Pacific cod (Gadus macrocephalus) is a species that supports large and successful fisheries in Alaska, but has declined precipitously in Puget Sound. Our previous genetic data demonstrated very clear differentiation of the Puget Sound population (Cunningham et al. 2009), originating from long isolation predating the last glacial maximum (Canino et al. 2010). Primarily based on these results, Pacific cod in Puget Sound was listed as a NOAA Species of Concern in 2011. Along the coast, our results showed an isolation-by-distance pattern that suggested surprisingly short dispersal distances for a species with a three months larval period (Cunningham et al. 2009). This work motivated follow-up studies by Ingrid Spies (NOAA) in Alaska, which found similar results and in part prompted the separation of the Aleutian Island and Bering Sea management areas. We are currently extending this work by applying next generation sequencing technologies, which suggest intrinsic barriers to gene flow between Puget Sound and coastal cod given complete absence of hybrids. In addition, using these new genetic approaches, we can assign individual cod to location of origin (Gruenthal et al. in prep), with immediate application to the investigation of seasonal migration and dispersal patterns (an ongoing project funded by the NOAA Saltonstall Kennedy program).
Currently, we are collaborating with NOAA scientists (Thomas Helser, Mike Canino) on Pacific cod in South Korea. Mary Fisher, an MS student in the group, will use next generation sequencing to refine knowledge on the population structure of Korean cod. In addition, she will further illuminate migration patterns by comparing genetic results with those from otolith microchemistry.
In part based on our cod work, I am now also collaborating with Torild Johansen of the Norwegian Institute of Marine Research (IMR) on a project on the population structure of saithe (Pollachius virens), a species related to cod in the Atlantic (Saha et al. 2016).