01/10/2012 10:45 BST | Updated 01/10/2012 10:46 BST

Global Warming Could Shrink Fish, Say University Of British Columbia Scientists

Global warming means increases in ocean temperatures – and this could lead to smaller fish, a new study says.

Researchers from the University of British Columbia (UBC), using computer modelling, predict that the maximum body weight of fish could decline by 14 to 20% by 2050, with creatures in the tropics being worst effected.

The crux of the problem is that as oceans warm the fish aren’t able to absorb enough oxygen to grow properly.

Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author, said: "It's a constant challenge for fish to get enough oxygen from water to grow, and the situation gets worse as fish get bigger.

“A warmer and less-oxygenated ocean, as predicted under climate change, would make it more difficult for bigger fish to get enough oxygen, which means they will stop growing sooner."

The study's lead author, William Cheung, an assistant professor at the UBC Fisheries Centre, said: "We were surprised to see such a large decrease in fish size.

“Marine fish are generally known to respond to climate change through changing distribution and seasonality. But the unexpectedly big effect that climate change could have on body size suggests that we may be missing a big piece of the puzzle of understanding climate change effects in the ocean."

The study authors warn that greenhouse gas emissions must be lowered and strategies developed to monitor changes in ocean ecosystems, or fisheries and food security could be disrupted.

The study was published in the journal Nature Climate Change.