According to the U.S. Fish and Wildlife Service, a screening test on a wild Penobscot River Atlantic salmon has revealed a suspected case of a potentially fatal virus.

Dr. Mamie A. Parker, Northeast acting regional director of the federal agency, issued a press release late Thursday saying fishery biologists removed the single fish to a separate pool and are initiating a 28-day cell-culture test to determine if infectious salmon anemia virus is present.

According to the press release, the fish was returning from the ocean when Maine Atlantic Salmon fishery biologists removed it from the river for use as brood stock at Craig Brook National Fish Hatchery in East Orland. Forty-two of the 85 wild salmon removed from the Penobscot River this year have undergone the same blood test. This is reportedly the only suspect blood test to date. The tests were conducted at the government’s Fish Health Center in Lamar, Penn. The screening is preliminary and has been known to produce false results for the virus, according to Parker’s press release.

The 28-day cell-culture test is the best available science for confirming the presence of the virus.

The press release indicated that infectious salmon anemia virus, or ISAv, is a potential threat to Atlantic salmon recovery and restoration programs and was one of the reasons for Endangered Species Act protection of the Maine distinct population segment of wild Atlantic salmon.

For three years, biologists have been monitoring fish for ISAv from the eight rivers where fish are considered endangered by the federal government. Fish in the main stem of the Penobscot River are not protected as endangered, but fish in one of the river’s tributaries, Cove Brook, have the endangered designation.

ISAv was confirmed in March 2001 in commercial sea-pen facilities in Maine. The disease can cause death in salmon in salt water, but fishery biologists do not know what effect the disease will have on fish in fresh water.

The discovery of the possibly infected fish comes on the heels of a visit to Bangor by a panel of the National Academy of Sciences. The group convened at the request of Maine politicians who don’t think the Atlantic salmon exists as a distinct species and therefore shouldn’t be listed as endangered. Gov. Angus King has opposed the listing and testified before the panel.