Linking loggerhead locations: using multiple methods to determine the origin of sea turtles in feeding grounds
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Many marine megavertebrate taxa, including sea turtles, disperse widely from their hatching or birthing locations but display natal homing as adults. We used flipper tagging, satellite tracking and genetics to identify the origin of loggerhead turtles living in Amvrakikos Gulf, Greece. This location has been identified as hosting regionally important numbers of large-juvenile to adult sized turtles that display long-term residency and/or association to the area, and also presents a male biased sex ratio for adults. A total of 20 individuals were linked to nesting areas in Greece through flipper tagging and satellite telemetry, with the majority (16) associated with Zakynthos Island. One additional female was tracked from Amvrakikos Gulf to Turkey where she likely nested. Mitochondrial DNA mixed stock analyses of turtles captured in Amvrakikos Gulf (n = 95) indicated 82% of individuals originated from Greek nesting stocks, mainly from Zakynthos Island (63%), with lesser contributions from central Turkey, Cyprus and Libya. These results suggest that the male-biased sex ratio found in Amvrakikos Gulf may be driven by the fact that males breed twice as frequently on Zakynthos, resulting in their using foraging grounds of greater proximity to the breeding site. Conservation measures in localised foraging habitats for the protection of marine vertebrates, such as sea turtles, may have positive impacts on several disparate breeding stocks and the use of multiple methods to determine source populations can indicate the relative effectiveness of these measures.
Fieldwork in 2002/2003 was part-funded by EU LIFE project LIFE99NAT/006475. The British Chelonia Group provided a grant to support surveys in 2012. The 2013 fieldwork and tracking took place in the context of the project ‘PRO ACT NATURA 2000 / Protection Actions for Cross-Border and Joint Management of Marine Sites of Community Interest (NATURA 2000)’ (Subsidy code I1.32.01 of the European Territorial Cooperation Programme Greece – Italy 2007-2013).
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.
Vol. 164, 30