Each year usually starting in April, large schools of striped bass (also called “stripers,” “rockfish,” and a few other names) make their way north along the coast. Most make a journey of 500 miles (800 km) or more from the Chesapeake Bay.
Female striped bass can be over 3½ feet (1 m) in length and weigh 30-40 pounds (14-18 kg). Striped bass never stop growing as they age. Some fish live to be thirty years or older, with some weighing over 80 pounds (36 kg).
Fishermen along the northeast coast have eagerly sought striped bass since long before the advent of graphite rods and high-tech spinning reels. Many Native American tribes in the northeast traveled to the coast to establish seasonal fishing villages. Striped bass were caught, along with other migrating fish, in wooden traps called weirs.
When European colonists arrived, they were poorly equipped to farm New England’s thin rocky soil. Striped bass, along with river herring and shad, became an important food source, as they were easily caught by the thousands in tidal creeks and estuaries. Striped bass were considered so vital to the Massachusetts Bay Colony that in 1639, their use as fertilizer was banned to force colonists to develop fishery commerce with Europe.
Striped bass were originally found along the east coast from the St. John’s River in Florida to the Gulf of St. Lawrence, and on the gulf coast, in the Apalachicola River.
South of the Mid-Atlantic States, striped bass spend most of their time in rivers during summer when water temperatures are high in tidally influenced (salt water) sections of the river and move into tidally influenced sections when water temperatures drop.
The west coast has an established population, the bass having been introduced into California as an exotic species in the late nineteenth century. Landlocked populations have also been established in thirty-one states across the country.
The largest concentrations of striped bass are found in the area from the Mid-Atlantic States through southern New England, ranging from North Carolina to the southern Gulf of Maine.
Principal spawning areas include Chesapeake Bay, the Hudson River, the Delaware River and the Roanoke River/Albemarle Sound area.
The Chesapeake Bay area is by far the single most important spawning ground for striped bass. The bay’s many tidal estuaries and backwaters provides a vast amount of natal and nursery habitat. The broad, shallow bay itself is a fertile feeding ground for juvenile rockfish.
The migration journey taken by an individual striper is subject to a number of variables. Rockfish south of North Carolina are non-migratory. Canadian stocks of striped bass make short localized migrations along the coast. The general pattern of migration for most mid-Atlantic striped bass is for mature adults to gather during the winter months off the Virginia and North Carolina coasts. They will remain here until mid-spring, when they return to their natal rivers to spawn.
Soon after spawning, adults will leave freshwater and will travel north along the coast. Females will generally travel faster than males. But since males mature earlier than females, they will join the coastal migration several years sooner. For some, the destination is the waters of coastal New Jersey or New York. Many enter Narragansett Bay in Rhode Island. But most will spend the months of summer and early autumn feeding near the islands of Martha’s Vineyard and Nantucket, near Cape Cod, or in the southern Gulf of Maine. A few will travel as far as the northern Gulf of Maine or into the Bay of Fundy.
By mid-autumn, the migration is reversed, and the stripers return south once again. A few fish will remain in northern waters, overwintering in isolated pockets all along the coast, then returning to spawn in the spring. Some Delaware and Hudson River fish will travel only as far as the waters off the New Jersey coast. But most fish of all stocks return to the Mid-Atlantic overwintering grounds.
By early April, mature striped bass have begun to move into the mouths of their natal rivers. While some may travel as much as 200 miles (300 km) upstream, most will spawn in the slightly brackish or freshwater sections just above the upper estuaries of large rivers, in waters less than 20 feet (6 m) deep. Water temperature is the key factor in determining when spawning will occur. Peak spawning activity occurs when the water is about
60°-65° F (15°-18° C). This occurs from mid-April to mid-May in the Mid-Atlantic region.
Females will release their eggs at or near the surface of the water. As the fish grow older and larger, the number of eggs released also grows. A female rockfish in her first spawning season will release about four hundred thousand eggs. Toward the end of her life, a large healthy female can distribute ten times as many, releasing over four million eggs in a single season. Similar to many other types of fish, striped bass release large numbers of eggs to offset intense predation. During early life stages, they are preyed upon by many other species.
But striped bass eggs have an additional obstacle to overcome. In order to successfully hatch, they must remain suspended in the water. Since striped bass eggs are slightly heavier than water, they begin to sink slowly as soon as they are laid. Any eggs which fall to the bottom are unlikely to hatch. The eggs depend on sufficient river current and tidal flow to keep them suspended.
Each egg contains a yolk sac, which provides nutrition for the developing embryo, and an oil globule, which also feeds the growing fish. Eggs of striped bass which spawn in slow-moving rivers have a slightly larger oil globule, making them more buoyant and more likely to stay suspended long enough to hatch successfully.
Eggs that remain afloat will hatch in one and a half to three days, depending on water temperature. The eggs hatch to release larvae, which are about ¼ inch (8 mm) long. The attached yolk sac and oil globule will continue to feed the larvae for about a week. They will then begin to feed on microscopic organisms called zooplankton, which are suspended in the water. Larvae will continue to feed in the open water of their natal river for four to six weeks, drifting slowly downstream.
When the young have grown to about 1¼ inches (32 mm) long, they develop into the juvenile stage and more closely resemble adults. They begin to exhibit schooling behavior, forming groups of as many as several thousand fish. As the summer months pass, they move downstream into saltier water, inhabiting the inshore tidal creeks of the upper to mid-estuary.
In the Chesapeake Bay area, immature rockfish remain in the tidal freshwater or brackish stretches of their natal river for two to four years. They then move through the lower estuaries into the open bay, moving generally north during the summer. By autumn, they move inshore and southward, settling into the deep channels of the lower bay during winter.