Science

Culling sharks may make climate change worse: study

A danger sign at a beach.
(AAP)

Australian researchers say sharks culls impact climate change - as carbon stored in the sea-bed can be increasingly eaten by shark prey.

Culling sharks may make climate change worse.

That is the not-so-bizarre conclusion from Australian researchers who say a flow-on effect of culls and over-fishing unlocks carbon stores beneath the sea.

Smaller numbers of large marine predators allow prey, such as sea turtles, to flourish and consume more seagrass.

Seagrass is known to hold vast amounts of carbon in its sediment.

Deakin University scientist Dr Peter Macreadie said urgent research was needed to investigate the consequence of shark culls.

He said overgrazing by sea-turtles was evident in Western Australia's Shark Bay where areas greatly impacted by shark hunts had half the amount of carbon storage as those abundant with sharks.

"At the extreme level, we see turtles without predation pressure eating themselves out of house and home and destabilising carbon stocks that have been locked away for millennia," Dr Macreadie said.

"Stronger conservation efforts and stricter fishing regulations are needed to reinstate the important role that predators play in the ocean's carbon cycle."

Researchers hope further study of the topic will more closely link the loss of blue carbon stores to fewer top-level predators.