Examinando por Autor "Espinoza, P."

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    Niveles de mercurio en el tiburón martillo Sphyrna zygaena (Carcharhiniformes: Sphyrnidae) del norte del Perú [Mercury levels in the smooth hammerhead Shark Sphyrna zygaena (Carcharhiniformes: Sphyrnidae) from Northern Perú]
    (Facultad de Ciencias Biologicas, Universidad Nacional Mayor de San Marcos, 2017) Gonzalez-Pestana, A.; Alfaro-Shigueto, J.; Mangelu J.C.; Espinoza, P.
    The smooth hammerhead shark Sphyrna zygaena (Linnaeus, 1758) is one of the elasmobranch species most used for human consumption in Perú. However the level of mercury in hammerhead muscle tissue is unknown. This study assessed the level of mercury found in the muscle of hammerhead sharks and its relation with human health. Moreover we evaluated the relationship between shark body size and mercury levels. We analyzed 27 muscle samples of neonates and juveniles captured in northern Perú. Mercury concentrations varied between 0.13 and 0.86 mg kg-1 wet weight. Moreover we found a negative and significant relationship between shark body size and mercury levels. This study represents the first evaluation of mercury levels of sharks in Perú. Although the values found do not exceed levels recommended by the World Health Organization (< 1 mg kg-1), we recommend expanding this study to include other size classes of sharks as well as other marine resources used for human consumption.
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    ÍtemAcceso Abierto
    Trophic ecology of the smooth hammerhead shark (Sphyrna Zygaena) off the coast of northern Peru
    (National Marine Fisheries Service, 2017) Gonzalez-Pestana, A.; Acuña-Perales N.; Coasaca-Cespedes J.; Cordova-Zavaleta F.; Alfaro-Shigueto, J.; Mangel, J.C.; Espinoza, P.
    The smooth hammerhead (Sphyrna zygaena) is the third most captured shark species in Peru, a nation with one of the largest shark fisheries in the Pacific Ocean. We sought to better understand the trophic ecology of this shark in northern Peru by analyzing stomach contents. From 2013 through 2015, we collected 485 samples of gut contents from sharks measuring 53-294 cm in total length. Our results show that the smooth hammerhead is a top predator with a diet dominated by jumbo flying squid (Dosidicus gigas) and the Patagonian squid (Doryteuthis (Amerigo) gahi). Smooth hammerheads displayed different diets with different body size, and this finding indicates that sharks change their distribution and habitat during development. This study represents the most comprehensive investigation to date of the trophic ecology of smooth hammerhead in waters off Peru. We propose that these waters represent an important eastern Pacific Ocean feeding ground for smooth hammerhead. Because this species is commercially important and also preys upon other commercial species, these findings could contribute to the design and implementation of plans for ecosystembased fisheries management. © 2017, National Marine Fisheries Service. All rights reserved.