Studies and Reports

Health of Striped Bass in the Chesapeake Questioned

The Chesapeake Bay Ecological Foundation, Inc. has requested assistance from the United States Fish and Wildlife Service to help investigate the diseased striped bass problem in the Chesapeake Bay region.

Two conferences have been held, one at the USFWS Office in Annapolis MD, and the other at the Maryland Department of Natural Resources Cooperative Laboratory, Oxford MD. Following the conferences, CBEF presented data compiled on striped bass lesions and the declining forage base in the Chesapeake Bay to the Living Resources Subcommittee Work Group for the Chesapeake Bay Program. MD-DNR has classified the external lesions on striped bass as Ulcerative Dermatitis Syndrome. According to published scientific literature, some of the causes of ulcerative dermatitis are environmental stressors, such as high temperature, and nutrient loading of inshore waters, coupled with fish that are in poor nutritional condition.

Due to the high percentage of adult striped bass that are in poor nutritional condition in the Chesapeake Bay, there is a growing concern about the declining forage base, primarily Atlantic menhaden. MD-DNR Juvenile Finfish Survey data shows the average geometric mean from 1993 to 1997 for Age-0 Atlantic menhaden has declined 84% since 1990. Also, the catch-per-unit effort for Atlantic menhaden in Maryland pound nets has decreased 90% since 1981 and Virginia’s pound net landings have declined 86% since 1977. During the 1997 summer and fall season, approximately 10% of the striped bass over 18″ were exhibiting visual external lesions in Maryland’s portion of the Chesapeake Bay. Over 70% of the striped bass that were examined in one survey had very little fat in the body cavity and were in poor nutritional condition. The stomach contents of the striped bass that were examined also indicated a change in their diet from Atlantic menhaden to grass shrimp, sand shrimp, white perch, blue crab, bay anchovy, and spot, during the fall of 1997 when Atlantic menhaden should have dominated their diet, based on the latest scientific study on striped bass conducted by Kyle J. Hartman and Stephen B. Brandt in the Chesapeake Bay from 1990 to 1992. We need to determine if the decline in Atlantic menhaden utilizing the Chesapeake Bay has contributed to the poor health of the adult striped bass population in the bay. Striped bass with lesions and bacterial infections exhibiting signs of being undernourished have been observed as far north as Rhode Island. Research is needed to determine if we have reached the point where the declining menhaden stock is inadequate to supply the growing numbers of striped bass in the Chesapeake Bay and along the Atlantic coast and what impact the diseased striped bass migrating out of the Chesapeake Bay are having on the entire Atlantic coastal population of striped bass.

Poor recruitment of Atlantic menhaden in recent years, coupled with increased exploitation rates, have dramatically reduced the Atlantic menhaden population. The 1997 estimated Atlantic menhaden population has continued to decline and is currently near it’s historically lowest level on record, according to data obtained from the National Marine Fisheries Service.

A workshop to investigate living resources and water quality monitoring data, that are showing declining or degrading trends in the Chesapeake Bay, is being sponsored by the Science and Technical Advisory Committee of the Chesapeake Bay Program on July 8 & 9, 1998. CBEF has requested that striped bass be given special attention, and be considered as a target species to be studied under the current USFWS National Wildfish Health Survey.