Movements and post-release mortality of juvenile sea turtles released from gillnets in the lower Cape Fear River, North Carolina, USA

摘要

North Carolina coastal waters are an important seasonal foraging habitat for juvenile green Chelonia mydas and Kemp's ridley Lepidochelys kempii sea turtles. Sea turtle mortality due to incidental capture in gillnets is a topic of great concern in this region, and fisheries regulations have been implemented to minimize sea turtle bycatch. Current regulations are based on estimates of fisheries-related sea turtle mortality derived from analyses of fishing effort, observed bycatch, and strandings data. Information regarding the health status of sea turtles at the time of release and doc-umentation of post-release mortality are necessary in order to refine the mortality estimates used to govern management decisions. The primary goals of the present study were to use satellite teleme-try to monitor post-release movements of sea turtles released from gillnets, document post-release mortality, and evaluate the feasibility and reliability of using blood biochemistry data collected at the time of capture to predict post-release mortality. Satellite telemeters were deployed on, and blood samples were collected from, juvenile green and Kemp's ridley sea turtles released from a 14 cm mesh gillnet set in shallow waters (1 to 5 m deep) in the lower Cape Fear River, North Carolina, USA. Twelve of 14 turtles released from the gillnet stayed in the lower Cape Fear River throughout the post-release tracking duration. We documented 1 confirmed and 3 suspected post-release mortali-ties. Blood chemistry analyses revealed differences in plasma ion (K~+, Cl~-, Na~+) and lactate levels between the turtle that died (confirmed mortality) and all other study animals, suggesting that these variables could serve as chemical predictors of post-release mortality.