Spatiotemporal Heterogeneity in Cutlassfish (Trichiurus spp.) Population Dynamics Reflects Responses to Different Regional Environmental Conditions in China Seas

Cutlassfish (Trichiurus spp., Linnaeus, 1758) is one of the major commercial species along the east coast of China. Trichiurus are voracious predators, whose diets are composed of a variety of prey species, including pelagic and benthic species. Comparison of the cutlassfish (T. spp.) spatiotemporal heterogeneity in population dynamics and connecting these variation to the regional oceanographic conditions (e.g., Seas in China include South China Sea, East China Sea, Yellow Sea and Bohai Sea) is largely lacking. The Chinese government started the Summer Closer Season Policy since 1995, which had effectively protected those marine fisheries resources to an extent. Most of the commercial catches of cutlassfish come from the shelf regions of the China Seas. Three cutlassfish species, i.e. T. japanicus, T. brevis, and T. nanhaiensis, are commonly found along the coast and have contributed majority of the Trichiurus catch in China. Different dynamics responses of cutlassfish populations to fluctuating regional oceanographic conditions has been found to be important. Spatiotemporal heterogeneity in population dynamics of cutlassfish has been connected to density dependency, climate ocean oscillation and primary productivity. The observed differences among cutlassfish population dynamics in the China Seas may reflect their responses to the differences in regional primary productivity changes.