by Ian Cresswell, Andrew John Constable, Keith Reid and Nic Bax, The Conversation
Macquarie Island, about 1,500 kilometers southeast of Tasmania, is more than a remote rocky outback. In fact, it is the only piece of land on the planet formed entirely from the ocean floor, which rises above the waves to form peaks teeming with penguins and other bird species, some of which are found nowhere else on Earth.
These are just some of the reasons why this unique island, and the seas that surround it, have globally important conservation values. The new independent assessment of these values forms the scientific basis behind Federal Environment Minister Tanya Plibersek’s announcement last month of plans to significantly increase protection of the waters surrounding Macquarie Island.
By thoroughly assessing the available data on the marine ecosystems and the many species that live on and around Macquarie Island, our report reveals a sub-Antarctic environment that is vital for breeding and feeding millions of seabirds and thousands of marine mammals.
Macquarie Island and the surrounding seas (within 5.5 km) are already protected as a Tasmanian reserve and the area (this time including seas within 22 km) is also a World Heritage Site. A Commonwealth Marine Park also covers most of the southeastern quadrant of the island’s “economic exclusion zone,” including a sanctuary zone and two seabed management zones.
The federal government’s proposed marine park expansion would cover the entire island’s economic exclusion zone, increasing the area of Australia’s marine reserves by more than 388,000 square kilometres, an increase larger than the area of Germany.
An excellent sight
Macquarie Island is the exposed top of the 1,600km long Macquarie Undersea Ridge, which makes Macquarie Island the only piece of land in the world composed entirely of oceanic crust.
Macquarie Ridge is one of only three such ridges that block the eastward flow of a current called the Antarctic Circumpolar Circulation, resulting in distinct differences between the western and eastern sides of the ridge, which are used in different ways by different species.
The oceanography is further divided from north to south by two major ocean fronts, the Sub-Antarctic Front and the Polar Front, creating three distinct bodies of water. They are closer here than anywhere else in the Southern Ocean, and as they interact with the Macquarie Ridge they create at least six different large-scale oceanographic habitats.
This creates an outstanding spectacle of wild, natural beauty and a diverse set of habitats that support huge assemblages of wildlife, including penguins and seals. Fifty-seven species of seabirds, including four species of penguin and four species of albatross, have been recorded on Macquarie Island, and 25 of these species have been observed breeding there. Macquarie Island’s king penguin and emperor marsupial live nowhere else on Earth.
The ridge includes a series of seamounts that act as “stepping stones” connecting subantarctic and polar seafloor animals such as brittle stars.
Needs more protection
Our report shows that the area around Macquarie Island is not well represented by the current marine park. In particular, the entire area to the west, and most of the northern and southern sections of Macquarie Ridge, are not protected by the current marine park, but will be included in the proposed extension.
Our report also examines various options for protecting the region’s unique ecosystems and concludes that the most sensible approach, given the available data, would be to declare the entire area around Macquarie Ridge a marine park, increasing protection beyond of the current refuge zone. while allowing the current fishery to continue in a habitat protection zone.
This provides the simplest, fastest stock planning that is relatively easy to implement, achieves environmental protection and sustainable fisheries, recognizes the importance of the entire Macquarie Island region and provides the greatest resilience to climate change.
Direct human impacts on the region are mainly due to fishing and marine debris, although climate change is also an ever-present threat. The fishery targets deep-water Patagonian toothfish using bottom longlines, mainly in the central zone of the Macquarie Ridge. This fishery is generally well regarded for its best practice fishing methods and commitment to positive environmental outcomes, and this fishery will continue under the new plans.
But if new fisheries targeting midwater species were allowed to develop, or new industries such as seabed mining were allowed, they could directly affect seabirds, marine mammals and other species that live in these areas.
The proposal tabled by Minister Plibersek protects all Commonwealth waters in two different zones of a marine park, effectively tripling the size of the current marine park. It protects the marine area and allows current fisheries to continue without significant changes to current practices or catches.
Limits on any possible future fishing would be determined by the allocation of “refuge zones” that would exclude fishing and “habitat/species zones” that could accommodate sustainable fishing. Mining will be excluded in any protection category.
The government’s proposal signals a clear priority for protection over development in this area. A public consultation period on the proposal will begin in March. Any future development of the marine park should be orderly and careful, including prior consideration of environmental impacts. Any changes to current fisheries management arrangements should ensure that the changes maintain or improve conditions for a long-term sustainable fishery.
More broadly, our report also demonstrates the potential and importance of gathering the most up-to-date data available for any area prior to any formal review process to update Australia’s marine park network.
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Reference: Penguin Paradise and geological freak: Why Macquarie Island deserves a greater marine park (2023, 10 March) retrieved 10 March 2023 from https://phys.org/news/2023-03-penguin-paradise-geological-freak – macquarie. html
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