It is important to understand the characteristics of fishing conditions for each fishing ground in the Seisyou region of Sagami Bay in order to explain the mechanism of catch fluctuation. Species compositions of fish caught by six large-sized set-nets were analyzed by cluster analysis.
Yearly similarities in species composition by cluster analysis showed a tendency of dominant species catches. The trend varies a little, influenced by species composition for each fishing ground. Furthermore, the trend of the Seisyou region is generally influenced by the Komekami and Koyawata fishing grounds. The change of the set-net construction for the Iwae fishing ground, from trap net (1970-1983) to trap net with bottom-layer bag (1987-1993) had a great effect.
