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W. T. Yasutake

Publications and source records attributed to W. T. Yasutake.

At least 19 recordsLinked to original sources
USGS2006

Virus diseases of salmonidae in the western United States. II. Aspects of pathogenesis

During the 10 to 15 years investigators from Europe and eastern United States have reported fish diseases of virus etiology. Rucker et al. in 1953 were the first to report a disease of possible virus origin in fish in the western United States. Since then many workers in the western states have described various epizootics caused by transmissible and filterable agents. The etiology and pathology of epizootics reported to date have been three viral diseases: (1) specific for sockeye salmon (Onchorhynchus nerka), (2) specific for chinook salmon (O. tshawytacha); and (3) isolated from rainbow trout (Salmo gairdneri). brook trout (Salvalinus fontinalis). and cutthroat trout ( Salmo clarkii). The most recent historical, etiological and morphological study of diseases of viral and possible viral origin occurring the West has been reported in detail by Parisot et al. With the exception of two investigations, histopathological accounts have been brief and cursory and, to date, pathogenesos of these viral diseases have not been recorded. This study was undertaken to initiate a series concerning pathogeneses of infectious diseases of salmonids. The two viral diseases covered in this paper are the Oregon sockeye disease (OSD) and Sacramento River chinook disease (SRCD). Some preliminary data on pathology of the corresponding material from the hatchery epizootics will also be described and discussed.

Annals of the New York Academy of Sciences↗
USGS2006

Some potentials and limits of the leucocrit test as a fish health assessment method

The sensitivity of the leucocrit as a stress tolerance and fish health assessment method was evaluated by subjecting juvenile coho salmon, Oncorhynchus kisutch , or steelhead trout, Salmo gairdneri , to standardized crowding, handling, temperature and disease challenges. The leucocrit was a sensitive indicator of the physiological stress resulting from crowding at population densities of 0·2–0·4 kg l −1 , and to the stress of handling and to temperature changes. It was relatively insensitive to physiological sampling procedures which supports its continued development as a stress assessment method. In the case of fish diseases, subclinical or active Renibacterium salmoninarum and Yersinia ruckeri infections had essentially no effect on leucocrit values. In contrast, active Aeromonas salmonicida infections significantly depressed the leucocrit. However, no change was seen during the subclinical (incubation) phase prior to the development of an epizootic. Thus, the potential of the leucocrit as a fish health assessment method appears limited.

Journal of Fish Biology↗
USGS1989

Spiral swimming behavior due to cranial and vertebral lesions associated with Cytophaga psychrophila infections in salmonid fishes

C. psychrophila infections of the cranium and anterior vertebrae in salmonid fishes were associated with ataxia, spiral swimming along the axis of the fish, and death. The syndrome was observed in 2-10% of underyearling coho salmon Oncorhynchus kisutch, rainbow trout Salmo gairdneri, and steelhead trout S. gairdneri at several private, state, and federal hatcheries in Washington and Oregon, USA, between 1963 and 1987. Affected fish did not recover and ultimately died. Histological examination consistently revealed subacute to chronic periostitis, osteitis, meningitis, and ganglioneuritis. Inflammation and periosteal proliferation of the anterior vertebrae at the junction of the vertebral column with the cranium with extension into the cranial case was a consistent feature. The adjacent nervous tissue, particularly the medulla, was often compressed by the proliferative lesion, and this may have caused the ataxia. Though bacteria were seldom observed in these lesions. C. psychrophila was isolated in culture from the cranial cavity of all affected fish that were tested. Epidemiological observations suggested that this bacterium is the causative agent because the spiral swimming behaviour and lesions were observed only in populations that had recovered from acute C. psychrophila infections.

Diseases of Aquatic Organisms↗
USGS1987

Summer spawning in the fourhorn sculpin, Myoxocephalus quadricornis, from Alaska

Histological ovarian analysis indicates summer spawning occurs in Myoxocephalus quadricornis (Fourhorn Sculpin) from Alaska. Previous studies have shown this species spawns during winter in the Baltic Sea; the data presented herein suggests that geographical variation may occur in the timing of spawning of this species.

Alaska↗
USGS1986

Parasite burdens in experimental families of coho salmon.

We examined the possibility that parasites affect survival rates of anadromous hatchery coho salmon Oncorhynchus kisutch during their period in the wild. Survival was estimated from the rates at which adults returned to the hatchery. The frequency of infection of heart tissue by metacercariae of Nanophyetus sp. was higher in individuals from families with relatively high survival. Various degrees of parasitic and bacterial infection were observed in all groups. We frequently saw extensive infection and tissue reaction to trophozoites of Ceratomyxa sp. (probably C. shasta) in the apparent absence of spores, suggesting that the clinical method now used to determine the presence of Ceratomyxa infection needs to be reassessed.

Transactions of the American Fisheries Society↗
USGS1986

A hermaphroditic Arctic flounder, Liopsetta glacialis (Pleuronectidae), from Alaska

We discovered a hermaphrodite Liopsetta glacialis while examining tissues from a sample of 30 representatives of this species for a histopathological survey of fishes from the Beaufort Sea, Alaska. L. glacialis occurs in the Arctic Ocean from Queen Maude Gulf in arctic Canada, along the North American and Siberian coasts to the White Sea and Barents Sea (Morrow, 1980). The specimen was collected from Beaufort Lagoon on July 29, 1984, weighed 15, measured 100 mm (total length) and was between 3 and 4 years old.

Alaska↗
USGS1985

Direct fluorescent antibody technique for the detection of bacterial kidney disease in paraffin-embedded tissues

The direct fluorescent antibody technique (FAT) was successfully used to detect the causative agent of bacterial kidney disease (BKD), Renibacterium salmoninarum, in Bouin's solution flexed and paraffinembedded egg and tissue sections. This method is superior to gram stain and may be particularly useful in detecting the BKD organism in fish with low-grade infection.

Fish Pathology↗
USGS1984

Effects of freshwater exposure to arsenic trioxide on the parr-smolt transformation of coho salmon ( Oncorhynchus kisutch )

The effects of chronic (6 months) exposure to arsenic trioxide in fresh water on the Parr-smolt transformation of coho salmon ( Oncorhynchus kisutch ) were evaluated. Exposure to 300 μg As/L (as As 2 O 3 ) appeared to delay the onset of the normal increase in plasma thyroxine concentration and cause a transient reduction of gill Na + ,K + -ATPase activity. Fish exposed to 300 μg As/L also migrated to the sea less successfully than did nonexposed smolts, but there were no effects on the survival and growth of smolts held in 28‰ salt water for 6 months.

Environmental Toxicology and Chemistry↗
USGS1975

Phoma herbarum , a fungal plant saprophyte, as a fish pathogen

Phoma herbarum , a fungal plant saprophyte, was isolated from diseased hatchery-reared coho salmon ( Oncorhynchus kisutch ), chinook salmon ( O . tshawytscha ), and rainbow trout ( Salmo gairdneri ). The disease was observed at 10 national fish hatcheries in Washington and Oregon, but the low incidence of experimental infections indicate that it is only weakly contagious. Histopathological examination suggests that the air bladder is one of the primary organs infected. The visceral organs are also affected in both natural and experimental infections.

Journal of the Fisheries Research Board of Canada↗
USGS1973

Scolecobasidium humicola , a fungal pathogen of fish

Scolecobasidium humicola , a previously undescribed fungal pathogen of fish was isolated from coho salmon ( Oncorhynchus kisutch ). In natural infections the kidney was the organ most affected. The disease was difficult to transmit experimentally and appeared to be only weakly contagious.

Journal of the Fisheries Research Board of Canada↗
USGS1973

Stress of formalin treatment in juvenile spring chinook salmon (Oncorhynchus tshawytscha) and steelhead trout (Salmo gairdneri>)

The physiological stress of 200 ppm formalin treatments at 10 C is more severe in the juvenile steelhead trout ( Salmo gairdneri ) than in the spring chinook salmon ( Oncorhynchus tshawytscha ). In the steelhead, a marked hypochloremia follows a 1-hr treatment and recovery requires about 24 hr. During longer treatments, hypercholesterolemia together with reduced regulatory precision, hypercortisolemia, alkaline reserve depletion, and hypocapnia unaccompanied by a fall in blood p H occur — suggestive of compensated respiratory alkalosis. In the spring chinook, hypochloremia and reduced plasma cholesterol regulatory precision are the significant treatment side effects but recovery requires only a few hours. Formalin treatments also cause epithelial separation, hypertrophy, and necrosis in the gills of both fishes but again, consistent with the physiological dysfunctions, these are more severe in the steelhead.

Journal of the Fisheries Research Board of Canada↗
USGS1970

An obscure disease of rainbow trout

An annul mortality among Rainbow Trout (Salmo gairdneri) has plagued the Shelton Hatchery of the Washington State Department of Game for the last several years. No infectious agent could be isolated from the moribund fish, but histopathologica1 changes in the liver of 1-month-old fish suggested the presence of a toxic substance. Scoliosis in 3-month-old fish suggested a possible deficiency in vitamin C. With this background in mind, we designed studies to determine the nature and source of possible toxicants and the role of vitamin C deficiency in the etiology of this disease.

Progressive Fish-Culturist↗