ALSO READTemperature rise: US already feeling effects of climate change, says report Time for geoengineering governance? Farmer suicides: Climate change claimed 59,000 lives in 30 yrs, says study European leaders make sales pitch to Trump on climate accord Climate change: Trump hints at u-turn; opens door to rejoining Paris accord
Fish are expected to shrink in size by 20 to 30 per cent if ocean temperatures continue to climb due to climate change, a study has warned.
"Fish, as cold-blooded animals, cannot regulate their own body temperatures. When their waters get warmer, their metabolism accelerates and they need more oxygen to sustain their body functions," said William Cheung, associate professor at the Institute for the Ocean and Fisheries.
"There is a point where the gills cannot supply enough oxygen for a larger body, so the fish just stops growing larger," said Cheung.
For example, as a fish like cod increases its weight by 100 per cent, its gills only grow by 80 per cent or less.
When understood in the context of climate change, this biological rule reinforces the prediction that fish will shrink and will be even smaller than thought in previous studies, researchers said.
Warmer waters increase fish's need for oxygen but climate change will result in less oxygen in the oceans. This means that gills have less oxygen to supply to a body that already grows faster than them.
Some species may be more affected by this combination of factors. Tuna, which are fast moving and require more energy and oxygen, may shrink even more when temperatures increase, researchers said.