Aspectos biológicos básicos de Pinctada imbricata (Bivalvia: Pteriidae) en la laguna de La Restinga, isla de Margarita, Venezuela Basic biological aspects regarding Pinctada imbricata (Bivalvia: Pteriidae) in the La Restinga Lagoon, Margarita Island, Venezuela

Pearl oysters are abundant bivalves in the northeastern coast of South America that form dense shoals in the Caribbean Sea, where they are exploited for marketing, making them a valuable resource in northeastern Venezuela. In order to provide information on Pinctada imbricata in the La Restinga Lagoon, its growth, size structure, condition index and natural mortality were estimated from April 2012 to January 2013. A total of 40 random samples of pearl oysters were collected on a monthly basis by freediving in a linear transect of approximately 200 m. The total length and total weight ratio indicated a negative allometric growth. A multimodal distribution was shown in almost all sampling months, with sizes ranging between 21.56 and 54.61 mm of total length. The modal peak observed in most of the months was between 24 and 28 mm, indicating a continuous recruitment throughout the year. The maximum peak of the monthly condition index was in May 2012, while the minimum was in November 2012. Growth parameters were L∞ = 68.5 mm, K = 1.18/year and t 0 = 0.37, reaching the regulatory market size of 50 mm at approximately 18 months, with an estimated 2.92 year maximum longevity. Total mortality, corresponding to natural mortality M, was calculated as Z = 1.40/year.