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MARINFORSK-Marine ressurser og miljø

Genetic variability in population responses of Atlantic cod to environmental change

Alternativ tittel: Genetisk variabilitet i populasjonresponser hos torsk som følge av klimaendringer

Tildelt: kr 1,9 mill.

The research progressed as planned. Cod obtained from three populations were allowed to spawn undisturbed at the Institute of Marine Research's facilities at Flødevigen near Arendal. One spawning group was obtained from inside a fjord near Risør on the Skagerrak coast. A second group is a genetically distinct spawning group inhabiting coastal waters directly outside the fjord. The third group came from northern coastal waters near Mo i Rana. The adult cod were allowed to spawn in large tank facility. Eggs were collected daily for three months. Genetic analyses were undertaken on DNA from several thousand cod larvae to determine the origins of their parents. The larvae were reared at different temperatures to determine their responses to the temperature changes expected to occur as a result of global warming. RNA was obtained from larvae at different developmental stages during their development. This was done to identify the gene and genomic profiles associated with thermal plasticity for each cod population. Using gene-sequencing techniques, we have been able to determine the genes that are expressed as a function of developmental stage and temperature, and how these interactions vary among populations. We have also undertaken research to examine life history differences among cod populations at very small spatial scales along the Skagerrak coast.

A key challenge to successful management and the resolution of conflict is to correctly identify the spatial scale at which strategies for harvesting and climate-change mitigation should be developed. A spatial mismatch between management and biological u nits can have severe and long-term socio-economic consequences. Catch levels set at an inappropriately large spatial scale will result in higher fishing mortality, and a greater risk of overfishing and depletion, on smaller stocks. From a climate-change p erspective, a spatial mismatch between management units and biological units will reduce Norway's ability to effectively adapt integrated management practices at spatial scales appropriate to the spatial scales of adaptation by marine organisms to climate change. If spatial mismatches between management units and biological/evolutionary units are not resolved, management cannot successfully adopt the changes necessary to jointly mitigate the impacts of fishing and climate change. The proposed research will serve to reduce this mismatch by determining the genetic basis of responses by Atlantic cod to environmental change, thereby allowing for a deeper understanding of the importance of local adaptation and spatial scale for successful management and co nflict resolution. The first component of the work will involve 'common-garden' experiments, whereby cod from different regions will be raised in the same environments. Different survival and growth responses to temperature (plasticity) by different popul ations will be indicative of genetic variation. We shall then identify the gene and genomic profiles associated with this plasticity for each cod population. Our proposal illustrates how research in ecology (growth, survival, thermal responses) and evolu tion (adaptive plasticity, gene expression) can be combined to inform strategies for conflict resolution and successful management given the challenges posed by harvesting and climate change.

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MARINFORSK-Marine ressurser og miljø