Twenty years of turtle tracks: marine turtle nesting activity at remote locations in the Pilbara, Western Australia

Little is known about the biology and ecology of marine turtles in the Pilbara region of Western Australia and most potential habitat is unconfirmed and, therefore, undescribed. Understanding basic biological parameters at a regional level is critically important for effective long-term management. We used the track census' methodology to identify reproductive habitat and assess species-specific abundance of adult flatback (Natator depressus), green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles at 154 locations in the Pilbara region of Western Australia. Between 1992 and 2012, potential nesting habitat was assessed via either ground or aerial snapshot' (single visit) or census' (more than one night) surveys and additional information obtained using the Expert Elicitation Method. Species-specific abundance (tracks night(-1)s.d.) was varied; green turtles were most abundant, nesting at fewer locations (n=47) but in greater numbers (1200.5 +/- 62.0) than flatback or hawksbill turtles and primarily (93%) at island locations. Flatback turtle nests were more widely distributed (n=77) than those of green or hawksbill turtles, yet abundance (877.4 +/- 29.5) was lower than that of green and greater than that of hawksbill turtles. Activity was primarily (76%) island-based and activity on the mainland coastline was concentrated close to Mundabullangana and Cemetery Beach. Hawksbill turtle abundance (314.1 +/- 17.1) was lowest and the least widespread (n=43), concentrated primarily in the Onslow and Dampier subregions with no activity recorded in the Port Hedland subregion or on the mainland coastline. The findings provide information with which the Federal government can meaningfully assess the status and distribution of EPBC Act-listed species where habitat overlaps with areas zoned for development. We highlight the urgent need for the Federal Government to regulate the process by which we accumulate data to support data quality and provide meaningful information to enhance efficacy in state and Federal management of species of concern.