Introduction and Acclimatisation of the Pacific Carpet Clam, Tapes Philippinarum, To Italian Waters

Abstract

In 1983 the exotic clam Tapes philippinarum was introduced to the lagoons of the north Adriatic as an aquaculture project. The purpose was to surrogate the insufficient production of the nearly identical native T. decussatus. Seed was obtained from European and North American hatcheries. Loose sediment in shallow, non-turbulent but well-flushed waters constitutes the habitat of the species. By 1986 there was evidence that the species was breeding freely and colonising all suitable areas. By 1990 the commercial yield from the culture parcs and natural beds had reached 20,000 tons year^-1 furnishing the livelihood to a labour force of about 4,000 units. In the most productive areas densities of > 1,000 ind m^-2 are common. Acclaimed as a great success by the fisheries sector, this initiative has been condemned by scientists and environmentalists as infringing the general principle of keeping out alien species and more specifically because the exotic clam is thought to have caused the disappearance of the native sympatric counterpart and generally upsetting the indigenous benthos. Field surveys carried out before and after the arrival of the alien clam show that the accusations are unfounded or cannot be demonstrated.