,I,,,:I’, 1:. The Status of the Dugong in Torres Strait

In November 1987, dugongs were counted from the air at an overall sampling intensity of 7.4 % over a total area of 30,533km2 in the Torres Strait region and adjacent waters of the Great Barrier Reef Marine Park. About half the survey was repeated in March 1988: persistently bad weather prevented its completion. We corrected for perception bias (the proportion of animals visible in the transect which are missed by observers), and standardized for availability bias (the proportion of animals that are invisible due to water turbidity) with survey-speci ~ correctibn fbdors. The resultant minimum population estimate in November 1987 was 12,522 + S.E. 1,487 dugongs at an overall density of 0.41+ S.E. 0.05 km2, a precision of 12%. Although there were no significant differences between population and density estimates obtained from the repeat surveys of the same areas, relatively more dugongs were sighted clok to the major western islands in the March suroey. Our data suggest that if the dugong population were increasing maximally, this region could support an unselective man-induced mortality of 700 dugongs per year at most. If the current rate of increase is similar to that estimated from the Daru dugong catch between 1978 and 1982, the maximum unselective harvest will be of the order of 300 dugongs. If significantly more females than males are being caught, these figures are overestimates. In the absence of adequate catch statistics and current life histo y information, it is impossible to confirm whether the current dugong harvest in Torres Strait is likely to be below the sustainable yield. A high priority should, therefore be placed on public education in an attempt to pre-empt any increase in catch: The resultant maps of distribution and density Torres Strait Baseline Study Conference suggest that, if the Tomes Strait dugong sanctua y area is to be t@ctive, its boundaries should be renegotiated or an additional protection area established around Buru (Turnagain) Island