Striped Bass Of Chesapeake Bay

Striped Bass (morone saxatilis)

Life History
The silvery striped bass gets its name from the 7 or 8 dark, continuous lines along the side of its body. Most striped bass weighing more than 30 pounds are females. The fish can weigh up to 100 pounds and reach nearly 5 feet in length!

Striped bass spawn in fresh water but spend most of their adult lives in the ocean. On the Atlantic coast they range from the St. Lawrence River in Canada to Florida's St. Johns River, although they are most prevalent from Maine to North Carolina.

After about 3 years, at the juvenile stage, the females begin to migrate to the ocean where they mature. The males tend to remain in the estuary longer than the females. After 5 to 7 years, females return to spawn for the first time. It takes several years for spawning females to reach full productivity. An average 6 year old female produces half a million eggs while a 15 year old can produce three million.

When water temperature begins to rise in the spring, mature fish begin their spawning runs. Most Atlantic Coast striped bass spawn in freshwater rivers and streams of Chesapeake Bay. Other important areas include the Hudson River, Delaware River and rivers along the North Carolina coast.

Once the female deposits her eggs, they are fertilized by milt (sperm) ejected from the males. Because they are only semi-buoyant, the eggs require enough water flow to stay suspended for 2 or 3 days until they hatch.

Larval striped bass obtain nutrients from the yolk sac for about 5 days after hatching. The larvae are particularly vulnerable to pollution, starvation and predators during this stage.

Cause for Concern
The decline of Atlantic Striped Bass was so alarming that Congress enacted an Emergency Striped Bass Act in 1979. Under the Act, a study was initiated to assess the size of the migratory stock, investigate the causes of the decline, calculate its economic importance and recommend measures for restoration.

From this research, scientists from the U.S. Fish and Wildlife Service,state agencies and universities discovered new information about striped bass to assist them in restoration. Careful assessment of the stock showed that, because of overfishing, the striped bass population was much more susceptible to natural stresses and pollution. They also discovered that fluctuation of water temperature at spawning grounds is the most significant natural stress the fish face.

Research conducted in the Chesapeake's Nanticoke and Choptank rivers indicated that highly acidic rain reacts with aluminum in the soil, causing it to dissolve in the water. The combination of high acidity and aluminum is lethal to newly hatched stripers. Larval striped bass are also very susceptible to toxic pollutants like arsenic, copper, cadmium, aluminum and malathion, a commonly used pesticide. Studies showed that chlorination of effluent from sewage plants and electric power stations adversely affects zooplankton, leading to starvation of newly hatched striped bass that feed on it.

The study team also concluded that reducing fishing pressure would have an immediate positive effect by enabling females with eggs to spawn. An Atlantic States Marine Fishery Commission management plan, based partly on recommendations of this study, set size and pound limits to reduce the catch.

In 1985, Maryland imposed a total moratorium on striped bass. Virginia followed by banning striped bass fishing in spawning areas. Fours years later, Virginia also imposed a total ban on striped bass fishing. However, fishery managers knew that harvest restrictions alone would not permanently restore striped bass to the Bay.

Bringing the Striper Back
Under the Emergency Striped Bass Restoration Act, Congress designated the Fish and Wildlife Service as the lead federal agency to determine the cause of the fishery's decline. Striped bass restoration began in 1980. Water quality problems on spawning grounds were evaluated. By 1985, a coast-wide striped bass tagging and hatchery program was initiated to determine the rates of exploitation and natural mortality, and determine if hatchery-reared fish could supplement wild stocks in severely depleted rivers.

Fishery managers and biologists from the Fish and Wildlife Foundation, National Marine Fisheries Service, state agencies from Massachusetts to North Carolina and universities continue to participate in the striped bass tagging program. A central database, designed and managed by the Service, stores stocking information, migratory data from tag returns and other information upon which management decisions are based.

Since 1985, more than 190,000 hatchery-reared and wild striped bass have been tagged with external anchor or "spaghetti" tags. Anglers returned more than 30,000 of these tags by 1993. In addition, all hatchery-raised striped bass, more than 9 million fish in all, are tagged with tiny micro-encoded pieces of wire that anglers cannot see but researchers can read with specialized equipment. These hatchery-reared striped bass provide managers with information about population dynamics, growth and migratory patterns. In 1988, hatchery fish comprised nearly 50 percent of Maryland juvenile striped bass in some rivers like the Patuxent. Today, as hoped, wild fish far outnumber hatchery fish. Evaluations continue on the potential contribution of hatchery fish to depleted stocks.

During the years of the moratorium in Maryland, fishery managers continued to monitor striped bass populations in Chesapeake Bay. In particular, the juvenile index survey was closely watched. Conducted annually since 1954, this survey of the young-of-the-year reflects the success of spawning. The striped bass management plan set a goal for loosening restrictions based on this index. The juvenile indices averaged from 1987 to 1989 met the management plan goal. In 1989, both Virginia and Maryland lifted their moratoriums on striped bass. Limited commercial and recreational striped bass fishing resumed.

The Future of the Fishery
Striped bass stocks continue to gradually increase. The 1993 juvenile index was the highest since the survey first began. Besides the young-of-the-year index, managers have noted an increase in adult striped bass and in the proportion of spawning females, age 8 or older. This information is critical to establishing fishing seasons, minimum fish lengths, daily catch limits and harvest quotas.

Since Chesapeake Bay is the primary spawning and nursery area for 70-90 percent of the Atlantic stocks of striped bass, restoration depends on protecting and improving habitat and water quality. We have much to gain from restoring striped bass and Chesapeake Bay; we have much more to lose if we decline the challenge. Through harvest restrictions, pollution control, stocking and commitment we can restore the Striped Bass to Chesapeake Bay.