May 7th, 2019 10:00 (PST): FSH 203
Genetic evidence of a northward range expansion in the Eastern Bering Sea stock of Pacific cod
Abstract: Poleward species range shifts have been predicted to result from climate change, and many observations have confirmed such movement. The abundant center hypothesis predicts that range shifts will take place by movement of individuals from core habitat to marginal habitat. However, poleward shifts may also represent a homogeneous shift in distribution, northward movement of specific populations, or colonization processes at the poleward edge of the distribution. The ecosystem of the Bering Sea has been changing along with the climate, moving from an arctic to a subarctic system. Several fish species have been observed further north than previously and in increasing abundances. We examined one of these fish species, Pacific cod, in the northern Bering Sea to assess whether they migrated from another stock in the eastern Bering Sea, Gulf of Alaska, or Aleutian Islands, or whether they represent separate populations. Genetic analyses using 3,457 SNP markers indicated that non-spawning cod collected in August 2017 in the northern Bering Sea were similar to spawning stocks of cod in the eastern Bering Sea. This result suggests escalating northward movement of the large eastern Bering Sea stock of Pacific cod that may be consistent with the abundant center hypothesis.