OVERFISHING is putting sea cucumbers in a pickle on the Great Barrier Reef, marine biologists say.
Sydney University's Professor Maria Byrne and Dr Hampus Eriksson, a post-doctoral researcher at Stockholm University, say more than 24 sea cucumber fisheries have closed in recent years.
Over 70 per cent of tropical sea cucumber fisheries are now considered depleted, fully exploited or over-exploited.
After analysing catches in the Great Barrier Reef over the last 20 years, the researchers say sea cucumber fishing is now showing worrying signs of being unsustainable.
"Sea cucumbers play a vital role in reef health and our previous research indicates that they may help reduce the harmful impact of ocean acidification on coral growth," Prof Byrne said in a statement.
"The crown-of-thorns starfish is often singled out as responsible for the decline in the barrier reef.
"This work suggests that overfishing of ecologically important species such as sea cucumbers, may have also contributed to this decline."
Dr Eriksson said that with declining catches of high value sea cucumber species, Australian fishers had turned to other, lower value species, which were also being overfished.
"Pursuing profits by targeting abundant species which sell for less while continuing to fish scarce high-value species is a pathway to their extinction," Dr Eriksson said.
Prof Byrne said further studies were needed to understand the impact of declining sea cucumber numbers on the reef.
"We recommend introducing precautionary reductions in sea cucumber fishing," she said.