Food habits of fish communities in a Sargassum confusum bed off the coast of Ishikari, Hokkaido, Japan

Abstract

Seasonal changes in the composition and food habits ofˆsh communities in a Sargassum confusum-dominated bed oŠ the coast of Ishikari, Hokkaido, Japan were examined. Twenty-seven species, a total of 997 individuals, were collected by beach seine surveys from June 2002 to August 2003. Numbers of individuals and species increased in spring to fall compared to winter. A cluster analysis based on stomach contents composition showed that theˆsh communities comprised eight feeding groups: A) phytal amphipods, B) phytal and benthic amphipods, C) benthic polychaetes and phytal amphipods, D) phytal amphipods and isopods, E) benthic copepods and amphipods, F) planktonic copepods, G) phytal mysids and planktonic copepods, and H) phytal mysids feeders. Ontogenetic diet shifts were recognized in Pholidapus dybowskii, Aulichthys japonicus, Hexagrammos otakii and Syngnathus schlegeli, although Blepsias cirrhosus, Neozoarces steindachneri and Zoarchias veneˆcus were included in

Mapping of Sargassum meadow for estimation biomass by side scan sonar

“…Their meadow plays important roles in coastal ecosystems. For example, experiments by Levin and Hay (1996) suggested that the Sargassum meadow has a sh aggregation effect, and it was reported that the number of migrating sh decreased with a decrease the Sargassum meadow in Hokkaido (Sakurai et al 2009). Sargassum meadow also serves as food for abalone and other useful shery species (Uki et al 1986).…”