Green Sea Turtles Stranded by Cyclone Kathy on the South-Westeern Coast of the Culf of Carpentaria

Abstract

Cyclone Kathy on 23 March 1984 stranded many green turtles, Chelonia mydas, on the coast adjacent to the Sir Edward Pellew Is. It is estimated that over 1000 were thrown up by the storm surge and that over 500 were left stranded by the receding waters, including migrants from the Raine I. rookery. These turtles, which were predominately large females, had been feeding close inshore on seagrass. Of the mature females sampled, 62% were preparing to breed in the next breeding season but none had bred in the previous season. The flatback turtle, Chelonia depressa, the principal species breeding on the Sir Edward Pellew Is, was not involved in the stranding. Hawksbill turtles, Eretmochelys imbricata, and olive ridley turtles, Lepidochelys olivacea, which occur in the deeper offshore waters were also not stranded. Some of the rescued turtles were subsequently recaptured nesting at Raine I.

Demographic and health parameters of green sea turtles Chelonia mydas foraging in the Gulf of Carpentaria, Australia

“…However, even if these individuals were all adult females, the male bias would still be strong. In contrast, Limpus & Reed (1985a) observed a bias towards larger individuals that were not adult males when they surveyed C. mydas stranded on the mud flats between the mouths of the McArthur and the Wearyan Rivers (an area of the mainland in close proximity to the SEP Islands) in the aftermath of Cyclone Kathy in 1984. If the stranded turtles represent a sexually unbiased sample of the offshore population (Limpus & Reed 1985a), this might suggest several things and disaggregating between possibilities will require future surveys in the SEP Islands area.…”

“…While we caught most of our turtles on the northern reefs of West Island, Limpus & Reed (1985a) reported data from turtles that stranded in the mangroves adjacent to the McArthur River mouth. While sex ratio has been found to be independent of size class for Chelonia mydas at Heron Island, Moreton Bay and Shoalwater Bay in Queensland (Limpus & Reed 1985b), size-related differences have been found in Fog Bay and Torres Strait (Whiting 2002, Hamann et al 2005).…”

“…First, the differences between our data and that of Limpus & Reed (1985a) could reflect fine-scale, local variation in sex ratio, modest sample sizes or sampling bias.…”

“…Second, fine-scale local variation in sex ratio between our data and that of Limpus & Reed (1985a) could reflect sampling habitat. While we caught most of our turtles on the northern reefs of West Island, Limpus & Reed (1985a) reported data from turtles that stranded in the mangroves adjacent to the McArthur River mouth.…”

“…Aboriginal people have resided in this coastal area for thousands of years, and sea turtles and other marine products form an important part of their diet and culture (Bradley 1997a,b, Baker 1999. Despite these long and traditional links, western science first became aware of the SEP Islands' significance as an important sea turtle foraging area in 1984, when Cyclone Kathy stranded several hundred sea turtles and dugongs on the mud flats near the mouth of the McArthur River (Limpus & Reed 1985a).…”