Feeding habits of three round stingrays (Rajiformes: Urotrygonidae) in the central Mexican pacific [Hábitos alimentarios de tres especies de raya (Rajiformes: Urotrygonidae) en el Pacífico central mexicano]

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

Feeding habits of three round stingrays (Rajiformes: Urotrygonidae) in the central Mexican pacific [Hábitos alimentarios de tres especies de raya (Rajiformes: Urotrygonidae) en el Pacífico central mexicano]

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

Trophic interactions of the six most abundant fish species in the artisanal fishery in two bays, central Mexican Pacific [Interacciones tróficas de las seis especies de peces más abundantes en la pesquería artesanal en dos bahías del Pacífico central Mexicano]

We surveyed the trophic components in six species of Bahía de Navidad and Bahía de Chamela: Microlepidotus brevipinnis, Caranx caballus, Haemulon flaviguttatum, Lutjanus guttatus, L. argentiventris and Mulloidichthys dentatus. Two main seasonal periods were considered: 1) North Equatorial Counter Current NECC period influence (T1) and 2) California Current CC period influence (T2). In Bahía de Navidad 78 prey taxa were identified in the stomachs. From July to December (T1), 64 prey taxa were found, and from January to June (T2), 45 prey items. In Bahía de Chamela 93 prey items were identified; 74 during T1 and 60 during T2. The highest prey number was found in the stomachs of M. dentatus during T1 in Bahía de Navidad and the lowest prey number (7) was recorded in H. flaviguttatum in Bahía de Navidad in the same period. Crustaceans were the most frequently recorded prey items, followed by fishes, mollusks, polychaetes, and echinoderms in both seasonal periods and sites. The six fish species studied are considered as specialist feeders due the low values of the niche breadth index. There was little similarity among the diets

Trophic interactions of the six most abundant fish species in the artisanal fishery in two bays, central Mexican Pacific [Interacciones tróficas de las seis especies de peces más abundantes en la pesquería artesanal en dos bahías del Pacífico central Mexicano]

We surveyed the trophic components in six species of Bahía de Navidad and Bahía de Chamela: Microlepidotus brevipinnis, Caranx caballus, Haemulon flaviguttatum, Lutjanus guttatus, L. argentiventris and Mulloidichthys dentatus. Two main seasonal periods were considered: 1) North Equatorial Counter Current NECC period influence (T1) and 2) California Current CC period influence (T2). In Bahía de Navidad 78 prey taxa were identified in the stomachs. From July to December (T1), 64 prey taxa were found, and from January to June (T2), 45 prey items. In Bahía de Chamela 93 prey items were identified; 74 during T1 and 60 during T2. The highest prey number was found in the stomachs of M. dentatus during T1 in Bahía de Navidad and the lowest prey number (7) was recorded in H. flaviguttatum in Bahía de Navidad in the same period. Crustaceans were the most frequently recorded prey items, followed by fishes, mollusks, polychaetes, and echinoderms in both seasonal periods and sites. The six fish species studied are considered as specialist feeders due the low values of the niche breadth index. There was little similarity among the diets

Abundance, distribution, feeding habits and trophic interactions in five flatfish species (Pleuronectiformes) in the Mexican central Pacific [Abundancia, distribuci�n, h�bitos alimentarios e interacciones tr�ficas de cinco especies de lenguados (Pleuronectiformes) en el Pac�fico central mexicano]

We analyzed the spatial distribution patterns of the five most abundant flatfish species caught by shrimp trawl nets on the continental shelf of the Mexican central Pacific. Food diets and trophic interactions between of the flatfish species are described as well. Flatfishes are distributed between 20 and 60 m depth. Bothus leopardinus showed the greatest abundance during the cold season (January-May), the other species did not show significant differences between seasons (cold and warm). The diet of the flatfish species consist of crustaceans, fishes and cephalopods. B. leopardinus and Syacium ovale are consumers of crustaceans, such as crabs, shrimps and stomatopods. Cyclopsetta panamensis, C. querna and Monolene assaedae based their diet in fishes and cephalopods. The feeding strategy of the five species analyzed is considered to be generalist, consuming a high number of preys in both seasons. Between the flatfish species, low values of overlapping in the diets were observed in size class and periods of the year. The flatfish species consume the available food resources and could change the preys consumed, according to prey availability, to avoid intra and interspecific competition

Abundance, distribution, feeding habits and trophic interactions in five flatfish species (Pleuronectiformes) in the Mexican central Pacific [Abundancia, distribución, hábitos alimentarios e interacciones tróficas de cinco especies de lenguados (Pleuronectiformes) en el Pacífico central mexicano]

We analyzed the spatial distribution patterns of the five most abundant flatfish species caught by shrimp trawl nets on the continental shelf of the Mexican central Pacific. Food diets and trophic interactions between of the flatfish species are described as well. Flatfishes are distributed between 20 and 60 m depth. Bothus leopardinus showed the greatest abundance during the cold season (January-May), the other species did not show significant differences between seasons (cold and warm). The diet of the flatfish species consist of crustaceans, fishes and cephalopods. B. leopardinus and Syacium ovale are consumers of crustaceans, such as crabs, shrimps and stomatopods. Cyclopsetta panamensis, C. querna and Monolene assaedae based their diet in fishes and cephalopods. The feeding strategy of the five species analyzed is considered to be generalist, consuming a high number of preys in both seasons. Between the flatfish species, low values of overlapping in the diets were observed in size class and periods of the year. The flatfish species consume the available food resources and could change the preys consumed, according to prey availability, to avoid intra and interspecific competition