between 1982 and 2012, as well as time series of early marine prey biomass and predator abundance/biomass, to investigate the biological basis of agespecific return variability of chinook salmon (Oncorhynchus tshawytscha) from the Robertson Creek Hatchery. We used survival rate as the response variable and considered the rate to be an apparent one because it is the product of the survival and maturation rates. Results of multiple regression analyses (adjusted R 2 ranging between 0.43 and 0.59) showed that Pacific mackerel (Scomber japonicus) and Steller sea lion (Eumetopias jubatus) abundances accounted consistently for all of the explained variation in agespecific survival rate. We suggest that the persistence of the early marine (predation) effect with age shows that there is no effect of hatchery practice on age at maturity. Apparent survival rate variation was not explained when we used conventional physical oceanographic measurements (temperature, salinity, Pacific Decadal Oscillation Index, Northern Oscillation Index, Arctic Oscillation Index, Aleutian Low Pressure Index, Bakun Upwelling Index, timing of spring transition) in our analyses.

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Effects of smolt release timing and size on the survival of hatchery-origin coho salmon in the Strait of Georgia

Cited by 29 publications

References 19 publications

Factors Affecting Partial Migration in Puget Sound Coho Salmon

Factors Affecting Partial Migration in Puget Sound Coho Salmon

Ecological implications of changing hatchery practices for Chinook salmon in the Salish Sea

Exploring the Biological Basis of Age-Specific Return Variability of Chinook Salmon (Oncorhynchus tshawytscha) From the Robertson Creek Hatchery, British Columbia Using Biological or Physical Oceanographic Explanatory Variables

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