Relationship between Saury Fishing Grounds and Large-Scale Coherent Structures in the Ocean, According to Satellite Data.

AVISO satellite data on the speeds of geostrophic currents from 2004 to 2018 are used to associate a substantial reduction in the saury catch in recent years with a change in the oceanographic situation in the Russian fishing grounds off the coast of the southern and middle Kuril Islands and Hokkaido Island. Lagrangian maps of the origin of water masses, calculated for this period of time on the basis of the AVISO field, and with overlaid positions of fishing vessels of Russia, Japan and Korea, show that this catastrophic reduction is due to a change in the pathways of the nutrient-rich subarctic waters of the Oyashio current in recent years. The greatest changes in the hydrological regime since 2015 were caused by intensification of the third branch of the Oyashio, which transports the waters of this current to the open ocean. At the same time, traditional fishing grounds off the eastern coasts of Hokkaido and southern Kurils have been reduced, while good fishing grounds have appeared in the open ocean. [ABSTRACT FROM AUTHOR]