Performance of Tripfoid Pacific Oysters, Crassostrea gigas: Gametogenesis

Abstract

Triploid Pacific oysters, Crassostrea gigas, were produced by treating newly fertilized eggs with cytochalasin B. After a year of growth, diploid and triploid oysters were sampled throughout the reproductive season to determine the effect of triploidy on gamete formation and sexual expression. Relative to diploids, gametogenesis in triploids was retarded but not absent: both male and female triploids produced some gonad. Gametogenesis in most triploid males resulted in spermatid production; all triploid males produced numerous spermatocytes. Oocyte formation in most triploid females was severely retarded, although some triploid females produced numerous eggs. Hermaphroditism in the triploid population was markedly higher than in diploids: 29 versus 1%, respectively. The ratio of males:females was the same in diploids and triploids.