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Studies with eggs of steelhead trout Salmo gairdneri (hchardson) and coho salmon Oncorhynchus kisutch (Walbaum) showed that the eggs can be infected internally with Renibacterium salmonlnarum by immersing them prior to feruzation and water-hardening in coelomic fluid containing h~g h numbers of R. salmoninarum cells. These results support our hypothesis that, in vivo, salmonid eggs acquire their intra-ovum R. salmoninarum infections from heavily infected coelomic fluid that surrounds them in 'culprit' fish following their release to the body cavity. Whether eggs are also infected early in oogenesis is stdl not known. Intra-ovum infection rates obtained were low (3.5 to 5.0 %) and did not increase if eggs were fertilized while still immersed in the infected coelomic fluid. These and other data discussed in the paper lead to the conclusion that the male salmonid plays a relatively unimportant role in the vertical transmission of R. salmoninarum. Water-hardening of experimentally infected coho salmon eggs in erythromycin did not appear to affect the intra-ovum infection rate, and fry hatching from the treated eggs carried the pathogen.

Unfertilized, water-hardened eggs, obtained from a coho salmon, Oncovhynchus kisutch (Walbaum), with coelomic fluid containing large enough numbers of the kidney disease bacterium, Renibacterium salmoninarum, to make the fluid cloudy (~4x 10^ cells/ml), were examined by cultural and histological methods to determine fa) whether an earlier finding of the pathogen in coho eggs could be corroborated, and (b) whether iodine (500 mg/l, in the form of povidone-iodine) was as effective at ridding them of the intra-ovum pathogen as it was at freeing them of the extra-ovum pathogen. The results confirmed that the pathogen does indeed occur within the egg (ll-6%-15-l % of the eggs were infected in this manner), and suggested a location in the yolk for the pathogen. The findings also indicated that while iodine was very effective in killing the pathogen on the surface of the eggs it was completely ineffective in reducing the prevalence of the intra-ovum infections. The results point out the need for a method for treating eggs internally and confirm the inadvisability of using eggs from salmonids with cloudy coelomic fluid.

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