Fish Kills, Intersex, Other Histopathological Abnormalities and Contaminants of Emerging Concern in Tributaries of the Chesapeake Bay

摘要

Skin lesions, neoplasia, parasites and other abnormalities in wild fishes have been used for years as indicators of ecosystem stress. Recently, a number of fish health issues in tributaries of the Chesapeake Bay have raised the concerns of resource managers as well as the general public. These include major mortalities or fish kills of smallmouth bass, redbreast sunfish and other selected species, a high prevalence of intersex or testicular oocytes in smallmouth bass and reduced recruitment of yellowperch in certain urbanized tributaries. Within the Potomac drainage the smallmouth bass skin lesions and mortalities have occurred in mature adults during the spring. Reddened raised or ulcerative skin lesions may be observed as early as late March, with major mortality occurring in April and May. Kills have occurred in the South Branch of the Potomac (West Virginia), Shenandoah River (Virginia) and Monocacy River (Maryland). In the Susquehanna River major mortalities of smallmouth bass have also occurred, however, in this case it is the young-of-the-year that exhibit skin lesions and die. Hence, major mortality occurs in July and August.