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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, p < 0.0001). 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. Resumen: En México la captura de camarón es la principal actividad pesquera y la segunda especie en importancia es el camarón azul Penaeus stylirostris. Se analizaron especímenes de P. stylirostris en aguas interiores (bahía) y exteriores (ribera) del sistema lagunar Santa María la Reforma de 2016 a 2018. A los organismos se les determinó la longitud total (L) en mm y su peso (P) en g. Los sexos se diferenciaron por dimorfismo sexual. Los datos fueron transformados a logaritmo natural y fueron ajustados a siete modelos candidatos con un enfoque múlti-modelo (Lineal, Cuadrático, Cúbico, Línea Rota, Dos segmentos, Tres segmentos y Cuatro segmentos). En total se analizaron 30 439 organismos. Se encontraron diferencias estadísticas en L entre las zonas de captura (prueba KS, p < 0.0001). Se observó una alometría positiva y negativa de acuerdo con la relación biométrica y sexo. El mejor modelo se seleccionó con el menor valor del criterio de información de Akaike, resultando ser el de Cuatro segmentos. [ABSTRACT FROM AUTHOR]

To select the model that allows the growth curves of juvenile and sub-adult shrimp to be described more accurately, a study was carried out in a coastal lagoon in the south of the Gulf of Mexico on the species Farfantepenaeus brasiliensis (Latreille, 1817) and Farfantepenaeus duorarum (Burkenroad, 1939). The data were obtained from 11 monthly samplings, taken between April 2011 and February 2012, applying the catch strategies used by the local fishermen, including the fishing gear used. The carapace length (CL)-total weight (TW) relationship was estimated for both species. Frequency analyses were performed in order to follow the best represented cohorts over time and fit three non-asymptotic growth models: Power, Generalised Schnute and the Indeterminate Tanaka model. The CL-TW relationship of juvenile and sub-adult F. brasiliensis was TW = 3 Ã-- 10â '5CL3.75 and TW = 8 Ã-- 10â '5CL3.50 for F. duorarum, both of which presented positive allometric growth. In both species the Indeterminate Tanaka model proved to be the best fit to the modal groups of the juvenile and sub-adult shrimp due to its ability to describe the seasonal oscillations in shrimp growth. [ABSTRACT FROM AUTHOR]

The vertical distribution of penaeoid shrimp larvae along a 24 hr cycle was analysed from two samplings carried out in distinct periods, i.e., summer and autumn 1993 in the southern Gulf of Mexico. A total of 7238 larvae belonging to the genera Solenocera and Sicyonia, and to the family Penaeidae was collected. In summer, the abundance of shrimp larvae was comparatively lower, with a total of 1062 individuals. The very low number (33 individuals) of Sicyonia larvae collected during this period did not allow detecting a clear vertical migration pattern. In the larvae of the genus Solenocera (837 specimens) and of the family Penaeidae (192 specimens), a typical vertical migration pattern was observed, in which larvae concentrated in shallow strata at dusk, while at dawn they moved toward deeper areas. During autumn, the highest abundance of larvae was obtained, with 6176 individuals captured. Larvae of the family Penaeidae adjusted to the typical vertical distribution pattern of meroplanktonic larvae, with a higher abundance near the surface during the day, and toward deeper strata at night. The Solenocera mysis (1685 individuals) showed a reverse behaviour, with high concentrations between 10 and 45 m depth. The Sicyonia mysis larvae (2465 specimens) increased their dispersion pattern along the water column at night. The distribution of the various penaeid larvae suggests a different vertical distribution behaviour for each group, with some overlap. The Solenocera's tend to remain mainly in the middle of the water column sampled, while Sicyonia larvae show a larger dispersion in that column, and the Penaeidae tend to concentrate near to the surface between 0 and 10 m depth. [ABSTRACT FROM AUTHOR]