Evidence for selective mortality in marine environments: the role of fish migration size, timing, and production type

Claiborne, Andrew M.; Miller, Jessica A.; Weitkamp, Laurie A.; Teel, David J.; Emmett, Robert L.

doi:10.3354/meps10963

Cited by 26 publications

(43 citation statements)

References 75 publications

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“…Early ocean growth rates estimated from otoliths for three of the stocks included here (and some of the same individuals) were very close to our estimated growth rates (Tomaro et al 2012;Claiborne et al 2014;Miller et al 2014), suggesting that our results are reasonably representative of the true growth rates.…”

Section: Validity Of Ocean Growth Assumptionssupporting

confidence: 65%

“…Studies designed to evaluate size-selective mortality have either failed to find evidence of it or have found mixed results (occurring in some but not all years) for Chinook Salmon, including studies focused on Columbia River salmon (Claiborne et al 2011(Claiborne et al , 2014Tomaro et al 2012;Miller et al 2013Miller et al , 2014. Early ocean growth rates estimated from otoliths for three of the stocks included here (and some of the same individuals) were very close to our estimated growth rates (Tomaro et al 2012;Claiborne et al 2014;Miller et al 2014), suggesting that our results are reasonably representative of the true growth rates.…”

Section: Validity Of Ocean Growth Assumptionsmentioning

confidence: 99%

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Stock‐Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

et al. 2015

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Juvenile salmon transitioning from freshwater to marine environments experience high variation in growth and survival, yet the specific causes of this variation are poorly understood. Size at and timing of ocean entry may contribute to this variation because they influence both the availability of prey and vulnerability to predators. To Subject editor: Carl Walters, University of British Columbia, Canada This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/ licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The moral rights of the named author(s) have been asserted. *Corresponding author: laurie.weitkamp@noaa.gov Received January 16, 2015; accepted April 28, 2015 370 Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science 7:370-392, 2015 Published with license by American Fisheries Society ISSN: 1942-5120 online DOI: 10.1080/19425120.2015 explore this issue, we used stock assignments based on genetic stock identification and internal tags to document the stock-specific size and timing of juvenile hatchery and presumed wild Columbia River Chinook Salmon Oncorhynchus tshawytscha and steelhead O. mykiss at ocean entry during 2007-2011. We found that juvenile salmon and steelhead had consistent stock-specific capture dates, with lower-river stocks typically having earlier timing than those originating farther upstream. Mean size also varied among stocks and was related to hatchery practices. Hatchery yearling Chinook Salmon and steelhead were consistently larger than wild fish from the same stocks, although timing in the estuary was similar. In contrast, hatchery subyearling Chinook Salmon were of similar size to wild fish but entered the ocean up to a month earlier. We evaluated the potential importance of these traits on early marine growth by estimating stock-specific growth rates for Chinook Salmon caught in estuarine and ocean habitats. Growth rates were related to relative ocean entry timing, with lower growth rates for stocks that had only recently arrived in marine waters. Our results demonstrate that stocks within a single basin can differ in their size and timing of ocean entry, life history traits that contribute to early marine growth and potentially to the survival of juvenile salmon. Our results also highlight the necessity of considering stock-specific variation in life history traits to understand salmon ecology and survival across the entire life cycle.The movement of juvenile salmon from freshwater to marine habitats is a poorly understood but critical transition (Pearcy 1992;Pearcy and McKinnell 2007). During this transition, fish must not only physiologically adapt to salt water, but also contend with entirely new prey, predators, and habitats (Spence and Hall 2010). The size at and timing of ocean entry have been identified as important factors during this period. Minor variation in timing can have...

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Section: Validity Of Ocean Growth Assumptionssupporting

confidence: 65%

Section: Validity Of Ocean Growth Assumptionsmentioning

confidence: 99%

Stock‐Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

et al. 2015

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“…Distributions for natural Chinook from the Puget Sound are based on trap data (see Materials and Methods). Chinook salmon of natural origin, which are typically smaller than hatchery fish, also survive at significantly higher rates (Claiborne et al 2014, Neville et al 2015, Losee et al 2019. The length range associated with Lance et al (2012) is based on the season with the highest percentages of juvenile Chinook in the seal diet (July-September).…”

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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“…Despite these advances, however, one aspect of the marine ecology of juvenile salmon, predation, remains poorly understood (Pearcy 1992;Pearcy and McKinnell 2007;Emmett and Krutzikowsky 2008). Many fundamental questions regarding predation on salmon during the marine phase of the life cycle remain unanswered (Miller et al 2013;Claiborne et al 2014) including: (1) What is the identity of predators by major taxon (i.e., bird, fi sh, marine mammals)? (2) When does most predation occur?…”

Section: Introductionmentioning

confidence: 99%

The Influence of Environmental Variation on the Columbia River Estuarine Fish Community: Implications for Predation on Juvenile Salmonids

Weitkamp¹,

Good²,

Lyons³

et al. 2016

NPAFC Bull.

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Evidence for selective mortality in marine environments: the role of fish migration size, timing, and production type

Cited by 26 publications

References 75 publications

Stock‐Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

Stock‐Specific Size and Timing at Ocean Entry of Columbia River Juvenile Chinook Salmon and Steelhead: Implications for Early Ocean Growth

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

The Influence of Environmental Variation on the Columbia River Estuarine Fish Community: Implications for Predation on Juvenile Salmonids

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