TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 Significance Of Yersinia ruckeri And Aeromonas salmonicida Among Threatened Stocks Of Atlantic Salmon From Rivers In Maine Rocco C. Cipriano National Fish Health Research Laboratory, U.S.G.S., Biological Resource Division, 1700 Leetown Rd, Kearneysville, WV 25430 Atlantic salmon runs in the Northeastern United States historically averaged 500,000 fish per year, but environmental alterations have seriously reduced this resource. Hydroelectric dams, for example, impede salmon migrations, increase predation, alter flows and water quality, and increase water temperature. Despite restoration efforts, about 2,000 salmon annually return to New England Rivers; most (about 75%) return to the Penobscot River. Although North American stocks are distinct from those in Europe, variability within North American stocks is minimal. Still, persistence of native stock reproduction in specific rivers is a critical factor when evaluating the significance of river-specific populations. In 1995, salmon stocks in the Sheepscot, Ducktrap, Naraguagus, Pleasant, Machias, East Machias and Dennys Rivers were proposed for listing as a threatened species under the Endangered Species Act. In addition, Atlantic salmon in the Penobscot River were identified as a Class II or candidate species for future listing as a threatened species. In December 1997, however, the Endangered Species Proposal was withdrawn in lieu of a recovery effort spearheaded by the state of Maine as listed in the Atlantic Salmon Conservation Plan. The plan continues development of river-specific broodstocks, stocking of juvenile salmon into Maine rivers, habitat reclamation, improvement of fish passage, changes in aquaculture and agriculture practices to reduce threats to salmon survival, and monitoring programs to evaluate progress. Efforts to develop river specific broodstocks are focused primarily at the Craig Brook National Fish Hatchery (East Orland, ME). Quarantine of sea-run broodstocks segregated by river systems within the same facility requires effective management of pathogens. The limited nature of this resource necessitates that management be based on reliable, yet non-lethal, detection protocols. This presentation discusses the historical relevance, as well as current detection and control procedures for Yersinia ruckeri and Aeromonas salmonicida, within these fish.   Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page