Large shifts in fish habitat from climate change

Research says climate change is driving hundreds of fish species north from their usual seas and some of the biggest effects will be along Canada’s Pacific coast.

That is likely to create new challenges for governments seeking to regulate and share catches between competing jurisdictions, said James Morley of Rutgers University in New Jersey.

Morley found that even if climate change is kept under two degrees, species off Canada’s west coast will move by an average of more than 200 kilometres.

“Even in the best-case scenario, on the west coast we still expect to see some pretty substantial shifts of species northward.”

Morley looked at the impact of warming seas on 636 species of marine life on the Atlantic and Pacific coasts. About onequarter of those species have some commercial value, he said.

He used extensive data about where those species hang out and collected oceanographic information on currents, water temperature and the shape of sea floors. He ran all that through 16 different climate models, once to estimate the impact of two degrees of warming and once to estimate for four degrees.

Previous studies have already suggested that climate change will drive fish stocks northward. The size of Morley’s dataset makes his conclusions, published in a paper this week in the online journal publication PLOS-One, more detailed and specific.

He concludes that with no more than two degrees warming -- the goal agreed to in the Paris agreement -- fish stocks on the Pacific coast will migrate north by an average of 236 kilometres. The Atlantic side will see average movement of about 100 kilometres.

If the climate warms by four degrees — the so-called business-as-usual case — many Pacific stocks are likely to school as far as 1,500 kilometres north of the current centre of their habitat. The east coast shift would be about 600 kilometres.

“They were pretty large changes throughout the west coast.”