Age and growth of the squalid callista Megapitaria squalida (Bivalvia: Veneridae) in the Eastern coast of the Gulf of California

Abstract

Background. The squalid callista Megapitaria squalida is an important fishery resource along the east coast of the Gulf of California. To manage this resource sustainably, we need to address its individual growth pattern. Previous studies on M. squalida growth have fitted the von Bertalanffy growth model (VBGM) without examining alternative models. Goals. In this study, the main objective was to analyze the individual growth of the squalid callista via a multi-model inference approach rather than simply applying the VBGM. Methods. Three growth models - Logistic (LM), Gompertz, and VBGM - were tested. The parameters of each model and their confidence intervals (CI) were computed using the maximum
likelihood method. Results. Growth rings of 719 individuals collected in the littoral area of Yavaros, Sonora, were counted. The minimal size recorded was 33 mm of total shell length and the maximum was 104 mm; the average was 68.9±10.2 mm, and the coefficient of variation (CV) was 14.8%. Individuals with a minimum of one growth ring year and maximum of 10 growth rings were recorded. The average growth rings were 6±1, CV 22.9%. The LM better described the individual growth of squalid callista since its Akaike weight value was 92.4% whileit was undetectablefor the MCVB. The value of L?, with LM was 85.5 mm (95% CI: 85.0-86.2 mm). Conclusions. We concluded that M. squalidagrowth is best described by a sigmoid model, and that the MCVB is not suitable for this species.