Ancient toothy fish caught in 'remarkable' discovery on tropical Aussie island

Discovering something new is the dream of all researchers – even when it looks as strange as this.

Australian brook lampreys in close up, showing its 'terrifying' toothy mouth.
Australian brook lampreys are "terrifying" when they are viewed up close. Source: David Moffatt

A “terrifying” species of ancient fish has been discovered during a recent fishing expedition in Queensland. The men originally thought the creature was an eel, but when they took a closer look they spotted rows of sharp teeth inside its jawless mouth, sparking intense curiosity.

“At first I went to put it in the bucket and then I thought: Hang on a second, that's something different. We pulled it out and had a better look at it, and I said, 'Oh my God, it's a lamprey',” Dr Luke Carpenter-Bundhoo told Yahoo News Australia, reflecting on his incredible find.

“It’s so rare now to find something new. Whether it be a new species, or discovering something in a new area is remarkable.”

What Carpenter-Bundhoo had discovered was a 15 cm long Australian brook lamprey in a harsh, tropical environment where it had been thought they couldn't survive. While it's menacing teeth may look scary, it doesn’t actually use its mouth to attack or suck blood.

The first three years of the lamprey's rather "unglamorous" life are spent at the bottom of muddy streams where it eats by filtering out nutrients from the water. For the remaining year of its adult life it doesn't bother to feed anymore and eventually dies.

From the side an Australian brook lamprey in close up in a tank.
From the side, the lampreys resemble an eel. Source: David Moffatt

While these attributes may seem bizarre, lampreys as a group have evolved to a near perfect physical design which allows them to thrive within their environmental niche. They are at least 395 million years old, and have remained unchanged for 125 million years, while DNA suggests modern humans have only walked the earth for 300,000 years.

The Australian brook lamprey was first described in 1968, and its south coast NSW habitat had been widely impacted by the building of waterfront homes. After state authorities returned to the discovery site and didn’t find it, researchers had quietly discussed its possible extinction.

What continued to stoke hope that the species had survived is that it's known to be very difficult to find. Because they can't be hooked on a line, Carpenter-Bundhoo and his Griffith University team used electro-fishing to paralyse the fish, a non-invasive technique that doesn't harm them.

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What made Carpenter-Bundhoo’s rediscovery so remarkable is that he found the fish in a creek on a balmy island north of Brisbane, 1400 km north of the creature's known range. Until now it had been assumed all 47 known species of lampreys could only live in colder anti-tropical environments – and Australia’s three varieties hadn’t been seen further north than Sydney.

Scientists wading in streams at K'gari.
The Australian brook lamprey was rediscovered on K'gari. Source: Luke Carpenter-Bundhoo

Carpenter-Bundhoo describes the strange fish as "charismatically, non charismatic". "I'm not going to say they're ugly, but they are terrifying close up. They certainly don't have the appeal of a polar bear or a koala, but there's something that's so weird and foreign to us that it's interesting."

While the rediscovery of the lamprey is good news, it remains under threat of extinction and has been listed as endangered. Bushfire, development, erosion of river banks, and climate change are all believed to be threats to its survival. "But we can't say with absolute confidence what their exact threats are, because they're so hard to find and study," Carpenter-Bundhoo said.

The last sighting of one was earlier this year, when Carpenter-Bundhoo returned to the K’gari stream with his colleague David Moffatt from the Department of Environment (DESI).

The original rediscovery occurred in 2022 while the scientists were researching the impact of the Black Summer bushfires on freshwater rivers using funding from the National Environmental Science Program’s Resilient Landscapes Hub. The find was announced this week after Carpenter-Bundhoo and Moffatt co-authored a paper about it in the journal Endangered Species Research.

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