Temperature-Oxygen Habitat for Freshwater and Coastal Striped Bass in a Changing Climate

Habitat space for a fish species is normally constrained by extreme temperatures and low dissolved oxygen concentrations that the fish avoid. Both latitudinal limits to a speciesˈ geographic distribution and availability of suitable habitat on the local level may be altered by climate change. During the next century, average temperatures are expected to rise globally, and rainfall is expected to decrease in mid latitudes and increase in high latitudes. I have predicted some possible effects of climate change on distribution of anadromous and landlocked stocks of striped bass Morone saxatilis. The tenuous existence of striped bass along the northern coast of the Gulf of Mexico and in Florida will likely be jeopardized by regional warming and reduced streamflow. In many freshwater lakes, reservoirs, and estuaries, the existing summer constriction of suitable habitat by high temperatures and low oxygen concentrations may be aggravated by warming, altered streamflow, and increased hypoxia. A major loss of habitat is predicted to occur in the Chesapeake Bay, where the species has had its greatest abundance historically. An expansion of the speciesˈ range around Nova Scotia and farther into the Gulf of St. Lawrence may occur, although the cold Labrador Current may increase in volume and cancel any potential water temperature increases in the northernmost range of the species. Our understanding of the habitat requirements of many commercially and recreationally important fish species exceeds our confidence in climate models, but will allow forecasts of changes in regional and local habitat suitability as our understanding of climate and our ability to forecast it improve.