May 24, 2023
Maugean skate (Zearaja maugeana).
Image credit: courtesy Jane Rucker/IMAS
Numbers of this ancient fish species plunged by almost half in seven years in its last remaining habitat.
The Maugean skate (Zearaja maugeana) is found only in Macquarie Harbour on Tasmania’s west coast and marine researchers say environmental changes in the waterway have left the declining fish vulnerable to extreme weather.
The fish’s numbers fell by almost half over a seven-year period, a drop environmental activists blame on reduced oxygen levels in the harbour brought about by climate change and the local salmon industry.
Environment Tasmania has called for the skate to be listed as critically endangered and says its demise would make a mockery of the federal government’s “no new extinctions” pledge.
The skate’s lineage goes back to the time of the dinosaurs and the bottom-dwelling fish has been dubbed the thylacine (or Tasmania tiger) of the sea.
The University of Tasmania’s Institute for Marine and Antarctic Studies (IMAS) monitored skates since 2021 and found its population fell 47 per cent between 2014 and 2021.
“We recently found that Macquarie Harbour was the last remaining habitat for Maugean skate and, like other endemic species, this limited range means their conservation is inextricably linked with the health of the system they live in,” IMAS researcher David Moreno says.
The fall in the skate’s numbers and its limited range and genetic diversity “is clear evidence that the population is at risk,” he adds.
David says activities such as recreational fishing in the harbour needed to be managed, along with those that affected the environment such as salmon aquaculture and river flow management for hydro production.
Fast Facts: Maugean skate
Scientific name
Zearaja maugeana
Description
The Maugean skate is a medium-sized species, with mature females reaching a maximum of 84cm in total length, and males reaching a maximum of 70cm. Male Maugean skate can be differentiated from females by the presence of claspers at the beginning of the tail.
Endangered status
The Maugean skate is listed as endangered under both Tasmania’s Threatened Species Protection Act 1995 and the Environment Protection and Biodiversity Conservation Act 1999.
The species is also included in the top 110 priority threatened species under the Australian Government’s Threatened Species Strategy Action Plan 2022–2032.
-Information courtesy: Department of Natural Resources and Environment Tasmania
-Image courtesy: Last, Peter R. & Gledhill, Daniel C (CSIRO)
IMAS professor Jayson Semmens says the harbour’s environmental changes had increased the skate’s vulnerability to “sudden high-impact events, such as water column turn-over driven by westerly winds, which can happen at any moment and potentially decimate the population”.
Environment Tasmania said it supported calls for the Maugean skate to be upgraded from endangered to critically endangered and called on federal Environment Minister Tanya Plibersek to intervene.
“Without drastic action, Tasmania will have the grim record of the second bony fish extinction in the world on its record, after the smooth handfish,” marine campaigner Rebecca Howarth says.
“Not only would the extinction of the Maugean skate be an absolute tragedy for Tasmania, but it would also be an embarrassment to federal Environment Minister Tanya Plibersek, who pledged zero extinctions on her watch.”
Federal environment minister promises action
Federal environment minister Tanya Plibersek has responded to the calls for drastic action.
Ms Plibersek says she will write to her state counterpart, Tasmanian environment minister Roger Jaensch, demanding “extreme intervention” to save the species from extinction.
Related: This is the face of one of the rarest animals in Australia