World Status, Exploitation and Trade - WIDECAST

AUSTRALIARANCHINGIn 1973, the Australian Government set up Applied Ecology Pty Ltd toundertake research into industries which were compatible with the way oflife of the indigenous peoples. One of the projects that the companyundertook was to establish turtle rearing farms on islands in the TorresStrait. Farms were originally set up on ten islands but soon these werereduced to eight (Thomson, 1979). In October 1973, Carr and Main (1973)reported that there were a total of 112 farmers, spread from Murray Island,on the Great Barrier Reef to Western Australia. C. mydas were seen on farmson Maer, Darnley and Yorke Islands, and a photograph is given of thisspecies on Yam Island. E. imbricata was reported to be present on Kubin,Moa, Badu, Sue, Yam, Cocoanut and Yorke Islands. The oldest farms were saidto be on Haer and Darnley Islands, where the turtles were said to be one totwo years old, indicating that they had started in 1971. The C. mydas wereintended primarily for human consumption, although some sale of carapaceswas envisaged. The E. imbricata were to be used primarily for theproduction of small, stuffed turtles (Carr and Main, 1973).Sources of stock In the early stages of the operation, eggs wereprocured from a variety of islands (Carr and Main, 1973), including RaineIsland, but later collections were only made on Bramble Cay. On thisisland, eggs were taken only from areas of the sand spit which wereregularly eroded, and this activity was therefore thought to have had aminimal effect on the wild population. The eggs were transported to thefarms for incubation in styrofoam containers. It was found that hatchabilitywas not reduced if the eggs were moved within six hours of laying, but thatmortality increased to 100% if they were disturbed subsequently. There werealso plans to maintain some adults for captive breeding, but these werenever implemented (Thompson, 1979).Husbandry Various husbandry techniques were experimented with, includingimpoundments on the foreshore, floating cages and a variety of tanks andponds. The standard ponds adopted were 3-m diameter fibre-glass tanks forthe hatchlings, and plastic swimming pools for the larger animals, roofedover to provide shade (Thompson, 1979). Water in the ponds was changedseveral times a day, which was a labour-intensive process (Carr and Main,1973) until mechanical pumps were introduced (Thompson, 1979). Thehatchlings were fed a diet of fish, but it was found necessary to add greenvegetable material, either sea grass or terrestrial plants, to optimisegrowth. The sizes attained by hatchlings on the farms varied from 600 g to1200 g after one year, 1700 g to 3100 g after two years, and 3000 g to8000 g after three years.After operating the farms for five years. Applied Ecology recommended thatthe experiment be discontinued for economic reasons, because the growth rateof turtles was so low that they had to be kept for too long before attainingslaughter weight.AUSTRALIA:WESTERN AUSTRALIAPOPULATION:Chelonia mydasNesting Sites The Lacepede Islands are probably the most important nestsite off the Kimberley coast, followed by Browse Island and Cassini Island(R.I.T. Prince in litt. . 1 July 1988); the Dampier Archipelago and the MonteBello Islands and Barrow Island, about ISO km west of the Dampier78