Perspectives for development of low impact aquaculture in a Western Mediterranean lagoon: the case of the carpet clam Tapes decussatus

Some 30,000 specimens of the Mediterranean clam Tapes decussatus were
suspended in nylon bags of two different mesh sizes and pre-grown in the Calich
lagoon (Sardinia, Italy) from March to June 2001. The samples differed in size at the
end of the pre-growth stage. They were then sown at a density of 650 specimens m)2
in two stations of the lagoon. The growth rates in the stations were different according
to the Von Bertalanffy model. Primary and secondary plankton production was calculated
by field measurements as well as by modelling. The results indicate that the
Calich lagoon could produce a maximum of 753.25 g m)2 yr )1 WW, with shell, for
Tapes decussatus. Our culture experiments lasted 15 months with an estimated mortality
of 50% and the yield of T. decussatus was 4.3 times greater than the calculated
natural production.