The high percentage of Chesapeake Bay striped bass in poor nutritional condition raises concern about the declining forage base for all predator species using the Bay, including the common loon. During 1997 and 1998, more than 60 percent of the striped bass from Maryland's portion of the Bay that were examined by the Chesapeake Bay Acid Rain Foundation (CBARF) had little, or no fat in the body cavity and exhibited signs of poor nutrition and starvation; approximately 12 percent of these fish had visual external lesions, ulcers or sores.
This ulcerative dermatitis in Bay striped bass was first reported to the Maryland Department of Natural Resources in September 1994, after poor recruitment for the 1993 year class of Atlantic menhaden within the
Chesapeake. During the fall and winter, when the water temperatures decrease and forage becomes more available, the condition of the striped bass population improves, with most of the lesions and sores healing, indicating that the chronic outbreak of various skin anomalies may be related to poor nutrition coupled with peak late summer water temperatures. The CBARF is working with officials from the University of Maryland Eastern Shore, Chesapeake Bay Program, Maryland DNR, U.S. Fish & Wildlife Service and the National Marine Fisheries Service to investigate what effects reduced numbers of Atlantic menhaden have on the diet and health of fish and bird populations in the Bay and along the coast.
Atlantic menhaden are an extremely important link in the coastal marine food chain, transferring enormous amounts of nutrients into forage biomass, while at the same time improving water quality - they have the potential to consume up to 25 percent of the Bay's nitrogen. No other fish has the capability to replace this unique species. Historically, during their residence in the Bay, a healthy population of Atlantic menhaden had the capacity, in less than two days, to filter a volume of water equal to the entire Chesapeake Bay.
The Atlantic menhaden stock was considered severely depressed from 1964 through 1968 when the population was 4.65 billion fish, according to the Atlantic States Marine Fisheries Commission's Menhaden Fisheries Management Plan. The estimated population of 4.55 billion fish in 1997 is lower than the 5-year average for the mid-1960s. Even though the total coastal Atlantic menhaden population has declined 58 percent since 1991, Bay landings have remained relatively high, averaging 150,000 metric tons per year and actually increasing to approximately 160,000 metric tons in 1997.
Approximately 60 percent of the total weight of Atlantic menhaden caught on the entire East Coast during the 1997 season were harvested from Virginia's portion of the Bay.
Poor Atlantic menhaden recruitment in recent years, coupled with the concentrated effort of the reduction fishery in Virginia's portion of the Bay and adjacent coastal waters, have substantially reduced the Atlantic menhaden population in Maryland's section of the Bay. The Maryland DNR's 1998 Juvenile Finfish Seining Survey index for Atlantic menhaden is the lowest since 1970, indicating another year of poor recruitment for juvenile menhaden in the Bay and the Atlantic Coast based on data examined in our investigation, which correlated Maryland's survey results with the National Marine Fisheries Service population estimates for Atlantic coast menhaden recruitment.
A Maryland DNR report from the 1960s stated, "Previous food habitat studies by us have indicated that during the summer and fall months, most striped bass of legal size (12-inch minimum) or larger have switched from a diet of predominantly anchovies to a diet of menhaden." University research on the diet and growth of striped bass, printed in Transactions of the American Fisheries Society (124:520-537, 1995), stated: "Atlantic menhaden represent the largest percentage of the diet of age-2 and older striped bass. Atlantic menhaden are of considerable importance to annual production of striped bass and bluefish, because much of the annual growth of these predators occurs when menhaden dominates the diet."
Recent striped bass diet studies in the Bay indicate an increase in the consumption of bay anchovy by age-2 and older striped bass because Atlantic menhaden have not been available in sufficient numbers to provide an adequate source of forage. However, bay anchovy numbers have now been reduced to historically low levels as well, resulting in a decrease in growth rates for striped bass because of their strong dependency on these two species. The Maryland DNR Juvenile Finfish Seining Survey data indicates the bay anchovy population declined dramatically, after the low recruitment of Atlantic menhaden in 1993.
Striped bass of 18-inch in total length, examined in a 1998 CBARF survey, averaged 23 percent less in weight compared with healthy striped bass tagged and released in a CBARF and Maryland DNR study in 1984, when Atlantic menhaden were more abundant in Maryland's portion of the Bay. The 1996-1997 USF & WS Federal Aid Report F-42-R-10, prepared by the Maryland DNR, stated, "since 1994, age-5 and age-6 striped bass harvested in the gill net fishery have decreased in weight and in length. The mean weight of 6-year-old striped bass in 1997 equaled the mean weight of 5-year-old fish in 1994 and the mean weight of 5-year-olds in 1997 equaled that of 4-year-olds in 1994."
In a 1997-98 survey conducted by the CBARF in Maryland's portion of the Bay, Atlantic menhaden were found in 6 percent of 203 striped bass examined. In a study conducted by the University of Maryland for the DNR from April-October 1998, Atlantic menhaden represented only 1 percent of the food items identified in 482 striped bass. According to population estimates from the ASMFC's management plans for Atlantic menhaden and striped bass in 1982, there were approximately 1,500 age-0-2 Atlantic menhaden for every kilo of striped bass age-2+ in the Atlantic coastal population. By 1996, the ratio had decreased 96 percent, to approximately 60 menhaden per kilo of striped bass age-2+ in the coastal population.
On June 8, 1998, at the request of the Maryland DNR, the CBARF presented data from its investigation into the current status of the Atlantic menhaden stock to the ASMFC's Atlantic Menhaden Management Board for their annual review. The ASMFC announced that on June 11, 1998, that it would conduct an external peer review of the current Atlantic menhaden stock assessment. The CBARF submitted the results of its investigation and gave testimony during the Peer Review Meeting held Nov. 16-18, 1998, in Baltimore. On Nov. 21, 1998, the CBARF, Coastal Conservation Association of Maryland, and the Chesapeake Bay Foundation sponsored a symposium, "Striped Bass In Crisis?" at the Kent Island High School Auditorium. Approximately 200 concerned citizens attended.