Juvenile sockeye salmon distribution, size, condition and diet during years with warm and cool spring sea temperatures along the eastern Bering Sea shelf

Farley, Ed; Murphy, James M.; Adkison, Milo D.; Eisner, Lisa B.

doi:10.1111/j.1095-8649.2007.01587.x

Cited by 32 publications

(37 citation statements)

References 17 publications

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“…It was not surprising to find that warmer summers, in general, corresponded to improved productivity for sockeye salmon populations from this region of Alaska. This supports previous research which has found that warmer SSTs during the early marine life stage correspond with greater survival (Mueter et al , 2002; Martinson et al , 2009) and growth (Rogers & Ruggerone, 1993; Farley et al , 2007), and that warmer lake temperatures lead to increased growth during freshwater life stages (Schindler et al , 2005; Rich et al , 2009), which can be related to subsequent survival in the marine environment (Koenings et al , 1993). However, the difference in sensitivity by rearing lake was unexpected.…”

Section: Discussionsupporting

confidence: 90%

“…Here, only coarse metrics of ocean thermal conditions or general climate indices (i.e., PDO) were used as potential environmental drivers. More precise mapping of salmon migration patterns in the ocean relative to the spatial and temporal variation in environmental conditions they experience in this phase of their life (Farley et al , 2007) may greatly improve the ability of statistical models to detect the effects of marine conditions on salmon population productivity. However, at present, such data simply do not exist over the time period considered in this study, or at the scale of individual populations.…”

Section: Discussionmentioning

confidence: 99%

“…Without data on these specific factors, we used regional sea surface temperatures (SSTs) to characterize the nearshore marine environment. Farley et al (2007) found that warmer nearshore waters were associated with enhanced growth of Bristol Bay sockeye salmon in their first summer at sea, thus temperature may be a reasonable proxy for relevant ecosystem processes where upwelling is generally not an important controlling mechanism for biological productivity.…”

Section: Methodsmentioning

confidence: 99%

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Scale and the detection of climatic influences on the productivity of salmon populations

Rogers

Schindler

2011

Global Change Biology

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Ecological studies relating population parameters to climate conditions are limited by a lack of experimental control systems and rely instead on correlative evidence to draw inferences about how populations respond to environmental forcing. Consequently, some correlations turn out to be spurious and not ecologically meaningful. To strengthen inferences, multiple populations may be examined simultaneously to confirm whether relationships can be generalized across multiple systems; however, this assumes that populations respond similarly to climate drivers, ignoring the potential for ecological complexity. Using data on eight sockeye salmon populations from southwestern Alaska, we constructed a series of models based on ecological hypotheses, relating salmon population productivity to climate factors experienced at different life stages. We modeled populations at a range of organizational scales, from distinct populations, to populations grouped by common nursery lake, to all populations within a watershed, and determined the relative statistical support for climate drivers at each scale. In general, warmer lake and sea surface temperatures in the summer coincided with increased productivity of these populations, but the most sensitive life-stage for climate effects varied among populations, particularly among nursery lakes. The best model when considering all populations together, despite strong statistical support, failed to represent the complexity which became evident when populations were modeled by common nursery lake, or independently. These results emphasize that the most appropriate organizational scale to model salmon stocks will depend on specific management, scientific, or conservation goals.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Scale and the detection of climatic influences on the productivity of salmon populations

Rogers

Schindler

2011

Global Change Biology

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“…Thus, the relationship between fish size and their stable isotopes suggests that larger fish may forage in habitat further offshore than their smaller counterparts; this is corroborated by high seas data (e.g. Farley et al 2007). …”

Section: Stable Isotopes and Fish Sizesupporting

confidence: 64%

Four decades of foraging history: stock-specific variation in the carbon and nitrogen stable isotope signatures of Alaskan sockeye salmon

Johnson

Schindler²

2012

Mar. Ecol. Prog. Ser.

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Broad-scale shifts in climate during the 20th century had large effects on the ecology of the North Pacific Ocean, including a substantial change in the composition of the dominant food web. Salmon production in Alaskan stocks increased with a concurrent shift of the Pacific Decadal Oscillation in 1977. Salmon production has since been persistently high through 2010, yet the biological mechanisms for this increase in production remain unclear. Carbon and nitrogen stable isotopes of sockeye salmon scales collected from 8 rivers in Bristol Bay between 1964 and 2003 were analyzed to assess whether the trophic ecology of these fish changed systematically over this period, during which there were substantial changes in oceanographic conditions. Isotope values were remarkably stable over the study despite substantial changes in salmon production and oceanographic conditions in this region. Our results also suggest river-specific patterns in the variation of stable isotopes through time; stable isotope changes were related to stock identity and showed some geographic organization. Larger salmon tended to have depleted δ 15 N and δ 13 C. Isotopic characteristics among rivers became more variable during the period of high ocean productivity (after the 1977 regime shift and before the 1989 regime shift). Some of the dominant signals of variation in stable isotope variation were related to important environmental physical processes, but they appear to have unique effects on the isotopic characteristics of stocks from different rivers, suggesting important connections between the ecology of sockeye salmon in freshwater and in the ocean. 460: 155-167, 2012 Changes in the climate regime during the mid1970s were also associated with large-scale changes in Pacific salmon (Oncorhynchus spp.) production (Mantua et al. 1997). Climate forcing, as captured by PDO dynamics, is correlated with salmon production such that small changes in the physical environment, such as nearshore warming and offshore cooling in the ocean, translated into substantial changes in fisheries production (Mantua et al. 1997). In addition, there was geographic organization in the responses of salmon production to climate change. Pacific salmon production in Alaska increased sharply after the late 1970s but declined substantially in Canada and the Pacific Northwest (Mantua et al. 1997, Hare et al. 1999. Although several studies have modeled variation in marine food webs in response to climate change that affects salmon survival (e.g. Francis et al. 1998, Beamish et al. 1999, Aydin et al. 2005, there has been little assessment of the patterns of marine salmon foraging in relation to climatic variation over the periods encompassing the major food web reorganization associated with shifts in the PDO. Thus, the linkages between changes in climate forcing variables, oceanographic conditions and the trophic ecology of Pacific salmon remain poorly understood. OPEN PEN ACCESS CCESSMar Ecol Prog SerThe term biocomplexity has been used to describe the div...

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“…Compensatory growth has been documented in over 20 fish family taxa in laboratory experiments and in natural populations of Atlantic Salmon Salmo salar, Atlantic Herring Clupea harengus, Common Carp Cyprinus carpio, Atlantic Cod Gadus morhua, and Pacific Cutlassfish Trichiurus lepturus (Ali et al 2003). In the eastern Bering Sea, smaller age-1.0 Sockeye Salmon feed at higher rates than larger age-2.0 juvenile Sockeye Salmon (Farley et al 2007b), providing initial evidence for compensatory growth. For Bristol Bay Sockeye Salmon, we hypothesized that smaller and younger smolts at ocean entry would exhibit faster growth during their first year at sea as a means of obtaining a critical size for survival.…”

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confidence: 99%

Trends and Factors Influencing the Length, Compensatory Growth, and Size‐Selective Mortality of Juvenile Bristol Bay, Alaska, Sockeye Salmon at Sea

et al. 2016

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The productivity of Bristol Bay, Alaska, Sockeye Salmon Oncorhynchus nerka increased during the mid‐1970s. This increase is believed to be partially due to an increase in early marine growth associated with the 1976–1977 cool‐to‐warm shift in summer sea surface temperature (SST). The body size of juvenile salmon during their first year at sea is believed to regulate their ability to survive over winter. The back‐calculated smolt length, first‐year ocean growth, and total juvenile length of Sockeye Salmon from five Bristol Bay river systems (Egegik, Kvichak, Naknek, Ugashik, and Wood) and two smolt ages were used to examine trends and factors influencing total juvenile length, compensatory growth, and size‐selective mortality in the first year in the ocean from 1962 to 2007. Juvenile length increased in relation to summer sea temperature, the 1977–2001 and 2002–2007 warm temperature regimes, smolt length, and compensatory growth. Compensatory growth—an inverse relationship between first‐year ocean growth and smolt size—increased over time as well as after the 1976–1977 climate regime shift, was more common in age‐1.0 fish than in age‐2.0 juveniles, and was important in determining the length of juvenile Sockeye Salmon from the Wood River (the shorter fish among rivers and smolt ages). The coefficient of variation in length did not change with SST, suggesting that size‐selective mortality occurred prior to the end of the first year at sea for all 10 fish groups. The predictor variables that were significant in the models varied among river systems and smolt ages. This study demonstrated that the frequency of compensatory growth and the total lengths of juvenile Sockeye Salmon during their first year at sea increased with summer SST (range, 7.5–10.5°C) in the eastern Bering Sea, a possible mechanism for the increased productivity of Bristol Bay Sockeye Salmon associated with warmer sea temperatures. Received June 2, 2015; accepted February 23, 2016

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Juvenile sockeye salmon distribution, size, condition and diet during years with warm and cool spring sea temperatures along the eastern Bering Sea shelf

Cited by 32 publications

References 17 publications

Scale and the detection of climatic influences on the productivity of salmon populations

Scale and the detection of climatic influences on the productivity of salmon populations

Four decades of foraging history: stock-specific variation in the carbon and nitrogen stable isotope signatures of Alaskan sockeye salmon

Trends and Factors Influencing the Length, Compensatory Growth, and Size‐Selective Mortality of Juvenile Bristol Bay, Alaska, Sockeye Salmon at Sea

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