Climate change is a big factor for lobsters and other marine species moving north in large numbers, according to new research published in the journal Science, co-authored by a Halifax university professor.
The study, co-authored by Dalhousie University marine biology professor Dr. Boris Worm, compiled 40 years worth of data to explain several significant marine species shifts seen in the Atlantic and Pacific oceans.
"The question we asked was 'Are fish on the move?' — generally — and if they are, are they moving in the direction the temperature is moving or are they doing something else?” he said.
The study found that in all areas of coastal North America, the organisms followed cooler water.
“What we found is that they're tracking the local climate velocity — that is the direction and rate of climate change across the landscape -- very, very accurately. So if you know where the temperature is going, you know where the fish are going," said Worm.
Earlier this year, scientists with the Department of Fisheries and Oceans were at a loss to explain the record amount of lobster being caught off Atlantic Canada.
"The increase is about three to four-fold over the last 30, 40 years," said Marc Lanteigne, the manager for aquatic resources for the gulf region in a December interview.
Catches have also jumped to about 20,000 tonnes in the past few years, up from 8,000 tonnes in 1975, said Lanteigne.
"The only thing that we know is that it's a global factor for the entire range of lobster from Cape Cod to Labrador," he said.
The relatively cool waters are a draw for marine species, said Worm.
“In our region the climate seems to be just right, so lobster seems to be doing quite well. Whether this will be the same in the future and maybe the more distant future is hard to say. It depends on the rate and direction of climate change in our region,” said Worm.
Another factor playing a role in the abundance of lobster off Atlantic Canada, he said, is the fact that many species of predators that hunt lobster have been fished-out.
Worm said lobsters are moving from the waters off southern New England into those off of Atlantic Canada at a rate of six kilometres per year.
The study examined the North Atlantic, the Gulf of Mexico, the Pacific shelf and waters around Alaska. The study was the first ever to combine U.S. and Canadian fisheries data for all of coastal North America.
The data collected over four decades included 128-million samples of 360 different marine species.