Climate change could cause fish to shrink by 30 percent, claims study

Rising ocean temperatures due to climate change could shrink the size of fish by 20 to 30 percent, a new study emerging from University of British Columbia (UBC), Canada, has claimed.

The new research published in journal, Global Change Biology provides a deeper explanation of why the fishes are likely to shrink. According to the lead author Daniel Pauly the findings apply to animals with gills, such as fish, sharks, squid, and lobsters.

William Cheung, co-author and associate professor at the Institute for the Ocean and Fisheries, said, "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".

"There is a point where the gills cannot supply enough oxygen for a larger body, so the fish just stops growing larger", Cheung explained further.

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The study explains that as the body of a fish grows in size, it demands more oxygen because the body mass becomes larger. However, the surface area of the gills from where the oxygen is obtained does not grow at the same pace as the rest of the body.

Daniel Pauly describes this set of principles as "gill-oxygen limitation theory."

Some species may be more affected by this combination of factors. For example Tuna, which are fast moving and require more energy and oxygen, may shrink even more when temperatures increase, researchers said.