Submitted to: Annual Eastern Fish Health Workshop
Publication Type: Abstract only
Publication Acceptance Date: 2/5/1999
Publication Date: N/A
Citation: FISH HEALTH ASPECTS OF PFIESTERIA INVESTIGATIONS IN MARYLAND. 24th ANNUAL EASTERN FISH HEALTH WORKSHOP. 1999. Interpretive Summary:
Technical Abstract: A suite of fish health investigations was undertaken in Maryland's Chesapeake Bay and tributaries during 1998. One purpose of these studies was to monitor for the effects of Pfiestiera piscicida and other Pfiesteria-like organisms both to observe impacts on fish populations and communities, and to alert the public should outbreaks of these toxic dinoflagellates occur. A second purpose was to gain better information about the causes, progression and outcomes of the high prevalence of fish abnormalities seen in the Pocomoke River and Sound in 1997. In 1998, Atlantic menhaden (Brevoortia tyrannus) with ulcers were collected from several Chesapeake Bay tributaries through routine monitoring and examined histologically. They consistently showed evidence of invasive fungal disease. Unlike 1997, in 1998 there was no evidence of acute toxic or pathogenic effects on fish found in field sampling or experimental deployments in the Pocomoke River System. Additionally, the incidence of external anomalies on commercially harvested fish species dropped from 3.2% in 1997 to 0.19% in 1998. White perch (Morone americana) were held in in situ cages in the Pocomoke River system for extended periods of time to monitor prevalence of external anomalies. Fish held longer than 48 hours developed abrasions and tail rot, which became more severe over longer holding times. Based on these results, the high incidence of severe anomalies in Pocomoke system commercial fisheries during 1997 could not be attributed to the effects of the pound nets, fyke nets and bank traps in which they were captured and confined. The experimental systems and procedures developed during these studies can be employed effectively to monitor and identify potential acute toxic or pathogenic events, and could be used with Atlantic menhaden if great care is taken in capture and transport of the fish.