On average, fish are likely to get smaller by 2050 because of global warming. That’s according to a new study published this past weekend.
The research was led by author William Cheung of the University of British Columbia in Canada. The study says global warming will cut the amount of oxygen in the oceans in a shift that may also mean dwindling catches.
Reuters recently reviewed the data. It says average maximum body weights for 600 types of marine fish, such as cod, plaice, halibut and flounder, would contract by 14-24 percent by 2050 from 2000 under a scenario of a quick rise in greenhouse gas emissions.
The news agency had a chance to speak with Cheung, whose findings were published in the journal Nature Climate Change. He told Reuters, “The reductions in body size will affect whole ecosystems.”
Reuters reports that Cheung’s team of scientists said a trend towards smaller sizes was “expected to have large implications” for ocean food webs and for human “fisheries and global protein supply.”
“The consequences of failing to curtail greenhouse gas emissions on marine ecosystems are likely to be larger than previously indicated,” the U.S. and Canada-based scientists wrote.
The study suggests global warming will make life harder for fish in the oceans. This is mainly because warmer water can hold less dissolved oxygen, which is needed for respiration and growth.
“As the fish grow bigger and bigger it will be difficult to get enough oxygen for growth. There is more demand for oxygen as the body grows. At some point the fish will stop growing,” Cheung told Reuters.
The news agency reports that as water gets warmer, it also gets lighter. This limits the mixing of oxygen from the surface layers towards the colder, denser layers where many fish live. Rising water temperatures would also add stress to the metabolic rates of fish.
The scientists went on to tell Reuters that fish stocks were likely to shift from the tropics towards cooler seas to the north and south.
Photo by LASZLO ILYES