Using a combination of stereological and calorimetric methods, we studied reproductive effort of Pacific winged pearl oyster Pleria sterna during an annual cycle in Bahia de La Paz, B.C.S., Mexico. The relationship between changes in the volumetric fraction of germinal and somatic tissues (gonad, digestive gland, adductor muscle, and mantle tissue) and changes in their energy content was analyzed. These data were also correlated with changes in water temperature and availability of food (seston). Because P. sterna spawns several times a year, reproductive effort was estimated ∼400% in terms of energy increase from early development in October 2006 to the spawning occurring in January to February 2007. During this period, when water temperature was decreasing and seston concentration was increasing, P. sterna followed a conservative strategy for allocating energy from reserves previously stored in somatic tissues. In contrast, when productivity dropped in spring, the species followed an opportunistic strategy for sustaining gametogenesis from food energy. In decreasing order, total energy channeled for reproduction came from the digestive gland (23 KJ g 1), adductor muscle (19 kJ g 1), and mantle tissue (16 KJ g 1). Based on these results, we recommend that commercial pearl culture practices be conducted from mid-autumn (October) through early spring (April), when P. sterna is energetically more resistant to manipulation. An additional recommendation is to avoid grafting during the summer (June through September), when the species is energetically exhausted and highly vulnerable to manipulation.
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Vol. 28 • No. 3