Village-based farming of the giant clam, Tridacna gigas (L.), for the aquarium market: initial trials in Solomon Islands

Abstract

Between 1989 and 1992, small-scale grow-out trials of cultured Tridacna gigas (L.) were established at 40 coastal villages in Solomon Islands. The juvenile giant clams were delivered to village participants at a mean size of 34.6 mm shell length (SL) and a mean age of 380 days. The clams were grown in cages of wire mesh placed on trestles in shallow, subtidal, coral reef habitats. After a mean grow-out period of 297 days, the clams were a mean size of 77.6 mm SL, a suitable size for sale to the aquarium market. Mean growth rate was 4.1 mm month-1. In 32 of the 53 cages involved in the trials, all clams were removed completely from the cage every 3 months for cleaning. The mean survival rate of these clams was 54%. The clams in the remaining 21 cages were not removed for cleaning and their survival was significantly lower (22%). The growth rate of clams removed for cleaning (3.7 mm month-1) was, however, significantly lower than the growth rate of undisturbed clams (4.8 mm month-1). At current prices for juvenile T. gigas in the aquarium trade, farmers who regularly cleaned clams would have netted a minimum of US$180 for a cage initially stocked with 390 clams. Fanners who did not clean their clams would have netted only US$40 per cage due to poorer survival.