Milman Island, in the northern Great Barrier Reef, is the primary index nesting site for Torres Strait–northern Great Barrier Reef stock of hawksbill turtles. A ten-year study on Milman Island indicated an annual rate of decline of three per cent in the nesting population.216 A later study of foraging animals inhabiting the Howick group of islands, also in the northern Great Barrier Reef and within the same hawksbill turtle stock, found a similar decline between the late 1990s and the late 2000s, with some stabilisation between 2003 and 2008.217
Figure 2.11 Marine turtle strandings, 2000–2013
Marine turtle strandings (dead or alive) in the Region in 2011 were about five times that of previous years. Higher than normal strandings were also recorded in 2012 and 2013. Only cases confirmed in the field by a trained person and later verified by an expert are graphed. Source: Department of Environment and
Heritage Protection (Qld) 213 and Department of Agriculture, Forestry and Fisheries (Qld) unpublished data 214
Wreck, Erskine and Tryon islands in the Capricorn group of islands and the Woongarra coast, just south of the Region, are key nesting locations for the eastern Australian loggerhead turtle stock. This stock continues to recover after declining by more than 80 per cent between 1970 and the early 2000s (Figure 2.12).6 Threats outside the Region may be affecting juvenile recruitment into the foraging population.6 Key nesting locations for the eastern Australian flatback turtle stock are Peak, Wild Duck and Avoid islands in the southern Great Barrier Reef. There has been no obvious trend in the size of the annual nesting population at these rookeries over three decades and the population is considered to be stable.209 However, there is no new published data since Outlook Report 2009 and there continues to be virtually no data on the foraging population.209 A very small number of leatherback turtles are known to have nested on mainland beaches adjacent to the Region but no nesting has been recorded since 1996. The Region’s population is considered to be part of the south-west Pacific genetic stock, which has declined.219 There is no nesting of olive ridley turtles in the Region and there is virtually no data on the foraging animals that visit the Region.220
Figure 2.12 Trends in loggerhead turtle nesting, Woongarra coast, 1967–2012
After a gradual decline in the loggerhead turtle nesting populations on the Woongarra coast, including Mon Repos Beach–a key nesting site for turtles that inhabit the Region–there is now evidence of recovery. Data for 1967 and 1968 are population estimates. Other data is derived from population census.
Source: Limpus et al. 2008 6 and Limpus (personal communication) 218
For those marine turtle species that migrate outside the Region, there is a poor understanding of their activities and the impacts on them in those other places.
2.4.12 Estuarine crocodiles
The estuarine crocodile population continues to recover steadily.
Estuarine crocodiles occur in most coastal waters of the Great Barrier Reef. They are also regularly reported at mid-shelf and some offshore islands. 221 Although crocodiles once were extensively commercially harvested, their numbers in northern Queensland are now recovering following full protection under Queensland legislation since 1974. 221 The most recent surveys conducted in 2009–10 in the southern two-thirds of the Region showed the population continues to steadily recover, with no southerly expansion of its range. 222 The species’ recovery is limited primarily by the availability of suitable nesting habitat. 223
Trends in seabird populations are highly variable between different species and locations.