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Results for “Journal of the Fisheries Research Board of Canada”

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100 records · Page 6Linked to original sources
USGS1978

Myxosoma cerebralis: Fluorescent antibody techniques for antigen recognition

Rabbits were immunized with antigens extracted from mature spores or prespore stages of Myxosoma cerebralis , and the resulting antisera and their globulins were used in direct and indirect fluorescent antibody techniques. Both kinds of antisera reacted with homologous spores and with stages of the organism that precede spores. When tested for specificity against spores of 12 other myxosporidans the direct fluorescent antibody technique showed cross-reactivity with only one other and that was a species of Myxosoma . The indirect fluorescent antibody technique showed some reactions across generic lines. The antisera have application in studies of the parasite's life cycle and in diagnostics.

Journal of the Fisheries Research Board of Canada↗
USGS1978

Evaluation of an aerial survey of Pacific walruses

An aerial survey of Pacific walruses ( Odobenus rosmarus divergens ) was evaluated to determine the reliability of estimates of population abundance. The probability of detecting groups of walruses on the pack ice remained uniform to at least 0.93 km from the flight line, whereas the probability of detection decreased significantly beyond 0.23 km for walruses in the water. Walruses were more abundant along the ice-edge zone between 162 and 165°W than in other areas of the Chukchi Sea during September 1975. Few walruses were observed in consolidated pack ice north of the ice-edge zone or in ice-free water to the south. More walrus groups and larger mean group size were observed on September 8 than on other days. We estimated abundance for each day and all days combined using methods based on sample area and numbers of strip samples. Estimates varied among days by over an order of magnitude; this variation is attributed to the combined effect of chance sampling of an aggregated population and variation in the fraction of walruses hauled out. The coefficient of variation of the estimates ranged between 0.25 and 0.99. This imprecision was due to the aggregated distribution of walruses and the large variation in group size. Using the survey data as a basis for stratification, we calculated that, due to the high variability within strata, a sample size of 40% of the total area or 56% of the total available strips would be required to obtain 95% confidence limits within 10% of the estimate of total abundance. Variation contributed by observer error in estimating group size also is relatively unimportant to the precision of abundance estimates. Studies of natural history, particularly those oriented toward activity and habitat selection, would help investigators estimate bias due to the variable fraction hauled out and design surveys based on meaningful strata. Estimates of total abundance based on limited survey efforts will provide information of little reliability.

Journal of the Fisheries Research Board of Canada↗
USGS1978

Rapid method for determining concentrations of Bayer 73 in water during lampricide treatments

Two simple, rapid, sensitive methods were developed for determining the concentration of the lampricide 2',5-dichloro-4'-nitrosalicylanilide (Bayer 73) in stream water. Bayer 73 was extracted from acidified water samples with chloroform and then hydrolyzed to 2-chloro-4-nitroaniline (CNA) with either acid or base. The CNA was diazotized with sodium nitrite, and an azo dye was formed with either N -( 1-naphthyl) ethylenediamine dihydrochloride (after acid hydrolysis) or 1-naphthol (after base hydrolysis). There was no interference from the lampricide 3-trifluoromethyl-4-nitrophenol (TFM) in either method. Standard curves were prepared with untreated water to compensate for interfering substances that occurred naturally in some streams. The methods were sensitive to about 0.005 mg/L (ppm). Time required for analysis of a sample ranged from 25 min to 1 h.

Journal of the Fisheries Research Board of Canada↗
USGS1978

A von Bertalanffy growth model with a seasonally varying coefficient

The von Bertalanffy model of body growth is inappropriate for organisms whose growth is restricted to a seasonal period because it assumes that growth rate is invariant with time. Incorporation of a time-varying coefficient significantly improves the capability of the von Bertalanffy equation to describe changing body size of both the bivalve mollusc Macoma balthica in San Francisco Bay and the flathead sole, Hippoglossoides elassodon , in Washington state. This simple modification of the von Bertalanffy model should offer improved predictions of body growth for a variety of other aquatic animals.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Myxosoma cerebralis: A method for staining spores and other stages with silver nitrate

Eleven dye substances were tested for their ability to stain Myxosoma cerebralis and to be retained through either the pepsin-trypsin-dextrose or the plankton centrifuge method of releasing and concentrating spores. Silver nitrate proved to be the best; it produced a distinctive brown color that has been retained by spores through 2.5 yr of storage. The method has applications in histologic studies of whirling disease, in quantifying the efficiency of spore detection procedures, and in teaching.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Immersion vaccination of sockeye salmon (Oncorhynchus nerka) with two pathogenic strains of Vibrio anguillarum

Sockeye salmon ( Oncorhynchus nerka ) were immersion-vaccinated in suspensions containing 5 × 10 7 , 5 × 10 6 , 5 × 10 5 , or 5 × 10 4 bacteria/mL of bivalent or monovalent, formalin-killed Vibrio anguillarum , Types I and II. The fish were split into two lots and held for 54 d. At that time one lot was challenged with living, virulent V . anguillarum , Type I, and one with living, virulent V . anguillarum , Type II. Immunization with bivalent bacterin effectively protected the fish from vibriosis, but monovalent vaccine was effective only against the homologous challenge. Immunization with the highest concentration of Type I monovalent bacterin resulted in 0% Type I and 58% Type II challenge mortality. Immunization with the highest concentration of Type II monovalent bacterin resulted in 41% Type I and 0% Type II challenge mortality. Immunization with the highest concentration of bivalent Type I/Type II bacterin resulted in 2% mortality in both challenges. Protective bacterins were effective at concentrations down to 5 × 10 5 bacteria/mL. Key words : immersion vaccination, bivalent vaccines, Vibrio anguillarum , vibriosis.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Plaque-forming cells and humoral antibody in rainbow trout (Salmo gairdneri) induced by immersion in a Yersinia ruckeri O-antigen preparation

Rainbow trout ( Salmo gairdneri ) were exposed to the O-antigen of Yersinia ruckeri by various immunization regimens. The passive hemolytic plaque assay was used to show specific splenic plaque-forming cells (PFC) and passive hemagglutination demonstrated humoral antibody titers in fish injected with or immersed in the antigen preparations. Preceding antigen immersion with a 2-min immersion in either a 5.2 or a 2.6% NaCl solution did not affect the numbers of PFC or levels of antibody. Fish held for 2 min in ethyl m -aminobenzoate methanesulfonate (MS-222 ® ) before antigen immersion showed no significant difference from the control fish. Dosage studies showed that the minimal concentration of antigen for induction of PFC by immersion was 5.0 μg/mL.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Exploitation of marine mammals: r-selection of K-strategists?

The importance of marine mammals as predators to the organization of marine communities is poorly known, although in several structurally analogous systems the ecological and evolutionary roles of predators are known to be of considerable importance. Occupation of the marine environment by mammals probably carried physiological constraints for single-young pregnancies thereby limiting all species to low intrinsic rates of population increase. As such, species subjected to high mortality rates from predation or other natural disturbances became extinct; those that survived probably were largely resource limited. In view of this scenario it is suggested that stable populations of marine mammals can be maintained at high levels without being manipulated in most communities. Exploitation probably constitutes a rather dramatic environmental change to marine mammals consequently subjecting them to selective forces fundamentally different from many of those under the influence of which they evolved.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Chloride inhibition of nitrite-induced methemoglobinemia in channel catfish (Ictalurus punctatus)

Exposure of channel catfish (Ictalurus punctatus) fingerlings for 24?h to 1.0, 2.5, and 5.0?mg/L nitrite (pH?=?7; hardness?=?40?mg/L; temperature?=?22–25 °C) produced methemoglobin levels of 20.7?±?1.9%, 59.8?±?1.9%, and 77.4?±?1.4% (SE), respectively. However, methemoglobin levels were not elevated when fish were simultaneously exposed to 1.0, 2.5, and 5.0?mg/L nitrite and 25, 50, and 100?mg/L sodium chloride, respectively. Acclimation to sodium chloride for 24?h before exposure to nitrite did not enhance the inhibitory action of sodium chloride. Fish exposed to 5?mg/L nitrite for 5?h developed 42.5?±?3.8% methemoglobin. When transferred to water containing 5?mg/L nitrite and 250?mg/L sodium chloride, methemoglobin levels returned to normal within 24?h. Environmental chloride probably inhibits methemoglobin formation by competing with nitrite for entrance into the gills of the fish. An ionic ratio of 16 Cl - to 1 NO 2 - is capable of complete suppression of nitrite-induced methemoglobin formation. Bicarbonate ion present in the test water (1?meq/L) may also have contributed to the inhibitive action of chloride.

Journal of the Fisheries Research Board of Canada↗
USGS1979

Fish viruses: A double-stranded RNA icosahedral virus from a North American cyprinid

A previously unreported virus disease of cultured golden shiners ( Notemigonus crysoleucas ) is described. The condition is called golden shiner virus (GSV) disease. The virus is icosahedral, measures approximately 70 nm, is ether and heat resistant, stable at pH 3, 7, and 10, and appears to have a double stranded RNA core. It was not neutralized by infectious pancreatic necrosis virus specific antiserum. GSV causes syncytial like cytopathic effect in fathead minnow cells but not brown bullhead, rainbow trout gonad (RTG-2) or channel catfish ovary cells. Severe mortalities in golden shiner culture ponds do not appear to be associated with GSV infections.

Journal of the Fisheries Research Board of Canada↗