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Sawfish tracked as part of project to better understand the vulnerable ‘rhinos’ of Australian wildlife

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The fantastically efficient inbuilt weapon sawfish use to attack prey is also their undoing, according to researcher Associate Professor David Morgan who has studied the fish for several decades.

“The saw-like rostrum on their heads is a morphological marvel,” Dr Morgan said.

“The rostrum is used to hunt, to strike food and for their own defence, but it also makes sawfish extremely vulnerable to being entangled in net.”

Sawfish are critically endangered around the world and the rostrums used to be cut off and collected as grim trophies. They became protected in Australia in 2006.

“They are the rhinoceros of Australia,” he said.

David Morgan is an associate professor at the Harry Butler Institute at Murdoch University’s Centre for Aquatic Ecosystems.

He is lead sawfish investigator on the Mardie Salt Marine Research Program, an offset project focused on the Pilbara Coast which is led by the Western Australian Marine Science Institution (WAMSI).

While coastal development and net fishing have taken their toll on the world’s five sawfish species Dr Morgan said the remoteness of Western Australia’s Pilbara coast had helped the area’s dominant species, green sawfish.

” Over 40 countries have lost at least one species of sawfish so this area is a lifeboat for three to four species globally.”

Dr Morgan said the research project had involved genetic studies from tissue sampling to establish family trees as well as tagging linked to acoustic monitors which helped establish the population and range of green sawfish.

“One thing we have found as part of this work is that the mouth of the Ashburton River is an important pupping site for sawfish, in other words where the females come to give birth.”

The study has shown that green sawfish have at least five pups in a litter.

“Our research has shown between 50 and 60 females used the Ashburton area to pup and once the young reach about three metres they move further offshore,” Dr Morgan said.

“We know they will keep returning to this site and our studies have shown the female pups once they have matured, will also return to the area.”

Acoustic and drone studies have been used to discover the distances travelled by sawfish.

“We put acoustic tags on sawfish much like the ones that are used to track white sharks and then set up receivers on moorings,” Dr Morgan said.

“We have noticed some sawfish moving relatively long distances and travelling in pairs.”

He said a new part of the study in 2025 involved looking at the movement of sawfish between Onslow and just south of Karratha.

“There is a big area where we want to find out more about how sawfish use the mangrove systems.”

Study examines 30 years of seagrass restoration to find best methods

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A major review of seagrass programs in Cockburn Sound has helped identify the best methods for restoring large scale seabed meadows and found community involvement was a key to success.

Seagrass meadows were decimated from the 1950s and restoration attempts in the past three decades have included everything from sprig and seed-based methods to mechanical plantings, seagrass in sandbags being placed on the seabed and wire coils being used to fix small plants into the sediment.

The project, which is part of the WAMSI Westport Marine Science Program, looked at more than 110 restoration efforts since the 1990s and re-visited 31 sites to assess their success.

The study was led by Professor Gary Kendrick from The University of Western Australia and Professor Jennifer Verduin from Murdoch University.

Professor Verduin said sprig-based programs, where mature seagrass shoots were collected by divers from natural meadows, were found to have achieved high transplant success rates.

“Survival was as high as 90 percent on larger scale sprig-based restoration trials of up to three hectares,” Professor Verduin said.

“We found over a period of 15 to 20 years, the growth of sprigs resulted in the formation of new meadows.”

The study found both sprig-based restoration and seeding programs, such as Seeds for Snapper, had developed viable methods for revegetating large areas of bare seafloor. But large-scale sprig-based restoration programs, while labour intensive, were particularly efficient in quickly stabilising the sediment and creating almost instant meadows. This accelerated the formation of natural meadows.

“Cockburn Sound and Owen Anchorage suffered a major loss of seagrass from the 1950s to the 1990s and while there have been dozens of programs since to rehabilitate the area, there has been limited follow-up to gauge their success,” Professor Verduin said.

“Restoration programs are important and contribute to the rapid natural recovery of seagrass habitats by ameliorating loss and supporting the recovery of grasses.”

“Some of the projects in the past have been on areas of no more than three hectares and we wanted to see if we could recommend a restoration package that could be scaled up to ten times that area to enhance restoration success.”

One of the main findings of the review was confirmation that engaging with local communities was key to the success of large-scale seagrass restoration programs.

Community-based citizen science and restoration projects working with volunteers were recommended as cost-effective approaches to increase the scale of restoration.

“These transplanting projects have already been successful at Southern Flats, Cockburn Sound, and Oyster Harbour, Albany,” Professor Verduin said.

Seagrasses, sometimes referred to as the ‘oceans’ lungs’ are a vital part of the ecosystem. They reduce coastal erosion by stabilising sediment, provide critical habitat for marine animals and efficiently store carbon.