Climate Indicators of Salmon Survival 12 (original) (raw)
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Transactions of the American Fisheries Society, 2014
We examined the hypotheses that density and morphometric condition of subyearling juvenile Chinook Salmon Oncorhynchus tshawytscha would decline during periods of high water temperature in the lower Columbia River and estuary. The hypotheses were tested using salmon density measurements and a condition anomaly calculated from residuals of the length-weight linear regression based on 5,536 subyearlings collected from brackish estuarine and tidal freshwater (TFW) habitats. We captured Chinook Salmon at all temperatures encountered (4.2-23.5 C). In the TFW zone, densities were highest at optimal temperatures and lowest at suboptimal and supraoptimal temperatures; in the estuary, density did not differ among temperature regimes. Fish condition was lowest in winter, when temperatures were suboptimal, and highest in summer, when temperatures were supraoptimal. Pairwise comparisons of fish condition between periods of optimal temperature (spring) and supraoptimal or stressful temperature (summer) showed little change in the estuary but a large, positive increase with temperature in the TFW zone. Similarly, we examined seasonal differences in the condition of 50-60-mm fry and again found condition to be lowest in winter and highest in summer. Finally, using genetic information, we identified stock-specific differences in migration timing and concluded that most large yearlings and many subyearlings migrated in late winter or spring and therefore were never exposed to high temperatures. Other prevalent stocks persisted in the estuary during periods of elevated temperature; however, the condition of those fish also tended to be higher or neutral in summer than in spring. High temperatures appeared to influence migration timing, as evidenced by reduced density in TFW reaches during summer. However, we found little support for the hypothesis that condition of juvenile Chinook Salmon is reduced during periods of high water temperature in the lower Columbia River and estuary.
Fisheries Oceanography, 2013
Pacific Northwest Chinook, Oncorhynchus tshawytscha, have exhibited a high degree of variability in smoltto-adult survival over the past three decades. This variability is summarized for 22 Pacific Northwest stocks and analyzed using generalized linear modeling techniques. Results indicate that survival can be grouped into eight distinct regional clusters: (1) Alaska, Northern BC and North Georgia Strait; (2) Georgia Strait; (3) Lower Fraser River and West Coast Vancouver Island; (4) Puget Sound and Hood Canal; (5) Lower Columbia Tules; (6) Columbia Upriver Brights, Willamette and Cowlitz; (7) Oregon and Washington Coastal; and (8) Klamath River and Columbia River Summers. Further analysis for stocks within each of the eight regions indicates that local ocean conditions following the outmigration of smolts from freshwater to marine areas had a significant effect on survival for the majority of the stock groups analyzed. Our analyses of the data indicate that Pacific Northwest Chinook survival covaries on a spatial scale of 350-450 km. Lagged time series models are presented that link large-scale tropical Pacific conditions, intermediate-basin scale northeastern Pacific conditions, and local sea surface temperatures to survival of Pacific Northwest stocks.
North American Journal of Fisheries Management, 2018
In this investigation, we assessed the effects of rearing conditions on survival and demographics for four yearling summer Chinook Salmon Oncorhynchus tshawytscha hatchery programs from the upper Columbia River basin over four release years. Juveniles from each hatchery program were initially reared at Eastbank Hatchery near Wenatchee, Washington (which uses groundwater for fish rearing), and experienced similar rearing temperatures until their first autumn in culture. Fish from two of the programs were subsequently transferred to surface water acclimation sites, where they were reared until release the following spring (surface water winter rearing). Fish from the other two programs were overwintered at the Eastbank Hatchery and then transferred to their acclimation and release sites one to two months prior to spring release (groundwater winter rearing). These two rearing strategies resulted in contrasting temperature profiles experienced by the fish, which in turn affected winter growth, age at maturation, and smolt-to-adult survival (SAS). Overall, the two release groups that were overwintered on colder surface water experienced reduced winter growth, reduced minijack rate, and smaller size at release, but achieved a two-to threefold higher SAS compared to the two release groups overwintered on warmer groundwater at Eastbank Hatchery. In addition, based on migration data compiled from fish tagged with passive integrated transponder tags, smaller juveniles tended to mature at older age-classes than larger smolts. We conclude that rearing of yearling hatchery summer Chinook Salmon under more natural thermal regimes (surface water) may result in the return of larger, older adults that have a higher survival rate compared with fish reared under constant or less natural thermal regimes (ground water). These results highlight the importance of the hatchery-rearing environment in shaping the survival and life history of summer Chinook Salmon juveniles released into the Columbia River basin.
Global Change Biology, 2011
Mean summer water temperatures in the Fraser River (British Columbia, Canada) have increased by $1.5 1C since the 1950s. In recent years, record high river temperatures during spawning migrations of Fraser River sockeye salmon (Oncorhynchus nerka) have been associated with high mortality events, raising concerns about long-term viability of the numerous natal stocks faced with climate warming. In this study, the effect of freshwater thermal experience on spawning migration survival was estimated by fitting capture-recapture models to telemetry data collected for 1474 adults (captured in either the ocean or river between 2002 and 2007) from four Fraser River sockeye salmon stockaggregates (Chilko, Quesnel, Stellako-Late Stuart and Adams). Survival of Adams sockeye salmon was the most impacted by warm temperatures encountered in the lower river, followed by that of Stellako-Late Stuart and Quesnel. In contrast, survival of Chilko fish was insensitive to the encountered river temperature. In all stocks, in-river survival of ocean-captured sockeye salmon was higher than that of river-captured fish and, generally, the difference was more pronounced under warm temperatures. The survival-temperature relationships for ocean-captured fish were used to predict historic and future (2010-2099) survival under simulated lower river thermal experiences for the Quesnel, Stellako-Late Stuart and Adams stocks. A decrease of 9-16% in survival of all these stocks was predicted by the end of the century if the Fraser River continues to warm as expected. However, the decrease in future survival of Adams sockeye salmon would occur only if fish continue to enter the river abnormally early, towards warmer periods of the summer, as they have done since 1995. The survival estimates and predictions presented here are likely optimistic and emphasize the need to consider stock-specific responses to temperature and climate warming into fisheries management and conservation strategies.
Transactions of the American Fisheries Society, 2005
We tested the hypothesis that survival rates from spawners to recruits in Pacific salmon Oncorhynchus spp. are primarily related to coastal ocean conditions during migration to the sea and soon after. We correlated measures of survival rate in units of log e (recruits/spawner) for 110 stocks of pink salmon O. gorbuscha, chum salmon O. keta, and sockeye salmon O. nerka with regional-scale indices of coastal sea surface temperature, sea surface salinity, and upwelling as well as with a large-scale index of ocean climate. We examined correlations by month and at multiple lags spanning the periods of spawning, freshwater residence, and early ocean residence of salmon. Survival rates of all three salmon species were related to ocean temperatures just prior to, during, and after out-migration, which are indicative of the early marine conditions experienced by juvenile salmon. This is consistent with the hypothesis that the early marine period is critical to the survival of juvenile salmon. However, survival rates of sockeye salmon were most strongly correlated with coastal sea surface temperature during freshwater residency (i.e., the winter and spring prior to out-migration). Survival rates of pink salmon were also related to sea surface salinity conditions prior to out-migration. There was no evidence for any relationship between the survival rates of salmon and coastal upwelling conditions. As in previous studies, we found that correlations between the survival rates of pink or sockeye salmon in Alaska and sea surface temperature have opposite signs from correlations for stocks in British Columbia and Washington at most lags and at both regional and large (basinwide) spatial scales. In general, however, the measures of coastal ocean conditions that we examined explain a relatively small proportion of the environmentally induced variability in salmon survival rates.
Fisheries Oceanography, 2005
Effective conservation and management of natural resources requires accurate predictions of ecosystem responses to future climate change, but environmental science has largely failed to produce these reliable forecasts. The future response of Pacific salmon (Oncorhynchus spp.) to a changing environment and continued anthropogenic disturbance is of particular interest to the public because of their high economic, social, and cultural value. While numerous retrospective analyses show a strong correlation between past changes in the ocean environment and salmon production within the north Pacific, these correlations rarely make good predictions. Using a Bayesian timeseries model to make successive 1-yr-ahead forecasts, we predicted changes in the ocean survival of Snake River spring/summer chinook salmon (O. tshawytscha) from indices of coastal ocean upwelling with a high degree of certainty (R 2 ¼ 0.71). Furthermore, another form of the dynamic times-series model that used all of the available data indicated an even stronger coupling between smolt-to-adult survival and ocean upwelling in the spring and fall (R 2 ¼ 0.96). This suggests that management policies directed at conserving this threatened stock of salmon need to explicitly address the important role of the ocean in driving future salmon survival.
Decadal scale climate pattern and salmon survival: indicators, interactions, and implications
1996
The influence of decadal scale climatic variations on the decline of Columbia River salmon was not realized until recently. I evaluate the implications of this omission using a stock recruitment model with climatic and anthropogenic factors. I conclude that fisheries managers over the past century have misinterpreted the anthropogenic impacts on Columbia River salmon. In particular, I suggest three major events have been misinterpreted: 1) managers overestimated the significance of harvest on the catch decline after 1920 by not accounting for climatic changes that lowered ocean survival at this time, 2) managers under-represented the detrimental effects of the hydrosystem by not accounting for the contribution of good ocean survival during the years of hydrosystem development and, 3) managers underestimated the success of stock rebuilding measures in the last two decades because the concomitant poor ocean survival was not accounted for. I also suggest that the fisheries community is now evolving an ecosystem approach that considers both environmental and anthropogenic impacts on salmon.
Survival of Puget Sound chinook salmon
2014
We tested for competition between pink salmon (Oncorhynchus gorbuscha) and chinook salmon (Oncorhynchus tshawytscha) originating from rivers in the Puget Sound area using coded-wire-tagged subyearling hatchery chinook salmon. Following a 2-year life cycle, many juvenile pink salmon enter Puget Sound in evennumbered years, whereas few migrate during odd-numbered years. During 1984-1997, juvenile chinook salmon released during even-numbered years experienced 59% lower survival than those released during odd-numbered years, a trend consistent among 13 chinook salmon stocks. Lower even-numbered-year survival of chinook salmon was associated with reduced first-year growth and survival and delayed maturation. In contrast, chinook salmon released into coastal streams, where few pink salmon occur, did not exhibit an alternating-year pattern of survival, suggesting that the interaction occurred within Puget Sound and the lower Strait of Georgia. Unexpectedly, the survival pattern of Puget Sound chinook salmon was reversed prior to the 1982-1983 El Niño: chinook salmon survival was higher when they migrated with juvenile pink salmon during 1972-1983. We hypothesize that chinook salmon survival changed as a result of a shift from predation-to competition-based mortality in response to recent declines in predator and prey abundances and increases in pink salmon abundance. Alternating-year mortality accounted for most of the 50% decline in marine survival of chinook salmon between 1972-1983 and 1984-1997. Résumé : Nous avons évalué la compétition entre les saumons quinnat (Oncorhynchus tshawytscha) et les saumons roses (Oncorhynchus gorbuscha) provenant des rivières de la région du Puget Sound en utilizant des saumons quinnat de pisciculture âgés de moins d'un an et marqués avec des fils de fer codés. Après 2 ans de leur cycle, de nombreux jeunes saumons roses se déplacent vers le Puget Sound les années paires, mais peu le font les années impaires. En 1984-1997, les jeunes saumons quinnat relâchés durant les années paires ont connu une survie de 59 % inférieure à ceux qui ont été relâchés les années impaires et la tendance s'est maintenue dans 13 stocks de saumons quinnat. La survie réduite les années paires est associée avec une diminution de la croissance et de la survie la première année et une maturation retardée. En revanche, les saumons quinnat relâchés dans les cours d'eau côtiers, où il y a peu de saumons roses, n'ont pas expérimenté cette alternance d'une année à l'autre dans la survie, ce qui laisse croire que l'interaction se produit dans le Puget Sound ou le détroit de Géorgie inférieur. De façon inattendue, le pattern de survie des saumons quinnat de Puget Sound a été inversé avant l'El Niño de 1982-1983, alors que leur survie était plus élevée lorsqu'ils migraient en compagnie des saumons roses en 1972-1983. Notre hypothèse veut que la survie des saumons quinnat ait changé d'un contrôle de la mortalité par la prédation à un contrôle par la compétition en réaction au déclin récent des abondances de prédateurs et de proies et l'augmentation de l'abondance des saumons roses. La mortalité à tous les deux ans explique la plus grande partie du déclin de la survie en mer des saumons quinnat entre les périodes
1996
Distribution of pa for Priest Rapids chinook. Total biomass of hatchery contributions to Columbia River, 1976-89. Map of hatcheries used in this analysis. Normalized residual plots for Hilborn model, not adjusted for transportation. 8 8 9 9 Normalized residual plots for Hilborn model, adjusted for transportation. Normalized residual plots for CWT observed adult counts, not adjusted for transportation. Normalized residual plots for CWT observed adults counts, adjusted for transportation. Normalized residual plots for VPA estimates of survival to age 2. not adjusted for transportation. Normalized residual plots for VPA estimates of survival to age 2, adjusted for transportation. Summary of R' for single river conditions for the Hilborn et al. (1993a.b) model (1). unadjusted for probability of transportation. Summary table for best fit models using Hilborn et al. (1993a.b) model (1). unadjusted for the probability of transportation. Standard errors of the coefficient estimation are in parenthesis. Summary of R2 for single river conditions for the Hilborn et al. (1993a.b) log-linear model (2). adjusted for probability of transportation. Summary table for best fit models using log-linear response model (2). adjusted for the probability of transportation. Standard errors of the coefficient estimation are in parenthesis. Summary of R2 for single river conditions for each reference hatchery stock, using log-linear response model (3). unadjusted for probability of transportation. Summary table for the best models for each reference stock using loglinear response model (3). unadjusted for the probability of transportation. Standard errors of the coefficient estimation are in parentheses.. Summary of RL for single river conditions for each reference hatchery stock, using log-linear response model (4), adjusted for the probability of transportation. Summary table for best models for each reference stock using log-linear response model (4). adjusted for the probability of transportation. Standard errors of the coefficient estimation are in parentheses. Summary R2 for single river conditions for each reference hatchery stock, using log-linear response model (5) using VPA estimates, unadjusted for probability of transportation. Asterisk indicates factors significant at P ~2 0.05. Summary table for the best models for each reference stock using loglinear response model (5) based on VPA estimates, unadjusted for the probability of transportation. Standard errors of the coefficient estimation are in parentheses. Summary of R2 for single river conditions for each reference hatchery stock, using log-linear response model (6) based on VPA estimates, adjusted for probability of transportation.
Transactions of The American Fisheries Society, 2004
The relationships between the spawning stock and the subsequent recruitment of pink salmon Oncorhynchus gorbuscha and sockeye salmon O. nerka from the Fraser River improve significantly when the data are separated by climate and ocean regimes. Our analyses show changes in these relationships as regimes shift, indicating that the trend in marine survival of pink and sockeye salmon changes on a decadal scale. In general, the climate and ocean regime from 1977 to 1988 was productive for pink and sockeye salmon. However, the regime in the 1990s was characterized by reduced productivity for both species. The occurrence of a natural shift in the trend of pink and sockeye salmon production on a decadal scale should be incorporated into the management of Pacific salmon stocks to ensure that annual catches, escapements, and planned stock abundances are consistent with the productivity of a particular regime.