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Marine Mammal and Turtle Strandings in the Great Barrier Reef World Heritage Area

Kirstin Dobbs

Great Barrier Reef Marine Park Authority, TOWNSVILE, AUSTRALIA

Theme: TH5

Marine mammals and turtles regularly strand (alive and dead) within the Great Barrier Reef World Heritage Area (GBRWHA). A collaborative retrieval and necropsy programme operated by Queensland and Commonwealth departments assesses the distribution and causes of these strandings. Some animals are rehabilitated and released into the Great Barrier Reef. Information from both live and dead stranded animals is collated in a Queensland - wide database that allows managers to identify trends and patterns of marine wildlife strandings. On average about 20 cetaceans, 40 dugongs, and 200 marine turtles are reported and assessed annually in the GBRWHA. Dugongs have died as a result of cryptosporidiosis and pneumonia. Indo-Pacific humpback dolphins have died from toxoplasmosis. Death from trauma by penetration of stingray barbs has occurred in dugongs and inshore dolphins. Marine turtles have died from impacted guts, fibropapillomatosis and boat-strike. Post mortems on stranded whales and turtles have shown that several died from an impacted gut after ingesting foreign material (plastic bags, monofilament fishing line). Of the animals for which a cause of death has been established, 25% have been from natural causes and 62% from human-related activities. Temporal and spatial patterns are shown through the stranding programme. 'Hot spots' occur in the GBRWHA, including Cleveland Bay, where vessel strikes on green turtles are more frequent than in any other part of the GBRWHA. Seasonal trends occur in the numbers of animals being reported and located. For instance, more dugong, whale, dolphin and turtle strandings are reported during the winter months than at other times of the year.