Effects of Climate and Competition for Offshore Prey on Growth, Survival, and Reproductive Potential of Coho Salmon in Southeast Alaska

Shaul, Leon; Geiger, Harold J.

doi:10.23849/npafcb6/329.347

Cited by 16 publications

(11 citation statements)

References 96 publications

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“…Because most of our data come from commercial harvests that occur in ocean-phase fish prior to the development of obvious external secondary sexual characteristics, we did not analyze the sexes separately. However, other studies examining length at age with reliable sex determination have shown similar trends in size and age for males and females 33,59 . As in Lewis et al 19 , we assume our results reflect similar trends in male and female salmon.…”

Section: Methodsmentioning

confidence: 74%

Recent declines in salmon body size impact ecosystems and fisheries

et al. 2020

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Declines in animal body sizes are widely reported and likely impact ecological interactions and ecosystem services. For harvested species subject to multiple stressors, limited understanding of the causes and consequences of size declines impedes prediction, prevention, and mitigation. We highlight widespread declines in Pacific salmon size based on 60 years of measurements from 12.5 million fish across Alaska, the last largely pristine North American salmon-producing region. Declines in salmon size, primarily resulting from shifting age structure, are associated with climate and competition at sea. Compared to salmon maturing before 1990, the reduced size of adult salmon after 2010 has potentially resulted in substantial losses to ecosystems and people; for Chinook salmon we estimated average per-fish reductions in egg production (−16%), nutrient transport (−28%), fisheries value (−21%), and meals for rural people (−26%). Downsizing of organisms is a global concern, and current trends may pose substantial risks for nature and people.

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Section: Methodsmentioning

confidence: 74%

Recent declines in salmon body size impact ecosystems and fisheries

et al. 2020

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“…The variable survival rates of different sizes of smolting O . kisutch (Lum, ) and the nomadic nature of return spawners (Shaul et al ., ), also may act to limit population sizes.…”

Section: Discussionmentioning

confidence: 99%

Genetic assessment of the effects of streamscape succession on coho salmon Oncorhynchus kisutch colonization in recently deglaciated streams

Scribner

Soiseth²,

McGuire

et al. 2017

Journal of Fish Biology

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Measures of genetic diversity within and among populations and historical geomorphological data on stream landscapes were used in model simulations based on approximate Bayesian computation (ABC) to examine hypotheses of the relative importance of stream features (geomorphology and age) associated with colonization events and gene flow for coho salmon Oncorhynchus kisutch breeding in recently deglaciated streams (50-240 years b.p.) in Glacier Bay National Park (GBNP), Alaska. Population estimates of genetic diversity including heterozygosity and allelic richness declined significantly and monotonically from the oldest and largest to youngest and smallest GBNP streams. Interpopulation variance in allele frequency increased with increasing distance between streams (r = 0·435, P < 0·01) and was inversely related to stream age (r = -0·281, P < 0·01). The most supported model of colonization involved ongoing or recent (<10 generations before sampling) colonization originating from large populations outside Glacier Bay proper into all other GBNP streams sampled. Results here show that sustained gene flow from large source populations is important to recently established O. kisutch metapopulations. Studies that document how genetic and demographic characteristics of newly founded populations vary associated with successional changes in stream habitat are of particular importance to and have significant implications for, restoration of declining or repatriation of extirpated populations in other regions of the species' native range.

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“…; Ruggerone et al. ; Shaul and Geiger ). For example, length of age‐1.4 Chinook Salmon from six Alaskan stocks was negatively correlated with Pink Salmon abundance in 1983–2012 (average r = −0.55, P < 0.05; G. Ruggerone, unpublished analysis).…”

Section: Discussionmentioning

confidence: 99%

Numbers and Biomass of Natural‐ and Hatchery‐Origin Pink Salmon, Chum Salmon, and Sockeye Salmon in the North Pacific Ocean, 1925–2015

2018

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Numerical abundance and biomass values presented here for Pink Salmon Oncorhynchus gorbuscha, Chum Salmon O. keta, and Sockeye Salmon O. nerka in the North Pacific Ocean span 90 years , representing the most comprehensive compilation of these data to date. In contrast to less populous species of salmon, these species are more abundant now than ever, averaging 665 × 10 6 adult salmon each year (1.32 × 10 6 metric tons) during 1990-2015. When immature salmon are included, recent biomass estimates approach 5 × 10 6 metric tons. Following an initial peak during 1934-1943, abundances were low until the 1977 regime shift benefited each species. During 1990-2015, Pink Salmon dominated adult abundance (67% of total) and biomass (48%), followed by Chum Salmon (20%, 35%) and Sockeye Salmon (13%, 17%). Alaska produced approximately 39% of all Pink Salmon, 22% of Chum Salmon, and 69% of Sockeye Salmon, while Japan and Russia produced most of the remainder. Although production of natural-origin salmon is currently high due to generally favorable ocean conditions in northern regions, approximately 60% of Chum Salmon, 15% of Pink Salmon, and 4% of Sockeye Salmon during 1990-2015 were of hatchery origin. Alaska generated 68% and 95% of hatchery Pink Salmon and Sockeye Salmon, respectively, while Japan produced 75% of hatchery Chum Salmon. Salmon abundance in large areas of Alaska (Prince William Sound and Southeast Alaska), Russia (Sakhalin and Kuril islands), Japan, and South Korea are dominated by hatchery salmon. During 1990-2015, hatchery salmon represented approximately 40% of the total biomass of adult and immature salmon in the ocean. Density-dependent effects are apparent, and carrying capacity may have been reached in recent decades, but interaction effects between hatchery-and natural-origin salmon are difficult to quantify, in part because these fish are rarely separated in catch and escapement statistics. The following management changes are recommended: (1) mark or tag hatchery salmon so that they can be identified after release, (2) estimate hatchery-and natural-origin salmon in catches and escapement, and (3) maintain these statistics in publicly accessible databases.

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Effects of Climate and Competition for Offshore Prey on Growth, Survival, and Reproductive Potential of Coho Salmon in Southeast Alaska

Abstract: This book that contains 38 research articles on marine ecology of Pacific salmon and steelhead trout, is dedicated to the International Year of the Salmon and is the first scientific publication that contributes to the library of the project.

Cited by 16 publications

References 96 publications

Recent declines in salmon body size impact ecosystems and fisheries

Recent declines in salmon body size impact ecosystems and fisheries

Genetic assessment of the effects of streamscape succession on coho salmon Oncorhynchus kisutch colonization in recently deglaciated streams

Numbers and Biomass of Natural‐ and Hatchery‐Origin Pink Salmon, Chum Salmon, and Sockeye Salmon in the North Pacific Ocean, 1925–2015

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