Dr. William Cheung of the University of British Columbia is the lead author of a new climate change study that suggests some species of fish could be up to 24 percent smaller by 2050.
William says that as our oceans get warmer, it raises the body temperature of fish, increasing their metabolic rate - which, in return, requires more oxygen.
"As the fish grow bigger and bigger, their body cells and body materials increase. However, their ability to get oxygen from waters do not increase proportionately," he explains.
"At some point, the fish will run out of oxygen, which means that they can get only enough oxygen to support their normal body functions -- but no more oxygen for growth."
Data also suggests that there are more small-bodied fish in tropical waters. As ocean temperatures rise, these fish will seek a more comfortable environment, likely in a high-latitude ecosystem.
That movement - along with the physiological impact of the warming ocean - could lead to haddock and cod that are smaller in body size.
William says that limiting our use of greenhouse gases could reduce the rate of change in our oceans, and our fish.