After depositing their eggs into the brackish estuaries, the shad swim downstream, exit the Chesapeake Bay between Cape Charles and Cape Henry, and turn left. They spend the summer in northern waters, such as the Bay of Fundy and the Gulf of Maine.
There, in the cold waters above the coastal shelf and Georges Bank and west of the Gulf Stream, the shad feed and grow. In the fall, they migrate south again and spend the winter off the Carolina coastline. Come spring, the cycle is repeated with a new round of spawning in the estuaries. If you could put an odometer on a shad, the measuring device would need 4 digits, rolling past "999" and then "1,999" miles annually.
So a shad, a striped bass (rockfish), and other anadromous species look at Virginia as a part-time home. "Virginia is for lovers" could apply to fish as well as tourists. But for the fish, Virginia is not a safe haven. There are numerous dams blocking the way, creating impossible-to-leap barriers far more challenging than the natural waterfalls. Then the water quality is poor, at times. And assuming a fish survived its visit to Canadian waters, the winter in the Atlantic Ocean, and the trip to the spawning grounds - there are those Virginia fishermen waiting in April...
If you're the governor of Virginia rather than a fish (OK, no jokes about how it might be hard to tell the difference...), you can't go it alone to restore a fishery. Even the rockfish, which spends two-thirds of its lifespan in the Chesapeake Bay, is dependent upon water quality from New York, Pennsylvania, West Virginia, and Maryland as well as Virginia. Bottom line: If the governor of Virginia wants to protect or restore natural populations of fish, or migratory birds, then he or she will need to cooperate with the neighbors and the Federal government.
Before the Ice Age, and afterwards, each Virginia river had the potential of establishing unique species of fish, and especially suspecies (strains) that reflected adaptation to the particular environment of each watershed. Overharvest of the fish, excessive siltation from agriculture and timber harvest, blockage of fish passage by dams, chemical pollution by industrial plants, and 50 years of pesticides all degraded the aquatic habitats in Virginia.
As a result, much of the genetic diversity of Virginia's rivers was lost. Restocking of hatchery fish brought non-native genes, and even non-native species, to Virginia watersheds. The apparent recovery of the fish populations (in some cases) disguises the weakness of the reduced diversity. The current fish populations are not as pre-adapted to the stresses they may face... but then again, the stresses have changed dramatically as well in the last 400 years.
Does genetic diversity really have an impact? It may be hard to measure the effects in the state's fish populations, but every winter the 6.8 million humans in Virginia demonstrate the importance of being adapted.
Fish Passage and Dam Removal
Herring/Shad
Links
Habitats and Species
Geography of Virginia
