Zoning, a system of spatial planning and management, is one of the key management tools for the Great Barrier Reef. The amalgamated Great Barrier Reef Marine Park Zoning Plan177 and the complementary Marine Parks (Great Barrier Reef Coast) Zoning Plan178 were implemented in 2004. They provide for a range of ecologically sustainable uses, principally by defining the activities that are allowed, those that are prohibited, and those requiring a permit in each of seven zones. Their design and implementation set a global standard for marine reserve networks179,180 and they are recognised as having a wide range of benefits for biodiversity, with flow-on benefits for uses of the Region21. There is strong evidence that fish populations benefit from the protection provided by the Marine National Park (green) zone which is closed to fishing. There are consistently more and larger coral trout and other target fish in zones protected from fishing.21,169,172,181 Increased reproduction in the no-take zone as a result of more and bigger fish appears to also benefit fish populations in the entire ecosystem.182 Importantly, the zones operate as a connected network; most reefs (both open and closed to fishing) are within the range of dispersal from a reef closed to fishing.21,183,184 The zoning arrangements appear to benefit overall ecosystem health and resilience. Areas closed to fishing have served as refuges for fish after acute disturbances such as coral bleaching and flood events.165 Even highly vulnerable species, such as dugong and marine turtles, may benefit from the zoning arrangements, despite the area of each zone being much smaller than the ranges of these species.21,185,186 The effectiveness of zoning depends critically on effective compliance — even a relatively small amount of illegal fishing can have ecologically serious impacts. There is evidence that some areas in zones closed to fishing may be significantly depleted due to illegal fishing21 implying that the ecological benefits of the zoning could be greater still with better compliance. Given the major threat posed by climate change, the zoning network provides a critical and cost-effective contribution to enhancing the resilience of the Great Barrier Reef.
A network of zones is benefiting biodiversity
2.4.9 Sharks and rays
There are 136 shark and ray species known to inhabit the Region.9,187 Five are listed migratory species and seven are listed threatened species. Of the listed species:
One species of shark is likely to be near extinction or extinct in the Region.
• There have been significant range contractions and population declines recorded for the largetooth (previously called the freshwater), green and dwarf sawfish. • The speartooth shark has now become extinct on the east coast of Australia.188 • The whale shark, shortfin mako, longfin mako and porbeagle shark are pelagic species for which there is no information on status and trends. • The white shark and grey nurse shark are temperate species which are rarely sighted in the Region. A 2011 satellite tagging study revealed grey nurse sharks occupying deep-water habitats within the Region.189 While understanding of the life history traits of some of the Region’s shark and ray species has improved since 2009190, there is still limited information about the population status of many. There are concerns about the condition and vulnerability of a number of shark and ray species: • Seventeen currently caught shark species have been assessed as particularly vulnerable to exploitation191, principally due to slow growth rates, slow maturity and low reproductive rates. • There is concern for some species or groups of species including the grey and whitetip reef sharks,192,193 hammerhead sharks194, as well as some sharks and rays that interact with fisheries.9,195,196
The condition of most shark and ray species is unknown; many are considered at risk.