UBS Study Finds Warming Oceans Could Mean Smaller Fish

Researchers at the University of British Columbia in Vancouver
say changes in ocean and climate systems could lead to smaller fish.
The study, which was published online in the journal Nature Climate
Change on Sept. 30, offers the first-ever global projection of the potential reduction
in the maximum size of fish in a warmer and less-oxygenated ocean.
The study says changes in temperature, oxygen content and other
ocean biogeochemical properties directly affect the study of the physiology of organisms
with respect to their adaptation to the environment. However, the extent to which
these changes would exacerbate the impacts of climate and ocean changes on global
marine ecosystems remains unexplored, the scientists said.
The researchers used computer modeling to study more than 600
species of fish from oceans throughout the planet. They found that the maximum body
weight they can reach could decline by 14 percent to 20 percent between the years
2000 and 2050, with the tropics being one of the most impacted regions.
William Cheung, an assistant professor at the UBS Fisheries Centre,
was the lead author of the study. He said the researchers 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,” Cheung said. “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.”
This is the first global-scale application of the idea that fish
growth is limited by oxygen supply, which was pioneered more than 30 years ago by
Daniel Pauly, principal investigator with UBS’s Sea Around Us Project, and the study’s
The study highlights the need to develop strategies to monitor
and adapt to changes that are already being seen, or risk disruption of fisheries,
food security and the way ocean ecosystems work.
The study can be found online at