Knowledge on species taxonomic identity is essential to understand biological and biogeographical processes and for studies on biodiversity. Species the genus Tremoctopus have been confused in the past and are inconsistently identified. To clarify of the taxonomic diagnosis Tremoctopus violaceus Delle Chiaje, 1830, an evaluation of morphological and meristic characters, as well as morphometric indices and genetic analyses, was undertaken. The analyzed octopod was an opportunistically collected mature female of 640 mm in total length, with a mantle length of 135 mm and a total weight of 1.02 kg. Evidence of autotomy as a defensive mechanism for protecting the egg mass is presented. The 16S haplotype sequenced from this specimen represents the first one publicly available for this species from the Gulf of Mexico. The genetic divergence between this haplotype and those reported from the Pacific Ocean is representative of interspecific variation in other taxa, which suggests that “T. violaceus” in the Pacific Ocean (KY649286, MN435565, and AJ252767) should be addressed as T. gracilis instead. Genetic evidence to separate T. violaceus and T. gracilis is presented. The studied specimen from the Gulf of Mexico represents the westernmost known occurrence of T. violaceus and the first record from the southwestern Gulf of Mexico.

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...

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The number of studies of reproductive biology for Atlantic bluefin tuna carried out in the Gulf of Mexico is significantly lower than those undertaken in the Mediterranean Sea. Four spawning areas have been found for the eastern Atlantic bluefin tuna stock in the Mediterranean Sea, so it is not implausible that there is more than one spawning area in the Gulf of Mexico for the western Atlantic bluefin tuna stock. The individuals used in this study were caught as bycatch by the Mexican surface longline fleet between January and April 2015. A total of 63 individuals ranging between 192 and 293 cm LF (mean = 238 ± 22.52 cm) were measured. Gonads from 46 fish (31 females and 15 males) were collected for histological examination. All the individuals were classified as mature; 25 were reproductively active (in spawning capable and spawning stages). The histological analysis indicates spawning activity in Mexican waters (the southern Gulf of Mexico). Spawning occurred in March and April, when the sea surface temperature was 25.57 °C ± 0.69 in March and 27.03 °C ± 0.69 in April. Information on the location of the spawning areas is necessary for a correct management of species. The present study provides the first histological evidence of reproductive activity in Mexican waters, and indicates a wider spawning area, beyond just the northern zone, potentially encompassing the entire Gulf of Mexico.

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