Effect of predation by the crab Carcinus maenas and shrimp Crangon crangon on the survivalrate of shellfish Venerupis decussatus

In September 2013 the RAAK PRO project ‘Saline production’ was granted. This project involves a 4 year study in optimizing various types of near shore shellfish culture in Lake Grevelingen, Lake Veere and Oosterschelde. Focus of the project is off bottom (in cages) oyster farming, bottom culture of manila clams and cockles, and rope culture of mussels, all in close cooperation with local producers, companies and research institutes (a.o. Wageningen Marine Research).

Manila clam culture (Venerupis decussatus) is relatively new to the Dutch delta. To investigate whether cultivation of Manila clams is feasible and commercially interesting for grow-out production in the Eastern Scheldt, we want to conduct field- and laboratory studies. Predation by common shore crab (Carcinus maenas) and brown shrimp (Crangon crangon) is of major importance for Manila clam survival, particularly for spat. To quantify the effects of these predators, the predation rates of Common shore crabs and Brown shrimp on Manila clam spat (size range) will be tested in laboratory settings (Sealab). Additionally, in a field experiment Manila clam spat of different sizes will be distributed on predator-protected and -unprotected experimental intertidal plots to assess the effects of predation in situ. Crab traps will be used to monitor the abundance of Common shore crabs in vicinity of the experimental plots during springtime.