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At least 253 records · Page 14Linked to original sources

Control of infectious Hematopoietic Necrosis virus disease by elevating the water temperature

Studies were performed to determine if increasing water temperatures could control infectious hematopoietic necrosis virus (IHN) disease in sockeye salmon ( Oncorhynchus nerka ). Mortalities could be prevented if the water temperature was raised to at least 18 C within the first 24 hr after infection of the fish and if the fish were maintained at this temperature for 4–6 days. The disease did not recur after the elevated temperature treatment, but the fish would still contract the disease if they were reinfected. Reasons for the protecting action are discussed.

Journal of the Fisheries Research Board of Canada↗

Concentrations of trace elements in Great Lakes fishes

The concentration of 15 trace elements was determined by activation analysis of samples of whole fish and fish livers from three of the Great Lakes: Michigan, Superior, and Erie. The average concentrations of 7 elements in 19 whole fish from 3 species were as follows: uranium, 3ppb (parts per billion); thorium, 6ppb; cobalt, 28ppb; cadmium, 94ppb; arsenic, 16ppb; chromium, 1ppm; and copper, 1.3ppm. The average concentrations of 8 elements in 40 liver samples from 10 species of fish were as follows: uranium, 2ppb; thorium, 2ppb; cobalt, 40ppb; copper, 9ppm; zinc, 30ppm; bromine, 0.4ppm; arsenic, 30ppb; and cadmium, 0.4ppm. Other elements observed in most of the samples were: antimony, 5100ppb; gold, 25ppb; lanthanum, 120ppb; rhenium, 0.55ppb; rubidium, 0.064ppm; and selenium, 0.12ppb.Trace element concentrations varied with species and lake. Uranium and thorium varied with species, but not for the same species from different lakes. The levels of copper, cobalt, zinc, and bromine varied little between species and lakes. The concentration of cadmium, arsenic, and chromium varied between species and with species between lakes.

Great Lakes↗

Stress of anesthesia with M.S. 222 and Benzocaine in Rainbow Trout (Salmo gairdneri)

Rainbow trout ( Salmo gairdneri ) anesthetized with M.S. 222 for periods up to 12 min experience interrenal ascorbate depletion, uremia, and moderate hypercholesterolemia. Anesthesia with neutralized M.S. 222 ( p H 7) or benzocaine prevented these changes and significantly reduced the variability in plasma glucose, cholesterol, and cortisol, indicating that the stress of anesthesia with M.S. 222 is due to the low p K of the sulfonic acid moiety.

Journal of the Fisheries Research Board of Canada↗

Occurrence of whirling disease of trout in western United States

Whirling disease of trout, caused by Myxosoma cerebralis , was diagnosed in 1966 for the first time in rainbow trout ( Salmo gairdneri ) from California and Nevada hatcheries. In 1969 the first incidence of this disease in cutthroat trout ( S . clarki ) was reported in Nevada. To date these have been the only confirmed cases of whirling disease in western United States.

Western United States↗

Some blood chemistry values for the Rainbow Trout (Salmo gairdneri)

Normal distribution curves were graphically fitted to approximately 1400 clinical test values obtained from the plasma or kidney tissue of more than 200 yearling rainbow trout ( Salmo gairdneri ). Estimated normal ranges were ascorbate, 102–214 μg/g; blood urea nitrogen (BUN), 0.9–4.5 mg/100 ml; chloride, 84–132 mEq/liter; cholesterol, 161–365 mg/100 ml; cortisol, 1.5–18.5 μg/100 ml; glucose, 41–151 mg/100 ml; and total protein, 2–6 g/100 ml.

Journal of the Fisheries Research Board of Canada↗

Morphology of certain viruses of Salmonid Fishes. I. in vitro studies of some viruses causing Hematopoietic Necrosis

An electron microscope study was performed on three virus isolates that caused hematopoietic necrosis in salmonid fishes: infectious hematopoietic necrosis (IHN), Oregon Sockeye Disease (OSD), and Sacramento River Chinook Salmon Disease (SRCD). All three isolates were examined by negative staining of fathead minnow (FHM) monolayer tissue culture concentrates and IHN virus was also examined in thin sections of FHM cells. Viruslike particles were observed in infected tissues, but similar structures were not found in uninfected cultures. All three isolates were bullet-shaped, but oval and truncated forms were also observed. Mean measurements of particles from IHN-virus-infected tissue were 158 × 90 mμ. They consisted of an outer coat 15 mμ thick, a core 60 mμ in diameter, subunits about 5 mμ, and an axial pore about 20 mμ in diameter. These particles also were seen budding from the cytoplasmic membrane. Similar particles from SRCD were 159 × 90 mμ and isolates from OSD were 181 × 91 mμ. The three isolates were morphologically indistinguishable from one another and the greater length of OSD was considered insignificant. IHN, SRCD, and OSD viruses were tentatively placed in the rhabdovirus group, but serological studies are needed to determine if they are antigenically identical or should be included as separate members. Biochemical and physical characteristics of these viruses and a comparison with other salmonid viruses is also discussed.

Journal of the Fisheries Research Board of Canada↗

Morphology of certain viruses of Salmonid fishes. II. In vivo studies of infectious Hematopoietic Necrosis Virus

Juvenile sockeye salmon ( Oncorhynchus nerka ) were injected with the infectious hematopoietic necrosis (IHN) virus, and tissue samples from the anterior kidney, spleen, liver, intestine, and pyloric caeca of moribund fish were prepared for electron microscopy. Bullet-shaped virus particles measuring 158 × 90 mμ were observed in the hematopoietic tissues of the anterior kidney and spleen. Virus particles were also observed in the outer connective tissues of the pancreas or pyloric caeca, or both. No virus was found in the intestine or liver. The healthy appearance of erythrocytes, reticular cells, and endothelial cells in necrotic areas of the spleen and anterior kidney, and the absence of lymphocytes in these areas, suggested that lymphocytes might be one source of the virus.

Journal of the Fisheries Research Board of Canada↗

Precipitating antibody against Aeromonas salmonicida in serums of inbred albino Rainbow Trout (Salmo gairdneri)

Precipitins in albino rainbow trout serums were demonstrated by gel diffusion after a single parenteral exposure to the soluble antigens of Aeromonas salmonicida . The fraction of the serum containing antibody activity against the presented antigens was shown by immunoelectrophoresis to be in the nonmigrating region. This corresponded to the beta-2 fraction of rabbit serum. An antibody-containing component comparable with rabbit gamma globulin was not detected.

Journal of the Fisheries Research Board of Canada↗

Walleye fishery of Lake Erie in 1943-62 with emphasis on contributions of the 1942-61 year-classes

The commercial fishery for walleyes ( Stizostedion vitreum vitreum ) in Lake Erie virtually collapsed in the late 1950's. The extreme decline in production was attributed primarily to a succession of weak year-classes, caused by habitat deterioration (increased water temperatures, enrichment, and pollution) in western Lake Erie. Unusually high fishing intensity and high yields of walleyes in the mid-1950's contributed to the collapse.Annual lakewide production of walleyes dropped from a record high of 15 million lb in 1956 to a record low of 717,000 lb in 1962. Canadian catches exceeded those of the United States only during the high production years of 1956–58; U.S. fishermen took 71% of the total catch in 1915–62.On the basis of the numbers of fish of the various year-classes in the fall trapnet samples at Sandusky, Ohio, in 1943–62, all but one of the 1942–52 year-classes were above average strength, and all but one of the 1953–61 year-classes were below average. Fish of the 1953–61 year-classes grew much faster than those of the 1942–52 year-classes. The strong 1948 year-class was followed by a series of progressively weaker year-classes until 1958; year-class strengths remained low through 1962.

Journal of the Fisheries Research Board of Canada↗

Metamorphosis of the landlocked sea lamprey, Petromyzon marinus

The external metamorphosis of the sea lamprey was divided into four stages, based primarily on the condition of the mouth: mouth reduced, mouth fused, mouth enclosed, and mouth elongated. During metamorphosis, the eye enlarged greatly, the snout and mouth region changed from a fleshy hood enclosing a sieve apparatus to a large sucking disc, the nasopore membrane and the branchial area shrank, the branchiopores changed in shape, the general color changed from dark brown and yellow to an intense blue-black dorsally and white ventrally, and the total length increased. Metamorphosis began in early to mid-July and did not take place after August. The duration of external metamorphosis was about 3 months for lampreys transforming under natural conditions. The mean lengths of metamorphosing lampreys from tributaries of lakes Superior and Michigan were 145 and 136 mm, respectively.

Journal of the Fisheries Research Board of Canada↗

Temperature tolerance of bloater ( Coregonus hoyi )

Juvenile and young adult bloaters ( Coregonus hoyi ) were tested for tolerance to high temperatures. The ultimate upper lethal temperature of juvenile bloaters (26.75 C) appeared to be slightly higher than that of young adult bloaters, but was similar to that of juvenile ciscoes, Coregonus artedii (26.0 C), the only other North American coregonine for which a detailed description of temperature tolerance has been published.Regression equations are given that permit estimation of the thermal tolerance when the lethal temperatures are incompletely known. The estimated thermal tolerance of juvenile bloaters (617 units) was slightly less than that of the brook trout ( Salvelinus fontinalis ; 625 units), but was higher than that of other Salmonidae.

Journal of the Fisheries Research Board of Canada↗

Population biology of lake trout ( Salvelinus namaycush ) of Lake Superior before 1950

Scale samples collected in 1948 were used to estimate the instantaneous total mortality rate (0.70) and growth for lake trout ( Salvelinus namaycush ) in Lake Superior before the population had been significantly reduced by the sea lamprey ( Petromyzon marinus ). Indirect evidence indicates that the instantaneous natural mortality rate was probably 0.10–0.25. The Ricker model was used to calculate yield per recruitment, which varied with natural mortality and growth. Natural mortality was more critical than growth; yield per recruitment increased 183.3% with a 60% decrease in instantaneous natural mortality (from 0.25 to 0.10). For the prelamprey lake trout population the yield per recruitment was about 12–34 lb; the recruitment of about 3.6–10.1 million lake trout of age 1.5 resulted in an annual commercial production of 4 million lb.

Journal of the Fisheries Research Board of Canada↗

Plotting of bathythermograph transect data on a printer

A program for plotting bathythermograph transect data on a computer (IBM 1130) printer is available from the Great Lakes Fishery Laboratory. Temperature values are printed in positions proportional to their depths and distances from shore. Contour lines are drawn manually through the plotted points.

Journal of the Fisheries Research Board of Canada↗

Sampling of fish muscle for M.S.222 and quinaldine residues

Large variations in concentrations of M.S. 222 (tricaine methanesulfonate) and quinaldine (2-methylquinoline) residues occurred in various areas of fish fillets. Residue analyses of replicate samples from homogenized fillets yielded more representative results than samples cut from various areas of fillets.

Journal of the Fisheries Research Board of Canada↗

Some blood chemistry values for the juvenile coho salmon (Oncorhynchus kisutch)

Overlapping Gaussian distribution curves were resolved into normal ranges for 1800 clinical test values obtained from caudal arterial blood or plasma of more than 1000 juvenile coho salmon ( Oncorhynchus kisutch ) held under defined conditions of diet and temperature. Estimated normal blood chemistry ranges were bicarbonate, 9.5–12.6 mEq/liter; blood urea nitrogen (BUN), 0.9–3.4 mg/100 ml; chloride, 122–136 mEq/liter; cholesterol, 88–262 mg/100 ml; p CO 2 , 2.6–6.1 mm Hg (10 C); glucose, 41–135 mg/100 ml; hematocrit, 32.5–52.5%; hemoglobin, 6.5–9.9 g/100 ml; total protein, 1.4–4.3 g/100 ml; blood p H (10 C), 7.51–7.83. The calculated range of normal acid–base balance vs. water temperature is also presented.

Journal of the Fisheries Research Board of Canada↗

Giant American brook lampreys, Lampetra lamottei , in the upper Great Lakes

Five female American brook lampreys, Lampetra lamottei , collected in lakes Michigan and Huron averaged nearly twice as long and about six times as heavy as American brook lampreys of normal size. Three factors suggested that the giant lampreys may have fed parasitically after metamorphosis: morphological adaptations of the species for parasitic life, their large size, and absence of extremely large ammocetes among a million sampled.

Journal of the Fisheries Research Board of Canada↗

The stress of Formalin treatments in rainbow trout (Salmo gairdneri) and coho salmon (Oncorhynchus kisutch)

Changes in gill function, acid–base balance and pituitary activation occurring during standard 200 ppm formalin treatments of juvenile rainbow trout ( Salmo gairdneri ) and coho salmon ( Oncorhynchus kisutch ) were compared. Plasma Cl − , Ca ++ , total CO 2 , and interrenal vitamin C in the trout declined continuously and in proportion to the exposure time, but the salmon were able to maintain these metabolic parameters at approximately initial levels. Blood p H and alkaline reserve regulation of the salmon was also less affected by formalin treatments, especially during prolonged exposures. The oxygen consumption of both species was depressed, but substantially more so in the trout than could be accounted for by decreased ventilation rates. Little frank hemolysis occurred in either species, but there was a significant bilirubinemia in the trout.

Journal of the Fisheries Research Board of Canada↗

Virucidal activity of two Iodophors to salmonid viruses

Wescodyne ® and Betadine ® , organic iodine complexes, were compared in vitro for virucidal activity against infectious hematopoietic necrosis (IHN), infectious pancreatic necrosis (IPN), and viral hemorrhagic septicemia (VHS) viruses. Both iodophors were about equally effective on all three viruses. Each iodophor completely destroyed IHN virus within 30 sec at 12 ppm iodine, and was not affected by water hardness. Virucidal activity, however, was reduced at p H levels above 8.0 and in the presence of organic matter. Wescodyne was also compared with seven disinfectants commonly used in fish hatcheries, for virucidal properties against IHN virus. Wescodyne and chlorine were the only disinfectants to completely destroy the virus. Either Wescodyne or Betadine would effectively destroy the salmonid viruses at less than 25 ppm iodine within 5 min in solutions near neutrality.

Journal of the Fisheries Research Board of Canada↗