The use of an acoustic-sound feeding method to enhance the colonization of marked and released, cultivated
juvenile grouper, Epinephelus akaara, was investigated around artificial reefs off Shiraishijima Island in the Seto
Inland Sea. During underwater observations from May 1996 to December 1999, 35 species of fish were observed
around the artificial reefs and the fish biomass varied from 19 to l,247g/m
3. Three species, E.akaara, Sebastes
inermis and Sebastisucs marmoratus, dominated the fish community, and the biomass of each species varied among
months. Although the number of juvenile grouper remaining in the area dramatically decreased on the first day
of their release, 43.7% of the one year old fish remained where they were released on the artificial reef after one
year. Furthemore, 2-4% of the released grouper remained on the artificial reefs two or three years later.
Counts of juvenile grouper, however, varied significantly among both observation months and the reef sites. Yet,
on the central part of the artificial reef where the acoustic-sound feeding method was used, the number of released
grouper was significantly higher than at sites on the periphery of the reef. These results suggest that acoustic-sound
feeding systems associated with artificial reefs enhance colonization of released grouper. Such methods increase
wild and cultured fish populations in the nursery grounds.
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