Food Habits of The Asian Paddle Crab Charybdis japonica on the Jangbong Tidal Flat, Incheon, Korea

초록

The Asian paddle crab, Charybdis japonica (A. Milne-Edwards) is a portunid crab native to Central and South East Asia. The native range of this species includes coastal regions of China, Korea, Japan, Taiwan and Malaysia. In Korea, C. japonica is an important fishery resource. Despite its common occurrence and economical importance, little is known about their life cycle and trophic ecology. Food habits of this shore crab C. japonica populations were investigated on the Jangbong tidal flat near Incheon, Korea. Monthly samples were taken using a modified otter trawl from November 1999 to January 2001. Based on the stomach contents examination from 257 individuals, the frequencies of occurrence and the relative volumes of food items were investigated. The stomach contents analysis showed that the crustaceans (the brachyura, the cirripedia and the harpacticoid copepoda), the echinoderm (the ophiuroidea) and the mollusks (the cephalopoda Loligo beka, the bivalves Bivalvia unid. and Mytilus edulis) were important food for this species. To examine ontogenetic shifts in diets, individuals of C. japonica were sorted into 2 different size classes (< 60mm and > 61mm carapace width) representing sexually premature and mature stages. As a result, the difference in the proportions of the main prey items among these two size classes was statistically significant. Therefore, we can conclude that the feeding habits of C. japonica changed with growth.