Hot and stuffy! Global Warming Will Challenge Commercial Species in the Gulf of St. Lawrence

Recent models project a general warming trend for the surface, cold intermediate and deep layers that characterize the Estuary and Gulf of St. Lawrence (EGSL) in summer. Further, waters will be more acidic and the deep layer will be even more hypoxic than today. These changes will influence the physiology of fish and crustaceans, including commercial species. An obligatory consequence of increasing water temperature for these organisms is an increase in metabolic rate and oxygen requirements. A diminishing oxygenation level in deep water will make it harder to meet the increased oxygen requirements of warming. Distribution and abundance of the deep-water Greenland halibut are expected to be greatly diminished. The northern shrimp uses the same habitat, but can also use more coastal waters. Reductions in distribution and abundance are expected. The very stenothermic snow crab will suffer a loss of habitat (bottoms in contact with the cold intermediate layer) and abundance, following a temporary period of increased productivity. Cod and American plaice should have faster growth rates on shelves (warmer water), but will be excluded from the deep hypoxic channels. Warming should increase productivity and distribution of lobster, haddock and mackerel in the colder parts of the EGSL.