As Temperature Increases, Fish Size Decreases
A new study by researchers from the University of British Columbia (UBC) shows that changes in the ocean and climate could lead to smaller fish.
Fisheries scientists from UBC used computer models to study more than 600 species of fish from different oceans. This study is the first of its kind to provide a comprehensive, global overview of the decrease in the maximum size of fish in a warming and less-oxygenated ocean.

Juvenile bluefin tuna. Below, you can see just how big these fish can get. Photo credit: NOAA, Fishwatch.
“It’s a constant challenge for fish to get enough oxygen from water to grow, and the situation gets worse as fish get bigger,” explained Daniel Pauly, co-author and principal investigator with UBC’s Sea Around Us Project.
“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 research team found that between the years 2000 and 2050, maximum body weight could decline by 14 to 20 percent.
“We were surprised to see such a large decrease in fish size,” said lead author William Cheung, 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 ocean.”
To learn more:
- Check out the full press release from UBC: Fish getting smaller as the oceans warm
- Find the full paper published in the journal Nature Climate Change, here: Shrinking of fishes exacerbates impacts of global ocean changes on marine ecosystems
Copyright © 2012 by Marine Science Today, a publication of Marine Science Today LLC.


