1 Oct 2012

Warming oceans 'may cause fish to shrink'

11:50 am on 1 October 2012

Scientists are predicting that fish species around the world could shrink in size because of global warming, losing as much as a quarter of their bodyweight.

Writing in the journal Nature, the researchers said rising temperatures could have a serious effect on hundreds of species over the next few decades.

Researchers modelled the impact of rising temperatures on more than 600 species between 2001 and 2050, the BBC reports.

The model used data from one of the higher emissions scenarios developed by the Intergovernmental Panel on Climate Change (IPCC) to study how fish would react to lower levels of oxygen in the water.

Although this data projects relatively small changes in temperatures at the bottom of the oceans, the resulting impacts on fish body size are "unexpectedly large" according to the paper.

Lead author Dr William Cheung, from the University of British Columbia, says the level of oxygen in the water is key.

"Rising temperatures directly increase the metabolic rate of the fish's body function," he told the BBC. "This leads to an increase in oxygen demand for normal body activities. So the fish will run out of oxygen for growth at a smaller body size."

Previous research has suggested that changing ocean temperatures would affect both the distribution and the reproductive abilities of many species of fish.