The diet of demersal piscivorous fishes captured as bycatch of the commercial shrimping fleet off the Alvarado lagoonal system, Veracruz, Mexico, was studied. Nine collections distributed throughout the nortes (windy), wet, and dry seasons were made from November 1993 to January 1995. Sampling yielded a total of 646 fishes representing 10 families and 14 species, of which 44.9% had empty digestive tracts and were excluded from analysis. Trichiurus lepturus and Synodus foetens were the most abundant demersal predators in the collections. Differences in food consumption of the 7 most abundant predators were observed among the 3 seasons, with the greatest variety of prey (20 species) taken during the nortes season and the lowest variety (9 species) during the dry season. Five distinct trophic guilds were determined based on an index of relative importance of prey. Prey type and location of prey within the water column helped determine guild classification. The occurrence of different trophic guilds may allow for decreased competition for food resources on the continental shelf off Alvarado, Mexico. RESUMEN Se estudio la dieta de los peces piscívoros demersales capturados como fauna acompañante del camarón en la flota de barcos camaroneros del sistema de lagunas de Alvarado, Veracruz, México. Se obtuvieron nueve colecectas que abarcaron las temporadas de nortes, lluvias y secas desde noviembre de 1993 hasta enero de 1995. Las muestras produjeron un total de 646 peces representados por 10 familias y 14 especies; 44.9% fueron encantrados con el tracto estomacal vacíos y no fueron analizados. Trichiurus lepturus y Synodos foetens fueron los depredadores demersales más abundantes en nuestras muestras. Se observaron diferencias en el consumo de alimento en las tres temporadas. La temporada de nortes mostró la mayor variación de presa (20 especies), y la menor variación se observó en la temporada de secas (9 especies). Cinco distintivos gremios tróficos fueron identificados basados en el índice de importancia relativa de la presa. El tipo de presa y la localización de las presas en la columna de agua permitieron determinar la clasificación de los gremios. La existencia de diferentes gremios tróficos permite una disminución en la competencia por recursos alimenticios en la plataforma continental del Alvarado, México.

A study was carried out to assess the biological aspects of Dormitator maculatus, analyzing sex ratio, diet, and growth estimates based on the von Bertalanffy model. All organisms were captured with the help of 50 m. long cast fishing lines at ten sampling stations monitored between May 2015 and May 2017. 642 subjects were captured ranging between 3 to 14.7 cm total length for males, 3.9 to 15.9 cm for females. Sex ratio is 1:1 female:male, they consume nine different types of food, mainly Ruppia marítima, detritus, benthic algae and ostracods. The constants for the von Bertalanffy model for frequency analysis were, a Maximum Length (MaxL) of 22.37 cm for males, 22.71 and 22.93 cm or females, k= 0.20785 and 0.17199 for males, 0.20856 and 0.16749 for females. For scale analysis, the growth rate was MaxL =19.51, and k=0.26642. The grown rate estimate (Ø') ranging from 1.93 to 2.03 with the different adjustments. Currently, there is a reduction in population that may endanger its exploitation, affecting other species that feed from it, is recommended to increase the number of studies that aim at predicting the possible environmental impacts on productive use systems involving the ichthyofauna that inhabits the Alvarado lagoon.

L-W and eight biometric relationships for D. maculatus in the Alvarado lagoon, were performed on 500 specimens (252 females and 248 males), 23.7 - 143.9 cm TL and 0.95 – 59.1 g weight, sampled during May 2015 to May 2017, using traditional fishing gears. The b coefficient indicated isometric growth (b = 3.0195; r2 >0.9763; P < 0.05) for overall sample, females (b = 3.0507; r2 >0.989; P < 0.05) and males (b = 2.9953; r2 >0.9783 P < 0.05). Biometric relationships showed high correlations (r2 >0.9193 – 0.9992; P < 0.05) for the overall sample. females (r2 >0.9188 – 0.9981; P < 0.05) and males (r2 >0.9079 – 0.9995; P < 0.05). This study report for the first time L-W and biometric relationships for the Fat sleeper. These results will be useful to delineate a baseline for regulations and the sustainable fishery management of this fish species