Toward Selective Breeding of a Hermaphroditic Oyster Ostrea chilensis: Roles of Nutrition and Temperature in Improving Fecundity and Synchrony of Gamete Release

ABSTRACT Physiological characteristics of gametogenesis, fertilization, and early larval development in Ostrea chilensis (Philippi, 1845) pose a number of challenges for selective breeding, despite strong commercial potential. In wild populations, this larviparous protandric hermaphrodite exhibits asynchronous gonadal maturation and relatively low fecundity. Reproductive success and genetic diversity in a hatchery population are primarily determined by female fecundity and fertility, as well as synchrony of female gonad development. Better hatchery control of the reproductive cycle can lead to more cost-effective and reliable breeding. This study examined factors such as feed and temperature in an attempt to increase reproductive rates and female sex ratios in brood stock. Oysters held under two different hatchery conditioning regimes—flow-through outdoor nursery ponds and temperature-controlled indoor tanks—spawned earlier and had higher reproductive rates than natural or farmed populations. Oysters were...