Identification of potential predators for asari clam ruditapes philippinarum using time-lapse camera observations

Abstract

Predation is considered a significant factor contributing to the recently observed low survival rates of asari clam (Ruditapesphilippinarum) in Japan. Longheaded eagle ray, blackhead seabream, portunid crabs, predatory gastropods, and ducks are suggested as potential predators; however, the relative significance of these predators has yet to be evaluated. In this study, we conducted 31 single-day time-lapse camera observation trials during summer at 28 stations within 12 habitats of the asari clam in Japan (ranging from temperate to subaretic regions) to determine the relative abundance of predators in each habitat. And in a trial at the Nakalsu tidal flat in southwestern Japan, where a previous study observed a low survival rate of the asari clam, the absolute abundances of different predator taxa were estimated by quantifying the underwater visibility and visible area in images.