Predicted Response of Northwest Atlantic Invertebrate and Fish Stocks to CO2-Induced Climate Change

Abstract

We discuss the effect of changes in oceanographic conditions induced by a global increase in atmospheric CO2 on the location, composition, and recruitment of invertebrate and finfish populations inhabiting the region from the Gulf of Maine to the Labrador Shelf. Published studies exist for the region that link historical climate fluctuations with fish distributions or that use physical data as proxy variables for nutrient flux, advection, and stratification to predict species recruitment patterns and stock size differences. We used these models in conjunction with a physical oceanographic scenario resulting from a doubling of atmospheric CO2 to speculate on the most probable consequences to the fisheries of Atlantic Canada. For example, a general warming and freshening of the continental shelf waters is anticipated. We expect this to lead to shifts in the geographic distribution of several commercially important groundfish stocks, especially those that are presently at the extreme limits of their species ranges. Earlier arrival times and later departures are expected for pelagic species that undergo extensive seasonal migrations. Higher temperatures and increased water column stratification may result in less organic material reaching the bottom and tend to favor a pelagic fish community. Our analysis is highly speculative, in part because of uncertainties in the predicted physical changes, but also because of the limited knowledge of the processes linking physical oceanography with fisheries.