by S. fuscescens was also seaweed, constituting 85% of all food consumed, but other
organisms, such as skeleton shrimps, were also found in the stomach of these fishes.
Compared with K. bigibbus and S. fuscescens, K. vaigiensis showed a considerably
varied diet. K. vaigiensis mainly consumed crustaceans, such as skeleton shrimps,
and seems to be omnivorous rather than herbivorous.
The preference of captive K. bigibbus for 5 brown algae species including
Sargassum fusiforme, Undaria pinnatifida and Ecklonia kurome was studied using
multiple-choice feeding experiments. These brown algae are commonly found in the
western coastal areas of Kyushu. The experiments supported the results of the
stomach content analysis and showed that K. bigibbus selectively fed on Sargassum
fusiforme and Undaria pinnatifida. Ecklonia kurome was the least preferred by
K. bigibbus. E. kurome is an important species in the seaweed beds in Kyushu, which
is severely damaged by some fish species in its natural environment (Kiriyama et al.,
2001). Meanwhile, our stomach contents analysis confirmed that E. kurome was
rarely found in the stomachs of herbivorous fish. The biomass of S. fusiforme and
U. pinnatifida is low during winter; therefore, it is probable that during winter,
K. bigibbus consumes E. kurome. Similar experiments are currently being conducted
on other fish species.