Abstract.-The brown shrimp (Penaeus aztecus) fishery is the most important in the Gulf of Mexico. This fishery takes non-target species or by-catch fauna, mainly teleost fishes, which are incidentally captured. Some of the by-catch species has commercial use and the rest of them are discarded. Therefore, it is important to describe the composition of the discarded fauna, to determine the impacts under the ecosystem approach. Discarding catch of shrimp trawls carried out in 2013 on the continental shelf off the State of Veracruz in different depth intervals (22-46 and > 46 m) was analyzed. For each trawl, the shrimp catch, the commercial by-catch and the discarding were recorded and the catch ratios respect to shrimp, were obtained. A discard sample was taken and the species were identified, the total length was taken and the ecological parameters were calculated. The non-parametric multiple dimensional scaling test was performed. A total of 7,178 fishes were collected from 34 families, 46 genera and 51 species. The ratio of commercial species by-catch: shrimp and discard: shrimp was 15.41:1 and 40:1 kg, respectively. The species with high relative dominance were Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens and Upeneus parvus. The species with greater importance index were C. macrops, S. foetens, and D. bivittatum. The 43.14% of the discarded species are used as food and 7.84% as bait. The maximum diversity (H´) was 3.76 bits ind -1 and the trophic level was 4.31. The study of discard composition is a basis to assess the impact generated by the shrimp trawlers and provides guidelines for identify changes in the community structure. Key words: Discard, fishes, shrimp, Alvarado, VeracruzResumen.-La pesquería del camarón café Penaeus aztecus es la más importante en el Golfo de México. En esta pesquería se capturan de manera incidental especies no objetivo compuestas mayormente por peces teleósteos. Es importante describir la composición del descarte, para determinar el impacto de los arrastres camaroneros bajo un enfoque ecosistémico. Se analizó la captura de descarte de arrastres camaroneros realizados en 2013 en la plataforma continental del Estado de Veracruz en 22-46 y >46 m de profundidad. Para cada arrastre se registró la captura de camarón, fauna de acompañamiento comercial, descarte y fauna de acompañamiento. Se tomó una muestra del descarte, se identificaron las especies y se calcularon los parámetros ecológicos de la muestra. Se realizó una prueba de escalamiento dimensional múltiple no paramétrica. De 87 lances de pesca, se analizaron 7.178 organismos correspondientes a 34 familias, 46 géneros y 51 especies. Las especies con mayor dominancia relativa y mayor valor del índice de importancia fueron: Citharichthys macrops, Synodus foetens, Diplectrum bivittatum, Rhomboplites aurorubens y Upeneus parvus. Un alto porcentaje de las especies de descarte (43,14%) presentan uso potencial de alimento y 7,84% carnada. En promedio, la relación Fauna de Acompañamiento Comercia...

During two annual periods, the reproductive cycle of the gastropod Hexaplex princeps from Puerto Ángel, Oaxaca, Mexico was studied through gonadal histology. Sex proportion for the collected individuals was not statistically different from parity although most of the time, the number of males was slightly larger than that of females, which only outnumbered males during the spawning season. The maturity stages established for females were: (1) initial oogenesis, (2) previtellogenic maturity, (3) vitellogenic maturity, (4) maturity, (5) spawning, and (6) resting; and for males: (1) initial spermatogenesis, (2) maturity, (3) spawning, (4) onset of the rest, and (5) resting. Monthly variations of maturation stages showed that H. princeps has an annual reproductive cycle with a long period of gonadal activity. The spawning season comprised from November (females) and December (males) to March, with activity peaks in January. From March to October (females) and from May to June (males), reproduction resting occurred. Spawning was related to high chlorophyll concentrations due to the upwelling processes resulting from the winds and to the cooler sea surface temperatures occurring from November to March. This study provides baseline information that may serve to establish measures for sustainable exploitation strategies and for future aquaculture implementation of this species.

ABSTRACT. The reproductive cycle of the gastropod Hexaplex princeps (Broderip, 1833) from Puerto Ángel was studied through gonadal histology during two annual periods. The sex proportion for the total collected individuals was not statistically different from parity although most of the time the number of males was slightly larger than that of females, which only outnumbered males during the spawning season.