Detecting mugil curema (Perciformes: Mugilidae) phenotypic stocks in La Paz Bay, Baja California Sur, Mexico, using geometric morphometrics of otolith shape, growth, and reproductive parameters

In a holistic approach it is important to identify potential fishing units to better understand population structure and dynamics. The objective of this work was to evaluate the potential existence of a Mugil curema population structured in stocks in La Paz Bay. For this, a total of 709 specimens were collected between 2010 and 2013. Two fish groups were identified (G1, n = 212, and G2, n = 178), and the otolith shape was compared using geometric morphometrics, L_50% was estimated, age was assigned, and a multi-model approach was used to evaluate individual growth. Eight age groups were assigned for G1 (3-10) and 5 for G2 (3-7). The most adequate model to describe growth for both groups was the von Bertalanffy growth model (G1: L_∞ = 421.77, k= 0.32, t₀ = -0.05; G2: L_∞ = 406.5, k = 0.36, t₀ = -0.02). Differences in otolith shape and growth parameters between groups were significant; opposite, L_50% estimates (G1 = 325 mm LT; G2 = 330 mm LT) were not significant. Results suggest the presence of a M. curema population structured in at least 2 stocks in La Paz Bay: one stock reproduces in Spring (G1) and the other in the Fall (G2).