Thousands of tangled plastic fishing nets lost or abandoned in the Gulf of Carpentaria are threatening up to 15,000 endangered marine turtles, activists say.

A 2017 survey found nearly 9,000 samples of so-called Ghost Gear – nets, tackle and other detritus left behind or discarded by fishermen – catching Olive Ridley, Hawksbill, Green and Flatback turtles in the gulf over a one year period.

The research by CSIRO and Ghost Nets Australia has prompted a follow-up aerial count by the government science agency in partnership with James Cook University and the World Animal Protection group.

Thousands of tangled plastic fishing nets lost or abandoned in the Gulf of Carpentaria are threatening up to 15,000 endangered marine turtles, activists say. (Supplied - World Animal Protection)

Floating fishing gear is rapidly becoming the top debris threat to Australia's endangered marine animals, Ben Pearson from World Animal Protection told 9News in a statement.

"Fishing gear is designed to catch and kill, and when it is lost or abandoned in the ocean it continues to do this, becoming the most harmful form of marine debris for sea animals," Mr Pearson said.

"It's heart-breaking to know that animals caught in this incredibly durable gear can suffer from debilitating wounds, suffocate or starve to death over a number of months."

A 2017 survey found nearly 9,000 samples of so-called Ghost Gear – nets, tackle and other detritus left behind or discarded by fishermen – catching Olive Ridley, Hawksbill, Green and Flatback turtles in the gulf over a one year period. (Supplied - World Animal Protection)

Many of the nets harming the turtles are believed to have floated on sea currents from countries to Australia's north and become trapped in the gulf.

The aerial survey of the region plans to provide updated data on the extent of the damages to the Gulf of Carpentaria from ghost nets and the threat they present to marine life.

Dr Norman Duke from James Cook University told 9News that action was needed to reduce floating debris in Australian waters.

Floating fishing gear is rapidly becoming the top debris threat to Australia's endangered marine animals, the researchers say. (Supplied - World Animal Protection)

"I am acutely aware of how human impacts, such as plastic fishing gear pollution, are adding to the impacts and threats on marine and coastal habitats, and the species that depend on them," he said in a statement.

"It is critical we move towards developing long-term solutions that reduce marine debris to preserve ecosystems and protect endangered species."

The federal government has threat abatement plans to address ghost gear and allocated $16 million to the Pacific Ocean Litter Project to help reduce single use plastic cluttering the ocean.

Many of the nets harming the turtles are believed to have floated on sea currents from countries to Australia's north and become trapped in the gulf. (Supplied - World Animal Protection)

The aerial survey of the region plans to provide updated data on the extent of the damages to the Gulf of Carpentaria from ghost nets and the threat they present to marine life. (Supplied - World Animal Protection)

A separate study published earlier this year found that more than 414 million pieces of plastic were found washed ashore on remote Cocos Islands, an Australian territory 2750km west of Perth.

Much of the rubbish was single-use consumer items such as bottle caps, straws, shoes and sandals, and estimated to weigh more than 17 tonnes.