The biomass of the Pacific stock of Japanese anchovy Engraulis japonicus was estimated using virtual population analysis (VPA) which assumes that the natural mortality coefficient fluctuates with predation by the Pacific stock of chub mackerel Scomber japonicus and is expressed as a function of biomass of the mackerel stock. Data used in this analysis were catch-at-age for the anchovy stock and existing biomass estimates of the mackerel stock. Holling’s disc equation was used to indicate the relationship between predation by mackerel and biomass of predator mackerel and biomass of prey anchovy. Because the fluctuation in the exploitation rate is expected to increase due to errors in estimating biomass, unknown parameters were optimized to minimize the fluctuation in the exploitation rate. In the results, the exploitation rate was stable in the range of 0.03–0.18, but the natural mortality rate fluctuated widely in the range of 0.65–0.91 due to predation by the mackerel stock. The validity of the estimation results and the model, as well as issues in the estimation of abundance by VPA, were examined.

　To prevent the occurrence of harmful algal blooms, we investigated the bloom dynamics of harmful algae causing damage to the fishery industry in Uranouchi Inlet, Kochi Prefecture, Japan. From 2010 to 2023, Karenia mikimotoi and Chattonella spp. typically formed blooms during the summer, with the former tending to appear earlier than the latter. These harmful algae often formed mixed blooms, which were associated with fishery damage. Monitoring K. mikimotoi blooms may help predict subsequent Chattonella spp. blooms. These findings contribute to predicting harmful algal blooms in Uranouchi Inlet.

　People living in coastal areas have the advantage of accessing a high level of ecosystem services, but are exposed to the dangers inherent in living by the sea in areas prone to natural disasters. The structure of perceived satisfaction for five components of human well-being (“Security,” “Basic material for a good life,” “Good social relations,” “Health,” and “Freedom of choice and action”) derived from coastal ecosystem services was compared between two sites in southwestern Japan (southern Ehime and northern Miyazaki Prefectures) that share the same natural and social backgrounds: highly dependency on fisheries industry, and located in the same climate regime (temperate zone), and have similar topographical features (ria coast). Structural equation modeling using the results from questionnaire surveys showed that the two sites share a common basic structure of the interactions among the five components of human well-being. However, the intensity of interactions among components differed between the two sites. Questionnaire surveys on anxiety about natural disasters and future access to marine ecosystem services were simultaneously conducted at the two sites. The site-specific concern about tsunami was suggested to be responsible for the difference in the interactions among the five components of human well-being.