Global warming to shift North American fish species north, disrupting fisheries – “Dislocations will happen all over the continent and on both coasts throughout the 21st century”

Desdemona Despair

By Ken Branson
16 May 2018

(Rutgers Today) – Climate change will force hundreds of ocean fish and invertebrate species, including some of the most economically important to the United States, to move northward, disrupting fisheries in the United States and Canada, a Rutgers University-led study reports.

The study, published today in the journal PLOS ONE, covers the North American continental shelfs on the Pacific and Atlantic coasts. Previous studies have been global or regional, thus being too large or too small to get a clear picture of the future for North America’s fisheries. The species surveyed include finfish, sharks and rays, crustaceans, and squid. Among those most affected are Pacific rockfishes, Atlantic cod and black sea bass.

Fish are sensitive to the temperatures of the water where they live, and as it becomes too warm, populations often shift to where the water temperature is right for them. This process has already begun, though at different rates in different places. As climate change continues and the oceans warm up, the study shows, more species of fish will move north to where the temperature range is habitable for them.

“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-New Brunswick. “This study shows that such dislocations will happen all over the continent and on both coasts throughout the 21st century.”

“For commercial fishers, this often means longer trips and higher fuel costs,” said co-author Malin Pinsky, a professor of ecology, evolution and natural resources at the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. “Some species along the U.S. and Canadian Pacific coasts will move as much as 900 miles north from their current habitats.”

The researchers used 16 different climate models, each with both a low level of greenhouse gas emissions and a high level, to develop projections for future ocean temperatures around North America. The lower-level emissions scenario is in line with goals set by the Paris Agreement, from which President Trump withdrew the United States earlier this year. These climate projections were combined with statistical models of species temperature preference, which were based on bottom-trawl survey data from around the continent. While both high and low emission scenarios project some northward shift, the shifts in species habitat will be two to three times greater under a high emissions future.

Among the northward moving species is the Alaskan king crab. “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,” Pinsky said. “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 National Oceanic and Atmospheric Administration and the Pew Charitable Trusts funded the study.

Climate Change to Shift Many Fish Species North, Disrupting Fisheries, Rutgers-Led Study Finds

ABSTRACT: Recent shifts in the geographic distribution of marine species have been linked to shifts in preferred thermal habitats. These shifts in distribution have already posed challenges for living marine resource management, and there is a strong need for projections of how species might be impacted by future changes in ocean temperatures during the 21^st century. We modeled thermal habitat for 686 marine species in the Atlantic and Pacific oceans using long-term ecological survey data from the North American continental shelves. These habitat models were coupled to output from sixteen general circulation models that were run under high (RCP 8.5) and low (RCP 2.6) future greenhouse gas emission scenarios over the 21^st century to produce 32 possible future outcomes for each species. The models generally agreed on the magnitude and direction of future shifts for some species (448 or 429 under RCP 8.5 and RCP 2.6, respectively), but strongly disagreed for other species (116 or 120 respectively). This allowed us to identify species with more or less robust predictions. Future shifts in species distributions were generally poleward and followed the coastline, but also varied among regions and species. Species from the U.S. and Canadian west coast including the Gulf of Alaska had the highest projected magnitude shifts in distribution, and many species shifted more than 1000 km under the high greenhouse gas emissions scenario. Following a strong mitigation scenario consistent with the Paris Agreement would likely produce substantially smaller shifts and less disruption to marine management efforts. Our projections offer an important tool for identifying species, fisheries, and management efforts that are particularly vulnerable to climate change impacts.

Projecting shifts in thermal habitat for 686 species on the North American continental shelf