Theme D: Developing optimal release strategies
35. IMPACT OF FENCED SCALLOP (PECTEN MAXIMUS) SEA-RANCHING ON BENTHIC FAUNA
Øivind Strand, Tore Strohmeier and Ellen Sofie Grefsrud
Institute of Marine Research, P.O.Box 1870 Nordnes, 5817 Bergen, Norway
oivind.strand@imr.no
Sea ranching of the great scallop (Pecten maximus) in Norway is done by release of hatchery-reared spat to the seabed. The release areas are bordered by fences to prevent predatory crabs (Cancer pagurus) access to the scallops (Figure 1). A fence (50 cm high) of solid plates or plastic canvas is shown to be sufficiently efficient to obtain high scallop survival. Scallop sea-ranching is regulated under the Norwegian Aquaculture Act where measures are set to contribute to a sustainable development of the industry. The Institute of Marine Research aims to provide scientific knowledge on ecological effects from scallop sea ranching. Using fences on the seabed to prevent a target predator access to the area may also obstruct other mobile fauna, and the fence combined with high scallop density within the farmed area may influence the benthic fauna composition. It is also questioned whether increased biodeposition of organic matter by the farmed scallops may affect the benthic environment. We will present results from; 1) an initial study carried out to determine how macro epi- and infauna in a pilot scale sea-ranching area (0.25 ha) was changed after a full seabed production cycle of five years, and 2) a monitoring program carried out at two full scale sea-ranching areas (10 ha) to investigate dynamics of mobile fauna with special emphasis on potential predators on scallops (crabs and sea stars).
Figure 1. Fenced scallop sea-ranching site at Kvitsøy, Rogaland County, Norway.
Call For Papers