Results of new genetic research on Alaska red king crab stocks - included in the depressed Gulf of Alaska fishery - suggest the species has previously undetermined genetic diversity, making these crab more resilient to climate change.
Researchers at the NOAA Fisheries' Alaska Fisheries Science Center collaborated with Cornell University, the University of Alaska Fairbanks, and the Alaska Department of Fish and Game on the study involving whole genome sequencing data on red king crab across Alaska.
The benefit of genome sequencing over previous methods is that it's akin to reading the full story of an organism's makeup rather than just a chapter or two, said the study report released on Jan. 2.
Red king crab inhabit diverse environments, from coastal bays in the north to open sea shelves in the Bering Sea, as well as small bays and fjords fed by glacial melt in the Gulf of Alaska and Southeast Alaska. This environment generally includes the Gulf of Alaska, Southeast Alaska, the Aleutian Islands, the Eastern Bering Sea, Norton Sound and the Chukchi Sea. Scientists previously hypothesized that king crab in these regions are divided into three genetic groups: Gulf of Alaska/East Bering Sea, Southeast Alaska, and Aleutian Islands/Norton Sound.
This latest study reinvestigating genetic structure of red king crab in all five regions used high-resolution data derived from whole genome sequencing. They found substantial genetic structure within populations and genetic diversity between regions, including populations separated by only a few hundred kilometers.
Wes Larson, co-author of the research and genetics program manager at the the NOAA Alaska Fisheries Science Center, noted that there are a lot of fishermen, processors and community members getting more engaged in these issues, which prompts new and innovative research.
"Crabs have pelagic larvae, so this is very surprising given the potential for ocean currents to distribute these larvae long distances," said Larson. "However, these populations do not seem to be mixing and have become genetically isolated."
Researchers found previously unrecognized differences between Gulf of Alaska and East Bering Sea crab, and the East Bering Sea region is split into separate Bristol Bay and Pribilof Islands populations.
They also found that the Aleutian Islands and Norton Sound/Chukchi Sea crab are unique. Their data suggests that Norton Sound and Chukchi Sea may also have distinct populations, but further research is needed to confirm that.
Crab population structure and data will be used to help prevent overfishing on genetically unique populations. Researchers said they may also find with further study that some populations have better potential to do well in future climate conditions.
Finally, they said, with the Gulf of Alaska population being depressed, scientists would anticipate a higher potential for inbreeding and lower genetic diversity. They found no evidence, however, of reduced diversity - meaning that genetic health did not suffer as the population declined. This foundation of genetic diversity means that genetic factors should not limit recovery, researchers said.