Coastal and off shore operations have the potential to influence turtle behaviour and breeding success. Astron was commissioned to continue long-term monitoring of turtles on a Pilbara offshore island to assess whether operations were influencing turtle nesting and hatchling emergence and behaviour.
Eight nesting beaches were monitored with beach patrols conducted each evening. Turtles were tagged and tracks were counted at the start and end of each monitoring session.
Tagging data was used to estimate the number of turtles per season, annual nest abundance, and spatial and temporal distribution of turtles within and between beaches. Mark-recapture models were used to estimate population sizes of both Hawkesbill and Flatback Turtles. Turtle hatchling emergence was confirmed and nests were later excavated to estimate clutch size, hatching success and emergence success. The spread of hatchling tracks was used to quantify the influence of operations on hatchling orientation.
Astron’s appreciation of the importance of adhering to standardised monitoring methods ensured the continued rigour of the long-term turtle monitoring data set. Appropriate analysis was also important in order to assess the current state of the local turtle populations with confidence. This information is critical for evaluating management of the island with respect to potential impacts on turtles.