Atlantic Salmon Show Possible Longtime Exposure to Virus
Atlantic salmon in two New England rivers may have been exposed to a salmon virus as early as 1995, according to scientists with the U.S. Fish and Wildlife Service and the U.S. Geological Survey. The first indication of infectious salmon anemia virus in sea-run fish in this country was previously thought to be in 2001 when viral material was found in a Penobscot River salmon in Maine. The same year, the state of Maine reported the first confirmed case of ISAv in the United States in an aquaculture sea-pen salmon.
; "Our hatchery fish have not been infected with ISAv, but we remain concerned that the virus can be destructive under the right conditions," said the Services Northeast Regional Director Marvin E. Moriarty. "ISAv poses a threat to Atlantic salmon restoration in New England and the recovery of endangered Atlantic salmon in Maine."
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; There is no treatment for ISAv-infected fish. The virus can cause death in salmon; however not all infected fish die. The virus does not infect humans, and people cannot contract the disease from eating or handling infected fish, said John Coll of the Services Fish Health Center at the Northeast Fishery Center in Lamar, Penn.
; Moriarty said that the Service is exploring options for expanding disease screening already at their Craig Brook hatchery to other Service facilities. This could include additional quarantine and isolation of incoming fish.
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; ISAv was first described in Norwegian aquaculture in 1984. It caused significant numbers of fatalities in Canadian fish farms in 1996. Three years later, ISAv was reported in sea-run salmon in southern New Brunswick.
After Canadians found ISAv in their aquaculture sea-pens in 1996, Coll knew U.S. fish were at risk, and his team of fish health biologists began testing blood samples from salmon collected in the Penobscot River and taken to Craig Brook National Fish Hatchery in Maine for spawning. The team found positive results in a single fish in 2001, although there were no signs of disease.
Scientists with the USGSs National Fish Health Research Laboratory at the Leetown Science Center in West Virginia tested archived serum samples from more than 1,200 salmon. They found ISAv antibodies in serum from four Penobscot and 10 Merrimack river sea-run salmon taken between 1995 and 2002. Serum from Connecticut River salmon tested negative. The presence of antibodies suggests that the fish were either exposed to ISAv or vaccinated against the disease. The aquaculture industry in the United States began vaccinating salmon in 1999.
; More than a million Atlantic salmon at aquaculture sea-pens in Scotland, Canada and Maine have been destroyed and the sites left fallow for six months or longer in an effort to contain or limit the spread of ISAv.
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; Each year, the Service collects adult salmon returning to three New England rivers and holds them for spawning at three Service facilities: Craig Brook National Fish Hatchery in Maine (for salmon from the Penobscot River), Nashua National Fish Hatchery in New Hampshire (Merrimack River salmon) and Richard Cronin National Salmon Station in Massachusetts (Connecticut River salmon). Although these recent USGS findings showed the presence of antibodies in some of the fish, none showed any signs of the disease.
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; The fisheries program in the Northeast Region manages 11 national fish hatcheries, 13 fishery resource offices, a fish health center, and a fish technology center in 13 states from Maine to Virginia.
" Baskerville Old Face; Baskerville Old FaceThe U.S. Fish and Wildlife Service is the principal federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The Service manages the 95-million-acre National Wildlife Refuge System, which encompasses 544 national wildlife refuges, thousands of small wetlands and other special management areas. It also operates 69 national fish hatcheries, 63 fish and wildlife management offices and 81 ecological services field stations. The agency enforces federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Assistance program, which distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.
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