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Results for “Canadian Journal Fisheries and Aquatic Sciences”

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At least 397 records · Page 22Linked to original sources
USGS1991

Tumor frequencies in walleye ( Stizostedion vitreum ) and brown bullhead ( Ictalurus nebulosus ) and sediment contaminants in tributaries of the Laurentian Great Lakes

To better characterize neoplasm epizootics in the Great Lakes basin and their association with families of contaminants, we sampled five locations: the Fox and Menominee rivers, Lake Michigan; Munuscong Lake, St. Mary's River; and the Black and Cuyahoga rivers, Lake Erie. Frequencies of external and liver tumors were determined for brown bullhead ( Ictalurus nebulosus ) from all locations except the Black River and for walleye ( Stizostedion vitreum ) from the Lake Michigan and St. Mary's River sites. Sediment samples were analyzed for metals, polychlorinated aromatics, and polynuclear aromatic hydrocarbons (PAH). Liver neoplasms occurred in brown bullhead from the Cuyahoga River and Munuscong Lake; brown bullhead captured from Munuscong Lake were older than those collected from the other locations. Brown bullhead from these same two rivers had elevated hepatosomatic indexes. No liver neoplasms were found in brown bullhead from the Fox and Menominee rivers, although polychlorinated aromatics were highest in both Fox River sediment and Fox and Menominee brown bullhead, and arsenic was highest in Menominee River sediment and fish. Liver neoplasms in brown bullhead from the Cuyahoga River fit the prevailing hypothesis that elevated PAH in sediment can induce cancer in wild fish. The cause of the liver neoplasms in Munuscong Lake brown bullhead is undetermined.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1991

Nature and time course of acclimation to aluminum in juvenile brook trout ( Salvelinus fontinalis ): II. Gill histology

Gill samples from juvenile brook trout ( Salvelinus fontinalis ) acclimated to low-level aluminum at pH 5.2 showed severe damage by day 4, with necrosis and fusion of secondary lamellae and hyperplasia and hypertrophy of mucous cells. Over the following 20 d, there was a continual process of repair with proliferation and hypertrophy of mucous cells. Qualitative analysis of gill samples plus physiology and mortality data collected in a companion study indicated progressive development (by day 10 onward) of increasing acclimation to Al. Quantitative analysis of gill samples on day 13 showed that mucous cell volume density had tripled and mucous cell area had doubled in Al-exposed fish compared with control fish. A lamellar fusion index showed evidence of fusion in Al-exposed fish by day 4 with recovery to nearly control levels by day 13. Physiological disturbances appear to be directly related to the histological changes observed in the gill epithelium. At the cellular level, changes in either mucous cell production and secretion or changes in mucus chemistry contribute, in part, to acclimation to Al.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1991

U.S. federal policies, legislation, and responsibilities related to importation of exotic fishes and other aquatic organisms

Within the Federal government, the U. S. Fish and Wildlife Service (Service) has primary responsibility for legal and policy responsibility for introduced exotic species. The Lacey Act of 1900 authorizes the Service to prohibit the importation of species that are potentially injurious to native fish and wildlife. However, regulations under authority of the Lacey Act cover only a few species. The Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990 established a Task Force co-chaired by the Director of the Service and Under Secretary of Commerce for Oceans and Atmosphere. The Task Force consults with the Secretary of Transportation to develop regulations to prevent the importation and spread of aquatic nuisance species into the Great Lakes through exchange of ballast water. Federal agencies must comply with Presidential Executive Order 1198, Exotic Organisms, that prohibits Federal agencies or activities they fund or authorize from introducing exotic species. The Service conducts research and evaluation of exotic species to support Federal, State, and local efforts to prevent further importation of harmful species. Effective regulation will also depend on the full cooperation with Canada.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1992

Phosphate and iron limitation of phytoplankton biomass in Lake Tahoe

Bioassays were carried out to assess the response of inoculated, single-species diatom populations (Cyclotella meneghiniana and Aulocosiera italica) to additions of synthetic chelators and phosphate. A chemical speciation model along with the field data was also used to predict how trace metal speciation, and hence bioavailability, was affected by the chelator additions. Results suggest that phosphate was limiting to phytoplankton biomass. Other solutes, Fe in particular, may also exert controls on biomass. Nitrate limitation seems less likely, although Fe-limiting conditions may have led to an effective N limitation because algae require Fe to carry out nitrate reduction. -from Authors

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1992

Ruffe, Gymnocephalus cernuus : Newly introduced in North America

The Eurasian ruffe, Gymnocephalus cernuus , was collected from the lower St. Louis River, Lake Superior's westernmost tributary, in late summer 1987. This is the first known occurrence of the ruffe in North America. The likely vector for this species was ballast water of a transoceanic vessel dumped into the international port of Duluth-Superior located on the lower end of the St. Louis River. The ruffe is increasing in abundance and expanding its range into other tributaries and nearshore areas of Lake Superior.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1992

Food of the alewife ( Alosa pseudoharengus ) in Lake Ontario before and after the establishment of Bythotrephes cederstroemi

Diets and length–weight relationships of Lake Ontario alewife ( Alosa pseudoharengus ) in 1972 differed from those in 1988; the large cladoceran Bythotrephes cederstroemi colonized the lake during the mid-1980's. Micro-crustacean zooplankton were the dominant prey of alewife during April–October in 1972 and 1988. Although Bythotrephes was not found in 1988 net samples, it replaced other zooplankters in the alewife's diet. Typically, tailspines were the only part of Bythotrephes in alewife stomachs; their frequency was high in April–May, diminished rapidly in summer and was very low by fall. In spring 1988, alewife were in better condition than in spring 1972 and this may have been due to larger fish feeding more heavily on Bythotrephes . Variation in diet among widely separated sampling sites was due to differences in alewife abundance, stability of thermal structure, progress of zooplankton community development and distance to the mouth of the Niagara River (through which Bythotrephes probably enter the lake in summer and fall). In the Great Lakes, inter- and intralake differences in diet clearly exist, and these must be incorporated into models of alewife planktivory to gain an accurate understanding of energy flow between trophic levels.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1992

Functional response and capture timing in an individual-based model: predation by northern squawfish (Ptychocheilus oregonensis) on juvenile salmonids in the Columbia River

The behavior of individual northern squawfish ( Ptychocheilus oregonensis ) preying on juvenile salmonids was modeled to address questions about capture rate and the timing of prey captures (random versus contagious). Prey density, predator weight, prey weight, temperature, and diel feeding pattern were first incorporated into predation equations analogous to Holling Type 2 and Type 3 functional response models. Type 2 and Type 3 equations fit field data from the Columbia River equally well, and both models predicted predation rates on five of seven independent dates. Selecting a functional response type may be complicated by variable predation rates, analytical methods, and assumptions of the model equations. Using the Type 2 functional response, random versus contagious timing of prey capture was tested using two related models. ln the simpler model, salmon captures were assumed to be controlled by a Poisson renewal process; in the second model, several salmon captures were assumed to occur during brief "feeding bouts", modeled with a compound Poisson process. Salmon captures by individual northern squawfish were clustered through time, rather than random, based on comparison of model simulations and field data. The contagious-feeding result suggests that salmonids may be encountered as patches or schools in the river.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Complex interactions of multiple aquatic consumers: an experimental mesocosm manipulation

In 7-m 3 outdoor tanks filled with lake water, the presence/absence of omnivorous young-of-the- year Micropterus salmoides), zooplanktivorous Menidia beryllina , and herbivorous larval Hyla chrysocelis was experimentally manipulated. A cross-classified design was used to assess the interactive effects of these vertebrate consumers on the experimental food webs. The primary effects of the experimental manipulations on food web components were two- and three-way interactions in which the effect of a given treatment was dependent on the presence of another treatment. Results suggest that the addition or removal of consumers may not cause linear, additive changes in food webs.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Accumulation of PCBs by lake trout ( Salvelinus namaycush ): an individual-based model approach

To explain the variation in growth and in concentration of polychlorinated biphenyls (PCBs) among individual fish, an individual-based model (IBM) was applied to the lake trout ( Salvelinus namaycush ) population in Lake Michigan. The IBM accurately represented the variation in growth exhibited by the different age classes of lake trout. Uncertainty analysis of the IBM revealed that mean PCB concentration for the lake trout population was most sensitive to PCB concentration in their prey. The variability in PCB concentration among lake trout individuals was not adequately explained by the IBM, unless variation in prey fish PCBs was included in the model. To accomplish this, the simulated lake trout population was divided into subsets subjected to different levels of PCB concentration in the prey fish. Thus, model results indicated that variability in prey fish PCB concentration was an important component of the variation in PCB concnetration observed among individual lake trout comprising the Lake Michigan population.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Dissolved inorganic nitrogen composition, transformation, retention, and transport in naturally phosphate-rich and phosphate-poor tropical streams

The composition, transformation, and transport of dissolved inorganic nitrogen (DIN) was compared in waters associated with two lowland streams in Costa Rica. The Salto River is enriched by geothermal-based soluble reactive phosphorus (SRP), which raises the concentration up to 200 μg/L whereas Pantano Creek, an unimpacted tributary, has an SRP concentration <10 μg/L. Ammonium concentration in springs adjacent to the Salto and Pantano was typically greater than channel water (13 of 22 locations) whereas nitrate concentration was less (20 of 22 locations). Ground waters were typically high in ammonium relative to nitrate whereas channel waters were high in nitrate relative to ammonium. Sediment slurry studies indicated nitrification potential in two sediment types, firm clay (3.34 μg N∙cm −3 ∙d −1 ) and uncompacted organic-rich sediment (1.76 μg N∙cm −3 ∙d −1 ). Ammonium and nitrate amendments to each stream separately resulted in nitrate concentrations in excess of that expected after correction for dilution using a conservative tracer. SRP concentration was not affected by DIN amendment to either stream. SRP concentration in the Pantano appeared to be regulated by abiotic sediment exchange reactions whereas DIN composition and concentration were regulated by a combination of biotic and abiotic processes.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Mitochondrial DNA variation in chinook salmon and chum salmon detected by restriction enzyme analysis of polymerase chain reaction products

We analyze intraspecific mitochondrial DNA variation in chinook salmon from drainages in the Yukon River, the Kenai River, and Oregon and California rivers; and chum salmon from the Yukon River and vancouver Island, and Washington rivers. For each species, three different portions of the mtDNA molecule were amplified seperately using the polymerase chain reaction and then digested with at least 19 restrictions enzymes. Intraspecific sequence divergences between haplotypes were less than 0.01 base subsitution per nucleotide. Nine chum salmon haplotypes were identified. Yukon River chum salmon stocks displayed more haplotypes (8) occurred in all areas. Seven chinook salmon haplotypes were identified. Four haplotypes occurred in the Yukon and Kenai rviers and four occurred in the Oregon/California, with only one haplotype shared between the regions. Sample sizes were too small to quantify the degree of stock seperation among drainages, but the patterns of variation that we observed suggest utility of the technique in genetic stock identification.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Hormonal control of hepatic glycogen metabolism in food-deprived, continuously swimming coho salmon Oncorhynchus kisutch

The plasma cortisol concentration and liver cytosolic glucocorticoid receptor activities of continuously swimming, food-deprived coho salmon ( Oncorhynchus kisutch ) did not differ from those of resting, fed fish. Plasma glucose concentration was significantly higher in the exercising, starved fish, but there were no significant differences in either hepatic glycogen concentration or hepatic activities of glycogen phosphorylase, glycogen synthase, pyruvate kinase, or lactate dehydrogenase between the two groups. Total glucose production by hepatocytes did not differ significantly between the two groups; glycogen breakdown accounted for all the glucose produced in the resting, fed fish whereas it explained only 59% of the glucose production in the exercised animals. Epinephrine and glucagon stimulation of glucose production by hepatocytes was decreased in the exercised fish without significantly affecting hepatocyte glycogen breakdown in either group. Insulin prevented glycogen breakdown and enhanced glycogen deposition in exercised fish. The results indicate that food-deprived, continuously swimming coho salmon conserve glycogen by decreasing the responsiveness of hepatocytes to catabolic hormones and by increasing the responsiveness to insulin (anabolic hormone).

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1993

Genetic variability and glacial origins of yellow perch ( Perca flavescens ) in North America

Starch&ndash;gel electrophoresis was used to analyze muscle and liver tissue for variation in 13 enzymes representing 31 presumptive loci in yellow perch ( Perca flavescens ) from 13 localities scattered throughout the natural geographic range of the species in North America. Ten loci were polymorphic, but only three, alcohol dehydrogenase ( ADH-1 *), glucose-6-phosphate isomerase ( GPI-1 *), and phosphoglucomutase ( PGM-2 *), exhibited polymorphisms at relatively high frequencies across localities. Western populations were fixed for one allele at ADH-1 *, eastern populations were fixed for another allele, and populations from intermediate locations in Lake Ontario and Pennsylvania had both alleles. The distributions of alleles at GPI-1 * and PGM-2 *were similar to that of ADH-1 *, exhibiting strong differences between eastern and western populations, although the delineation was not as clear. Western populations were much less variable than eastern populations, and the distribution of alleles indicated that the two groups were derived from Mississippi and Atlantic glacial refugia. Populations near the physiographic discontinuity between the Mississippi and Atlantic drainages in western New York and Pennsylvania exhibited an admixture of typically western and eastern alleles. Such observations are consistent with the mixed faunal history of the region and limited postglacial dispersal of western and eastern populations across the boundary.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Northern squawfish Ptychochelius oregonensis, O2 consumption rate: Effects of temperature and body size

Northern squawfish, Ptychocheilus oregonensis (live weight range 0.361–1.973 kg), O 2 consumption was measured with temperature-controlled, flow-through respirometers for >24 h. Mean standard O 2 consumption rate of northern squawfish increased with acclimation temperature: 24.3, 49.1, 75.0, and 89.4 mg∙kg −0.67 ∙h −1 at 9, 15, 18, and 21 °C, respectively. Q 10 analysis showed that O 2 consumption rate temperature sensitivity was greatest at the intermediate acclimation temperatures (15–18 °C, Q 10 = 4.10), moderate at the lower acclimation temperatures (9–15 °C, Q 10 = 3.23), and lowest at the higher acclimation temperatures (18–21 °C, Q 10 = 1.80). Overall Q 10 was 2.96 (9–21 °C). Body size ( W , grams) and temperature ( T , degrees Celcius) were related to O 2 consumption ( , grams per gram per day) by W −0.285 ∙ e 0.105 T . Northern squawfish red to white muscle ratios significantly exceeded those of rainbow trout, Oncorhynchus mykiss , in cross sections at 50 and 75% of standard length. High metabolic rates and red to white muscle ratios argue for comparability of northern squawfish with active predators such as sympatric rainbow trout.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Temperature and CO2 Effects on Blood O2 Equilibria in Northern Squawfish, Ptychocheilus oregonensis

In vitro blood O 2 equilibrium curves were constructed at 9, 15, 18, and 21 °C from temperature-acclimated northern squawfish, Ptychocheilus oregonensis . At low (<1 mm Hg, 1 mm Hg = 133.32 Pa), P 50 s generally showed variable increases with temperature from 3.6 mm Hg at 9 °C to 8.7 mm Hg at 21 °C, leading to whole-blood temperature effects (Δ H , kilocalories per mole O 2 ) ranging from a low +4.4 at 15–18 °C to a peak −21.2 at 18–21 °C. High- (7.6 mm Hg) conditions decreased blood pH and increased P 50 s at each temperature (Bohr factor). Bohr factors (Φ) ranged from −0.46 at 21 °C to −0.70 at 18 °C. Considered together, Δ H and Φ values suggest an optimal temperature range of 15–18 °C for hemoglobin O 2 loading and unloading in northern squawfish. Nonbicarbonate buffer values ranged from −10.04 at 21 °C to −14.13 at 9 °C. Overall, the high O 2 affinities and hyperbolic blood O 2 equilibrium curves of northern squawfish resemble those of other large cyprinids (e.g., common carp, Cyprinus carpio , tench, Tinca tinca , Sacramento blackfish, Orthodon microlepidotus ) indicating a better ability to tolerate hypoxic environments than sympatric rainbow trout, Oncorhynchus mykiss . High northern squawfish blood O 2 capacities and Φs suggest high aerobic capacity, especially at temperatures <21 °C.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Why are the PCB concentrations of salmonine individuals from the same lake so highly variable?

An individual-based model (IBM) was applied to the Lake Michigan rainbow trout ( Oncorhynchus mykiss ) population, with the objectives of explaining the observed variation in growth and in polychlorinated biphenyl (PCB) concentration within the population. When variation in prey PCB concentration was incorporated into the model, variability in PCB concentration among individual rainbow trout was fully explained by the IBM. Although number of spawnings and number of years spent in a stream prior to first entering the lake were factors in determining growth, these life history characteristics appeared to have only a minor impact on PCB accumulation rate in rainbow trout. The IBM application to the rainbow trout population was compared with an application to the Lake Michigan lake trout ( Salvelinus namaycush ) population. Modeling results indicated that the lower observed PCB concentrations in rainbow trout compared with lake trout were chiefly due to greater longevity in lake trout. The IBM simulations identified gross growth efficiency, assimilation efficiency of PCBs from food, and diet as other important sources of variability in salmonine PCB concentrations.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Assessing smoltification of juvenile spring Chinook salmon Oncorhynchus tshawytscha using changes in body morphology

A morphometric measure of smoltification of juvenile spring chinook salmon ( Oncorhynchus tshawytscha ) was developed and evaluated. Fish were collected from hatcheries in Washington and Idaho prior to release and at McNary Dam on the Columbia River during their downstream migration. Distances between 15 anatomical landmarks were digitized from photographs of each fish resulting in 34 morphometric characters for analysis. The canonical variate calculated from a discriminant function based on several principal components was evaluated as a measure of smoltification. The canonical variate was significantly correlated with gill Na + –K + ATPase activity, a commonly used measure of smoltification. Measuring the morphometric characters and calculating the canonical variate is a relatively simple procedure and can be performed with little harm to the fish. This method of smoltification assessment may be ideally suited to studies in which sacrificing fish is not possible, such as those involving threatened or endangered species, or when access to a laboratory for sample analysis is not available.

Canadian Journal of Fisheries and Aquatic Sciences↗