Climate change, overfishing taking toll on world’s fish supply, warn Australian researchers

Ocean warming and common practices by the world’s fishing industries are likely to have a disastrous impact on the world’s stock of wild fish unless changes are quickly made, according to Australian researchers.

Scientists from the University of Melbourne in the state of Victoria, and the University of Tasmania, believed their report is the first of its kind to consider the dual threat posed by climate change and overfishing, in particular the pursuit of big fish.

“Wild fisheries provide food for billions of people worldwide, particularly in the Pacific region where fish is the major source of animal-based protein,” said researcher John Morrongiello.

“Past fishing practices have caused spectacular fishery crashes, so it is important that we adopt management approaches that will ensure our oceans continue to maintain sustainable fisheries.”

The research involved setting up a series of fish populations in a laboratory where the fish lived in water of varying temperatures.

Researchers then followed the fate of each population for three years, which represented about seven fish generations.

“Most experimental research on climate change impacts is done on relatively short timescales, where fish are studied for two or three generations,” said another researcher Asta Audzijonyte.

“We found that strong negative impacts of warming only became apparent after four generations. This suggests people might be underestimating the possible impacts of climate change on fisheries stocks.”

One of their main findings was that the fishing industry needed to stop targeting big fish.

“Our findings clearly show that protecting fish size diversity and large fish can increase their (fish population) resilience to climate change,” Audzijonyte said.

“While reversing climate change is hard, restoring and protecting fish size diversity is one thing we certainly can do, and we need to do it fast.”

The research was published this week in the scientific journal PNAS.