Two century-old sawfish rostra—long considered mere curiosities on pub walls—are being repurposed as vital scientific data points at Southern Cross University, rewriting our understanding of marine biodiversity in the face of extinction.

This research matters because sawfish are the most endangered marine fish globally, with numbers plummeting due to habitat loss and overfishing. By decoding the genetic and historical distribution of these two individuals, researchers are mapping the "lifeboat" habitats needed to prevent their total disappearance, a strategy that carries life-or-death implications for sawfish populations from the Australian coast to the shrinking mangrove estuaries of the Western Indian Ocean, including the Kenyan coastline.

The Curiosities Turned Evidence

In a laboratory at Southern Cross University in Coffs Harbour, two extraordinary objects sit on a table. They are long, flat, and lined with tooth-like structures along either side: rostra, or "saws." Once attached to living animals that navigated the rivers and coastal waters of New South Wales, these artifacts were typically preserved as grim trophies—curiosities kept to regale visitors over a drink. Today, they are being transformed into invaluable scientific records.

Adrienne Gooden, a PhD candidate at the university and intern with Sharks And Rays Australia, is leading this forensic reconstruction. Her team is using these rostra to estimate the body size of the long-dead animals, confirming they had reached sexual maturity before they perished. By extracting DNA from these samples, scientists can now assess historical population structures and compare them to contemporary populations across northern Australia, determining whether the lost east-coast individuals belonged to unique genetic networks or were part of a larger, interconnected species range.

The Silent Collapse of a Living Fossil

Sawfish have been evolving for millions of years, predating the dinosaurs and surviving mass extinctions. Yet, they have proven woefully unequipped for the rapid onset of industrial fishing. Green sawfish (Pristis zijsron) were once abundant from northern Australia down to Sydney, but are now classified as extinct in New South Wales, with the last confirmed sighting occurring in 1972 in the Clarence River. This localized extinction is a pattern repeated worldwide.

The biological traits that made them masters of their environment are the same that have facilitated their demise. Their long, tooth-lined rostra are incredibly effective for capturing prey, but they are also magnets for entanglement in gillnets and trawl nets. Because sawfish are slow-growing and have low reproduction rates, the loss of even a few breeding adults can destabilize entire sub-populations, leading to a downward spiral that is difficult to reverse.

• Species at Risk: All five species of sawfish globally are classified as critically endangered by the IUCN.
• Australian Snapshot: Four of the five species are found in Australian waters, which now act as a global "lifeboat" for their survival.
• Historical Misconception: Recent analyses suggest the species once inhabited a range 800 kilometers (approx. 500 miles) wider than previously recorded, highlighting how much of their history was lost before it could be documented.
• Human Impact: Entanglement in fishing gear remains the primary driver of decline, despite illegal status in many jurisdictions.

A Warning for the Indian Ocean

For readers in Kenya and across the Western Indian Ocean, the Australian narrative is a cautionary tale. Historically, sawfish were present in the estuaries and coastal waters from the Tana Delta to the Mozambique Channel. However, documentation of these sightings has dwindled to nearly zero. In the Kenyan context, the decline of sawfish tracks with broader trends of coastal degradation, loss of mangrove nursery habitats, and unmonitored small-scale artisanal fishing gear that incidentally captures these slow-breeding predators.

Marine biologists studying the Indian Ocean note that the "functional extinction" of sawfish in many African regions is not just a loss of a charismatic species, but a disruption of the marine ecosystem. Sawfish, as top-tier benthic predators, play a role in regulating the health of estuarine environments. If Africa does not act to secure its remaining pockets of biodiversity, the continent may soon face the same reality that now forces researchers in Australia to scavenge for DNA from dried-up trophies on pub walls: the realization that the species has vanished before science ever fully understood it.

The Regulatory Tightrope

Conservation efforts in Australia have moved toward stricter enforcement, including the permanent retirement of gillnet licenses in certain sensitive areas and the creation of gillnet-free zones spanning over 11,000 square kilometers. These policies serve as a model for what is required elsewhere. Yet, legislation is only as effective as the enforcement backing it. In many developing marine economies, where artisanal fishing provides the primary source of protein and income, total bans on specific gear types are difficult to implement without compensatory support or sustainable alternatives.

The challenge for conservationists globally is to transition from reactive protection to proactive stewardship. This involves mapping high-use nursery areas—where juvenile sawfish spend their early years—and protecting them from development. Scientists emphasize that the "Australian lifeboat" is fragile. Should these final northern Australian strongholds fail, or should the warming climate push these populations outside of protected zones, the extinction of the sawfish may become an irreversible global tragedy.

As researchers continue to decode the genetic history of the two New South Wales rostra, the lesson is clear: we cannot wait for a species to vanish to recognize its value. The story of the sawfish is a reminder that the ocean is not an infinite resource, but a complex, fragile web that requires constant, deliberate protection. If we continue to ignore the warning signs, we will be left only with skeletons on our walls to remind us of the giants that once swam our seas.