NOAA Fisheries Study Looks at Future of Pacific Cod Moving North

A Pacific cod in Alaska waters. Photo via NOAA Fisheries.

A new study, publicly released June 22 by NOAA Fisheries’ Alaska Fisheries Science Center (AFSC), says the success of reproduction of Pacific cod moving north because of climate change issues remains an unknown.

New collaborative research discussed in the study predicts how thermally suitable habitat for Pacific cod spawning in the Bering Sea may shift over the coming century of climate change.

The study coupled state-of-the-art climate modeling with information from laboratory experiments relating hatch success to temperature and looked at how changes in spawning habitat might affect Pacific cod productivity.

The study projects that suitable spawning habitat will expand and shift over this century, as current spawning hotspots likely become too warm for egg development and hatching. The report warns that the northern Bering Sea will remain too cold for successful spawning even by the end of the century.

AFSC study leader Jennifer Bigman said that understanding how warming will affect spawning habitat is critical in predicting and mitigating effects of climate change on Pacific cod populations and fisheries.

Laboratory experiments have shown that Pacific cod eggs have a very narrow thermal window for successful development and hatching. Juveniles and adults tolerate a much wider temperature range. The egg stage may act as a bottleneck for the species’ ability to adapt to warming, the report said.

Recent studies linked reduced thermal spawning habitat with a stark decline of Pacific cod production in the Gulf of Alaska, in the aftermath of an unprecedented marine heatwave in 2014-2016, but the Bering Sea is colder than the Gulf of Alaska.

“Bering Sea Pacific cod populations are currently constrained by cold rather than warm temperatures,” Bigman said.