Experiments on the artificial rearing of the larvae of Pinctada maxima (Jameson) (Lamellibranchia)

Abstract

Attempts to rear the larvae of P. maxima from the egg up to metamorphosis are described. A simple apparatus for the continuous culture of unicellular algae was developed. Local algae were isolated as possible foods but none of those available promoted rapid larval growth. Maximum gonad development of P. maxima occurs in the period September-March. Attempts to induce spawning in ripe oysters were unsuccessful. Artificial fertilization was accomplished during treatment of stripped gametes with ammonium hydroxide. Large numbers of larvae were produced but mortality was high. Early straight-hinged larvae were approximately 75 by 70 �, and the pediveliger stage was reached when larvae were approximately 130 by 110 �. The fastest rate of growth was recorded when larvae were fed on a mixture of Isochrysis and Monochrysis. A variety of substrata was offered for settlement but metamorphosis was not completed. Further studies are required before the feasibility of commercial rearing can be assessed.