Climate change has been impacting global fisheries for the past four decades by driving species towards cooler, deeper waters, according to University of British Columbia scientists.

In a Nature study published this week, UBC researchers used temperature preferences of fish and other marine species as a sort of "thermometer" to assess effects of climate change on the world's oceans between 1970 and 2006.

They found that global fisheries catches were increasingly dominated by warm-water species as a result of fish migrating towards the poles in response to rising ocean temperatures.

"One way for marine animals to respond to ocean warming is by moving to cooler regions," says the study's lead author William Cheung, an assistant professor at UBC's Fisheries Centre. "As a result, places like New England on the northeast coast of the U.S. saw new species typically found in warmer waters, closer to the tropics.

"Meanwhile in the tropics, climate change meant fewer marine species and reduced catches, with serious implications for food security."

"We've been talking about climate change as if it's something that's going to happen in the distant future - our study shows that it has been affecting our fisheries and oceans for decades," says Daniel Pauly, principal investigator with UBC's Sea Around Us Project and the study's co-author. "These global changes have implications for everyone in every part of the planet."

A summary of the study is available here.