Regresar

Resumen del producto

Aldana-Moreno, A., F., Galván-Magaña, J., Ketchum-Mejia, M., Hoyos-Padilla, R., González-Armas, P., Klimley & A., Trejo-Ramírez (2020). Residency and movements of the endangered scalloped hammerhead Sphyrna lewini in two island habitats: Revillagigedo and Espiritu Santo, Mexico. Northeast Pacific Shark Symposium IV. La Pa, Baja California Sur, México, marzo 5 - 7, 2020, 1.

Residency and movements of the endangered scalloped hammerhead Sphyrna lewini in two island habitats: Revillagigedo and Espiritu Santo, Mexico

Alejandro Aldana-Moreno, Felipe Galván-Magaña, James Ketchum-Mejia, Mauricio Hoyos-Padilla, Rogelio González-Armas, Peter Klimley y Abel Trejo-Ramírez

The scalloped hammerhead shark, Sphyrna lewini populations have declined globally due to overfishing and ecological changes, and are now considered a critically endangered coastal pelagic shark. Revillagigedo Archipelago (RA) and the Gulf of California, represent an important habitats and a refuge for these marine predators. The aim of this study is to describe the residency and diel movements of S. lewini in San Benedicto Island, Roca Partida Islet, and La Paz Bay (LPB). A total of 29 hammerhead sharks of total length 180-300 cm were tagged with coded ultrasonic transmitters at RA islands and BLP between 2009-2018. The residence index estimated the preference to know the amount of time spend at the sites between warm and cold seasons. Preliminary results (2009-2018) showed 64,125 acoustic detections from 20 hammerheads tagged. The sharks displayed high daytime residency in two of the four sites of RA, without migrating to the other islands of the RA, which may indicate a high fidelity and aggregation site in the island. A higher number of detections were observed during the morning, 06.00-12.00 h, in Canyon and Lava Flow and during the afternoon, 12.00-18.00 h, in Boiler and Cuevitas. Overall, a significantly lower number of detections were observed during the night. This pattern has been suggested as part of the feeding behavior and diel movements of S. lewini of other areas of Eastern Tropical Pacific. The sharks remained in the area for 1-27 months, with a mean of 8.9 months (S.E. ± 2.7). Residency index at the four sites of RA ranged from 08 to 73%, with a mean of 38% (S.E. ± 0.29. Seasonally, there was a decrease in the number of detections in April and May 2013, possibly related to the migration of females to the coast to give birth to their offspring. Furthermore, evidence of interconnected movements between an array of receivers in the surroundings of La Paz Bay are shown. This study generates a baseline for effective monitoring to improve the conservation and management of an iconic but critically endangered species.

Palabras clave: Sphyrna lewini; Residency; Espiritu Santo island; Revillagigedo island

Para obtener una copia del documento contacta la personal de la biblioteca a través del correo bibliocicimar{a}ipn.mx

Regresar