Stochastic modeling of eastern oyster (Crassostrea virginica) production in a Mexican tropical coastal lagoon using alternative stocking density management schemes

Abstract

A stochastic model was developed to analyze Crassostrea virginica production when cultivated at three stocking densities, defined as the area occupation (50, 75, and 100%) in Nestier-type trays, using juvenile oysters with an initial size (height) of 29.40 ± 0.18 mm. A 25-week grow-out was first conducted in the Rio Lagartos lagoon, showing that final oyster size was inversely related to density (P < 0.05), ranging from 61.87 mm (100% density) to 68.00 mm (50% density). At the same time, mortality was negligible (lower than 1.0%). The environmental conditions in the lagoon were stable, and the oyster growth rate positively correlated with water temperature and pH. Low pH was associated with slow oyster growth, possibly as an adverse effect of acidic conditions on the oyster shell formation. The model indicated that, for an initial 100,000 oyster population, the maximum production (oyster dozens) is obtained after 20 weeks (8310 at 50% density) and 25 weeks (8250 at 75%, and 6670 at 100% density). There was a 100% probability of oysters reaching a minimum commercial size (MCS) of 60.00 mm when using the 50 and 75% densities and 80.6% when using 100%. The model estimated that, for the maximum density, extending the grow-out up to 32 weeks would allow reaching MCS with 100% probability, although this should be experimentally confirmed. The random variability of oyster production in 50 and 75% densities was minimal, while at 100% density, it was extremely high. A sensitivity analysis indicated that for 50 and 75% densities, the main stochastic elements influencing production, are related to oyster mortality, while at 100% density, they are related to oyster growth.