Northern Australia is a ‘lifeboat’ for critically endangered green sawfish

Northern Australian waters are a “lifeboat” for the critically endangered green sawfish, new Murdoch University research has highlighted.

Green sawfish, distinguished by their long shark-like body and tooth-lined “saw” on the front of their heads, are on the verge of extinction, largely due to overfishing and habitat loss.

However, a study from Murdoch University’s Centre for Sustainable Aquatic Ecosystems, at the Harry Butler Institute, has revealed that Northern Australia, particularly WA, could play a crucial role in the species' recovery.

Led by Postdoctoral Research Associate Jack Ingelbrecht and Associate Professor David Morgan, a team from Murdoch University, supported by the Western Australian Marine Science Institution, the Save Our Seas Foundation, and BCI Minerals, has reviewed decades of research on the green sawfish, to provide a crucial resource to guide future conservation.

“Renowned zoologist Ferdinando Boero said it best - 'you can't protect what you don't know,'” Dr Ingelbrecht said.

“It's incredibly difficult to stay up to date with research on any topic, particularly when there's a lot of information to cover. Ultimately, if conservation experts don't fully understand the species they're trying to protect, they can't implement the most-suitable recovery initiatives.”

“By synthesising the current knowledge of green sawfish, we wanted to provide an all-in-one resource to guide conservation efforts and researchers, alike,” he said.

The review highlighted that northern Australia is one of the last remaining strongholds for the green sawfish.

“Although the species has disappeared from large parts of its historic range, including parts of Africa and southern Asia, northern Australia still supports some of the last intact populations left anywhere on Earth,” Dr Ingelbrecht said.

Dr Ingelbrecht emphasised that this has likely had a positive impact on green sawfish research in Australia.

“To research something, you first need specimens to study. Naturally, opportunities for green sawfish research will be greater in areas where this species still occurs in relatively high numbers.”

“Our review found that, for decades, Australia has been the global leader in green sawfish research. This is partly because green sawfish populations have been wiped out in many countries, but still exist in Australia,” he said.

“We're fortunate that the main factors responsible for the global decline of sawfish are less severe in northern Australia.”

“Interestingly, when we looked at the specific types of information that have been produced, we found that Australia has also been at the forefront of almost every major sub-discipline of research relating to green sawfish.”

The review also identified several key knowledge gaps, which will continue to hinder recovery efforts until they are addressed.

“Sadly, when it comes to the research areas most relevant to conservation – the size of remaining populations, the locations of critical habitat, and the number of mature individuals present in the wild – we realised that there's very little information currently available.”

Dr Ingelbrecht also said that, due to its position as the global leader in green sawfish research, Australia has an increased responsibility to support recovery initiatives through scientific input.

“Research is the lifeblood of conservation. In order to be successful, recovery efforts often need to be tailored towards the species they're intended for. To do that, you need scientific input,” he said.

“Conservation biologists bear the responsibility of enhancing recovery initiatives through research. If green sawfish populations continue to decline, that responsibility – that burden – will fall more and more towards Australia.”

Despite these issues, Dr Ingelbrecht said there was still cause to be optimistic about saving the green sawfish from extinction.

“It's not over yet. There's still a genuine opportunity to turn things around. With the right support, the right research, and the right conservation measures, we can ensure the survival of green sawfish. I hope Australia sets an example the rest of the world can follow,” he said.

Associate Professor David Morgan, who has led sawfish research in Australia for over 25 years, highlighted the importance of Western Australia's Pilbara region.

"The Pilbara region in particular has become one of the world's most important areas for green sawfish research, as it still supports relatively healthy populations of this species and provides critical habitat," Associate Professor Morgan said.

"It gives us a rare opportunity to understand how green sawfish use their environment, and identify which conservation measures would best facilitate their recovery."

The paper, The Critically Endangered green sawfish (Pristis zijsron): current knowledge and future directions, was published in the journal Reviews in Fish Biology and Fisheries.