The fisheries of the Chesapeake give identity to the region, and maintaining them in the face of various stresses remains our biggest obligation and challenge. Loss of habitat, degraded water quality, and overharvest have been vexing to sort out and address, and climate change potentially shifts the landscape entirely.
As a temperate estuary, the Chesapeake faces change regularly. Water temperature can change 50 degrees over a year. Salinity, a key determinant of where fish can live, ranges from zero (freshwater) at the head of the Bay to ocean saltiness at its mouth. From year to year this "salinity gradient" can shift dramatically depending on the amount of rainfall in the watershed. Certain species have adapted well to this changing environment. These are the ones the early settlers found in unbelievable numbers. And these "resilient" species are the ones that have supported our valuable fisheries: blue crabs, oysters, and rockfish.
The abundance of life in the Bay seemed limitless early in our history, but with hindsight we have learned there are limits to what we can take out sustainably. Add to that the historically reckless attitude toward the environment including denuding the land and damming the rivers, and the Bay's living resources faced new changes to which they were not adapted. American shad and oysters are two good examples. Both were harvested relentlessly, and both lost habitat quantity and quality.
Now climate change is adding a new layer of complication to this picture. Increasing temperature, rising sea level, and more variable precipitation present new challenges for Bay life. Species at the southern end of their range, like soft-shelled clams and eelgrass, already seem to be retreating northward up the Atlantic Coast. Atlantic menhaden haven't produced strong year classes in the Bay in 20 years. Might this be due to climate-related shifts in ocean currents interrupting their life cycle? Rockfish (striped bass) prefer young menhaden as food but may be shifting more to blue crabs as a result and suffering nutritional consequences. And crabs may also be facing new predators like red drum, which are expanding their range northward into the Bay.
There are no simple answers to addressing climate change or any of the other changes facing the Chesapeake Bay. Monitoring Bay conditions and adapting our strategies, much like fish and shellfish have to do, is the basic response. Managing our fisheries sustainably also requires being attentive and nimble. Ensuring there are enough fish to spawn and sufficient habitat for them to survive are fundamental principles. Science provides the basis for these assessments. Most importantly, when the science is incomplete, err on the side of the resource. Being conservative is the best course for both fish and fisherman in the face of change.
--Bill Goldsborough, CBF's Director of Fisheries