Biological Mechanisms Underlying Climate Impacts on Population Dynamics of Small Pelagic Fish

Abstract

Small pelagic fish account for more than 30% by weight of the total landings of marine fisheries in Japan and around the world. Their population dynamics have tended to be dramatic and cyclical in response to climate variability on multi-decadal time scales. However, the biological mechanisms linking climate variability to population dynamics are still unresolved. This chapter reviews the biological mechanisms underlying climate impacts on the population dynamics of small pelagic fish, taking examples from the species alternations between anchovy and sardine in the Kuroshio Current system. First, the chapter examines how environmental variability regulates the survival probability of small pelagic fish, highlighting the role of vital parameters such as growth rate and physiological condition as an amplifier linking subtle changes in environmental variables to dramatic changes in the population dynamics. Then, the chapter introduces hypotheses for the biological mechanism of species alternation, showing how environmental conditions differently affect the population dynamics of different small pelagic fish species. Lastly, recommendations for future research directions are presented.