Internal nutrient management associated with gonad quality and successful reproduction in the winged pearl oyster Pteria sterna

The winged pearl oyster Pteria sterna sustains the Mexican pearl industry, but recent problems ensuring the provision of spat for grafting operations have refocused research toward gonad maturation and hatchery production of spat. We used several indicators (morpho-physiological indices, histology, histochemistry, proximal and fatty acid composition) to analyze the management of nutrients involved in gonad quality, larval vigor, and successful reproduction of the species during its natural breeding season. Samples included two ripening peaks (February and April 2009), a pre-reproductive period (November 2008) and a post-reproductive period (June 2009). The indicators were related to changes in water temperature. Spawning occurred in February, April, and June, but the highest gonad quality to sustain larval development and spat production occurred only in April (water temperature was 21.8 °C). Also in April, post-vitellogenic oocytes were more abundant, attained larger sizes, and had high protein, lipid, triglyceride, and EPA contents. SAFA, rather than MUFA or PUFA, were actively accumulated in the gonad and digestive gland during the breeding season (February-June), indicating these fuels are reliable criteria of gamete quality. This finding provides information that has relevance in preparing suitable diets for broodstock and larvae, facilitating development of more effective hatchery protocols, and with this, increasing the supply of oysters for grafting operations. For that, we recommend inducing P. sterna to spawn over-ripe gametes in early winter and allow them to redevelop into new gametes of higher quality in early spring when the water temperature reaches 22 °C.