Preliminary report on black sea turtle research activities undertaken by the UABCS/UBath/Earthwatch team at Laguna San Ignacio, BCS, Mexico, in June 2009
William M Megill1, Volker Koch2, Robert P Templeton1, Agnese Mancini2, Amee J Lewis3, Rianna E Burnham1, Ranulfo Mayoral4
1 Ocean Technologies Laboratory, University of Bath, UK
2 Dept de Biologia, Universidad Autonoma de Baja California Sur, Mexico
3 School of Ocean Sciences, University of Bangor, UK
4 Grupo Tortuguero de las Californias, Laguna San Ignacio, Mexico
Abstract
This report summarizes the black sea turtle research activities which took place in June 2009. There were four objectives to the research that summer. The first was to contribute to ongoing population monitoring efforts for this species in Baja California. The second was to determine the sea turtle mortality rates and causes of mortality in the San Ignacio area. The third was focused on determining what use the turtles make of the habitat in the lagoon, and the fourth on where they fit in the lagoon food web. Turtles were captured mostly in the upper reaches of the lagoon using closely monitored entanglement nets, processed ashore, then released close to where they were captured. Turtles were measured, weighed, and flipper tagged. Some were selected to be tracked using a surface buoy equipped with a VHF transmitter and GPS recorder. Two turtles were outfitted with a carapacemounted underwater camera. Due to equipment failures, only one useful GPS track was obtained. Behavior during this track was not different from that observed in previous years. Two underwater movies were obtained, demonstrating that the attachment method worked and that simple inexpensive (and therefore expendable) cameras are sufficient for recording the animals’ behavior. Stable isotope analysis was conducted, and preliminary results suggest that there are two feeding strategies present among the turtles in the lagoon: one focused entirely on eelgrass, and the other split between eelgrass and invertebrates. No correlations were found with any of the turtles’ life history parameters,