Study: As Oceans Warm, Fish Are Moving North

(CN) – Climate change could shift the geographic distribution of hundreds of marine species that inhabit North America’s Atlantic and Pacific continental shelves, a new study finds.

The report, published in the journal PLOS ONE, offers projections for how marine species will react to high or low greenhouse gas emissions in the future.

While some marine species have already migrated south or north to more favorable habitats or deeper, cooler waters, the warming ocean may shift the distribution of 686 species off the coasts of North America alone.

“We’ve already seen that shifts of a couple of hundred miles in a species’ range can disrupt fisheries,” said lead author James Morley, a former postdoctoral researcher at Rutgers University. “This study shows that such dislocations will happen all over the continent and on both coasts throughout the 21st century.”

To evaluate the impact of greenhouse gas emissions on the habitats of North American continental shelf species, the team used data from long-term ecological surveys to develop statistical models of preferable habitats for 686 species. They then formulated 16 different ocean circulation models under future scenarios of either high or low greenhouse gas emissions.

Examples of east coast species projections as oceans warm and habitats shift north. (Morley et al, 2018)

The report predicted that climate change will shift the location and size of suitable habitats for many species, with all circulation models projecting similar adjustments for two-thirds of the species.

In the projections, habitats tended to veer north along the coastline, though these relocations varied based on specific species’ needs, seafloor characteristics and continental shift width.

“We found a major effect of carbon emissions scenario on the magnitude of projected shifts in species habitat during the 21st century,” Morley said. “Under a high carbon emissions future, we anticipate that many economically important species will expand into new regions and decline in areas of historic abundance.”

The models also predicted that the size of some species’ suitable habitats may expand, though habitats for other species like the East Coast sheepshead may shrink dramatically. Species off of the West Coast of the United States and Canada may shift the farthest, with some – such as West Coast canary rockfish – moving more than 620 miles under a high greenhouse gas emissions scenario.

The Alaskan king crab is among the species that would journey northward.

“People in that fishery already travel a long way to catch crabs – many from as far away as Seattle – so this may not make a big difference to them in the short term,” said co-author Malin Pinsky, a professor of ecology, evolution and natural resources at Rutgers.

“But if you’re based in North Carolina, fishing for black sea bass, and you have to travel 300 or 400 extra miles to do it, that’s a real problem.”

The team notes that their projections do not account for highly nuanced knowledge of every species, and the models diverged significantly for roughly 20 percent of the species.

The lower-level emissions scenario is in line with goals established by the 2015 Paris climate agreement, from which President Donald Trump withdrew the U.S. earlier this year.

The research was funded by the National Marine Fisheries Service and the Pew Charitable Trusts.

 

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