In Thau Iagoon (Mediterranean Sea), shellfish are cultured in suspension. Molluscs are reared on ropes that are suspended on frames. Principal species concerned by breeding are Crassostrea gigas, Mytilus galloprovincialis and, in a less extent, Ostrea edulis. A new sampling method was developped to assess the total stock of cultured shellfish and was tested in July 1998 and April 1999. The total stock was found to be 19500 tons (± 1120 SE) in 1998 and 14100 tons (± 830 SE) in 1999, thus exhibiting temporal variations. Temporal differences in the total stock are mainly attributable to the breeding cycle but also to sorne exceptionnal events which occurred in Thau lageon in 1997 and 1998 (water anoxia, bacteriological crisis, bloom of toxic algae). In the... |