Analysis of culture production and growth rate patterns of mussel ( Mytilus galloprovincialis Lmk.) cultured in the open ocean of the SE Bay of Biscay for the commercial product development

Mytilus galloprovincialis Lmk. mussels were cultured at two culture depths in a submerged longline system, located in the SE Bay of Biscay, from June 2013 to August 2014. The Von Bertalanffy Seasonal Growth Function (VBSGF) of the original seeded batch, without newly settled seed, at each culture depth was assessed. Mussels maintained their reached size during the slow growing months and size increased thereafter. In addition, to test both culture depth scenarios for resource management, the production of commercial pieces (“small” and “large” mussels) in quantity (mussel classification) was assessed. VBSGF output proved that commercial mussels may well be harvested throughout the year in the studied site. The culture period required to produce mussels of a commercial size was 1 to 1.5 years, depending on seeding date.