A new study suggests warming sea temperatures could result in smaller fish sizes.
August 22, 2017 — Warming temperatures and loss of oxygen in the sea will shrink hundreds of fish species—from tunas and groupers to salmon, thresher sharks, haddock and cod—even more than previously thought, a new study concludes.
Because warmer seas speed up their metabolisms, fish, squid and other water-breathing creatures will need to draw more oxygen from the ocean. At the same time, warming seas are already reducing the availability of oxygen in many parts of the sea.
A pair of University of British Columbia scientists argue that since the bodies of fish grow faster than their gills, these animals eventually will reach a point where they can’t get enough oxygen to sustain normal growth.
“What we found was that the body size of fish decreases by 20 to 30 percent for every 1 degree Celsius increase in water temperature,” says author William Cheung, director of science for the university’s Nippon Foundation—Nereus Program.
These changes, the scientists say, will have a profound impact on many marine food webs, upending predator-prey relationships in ways that are hard to predict.
“Lab experiments have shown that it’s always the large species that will become stressed first,” says lead author Daniel Pauly, a professor at the university’s Institute for the Ocean and Fisheries, and principal investigator for the Sea Around Us. “Small species have an advantage, respiration-wise.”
Still, while many scientists applaud the discovery, not all agree that Pauly’s and Cheung’s work supports their dramatic findings. The study was published today in the journal Global Change Biology.
