Effects of artificial reefs and the acoustic-sound feeding method on the colonization of released grouper seedlings

Abstract

In order to enhance the survival rate and retention rate of released grouper, Epinephelus akaara seedlings, the artificial reefs and acoustic-sound feeding method were used. Total of 10, 198 marked grouper seedlings (8-14cm TL) were released on the artificial reefs in the Seto Inland Sea from 1996 to 1999. By underwater observations, 43.7% of the one-year-old seedlings remained for one year on the artificial reefs where they were released. The groupers caught by gill nets around the artificial reefs fed mainly on arthropod (macrurans, anomurans, and brachyurans), fish, and artificial diet that was provided by an acoustic-sound feeding buoy system. These natural food items, which colonized on the artificial reef, may be the most important food for the groupers. Artificial reefs were very effective in supplying nursery grounds and food organisms for the released groupers. The acoustic-sound feeding method promoted the colonization of the grouper seedlings.