Climate Change Will Lead To Smaller Fish, Study Says

Climate change’s effects on the ocean and various climate systems could very likely lead to smaller ocean fish, according to new research by fisheries scientists at the University of British Columbia.

Their research, just published September 30th in the journal Nature Climate Change, is providing the “first-ever global projection of the potential reduction in the maximum size of fish in a warmer and less-oxygenated ocean.”

The research was done by using computer models “to study more than 600 species of fish from oceans around the world and found that the maximum body weight they can reach could decline by 14-20 per cent between years 2000 and 2050, with the tropics being one of the most impacted regions,” a University of British Columbia news release states.

“We were surprised to see such a large decrease in fish size,” says the study’s lead author William Cheung, an assistant professor at the UBC Fisheries Centre. “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 puzzle of understanding climate change effects in the ocean.”

The theory that oxygen supply limits fish growth was first pioneered more than 30 years ago by researcher Daniel Pauly, the principal investigator with UBC’s Sea Around Us Project and the study’s co-author. This is the first time that his idea has been applied on the global-scale.

“It’s a constant challenge for fish to get enough oxygen from water to grow, and the situation gets worse as fish get bigger,” explains Pauly. “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.”

This new research is emphasizing the value in urgently trying to limit greenhouse gas emissions and to come up with new strategies to “monitor and adapt to changes that we are already seeing, or we risk disruption of fisheries, food security and the way ocean ecosystems work.”

Source: University of British Colombia
Image Credits: Grouper and Shark via Wikimedia Commons

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