Morphometric relationships and growth models for the oyster Crassostrea corteziensis cultivated at the southeastern coast of the Gulf of California, Mexico

This study aimed to determine weight-size relationships and to fit the best growth model of the Cortez oyster Crassostrea corteziensis from early juvenile to adult during one single culture cycle. The morphometric data (n = 50 oysters sampled each two weeks during January 2010 to March 2011) of shell height-shell length [SH-SL], shell height-shell width [SH-SW], shell width-shell length [SW-SL], body weight-shell length [BW-SL], body weight-shell height [BW-SH] and body weight-shell-width [BW-SW] (log-transformed) were determined by regression analysis. The SL and SH measurements (R-2 = 0.98) were consistently proportional to the BW, being the BW-SL and BW-SH morphometric relationships the more suitable for growth evaluation of C. corteziensis in culture. Four different equations of the Schnute model, as well as Special cases 1 and 2 (equivalent to the Von Bertalanffy growth model, VBGM, and Logistic models, respectively), were evaluated utilizing length-at-age data to estimate individual growth parameters. The parameters were obtained using the maximum likelihood algorithm and the Akaike information criterion was applied to rank the models examined. The growth curve displayed a rapid increase until the size of 41.68 +/- 16.18 mm in length. In the present study, the symmetrical sigmoid curve was the best hypothesis that fit the data; however, it is assumed that the age data are sufficiently informative to describe the growth pattern of C. corteziensis, with either Schnute model Special case 2. Results from morphometry and growth model in this study represent useful tools to analyze growth performance of the Cortez oyster in culture better.