A marine ecology researcher diving off Albany has had the thrill of a lifetime after spotting a tiny fish so rare it has been officially recorded only once since its discovery in 1996.
The vividly coloured Pictilabrus brauni, known as Braun's wrasse, is found nowhere else in the world and has one of the smallest geographic ranges of any temperate fish in Australia.
It has been spotted in only a handful of locations along WA's south-west coast since first being described near Albany in 1996, and was last recorded during a scientific survey in 2009.
Océane Attlan, a PhD candidate with the UWA Oceans Institute, said that despite years of targeted surveys in the region, the species – which grows to less than 7.5cm in length and is extremely shy – hadn't been seen since.
"The marine heatwaves that have struck south-west Australia in recent years had raised concerns that the species had gone extinct, making this confirmed sighting particularly important," Ms Attlan said.
The surprise sighting came last week as Ms Attlan was conducting scientific surveys in kelp forests off Albany with four other UWA researchers from the Wernberg Lab within the Oceans Institute.
The group was on the final dive of a four-day expedition to chart any changes in the region following the series of marine heatwaves.
"I was conducting a fish survey and wasn't specifically looking for the Braun's wrasse," Ms Attlan said.
"When it appeared it took me a few seconds to register what I was seeing, because the species is so rarely encountered. Within moments I realised it was something special.
"I got very excited but out of nine dives that happened to be the only one where I didn't have a camera on me, so I needed to find a buddy to quickly try to get some shots."
The lone fish hung around long enough for fellow researcher Dr Albert Pessarrodona to snap just two photographs, before quickly disappearing back into the kelp forest.
The researchers later posted the images to a site which helps identify fish species, with two curators from the Western Australian Museum, along with the Tasmanian-based researcher who last spotted the species near Albany in 2009, confirming it was the Braun's wrasse.
Ms Attlan said the scarcity of Braun's wrasse sightings may be partly explained by the species' exceptional camouflage, but also by the limited number of ecological surveys conducted along large sections of WA's coastline.
"With relatively few active marine ecologists covering extensive and remote reef systems, many species may remain overlooked," she said.
The kelp forests where the species was spotted are part of the Great Southern Reef (GSR) system which stretches 8,000km along Australia's southern coastline, from Kalbarri in WA to New South Wales.
Ms Attlan said the sighting highlighted the biological richness of the GSR – a vast, continuous rocky reef system dominated by kelp and other seaweeds – and the significant gaps that remain in our understanding of its ecosystems.
"Despite its extent and productivity, the GSR remains far less well known than Australia's tropical reefs," she said.
"It is home to one of the highest levels of endemic marine flora and fauna in the world, hosting seaweed and fish species found nowhere else – making it a global hotspot for biodiversity conservation and particularly vulnerable to climate change."
During the trip the UWA team also recorded a sea snail 500km further south than its current known limit, and another rarely observed fish.
"These new observations highlight the importance of field-based research and diving surveys, particularly at a time where administrative and other burdens increasingly constrain opportunities for in-water research," Ms Attlan said.
"Continued monitoring and research on the GSR, particularly as climate-driven changes place increasing pressure on temperate marine ecosystems, is vital.
"Documenting rare and endemic species is a crucial step toward understanding, protecting, and managing these unique underwater environments."
