The Pacific cod fishery in the Gulf of Alaska will be shut down in 2020 because of low numbers that biologists are tying to high water temperatures caused by global warming. Pacific cod make up Alaska’s second-largest fishery by weight, and the federally-managed fishery in the Gulf of Alaska has been a major economic driver in the region since the 1980’s.
Fisheries managers announced the closure last week at a North Pacific Fisheries Management Council (NPFMC) meeting, citing alarmingly low cod numbers in the Gulf.
The shutdown is the culmination of a precipitous downturn in stocks that began in 2014 with the Blob, a mass of warm water that sat off the coast of Alaska. Biannual bottom trawl surveys revealed that the Pacific cod biomass in the Gulf dropped 79 percent from 2013 to 2017. Managers have consistently slashed quotas in the past years – including an 80 percent reduction in 2018 – but now they think they might not have done enough. NOAA biologist Steve Barbeaux, who authored the recent cod assessment report, told NPR satellite KMXT in Kodiak that he felt NPFMC should have shut the fishery down last year as well.
"A lot of the impact on the population was due to that first heat wave that we haven't recovered from," he said.
The Blob ended in 2017 and Mike Litzow, a NOAA Fisheries researcher based in Kodiak, told SeafoodSource last spring that the 2017 recruitment had improved. But Barbeaux stated that the new assessment turned up almost no new eggs and scientists are now monitoring new warming patches in the North Pacific, casting even more uncertainty over the future of Gulf cod stocks.
Biologists believe that warmer water raises cod’s metabolic demands while simultaneously decreasing the quality and quantity of prey, leading to starvation. A new NOAA study that simulates the Blob conditions in a laboratory is currently underway, with hopes of clarifying exactly how marine heat waves effect juvenile cod.
Katharine Miller, a NOAA Fisheries biologist at the Alaska Fisheries Science Center, is leading research that feeds young cod both Blob and pre-Blob prey.
“Understanding how temperature affects juvenile growth, condition, and survival is fundamental to determining and predicting Pacific cod stock strength. It is critical information for effective Pacific cod management in a changing climate,” Miller said in a NOAA news story released last month.
While the Gulf of Alaska cod stocks appear to be bottoming out, recent studies show that Pacific cod stocks in the eastern Bering Sea have been moving north because of a lack of sea ice, while Aleutian Island stocks are diminishing as well. The total allowable catch for the Bering Sea and Aleutian Islands has suffered incremental drops over recent seasons, and NPFMC will recommend year-on-year slashes in TACs at least through 2021.
Photo courtesy of Max Lindenthaler/Shutterstock
