Evidence That Reduced Early Marine Growth is Associated with Lower Marine Survival of Coho Salmon

Beamish, Richard; Mahnken, Conrad V. W.; Neville, Chrys

doi:10.1577/t03-028

Cited by 198 publications

(229 citation statements)

References 27 publications

(31 reference statements)

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“…Perhaps growth rates continued to decline after 1991, but slow-growing Sockeye Salmon died at higher rates than did faster-growing Sockeye Salmon (Ruggerone et al 2005;Farley et al 2011) such that measured growth rates in the survivors did not decline. We suggest that Sockeye Salmon survivals began to decline after 1991 for many stocks because an increasing portion of the juveniles were unable to grow to the size (or possess sufficient energy reserves) required to survive some life history stanza, similar to the critical size hypothesis (e.g., Beamish et al 2004a). Further evidence of increasing competition is the increased proportion of Chilko Lake Sockeye Salmon returning late after three winters at sea instead of two.…”

Section: Irvine and Akenheadmentioning

confidence: 59%

Understanding Smolt Survival Trends in Sockeye Salmon

Irvine

Akenhead

2013

Mar Coast Fish

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Many populations of Sockeye Salmon Oncorhynchus nerka in the eastern North Pacific Ocean experienced significant productivity declines that began about 1990, but there is no consensus on the mechanisms responsible. To better understand Sockeye Salmon survival trends, we examined the 50-year time series for two age-classes of Sockeye Salmon smolts from Chilko Lake in central British Columbia. Arranging survival time series for both age-classes by ocean entry year and combining them, weighted by a proxy model of sampling variance, reduced the sampling variance in the original age-1 smolt survivals sufficiently to indicate a linear trend of increasing survival from 1960 to 1990 that suddenly changed at or near 1991 to a lower and declining trend from 1992 to 2008. Neither density nor mean length influenced smolt survival. Returns in a given year were not good predictors of siblings returning in subsequent years. Time spent at sea increased linearly beginning around 1970. Although smolt survivals differed between ecosystem regimes, there was only the one clear pattern break about 1991. To improve our understanding of mechanisms, survival trends were compared with environmental indices that included catches and hatchery releases of potentially competing salmon from around the North Pacific Ocean. Smolt survivals were more similar to abundance indices of Sockeye Salmon, Chum Salmon O. keta, and Pink Salmon O. gorbuscha than to indices of global, regional, or local ocean climate. Our results are consistent with the hypothesis that salmon productivity in the North Pacific declined soon after 1990. We present a simple model to illustrate how increased competition at sea, related to the release of large numbers of hatchery salmon, in conjunction with changes in ocean productivity, may have played a significant role in improving Sockeye Salmon survivals while reducing their growth before 1991. After 1991, these factors may have acted to reduce survivals while the growth of survivors showed no effect.Anadromous Pacific salmon Oncorhynchus spp. comprise a multispecies complex of varying productivities. Their recent abundance in the Pacific Ocean, as reflected by commercial catch, is as high as it has ever been (Irvine and Fukuwaka 2011). Global abundances are driven primarily by Pink Salmon O. gorbuscha and Chum Salmon O. keta, as well as, particularly in the eastern North Pacific Ocean, by Sockeye Salmon O. nerka (Eggers 2009;Ruggerone et al. 2010;Irvine and Fukuwaka 2011). The status of Sockeye Salmon populations varies among regions however, and in British Columbia's Fraser River, low Subject editor: Suam Kim, Pukyong National University, Busan, South Korea *Corresponding author: james.irvine@dfo-mpo.gc.ca Received February 8, 2013; accepted July 24, 2013 numbers of returning salmon in recent years are a major concern (Grant et al. 2011;Rand et al. 2012).The Fraser River watershed is one of the world's greatest salmon producers (Northcote and Larkin 1989), although numbers returning annually are highly variable...

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Section: Irvine and Akenheadmentioning

confidence: 59%

Understanding Smolt Survival Trends in Sockeye Salmon

Irvine

Akenhead

2013

Mar Coast Fish

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“…Slower growth in fishes has been correlated with a variety of life history traits, including higher mortality as the result of predation and starvation (22); reduced food availability as the result of gape limitations (23); usually, but not always, shorter life spans (13,24); increased age at sexual maturity and/or smaller size at maturity (25) and, because of the relationship between size and fecundity (e.g., ref. 26), reduced age-specific fecundity (24).…”

Section: Discussionmentioning

confidence: 99%

Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish

Thresher

Koslow²,

Morison³

et al. 2007

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

120

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The oceanographic consequences of climate change are increasingly well documented, but the biological impacts of this change on marine species much less so, in large part because of few long-term data sets. Using otolith analysis, we reconstructed historical changes in annual growth rates for the juveniles of eight long-lived fish species in the southwest Pacific, from as early as 1861. Six of the eight species show significant changes in growth rates during the last century, with the pattern differing systematically with depth. Increasing temperatures near the ocean surface correlate with increasing growth rates by species found in depths <250 m, whereas growth rates of deep-water (>1,000 m) species have declined substantially during the last century, which correlates with evidence of long-term cooling at these depths. The observations suggest that global climate change has enhanced some elements of productivity of the shallow-water stocks but also has reduced the productivity, and possibly the resilience, of the already slow-growing deep-water species.fisheries ͉ marine ecology ͉ oceanography

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“…Nevertheless, other studies have indicated that salmon that have poor early growth are less likely to survive (Beamish et al 2004b;Farley et al 2011;Jonsson et al 2011). Larger salmonids may be better able to avoid predation (Beamish and Mahnken 2001) and survive better than small salmonids when prey resources are low due to increased lipid stores (Farley et al 2007(Farley et al , 2011.…”

Section: Reduction Of Growth May Affect Survivalmentioning

confidence: 99%

Marine growth patterns of southern British Columbia chum salmon explained by interactions between density-dependent competition and changing climate

Debertin

Irvine

Holt

et al. 2017

Can. J. Fish. Aquat. Sci.

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Thirty-nine years of scale growth measurements from Big Qualicum River chum salmon (Oncorhynchus keta) in southern British Columbia demonstrated that competition and climate variation affect marine growth and age-at-maturity. A longitudinal study design that accounted for correlation among individuals revealed growth at all ages was reduced when the biomass of North American chum, sockeye (Oncorhynchus nerka), and pink salmon (Oncorhynchus gorbuscha) was high. When North Pacific Gyre Oscillation (NPGO) was positive, indicating increased primary productivity, predicted growth increased. Climate variation influenced competition effects. For instance, density-dependent competition effects increased when NPGO became more positive and Pacific Decadal Oscillation became more negative (indicating cool conditions), causing the greatest range in predicted scale size. Chum salmon are likely to exhibit continued reduction in growth at age due to increased ocean temperatures driven by climate change and high aggregate salmon biomass that includes hatchery releases. If evidence of biomass and climate effects presented here are common among Pacific salmon populations, reduction of hatchery releases should be considered. Résumé :Des mesures sur 39 ans de la croissance des écailles de saumons kétas (Oncorhynchus keta) de la Grande rivière Qualicum, dans le sud de la Colombie-Britannique, démontrent que la concurrence et les variations climatiques ont une incidence sur la croissance en mer et l'âge à la maturité. Un plan d'étude longitudinale qui tient compte de la corrélation entre individus révèle que la croissance à tous les âges est plus faible quand la biomasse des saumons kétas, sockeyes (Oncorhynchus nerka) et roses (Oncorhynchus gorbuscha) d'Amérique du Nord est élevée. Quand l'oscillation du tourbillon nord-pacifique (OTPN) est positive, indiquant une productivité primaire accrue, la croissance prédite augmente. Les variations du climat ont également une incidence sur ces effets de concurrence. Les effets de la concurrence dépendant de la densité augmentent quand l'OTPN devient plus positive et l'oscillation décennale du Pacifique, plus négative (indiquant des conditions fraîches), ce qui produit la plus grande fourchette de tailles d'écailles prédites. Il est probable que les saumons kétas continueront de présenter une diminution de la croissance selon l'âge en raison de la hausse des températures océaniques causée par les changements climatiques et de la forte biomasse totale de saumons incluant les individus issus d'écloseries. Si les indices d'effets de la biomasse et du climat relevés dans la présente étude s'avéraient répandus dans les populations de saumons du Pacifique, il serait pertinent d'examiner la possibilité de réduire les lâchers de poissons issus d'écloseries. [Traduit par la Rédaction]

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Evidence That Reduced Early Marine Growth is Associated with Lower Marine Survival of Coho Salmon

Cited by 198 publications

References 27 publications

Understanding Smolt Survival Trends in Sockeye Salmon

Understanding Smolt Survival Trends in Sockeye Salmon

Depth-mediated reversal of the effects of climate change on long-term growth rates of exploited marine fish

Marine growth patterns of southern British Columbia chum salmon explained by interactions between density-dependent competition and changing climate

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