POPULATION-MODEL ANALYSIS FOR THE LOGGERHEAD SEA-TURTLE, CARETTA-CARETTA, IN QUEENSLAND

Worldwide declines of marine turtle populations have forced a need for sound conservation policies to prevent their extinction. Loggerhead t urtles, Caretta caretta, are declining rapidly at eastern Australian n esting beaches, which are visited by females from all feeding areas fo r the stock. In some feeding areas of eastern Australia, loggerheads h ave been protected from deleterious anthropogenic effects. Using long- term mark-recapture data from one such protected group of turtles feed ing on Heron Island Reef, Queensland, we created a matrix model to ana lyse loggerhead demography. We also produced a model for the females n esting at Mon Repos, Queensland, a major rookery where the annual nest ing population has declined at rates approaching 8% per year. As indic ated by a similar model for loggerheads in the USA, our models predict ed that small declines in annual survival rates of adult and subadult loggerheads can have a profound impact on population dynamics. A loss of only a few hundred subadult and adult females each year could lead to extinction of the eastern Australian loggerheads in less than a cen tury. Survival in the first year of life is relatively less important in these long-lived and slow-maturing animals. At Mon Repos, nesting f emale survival is apparently so low that even beach protection efforts resulting in 90% hatchling emergence success would not prevent popula tion decline. Our research suggests that continued mortality pressure on subadult and adult turtles in their dispersed feeding areas of east ern and northern Australia is a major threat to the eastern Australian loggerhead turtle population. Measures that protect adult and subadul t loggerhead turtles should be supported, including the use of turtle excluder devices (TEDs) on prawn trawls.