Stomach contents and dietary overlap of three round stingray species (Urobatis halleri, Urotrygon munda, and Urotrygon rogersi) captured off the central Pacific coast of Mexico were analyzed during the two main hydroclimatic periods (T1 and T2) that characterize the environmental variability in the area. The three round stingray species showed a narrow bathymetric distribution range, and the highest abundances were located at 20 m depth in both seasons. In general, the diets were mainly composed of benthic microcrustaceans (caridean shrimps) and to a lesser extent of fishes, polychaetes, and molluscs. The most abundant prey items in the diets were carideans of the families Processidae and Ogyriididae, and penaeids, followed by brachyuran and stomatopod larvae. All three stingrays exhibited a generalist feeding strategy. The diets showed high overlap values during period T1 in both inter- and intraspecies analyses, but lower values during period T2. There was no evidence of ontogenetic diet changes and sex was not a factor for trophic differences. The slight differences among diets were due to seasonal changes in the soft-bottom macrobenthic invertebrate assemblages in the shallow waters, and relationships like predation and competition were not the main factors influencing the population dynamics of the three stingray species.

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Reproductive biology of Anisotremus interruptus (Perciformes: Haemulidae) in the Mexican Central Pacific. Anisotremus interruptus is a widely distributed and commercially important species in the Eastern Pacific. A multi-year research on the reproduction of this species was carried out in coastal waters of Jalisco, Mexico. For this purpose, monthly samples were gathered with gillnets of different mesh sizes from 1998-2008. A total of 1 090 individuals were collected with a total length range between 15.6-61.0cm. Significant differences from expected 1:1 ratio were found for sex ratios in the total sample and for each size class, but not when comparisons among months and years were done. Temporal variations of the gonadosomatic index and proportions of maturation stages suggest that the main reproductive period is from February to May, although some less intensive spawning events were observed in other months. Seven stages of oocytes development were identified. Oocytes in different stages of development were identified in ovaries classified as mature, suggesting an asynchronic type of gonad development. Mean maturation length (L 50 ) was 31.0 for females and 29.7cm for males. The internal organization of testes is of lobular type. Rev. Biol. Trop. 60 (2): 709-720. Epub 2012 June 01.