Culture substrate for suspended culturing of the Manila clam Ruditapes philippinarum

Abstract

Manila clam Ruditapes philippinarum were grown in suspended culture using plastic containers and on-bottom culture using mesh bags on a tidal flat in Oonoura Bay, Mie, Japan. The suspended culture methods included containers of two substrate depths (36 and 72 mm) and two types of substrate (gravel and pumice). Clams grew faster and were in better nutritional condition in suspended culture than in on-bottom culture. However, losses of clams in suspended culture were higher than on-bottom culture as some were able to pass through the coarse net covering the container. Clams grew faster in containers with deep substrata (72 mm) than those with shallow substrata (36 mm), but growth of suspended clams was similar between the types of substrate. This study demonstrated the feasibility of suspended culture for yield of clams of commercial size and emphasized the value of enough deep substrata. Pumice can be used instead of gravel to reduce the weight of the container for easier handling without affecting the growth of the clam.