In Mexico, shrimp catch is the main fishing activity, and the second important species is the blue shrimp, Penaeus stylirostris. Specimens of P. stylirostris collected in 2016-2018 from inland waters (bay) and offshore (littoral) in the Santa María la Reforma lagoon (SMLR) system were analysed. The sexes were separated, and then individuals were measured in total length (L, mm) and weighed (W, g). The data were transformed into a natural logarithm and were adjusted to seven candidate models with a multi-model approach (Linear, Quadratic, Cubic, Broken stick, Two segments, Three segments and Four segments: the last two proposed in this study as new equations). A total of 30 439 specimens were analysed. Statistical differences were found in L between areas (KS test, ). Positive and negative allometry was observed according to biometric relationship and sex. The best model was selected with the lowest value of the Akaike information criterion, resulting in the choice of the Four segments model.

The crab fishery of the genus Callinectes is one of the most important fisheries in Mexico. Sonora and Sinaloa are the states on the eastern coast of the Gulf of California, the mainland coast. Sinaloa encompasses the greatest production in Mexico of these species, in particular the Bahía Santa Maria La Reforma (BSMR), supplying the most important catches. A mandatory administrative document for the fishery is the Management Plan of Crab. One of the main weaknesses found in it for Sonora and Sinaloa is the lack of fishery assessment in both states. For this reason, a size-structured method called CASA (Catch-at-Size Analysis) was applied in the BSMR, in the seasons 2000, 2011, and 2014, to C. bellicosus. The first catch size (CW50%) estimated for females was 97.5, 102.5, and 100 mm, while in males, it was estimated at 117.5, 107.5, and 102.5 mm. In the specific case of fishing mortality (F), the algorithm allowed us to find that in the larger sizes, a greater fishing pressure is applied for both females and males, yielding a weighted exploitation rate of 0.047 (2000), 0.119 (2011), and 0.426 (2014) for females and 0.045 (2000), 0.295 (2011), and 0.132 (2014) for males, all below 50% (E = 0.50). The crab C. bellicosus in BSMR is not at risk of overexploitation.

Growth is the most influential aspect in demographic species analysis. Collecting data on ages and sizes (such as length and weight) is a fundamental step in growth modeling, particularly in fishery science. Residual analysis plays a crucial role in parameterizing the mathematical models chosen to describe the growth patterns of the species under investigation. Using optimal residual criteria is essential to improving model performance and accuracy. In the present study, the length-at-age data of the Gulf corvina (Cynoscion othonopterus) were evaluated with the Schnute model to obtain the best error type and to establish the most accurate growth pattern. Later, the observed, constant, depensatory, and compensatory variance approaches were tested using the logistic model. The Bayesian information criterion (BIC) was used as the goodness-of-fit test to obtain the best variance approach parametrizing the growth model. The BIC values selected the observed variance as the best approach to parametrize the logistic growth model. The conclusion is that the observed variance approach produces robust results—that is, the observed variance produced the most plausible fits. It is suggested that the observed error structure should be used to estimate individual growth.

A study on the growth patterns of Callinectes arcuatus was carried out in the Teacapan-Agua Brava Lagoon System, Sinaloa, Mexico, based on monthly sampling conducted from August 2023 to July 2024. A total of 881 individuals were examined, with carapace width (CW) ranging from 25 to 115 mm. The length-weight relationship showed an isometric growth ( ; 95% CI: 2.87-3.02). The sex ratio revealed no significant differences between females and males throughout most of the sampling period. Among the growth models evaluated, the Gompertz with an oscillatory component provided the best fit according to the Akaike Information Criterion, yielding an estimated asymptotic CW of 119.19 mm, a growth coefficient ( k ) of 0.57 year ⁻¹ , and a low oscillation amplitude ( ), with the minimum growth rate occurring in November. These findings contribute valuable biological information relevant to the management and sustainable exploitation of C. arcuatus in the region.