Effects of nutrition on larvae production in the European flat oyster, Ostrea edulis

Abstract

The production of viable larvae of the European flat oyster, Ostrea edulis, was evaluated. Firstly, oysters pre-conditioned in fertilised sea water for 42 days prior to warm-water conditioning in the hatchery produced more broods of larvae than oysters pre-conditioned in unfertilised sea water. Secondly, larvae production was influenced by the diet provided to the broodstock during hatchery conditioning. The most productive treatments were either unfiltered sea water or filtered sea water supplemented with a mixture of Dunaliella tertiolecta and Tahitian Isochrysis, which produced 135 317 and 78 250 larvae per oyster, respectively. The least productive treatment was the single species diet of D. tertiolecta, where 10 820 larvae per oyster were released. These larvae showed a lower subsequent survival compared with larvae from other broodstock treatments. Compared with larvae released in the wild, the larvae from these experiments showed lower levels of total lipid. This result, together with the fact that hatchery-conditioned broodstock showed lower fecundity than wild stock, demonstrates that there remains considerable scope to improve the conditions for broodstock maintenance for aquaculture purposes.