Conservation and management of olive ridley sea turtles and their nesting habitat: A study at Rushikulya rookery, Odisha, east coast of India

Abstract

Odisha coast, along the east coast of India, has the world's largest mass nesting sites (rookeries) for olive ridley (Lepidochelys olivacea) sea turtles. It has three rookeries namely Gahirmatha, Devi and Rushikulya. Olive ridley sea turtles and their habitat along the Odisha coast often face natural and anthropogenic threats leading to failure of mass nesting (arribada) and a population decline. The focus of the present study is to understand the coastal processes near the Rushikulya rookery, assess the impacts of natural and anthropogenic threats to the nesting population and their habitat, and suggest a management plan for the conservation of sea turtles and their habitat. Coastal processes and the associated geomorphological changes, shoreline change, and cyclonic disturbances at the Rushikulya rookery from 2008 to 2019 were studied. It is revealed that the natural threats for arribada are cyclonic storms, high wave exposure, and sand spit growth leading to erosion of the nesting habitat and debris accumulation. Coastal processes, such as east-southeast to south-southeast waves with moderate wave height, lunar semidiurnal tide, moderate southwest current, and predominantly southerly and easterly winds with moderate speed, are identified as favourable conditions for the sea turtles prior to and during an arribada. The study reveals that nesting on the sand spit is vulnerable because of frequent wave exposure and washout, while the beach to the north of the estuary is the most preferred and safe habitat for arribada. Coastal development, incidental capture, entanglement in gill nets, fisheries bycatch and illegal take are revealed as the major anthropogenic threats. Based on natural and anthropogenic threats, the local knowledge of the fishermen and the status of legislation, the study suggests an integrated regional management plan for the conservation of olive ridley sea turtles and their nesting habitat.