The effect of climate change on the growth of Japanese chum salmon (Oncorhynchus keta) using a bioenergetics model coupled with a three-dimensional lower trophic ecosystem model (NEMURO) (original) (raw)
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Seasonal and annual marine growth of chum salmon (Oncorhynchus keta) from Fish Creek, Alaska, during 1972–2004 and from Quilcene River, Washington, during 1973–2004 were examined in relation to abundances of chum salmon and pink salmon (O. gorbuscha) and climate indices from that period. Pink salmon abundance indices were included in the analysis because of evidence for density-dependent effects on chum salmon growth and survival. In linear regression models, growth was negatively related to abundance of chum salmon or to the combined abundance of pink and chum salmon during the middle juvenile (July–Sept), 1st immature, 2nd immature, and maturing stages for the Fish Creek chum salmon and the 1st immature, 2nd immature, and maturing stages for Quilcene River chum salmon, indicating possible density-dependent effects on growth. Mid-juvenile and maturing growth models for the Fish Creek chum salmon and the maturing growth model for Quilcene River chum salmon performed well in model validation, when model predictions were tested against 20% of the data that were not used for model specification, and provided insight into the effects of climate and abundance on growth of chum salmon from 1972 to 2004.
Long-term climate-related changes in somatic growth and population dynamics of Hokkaido chum salmon
Environmental Biology of Fishes, 2011
We used multiple regression and path analysis to examine the effects of regional and larger spatial scales of climatic/oceanic conditions on the growth, survival, and population dynamics of Hokkaido chum salmon (Oncorhynchus keta). Variability in the growth of chum salmon at ages 1 to 4 was estimated from scale analysis and the back-calculation method using scales of 4-year-old adults returning to the Ishikari River in Hokkaido, Japan, during 1943-2005. Growth of chum salmon at age 1 was less during the period from the 1940s to the mid-1970s compared to the period from the mid-1980s to the present. On the other hand, growth of chum salmon at ages 2, 3, and 4 has declined since the 1980s. Path analysis indicated that growth at age 1 in the Okhotsk Sea was directly affected by warmer sea surface temperatures associated with global warming. The increased growth at age 1 led directly to higher survival rates and indirectly to larger population sizes. Subsequently, in the Bering Sea, the larger population size was directly associated with decreased growth at age 3 and indirectly associated with shorter adult fork lengths despite the lack of relationships among sea surface temperature, zooplankton biomass, and growth at ages 2 to 4. Therefore, higher growth at age 1 related to global warming positively affected the survival rate of juvenile chum salmon in the Okhotsk Sea. The higher survival rates in turn appear to be causing a population density-dependent effect on growth at ages 2 to 4 and maturation in the Bering Sea due to limited carrying capacity.
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...
Temporal and Spatial Variation in Growth Condition of Pacific Salmon
North Pacific Anadromous Fish Commission Bulletin, 2016
Temporal and spatial variation in the growth condition of Pacifi c salmon (Oncorhynchus spp.) were investigated using the prey-density function for consumption. Zooplankton prey density was estimated from an ecosystem model, NEMURO, embedded in a 3D physical model for the years 1948-2007. This study focused on three species of Pacifi c salmon (chum (O. keta), pink (O. gorbuscha), and sockeye (O. nerka)), all of which are zooplankton feeders. The prey dependence function for consumption of Pacifi c salmon varies on a decadal time scale, and its empirical orthogonal function fi rst mode was correlated with the Pacifi c Decadal Oscillation. The variation in the prey dependence function for consumption in the Bering Sea and the Western Subarctic Gyre was correlated with the variation in the carrying capacity of chum, pink, and sockeye salmon, indicating that these are key areas for connecting climate variability to the carrying capacity of Pacifi c salmon. In these areas, prey density increased after the 1976/77 regime shift, in synchrony with the increase in primary production due to enhanced nutrient supply through deepening of the mixed layer and/or stronger Ekman upwelling.
Progress in Oceanography, 2006
Fish scales were used to investigate the interannual variability in chum salmon growth rates at specific ages in relation to climatic/environmental changes during the 1980s-1990s. Scales were obtained from adult salmon returning to the east coast of Korea between 1984 and 1998. Assuming proportionality between scale size increments and fish length, distances between scale annuli were regarded as the growth conditions in different habitat areas with respect to the life stages of chum salmon. In estuarine and coastal areas, growth rates of fingerling salmon were higher in the 1990s than in the 1980s. Zooplankton abundance off the east coast of Korea increased after the late 1980s, which may have provided favorable growth conditions for young salmon in the 1990s. Growth of juvenile chum salmon during the first summer (Okhotsk Sea) was relatively stable, and neither SST nor zooplankton biomass fluctuated significantly during the study period. However, in the Bering Sea, salmon growth rates between age-2 and age-4 (i.e. ocean-phase immature salmon) were higher in the 1980s than in the 1990s. Variability in salmon growth in the Bering Sea was correlated to zooplankton biomass. These results suggest that the climate regime shift of 1988/1989 in the subarctic North Pacific affected salmon growth mediated by changes of zooplankton biomass, revealing a bottom-up process.
Deep Sea Research Part II: Topical Studies in Oceanography, 2005
Three independent modeling methods-a nutrient-phytoplankton-zooplankton (NPZ) model (NEMURO), a food web model (Ecopath/Ecosim), and a bioenergetics model for pink salmon (Oncorhynchus gorbuscha)-were linked to examine the relationship between seasonal zooplankton dynamics and annual food web productive potential for Pacific salmon feeding and growing in the Alaskan subarctic gyre ecosystem. The linked approach shows the importance of seasonal and ontogenetic prey switching for zooplanktivorous pink salmon, and illustrates the critical role played by lipid-rich forage species, especially the gonatid squid Berryteuthis anonychus, in connecting zooplankton to upper trophic level production in the subarctic North Pacific. The results highlight the need to uncover natural mechanisms responsible for accelerated late winter and early spring growth of salmon, especially with respect to climate change and zooplankton bloom timing. Our results indicate that the best match between modeled and observed high-seas pink salmon growth requires the inclusion of two factors into bioenergetics models: (1) decreasing energetic foraging costs for salmon as zooplankton are concentrated by the spring shallowing of pelagic mixed-layer depth and (2) the ontogenetic switch of salmon diets from zooplankton to squid. Finally, we varied the timing and input levels of coastal salmon production to examine effects of density-dependent coastal processes on ocean feeding; coastal processes that place relatively minor limitations on salmon growth may delay the seasonal timing of ontogenetic diet shifts and thus have a magnified effect on overall salmon growth rates. r
Canadian Journal of Fisheries and Aquatic Sciences, 2011
We developed spatially explicit representations for seasonal high-seas (open ocean) thermal habitats for six species of Pacific salmon ( Oncorhynchus spp.) and evaluated the effects of natural climate variability and projected changes under three Intergovernmental Panel on Climate Change scenarios of future greenhouse gas emissions. Changes in high-seas habitat due to natural climatic variation in 20th century were small relative to that under anthropogenic climate change scenarios for the middle to late 21st century. Under a multimodel ensemble average of global climate model outputs using A1B (medium) emissions scenario for the entire study area (North Pacific and part of Arctic Ocean), projected winter habitats of sockeye ( Oncorhynchus nerka ) decreased by 38%, and summer habitat decreased by 86% for Chinook ( Oncorhynchus tshawytscha ), 45% for sockeye, 36% for steelhead ( Oncorhynchus mykiss ), 30% for coho ( Oncorhynchus kisutch ), 30% for pink ( Oncorhynchus gorbuscha ), an...
Fisheries Research, 2013
We used empirically based simulation modelling of 48 sockeye salmon (O. nerka) populations to examine how reliably alternative monitoring designs and fish stock assessment methods can distinguish between changes in density-dependent versus density-independent components of productivity and identify the relative contribution of a climate-driven covariate. We explored a wide range of scenarios for ocean and freshwater conditions and the response of salmon productivity (adult recruits per spawner) to those conditions. Our results show that stock assessments based on historical relationships between salmon productivity and climate-driven oceanographic conditions will likely perform poorly when those relationships change, even when such changes are anticipated and incorporated into stock assessment models in a timely manner. Estimating the relative importance of climate-driven oceanographic influences as a driver of sockeye productivity will be difficult, especially if climatic changes occur rapidly and concurrently with other disturbances. Thus, better understanding of the mechanisms by which climatic changes and other drivers influence salmon productivity may be essential to avoid undesirable management outcomes. As well, an expansion of monitoring of juvenile salmon abundances on more salmon stocks is needed to help distinguish the effects of different drivers.