Regional differences of temporal trends in masu salmon coastal catch

Since the 2000s, coastal catches of masu salmon have decreased on the Sea of Japan side of Hokkaido and Honshu but increased on the Okhotsk and Pacific sides of Hokkaido, while neither increasing nor decreasing on the Pacific side of Honshu. This result suggests that annual coastal catches are influenced by natural environmental factors which change temporally such as climate change, and that hatchery fish stocking does not significantly affect annual coastal catches. For the management of masu salmon resources, therefore, we recommend using wild fish which are subject to natural selection rather than stocking hatchery fish.