Dynamics on Distribution, Production, and Biological Interactions of Pacific Salmon in the Changing Climate of the North Pacific Ocean (original) (raw)

Recent production trends of chum salmon Oncorhynchus keta under conditions of warming climate

2012

Pacific salmon (Oncorhynchus spp.) play an important role as a keystone species and in ecosystem services in the subarctic North Pacific. Planktivorous pink (O. gorbuscha) and chum salmon (O. keta) abundance has increased since the 1975/76 regime-shift until the present, but their abundances have shown stable or declining trends in Canada, Japan, and USA since the 1990s, even though Russian chum and pink salmon abundance have been increasing (Fig. 1). Run size of Japanese chum salmon showed a decreasing trend in Honshu Island since the late 1990s and in Hokkaido Island since the early 2000s (Fig. 2). The carrying capacity of sockeye (O. nerka), chum, and pink salmon has changed to a downward trend since the early 2000s (Kaeriyama et al. 2011). Abundance of wild chum salmon in the 1990s decreased to 50% below that of the 1930s, while there have been significant increases in hatchery populations (Kaeriyama et al. 2009). Hatchery-derived salmon genetically disturb native-wild Pacific s...

Response of Pink salmon to climate warming in the northern Bering Sea

Deep Sea Research Part II: Topical Studies in Oceanography, 2020

Life-history and life-cycle models of Pink salmon (Oncorhynchus gorbuscha) are developed to provide insight into production dynamics of northern Bering Sea Pink salmon. Arctic ecosystems, including freshwater and marine ecosystems in the northern Bering Sea, are warming at a rapid rate. Due to their short, two-year life cycle, Pink salmon are well known to respond rapidly to ecosystem change and can provide unique insight into ecosystem impacts of warming Arctic conditions. Life-cycle models suggest a lack of density-dependence for adult Pink salmon spawners in the Yukon River and potential for some density-dependence for adult Pink salmon spawners in the Norton Sound region. Life-history models identify a positive and significant relationship between the abundance index for juvenile Pink salmon and average Nome air temperature during their freshwater residency (August to June). This relationship supports the notion that warming air temperatures in this region (as a proxy for river and stream temperatures) are contributing to improved freshwater survival or increased capacity of freshwater habitats to support Pink salmon production. Life-history models also identify the number of adult Pink salmon returning to Norton Sound and the Yukon River is significantly related to the juvenile abundance in the northern Bering Sea. This result indicates that much of the variability in survival for northern Bering Sea Pink salmon occurs during early life-history stages and that juvenile abundance is an informative leading indicator of Pink salmon runs to this region.

Growth of chum salmon in relation to population abundance and climate in the eastern North Pacific Ocean and the recruitment of Pollock in the eastern Bering Sea

2013

Global climate change is expected to change the distribution and growth of marine species. Therefore, understanding how climate, ocean productivity, and population abundance affect the dynamics of marine species will help predict how growth and recruitment of marine species will respond to future changes in climatic and oceanic conditions. Statistically significant intertemporal correlations have been observed between a variety of environmental factors and recruitment, growth, mortality, and abundance of fish populations. However, because these correlative relationships are not reflective of the actual biophysical processes, the relationships can break down, particularly when used for forecasting. Failure of these simple correlative relationships motivates the search for biological indicators that integrate ocean productivity across ecological dimensions and through time. Measured distances along Chum Salmon (Oncorhynchus keta) scale radii and associated body morphology were used to...

Linkages between Alaskan sockeye salmon abundance, growth at sea, and climate, 1955–2002

Deep Sea Research Part II: Topical Studies in Oceanography, 2007

We tested the hypothesis that increased growth of salmon during early marine life contributed to greater survival and abundance of salmon following the 1976/1977 climate regime shift and that this, in turn, led to density-dependent reductions in growth during late marine stages. Annual measurements of Bristol Bay (Bering Sea) and Chignik (Gulf of Alaska) sockeye salmon scale growth from 1955 to 2002 were used as indices of body growth. During the first and second years at sea, growth of both stocks tended to be higher after the 1976-1977 climate shift, whereas growth during the third year and homeward migration was often below average. Multiple regression models indicated that return per spawner of Bristol Bay sockeye salmon and adult abundance of western and central Alaska sockeye salmon were positively correlated with growth during the first 2 years at sea and negatively correlated with growth during later life stages. After accounting for competition between Bristol Bay sockeye and Asian pink salmon, age-specific adult length of Bristol Bay salmon increased after the 1976-1977 regime shift, then decreased after the 1989 climate shift. Late marine growth and age-specific adult length of Bristol Bay salmon was exceptionally low after 1989, possibly reducing their reproductive potential. These findings support the hypothesis that greater marine growth during the first 2 years at sea contributed to greater salmon survival and abundance, which in turn led to density-dependent growth during later life stages when size-related mortality was likely lower. Our findings provide new evidence supporting the importance of bottom-up control in marine ecosystems and highlight the complex dynamics of species interactions that continually change as salmon grow and mature in the ocean. r

Climate change, pink salmon, and the nexus between bottom-up and top-down forcing in the subarctic Pacific Ocean and Bering Sea

Proceedings of the National Academy of Sciences, 2014

Climate change in the last century was associated with spectacular growth of many wild Pacific salmon stocks in the North Pacific Ocean and Bering Sea, apparently through bottom-up forcing linking meteorology to ocean physics, water temperature, and plankton production. One species in particular, pink salmon, became so numerous by the 1990s that they began to dominate other species of salmon for prey resources and to exert top-down control in the open ocean ecosystem. Information from long-term monitoring of seabirds in the Aleutian Islands and Bering Sea reveals that the sphere of influence of pink salmon is much larger than previously known. Seabirds, pink salmon, other species of salmon, and by extension other higher-order predators, are tightly linked ecologically and must be included in international management and conservation policies for sustaining all species that compete for common, finite resource pools. These data further emphasize that the unique 2-y cycle in abundance of pink salmon drives interannual shifts between two alternate states of a complex marine ecosystem.