Sea turtles and small-scale fisheries: Designing conservation policies for a marine area on Crete, Greece

Abstract

The purpose of this interdisciplinary study was to provide information useful for the development of management policies for Rethymno, Crete which hosts an important loggerhead turtle rookery for the Mediterranean region and is included in the EU’s NATURA 2000 network. I used satellite telemetry, data loggers and ultrasonography to study the behavior of sea turtles during the interesting interval. By satellite tracking 21 turtles I identified internesting habitat utilized by loggerheads, which extended along the northern coast of Crete. Twenty-five percent of turtles exhibited low site fidelity, likely depositing at least one clutch in areas up to 150 km away. MCP and Kernel Density analyses revealed high intensity use areas indicating that existing boundaries of the NATURA 2000 site were insufficient to protect this population. Some females (n = 4) overwintered in neritic habitats around Crete. I studied the diving behavior of 33 loggerhead turtles and found that diving behaviors were consistent with energy conservation strategies. Dives occurred at depths shallower than 10 m (data loggers: 89.2%, n = 8,241; transmitters: 90.1%, n = 30,804), indicating selection for habitats providing protection. Using x2 goodness of fit tests and ANOVA analyses, I found variation in diving behavior among individual turtles and at different times of day. More active behavioral patterns indicated selection for warmer waters or foraging. Females spent > 95% of their time in the top 5 m of the water column between 11:00 and 19:00. I visited 18 ports around Crete, conducting 101 semi-structured, questionnaire based interviews with small-scale fishermen. There was a link between observed decreases in catch (reported by 96.0% of respondents), increased fishing effort and an increase in intensity of interactions with sea turtles. Fishers discussed damages resulting from these interactions, but sea turtles were thought to pose limited (52.5%) or no threat (21.2%). Interactions with large marine vertebrates were included in the ‘top three challenges’ faced by 66% of respondents, who indicated that the government should provide compensations, suggesting that it was indispensable to prevent intentional killings of animals seen as threats. Respondents also discussed establishing MPAs as favorable interventions for regenerating fish stocks. They also suggested that closures would be acceptable, especially if temporary and combined with compensation for curtailed fishing access.Ph.D., Environmental Science -- Drexel University, 201