A systemic dinoflagellate disease was discovered in Tanner crabs Chionoecetes bairdi harvested from two-thirds of the major production areas in the northern southeast panhandle of Alaska during 1985 and 1986. Processed meats from infected crabs were unmarketable as a result of a bitter flavor imparted by the causative agent. The disease is chronic but lethal, causing 100% mortality in naturally infected crabs when maintained in flowing seawater during a 5 mo period. Feral Tanner crabs in at least one harvest area had a parasite prevalence of 95 '10 regardless of sex or age class. Disease pathogenesis and parasite description, probable life history, distribution and management imphcations are discussed.

Only one-third of the Pacific hernng Clupea harengus pallasi expected to spawn in Prince William Sound (PWS), Alaska, USA, in sprlng 1993 were observed. Of these herring, 15 to 43 ' % had external ulcers or subdermal hemorrhages of the skln and fins. A rhabdovirus identified as the North American strain of viral hemorrhagic septicemia virus (VHSV) was isolated from affected herring and 1 Pacific cod Gadus macrocephalus with skin lesions from PWS, and from herring with similar lesions collected near Kodiak Island. No other pathogens were detected in the herring examined. Although VHSV may have been responsible for the skin lesions, there was no confirmed mass herring mortality observed in PWS; hence the actual cause of the reduced herring numbers is still unknown. The same strain of VHSV was subsequently isolated from captive juvenile herring collected from Auke Bay, Alaska, near Juneau, from herring in British Columbia, Canada, and from Puget Sound, Washington, USA. These findings suggest the virus is an opportunistic pathogen that is widely indigenous to Pacific herring populations in the Pacific Northwest and that herring are a significant marine reservoir for North American VHSV.

The distribution of bitter crab syndrome in southeast Alaskan Tanner crabs Chionoecetes bairdi was determined from population surveys conducted by the Alaska Department of Fish and Game and commercial catch census data provided by seafood processors and fishermen. Both sources of data indicate the disease syndrome is widespread, affecting 1/3 of the total subdistricts fished during the 1988/1989 season. with the upper Lynn Canal areas having the highcst prevalenct?s (up to 95"/0). A conservative estimate of the total economic loss to fishermen due to rejected diseased crabs was about $220 500, representing 5 ' Yo of the total catch for the season. Disease prevalence in male and female crabs was nearly equal, with a significantly higher prevalence found in crabs of both sexes that have molted within the year (newshell). The latter finding was new information suggesting further considerations regarding the seasonality and transmission of the parasite. Increasing prevalences and spread of the disease syndrome to new areas is suggested by the commercial data but needs further verification from additional population surveys. Diseased crabs are known to have been introduced into some areas through improper disposal by processors and fishermen. Management of bitter crab syndrome may be possible by harvesting crabsearlier in the year when fewer crabs are severely parasitized and meats are more marketable. Promotion of increased public awareness of the disease syndrome and proper disposal of infected crabs are also necessary components in controlling dissemination of this parasite.

Thousands of dead Pacific herring Clupea pallasi, Pacific hake Merluccius productus and walleye pollock Theragra chalcogramma were reported in Lisianski Inlet near Pelican, Alaska, USA, on August 1, 1998. The Pacific hake and pollock continued to die through the end of September. Virological examinations of dead fish identified the North American strain of viral hemorrhagic septicemia virus (VHSV) from all 3 species of fish as well as associated high virus titers and possible histopathological lesions. No other primary fish pathogens were detected and there were no apparent environmental causes for fish mortality. This is the first report of VHSV in 2 new Alaskan fish host species and of a natural epizootic associated with VHSV in which progressive mass mortality was observed simultaneously in herring and 2 other species of free-ranging marine fish.

Ulcerative slun tissues from 2 Pacific cod Gadus rnacrocephalus caught in Prince William Sound, Alaska, USA, were examined for virus by Fish Pathology staff within the F.R.E.D. Division of the Alaska Department of Fish and Game. Six days after inoculation of Epitheliorna papulosum cyprini (EPC) cells at 14"C, diffuse rounding and lifting of cells from the monolayers suggestive of cytopathlc effect became visible in the lower sample dilutions. Ultrastructural examinations of affected EPC cells showed rhabdovirus particles within cytoplasmic vacuoles and on the cell surface membranes. Virus isolates from both cod were subsequently confirmed as viral hemorrhagic septicemia virus (VHSV) by serum neutralizabon and immunoblot assay. This is the first VHSV isolated from Pacific cod, which represents a new host species for the virus. Histologically, cod skin ulcers appeared to be caused by a foreign-body-type inflammatory response to foci of protozoa resembling X cells that also had plasmodial stages. Whether the rhabdovirus was incidental to the slun lesion or played a role in its etiology remains to be determined. The possible relationship between thls virus and the recent occurrences of VHSV in anadromous salmoruds from Washington State, USA, is discussed.