Maugean skate: IMAS researchers find drastic decline in population of Macquarie Harbour species

An endangered species dating back to prehistoric times is at the brink of extinction, with Tasmanian researchers saying “immediate action” is needed to save it.

Maugean Skate in Macquarie Harbour TAS (Credit Jane Ruckert). Picture: Jane Ruckert

An endangered species dating back to prehistoric times is at the brink of extinction, with Tasmanian researchers concluding that “immediate action” is needed to save the Maugean skate.

The last remaining vestige of the species is at Macquarie Harbour on the state’s West Coast and Dr David Moreno and Professor Jayson Semmens, of the Institute for Marine and Antarctic Studies (IMAS), have found that environmental conditions in the area have been degraded, putting the survival of the skate in jeopardy.

IMAS is undertaking a three-year gillnet survey monitoring program to gather data on the status of the last known population of the Maugean skate.

In an interim report covering the first year of sampling (2021), Dr Moreno and Prof Semmens said size composition data collected between 2012 and 2021 showed the median size of females had increased, while the number of juveniles captured had “significantly decreased”.

Maugean Skate in Macquarie Harbour TAS (Credit Jane Ruckert). Picture: Jane Ruckert

“Using catch per unit effort (CPUE) as a measure of relative abundance, we demonstrated a substantial decline in CPUE between 2014 and 2021 of 47 per cent,” they said.

“The scale of the overall decline and the scarcity of new recruits creates significant concern for the conservation of the species and implies the need for immediate action.

“Furthermore, our results highlight the vulnerability of the species to degraded environmental conditions and the need for further monitoring of the population.”

Dr Moreno said evidence in the monitoring report underlined the need to continue the program beyond 2023.

“The reality is that we risk losing an important species which only exists in this harbour,” he said. “So human activities related to the skate need to be managed, such as recreational fishing, and those that affect the marine environment such as salmonid aquaculture and river flow management for hydro production.”

The Australian Marine Conservation Society (AMCS) said urgent recovery measures for the skate were needed, including restoring the health of the harbour, development of a captive breeding program and ongoing monitoring of the population.

Maugean Skate (Zearaja maugeana). Picture: Supplied

The Maugean skate is part of the cartilaginous group of fishes, which also includes sharks and rays. Its estimated area of occupancy is 100 sq/km.

AMCS shark scientist Dr Leonardo Guida said action had to be taken to arrest the decline of the species.

“The Maugean skate has been around since Tyrannosaurus rex roamed the Earth but is now literally being choked to death in its home that man has turned into a putrid bathtub. If the Australian government does not act now, it may disappear on our watch,” he said.

“Tasmania is home to Australia’s most infamous extinction, that of the thylacine or Tasmanian tiger. Does the state really want the ignominy of hosting the world’s first extinction of a shark or ray in modern times due to human activity?”