Effect of global warming on the life history and population dynamics of Japanese chum salmon

Abstract

We have reviewed the effects of long-term climatic/oceanic conditions on the growth, survival, production dynamics, and distribution of Hokkaido chum salmon Oncorhynchus keta in Japan during the period 1945-2005 using path analysis, back-calculation, and scale analyses, and applied a prediction method based on the SRES-A1B scenario of the intergovernmental panel on climate change. The populations of Hokkaido chum salmon were found to have had high growth rates at age 1 year since the late 1980s. Path analysis indicated that the growth at age 1 year in the Okhotsk Sea was directly affected by warm sea surface temperature associated with global warming, with the increased growth at age 1 year resulting in higher rates of survival and large population sizes. Predictions on the global warming effects on the chum salmon were (1) decreased carrying capacity and distribution area, (2) occurrence of a strong density-dependent effect, and (3) loss of migration route to the Sea of Okhotsk, especially for Hokkaido chum salmon. We have also outlined the future challenges of establishing a sustainable conservation management scheme for salmon that include adaptive management and precautionary principles, as well as conservation of natural spawning populations and recovery of natural river ecosystems in Japan despite the warming climate.

Pacific Salmon and Steelhead: Life in a Changing Winter Ocean

“…To date, most evaluations of the potential eff ects of climate change on winter distribution of salmon have focused on projected changes in species-specifi c thermal habitat areas (Welch et al 1998a, b;Azumaya et al 2007 (also included salinity); Kaeriyama 2008;Abdul-Aziz et al 2011;Kaeriyama et al 2012Kaeriyama et al , 2014. In general, the results of all of these studies are similar.…”

“…For example, increases in sea surface temperatures due to greenhouse gas emissions are predicted to shrink the thermal habitats of salmon over vast regions of the North Pacifi c Ocean and adjacent seas (Welch et al 1998a, b;Azumaya et al 2007;Abdul-Aziz et al 2011;Kaeriyama et al 2012Kaeriyama et al , 2014. Nevertheless, salmon are capable of rapid microevolution that may allow them to adapt quickly (within one or two generations) to climate change (Kovach et al 2012).…”

Adapting Hokkaido Hatchery Strategies to Regional Ocean Conditions Can Improve Chum Salmon Survival and Reduce Variability

“…The numbers of early-run chum salmon (September-October) in the Japan Sea were related to the strength of Tsushima Warm Current in their return year (Kaeriyama et al 2014). Adult chum salmon may have diffi culty migrating when temperatures exceed 20°C, which has been interpreted as a negative effect of global warming (Kaeriyama et al 2014).…”

The current propagation systems and physiological studies of Japanese chum salmon

“…The mechanisms underlying the 8-year interval between juvenile release and adult return are not yet clarified; however, salmon biomass is considered to be negatively affected by long-term climate change in the North Pacific Ocean, which has experienced climate change within decadal oscillation [4]. Recent global warming has also positively affected the survival rate of juvenile chum salmon in the Okhotsk Sea and caused a population density-dependent effect on growth from ages 2 to 4 years and maturation in the Bering Sea [5].…”