Predation mechanism of Japanese rock crab Charybdis japonica on Manila clam Ruditapes philippinarum with possible countermeasures

Abstract

Japanese rock crab Charybdis japonica is a major predator forManila clam Ruditapes philippinarum and so the development of countermeasures against this predation would help restore the decreased clam resource. Choice experiments revealed that C. japonica approaches clams by using olfactory cues, and thus can nd clams that have burrowed into sand. Laboratory conditions that either disturbed sensory cues or provided cover failed to show any improvement in the survival of clams. However, eld trials in Maizuru Bay demonstrated that sparging small stones is ecient for improving the survival of clams.