Viral hemorrhagic septicemia virus (VHSV) was isolated from populations of Pacific sardine Sardinops sagax from the coastal waters of Vancouver Island, British Columbia, Canada, and central and southern California, USA. The virus was also isolated from Pacific mackerel Scomber japonicus in southern California, from eulachon or smelt Thaleichthys pacificus, and surf smelt Hypomesus pretiosus pretiosus from Oregon, USA. Mortality and skin lesions typical of viral hemorrhagic septicemia in other marine fish species were observed among sardine in Canada and in a few surf smelt from Oregon, but the remaining isolates of VHSV were obtained from healthy appearing fish. The prevalence of VHSV among groups of apparently healthy sardine, mackerel and smelt ranged from 4 to 8% in California and Oregon. A greater prevalence of infection (58%) occurred in groups of sardine sampled in Canada that sustained a naturally occurring epidemic during 1998-99. A captive group of surf smelt in Oregon exhibited an 81% prevalence of infection with clinical signs in only a few fish. The new isolates were confirmed as North American VHSV and were closely related based on comparisons of the partial nucleotide sequence of the glycoprotein (G) gene. The VHSV isolates from sardine in Canada and California were the most closely related, differing from isolates obtained from other marine fish species and salmonids in British Columbia, Canada, Alaska and Washington, USA. These new virus isolations extend both the known hosts (sardine, mackerel and 2 species of smelt) and geographic range (Oregon and California, USA) of VHSV.

A survey of wild fishes captured around marine net-pen salmon farms and from open waters for certain salmonid pathogens was conducted in the coastal waters of British Columbia. Viral hemorrhagic septicemia virus was detected in Pacific herring Clupea pallasi, shiner perch Cymatogaster aggregata, and threespine sticklebacks Gasterosteus aculeatus. Infectious hematopoietic necrosis (IHN) virus was detected in one Pacific herring (collected well away from the farms) and in tube-snouts Aulorhynchus flavidus and shiner perch collected from a farm experiencing an IHN outbreak. Renibacterium salmoninarum was observed in moribund Pacific hakes Merluccius productus collected from within a net-pen and was also detected in several ocean-caught salmon. Aeromonas salmonicida subsp. salmonicida (typical strain) was isolated from a juvenile chinook salmon Oncorhynchus tshawytscha, whereas the atypical strain of this organism was isolated from a lingcod Ophiodon elongatus. Loma salmonae (Microsporea) was observed in chinook salmon, chum salmon Oncorhynchus keta, coho salmon O. kisutch, sockeye salmon O. nerka, and pink salmon O. gorbuscha, all of which were captured well away from net-pens. Loma spp. (Microsporea) were observed in the gills of shiner perch, lingcod, Pacific tomcod Microgadus proximus, Pacific cod Gadus macrocephalus, walleye pollock Theragra chalcogramma, and sablefish Anoplopoma fimbria; all but the first species represent new hosts for Loma. Epitheliocystis, caused by a chlamydia-like organism, was detected in the gills of chinook salmon, chum salmon, coho salmon, pink salmon, lingcod, Pacific cod, Pacific hakes, Pacific tomcod, walleye pollock, sablefish, shiner perch, Dover soles Microstomus pacificus, Pacific sanddabs Citharichthys sordidus, and various species of rockfish Sebastes spp., most of which represent new host records for this infection. * Corresponding author: kent@dfo-mpo.gc.ca rhagic septicemia (VHS) virus, Renibacterium salmoninarum, Aeromonas salmonicida, Loma spp. (Microsporea), and the epitheliocystis organism.

A necrotic disease of erythrocytes of chum (Oncorhynchus keta) and pink (O. gorbuscha) salmon is described at the light and electron microscopic level. The disease is characterized by a single cytoplasmic inclusion in affected erythrocytes and by the presence of an associated intraerytnrocytic virus probably belonging to the icosahedral cytoplasmic deoxyribovirus (ICDV) group. Isolation of the virus was unsuccessful, but viral etiology was implicated by inoculation of chum and pink salmon using filtered preparations from diseased specimens of the former. Chinook (O. tshawytscha), coho (O. kisutch), andsockeye (O. nerka) salmon proved refractory. Key words: viral disease, Pacific salmon, blood, erythrocytes, anemia

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Epizootics of Ichthyophthirius multifiliis occurred in adult prespawning and spawning sockeye salmon Oncorhynchus nerka during the 1994 and 1995 spawning seasons in the Skeena River watershed in northern British Columbia, Canada. Exceedingly high mortalities occurred at Fulton River and in three spawning channels adjacent to Babine Lake. During these 2 years, the infection and subsequent death of prespawning adults resulted in an estimated 153.6 million fewer sockeye salmon fry produced from Fulton River and the three spawning channels adjacent to Babine Lake than the historical average. Resident fish were the most likely source of the parasite in the watershed because several species were found with light infections of I. multifiliis. Transmission of the parasite to anadromous sockeye salmon was enhanced by the high density of fish held below the spawning grounds for days or weeks prior to moving into the spawning channel. This is the first report of an epizootic of ichthyophthiriasis in wild spawning salmon.