Population structure of the Eastern oyster Crassostrea virginica (Gmelin,1791) (Mollusca: Bivalvia: Ostreidae) in Tamaulipas, Mexico

Background. In Tamaulipas, Mexico, the Eastern oyster, Crassostrea virginica, is one of the most commer-cially important species. Goals. The population structure of C. virginica in the Tigre River and Laguna de San Andres in the State of Tamaulipas, Mexico, was determined. Methods. Oysters were collected from three banks from January to December 2022 using the quadrat-based method. The size structure (length, width, and weight), instar distribution, weight-length relationship, abundance, and biomass of C. virginica were determined. Results. In total, 2,277 organisms were collected. The representative size, in the three banks, occurred in a range of 43-65 mm in length. Significant differences were recorded in the width, length, and weight of the oysters collected, with Bank 1 and 2 organisms having the greatest length and weight. The three banks presented negative allometric growth when establishing a b value <3. No significant statistical difference was recorded in the number of recruits between the banks. A statistically significant difference was observed between banks in the average number of juveniles-preadults, adults, and adults with more than one reproductive. The abundance on the banks is below the established minimum number (> 200 oys-ters/m2). There is inadequate management of the resource on the three banks, where most oysters captured are below the size allowed for extraction. Conclusions. The structure shows that most of the C. virginica population is below the size allowed for its extraction, which is why the development of studies focused on the sustainable management of this species is suggested.