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At least 469 records · Page 26Linked to original sources
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↗
USGS1994

Differential predation by northern squawfish Ptychocheilus oregonensis on live and dead juvenile salmonids in the Bonneville Dam tailrace (Columbia River)

Juvenile salmonids ( Oncorhynchus spp.) that have been killed or injured during dam passage may be highly vulnerable or preferred prey of predators that aggregate below dams. Salmonid loss due to predation will be overestimated using gut content analysis if some prey were dead or moribund when consumed. To examine this issue, field experiments were conducted in the Bonneville Dam tailrace (Columbia River) to compare rates of capture of live and dead juvenile salmonids by northern squawfish ( Ptychocheilus oregonensis ). Known numbers of coded-wire-tagged live and dead chinook salmon ( O . tshawytscha ) were released into the tailrace on six nights. Northern squawfish were collected after each release and their gut contents were examined for tags. When 50% of salmon released were dead, northern squawfish consumed 62% dead salmon. When 10% of salmon released were dead, comparable with dam passage mortality, 22% of the tags found in northern squawfish digestive tracts were from dead salmon. These results indicate that predator feeding behavior and prey condition are important considerations when estimating the impact of predation on a prey population.

Oregon, Washington↗
USGS1994

Cadmium, metal-binding proteins, and growth in bluegill ( Lepomis macrochirus</I.) exposed to contaminated sediments from the upper Mississippi River basin

We exposed juvenile bluegill ( Lepomis macrochirus ) to ~1000 mg∙L −1 of continuously suspended river sediment in a 28-d test with six treatments (randomized block with one sediment-free control and five sediments ranging from 1.3 to 21.4 μg Cd∙g dry weight −1 ). Each treatment had three replicates, each with 25 fish. Growth was reduced by exposure to suspended sediment, probably due to physical effects of sediment on feeding and to toxicity in the treatment with the greatest concentrations of metals. Mean whole-body concentrations of cadmium (0.04–0.14 μg∙g wet weight −1 ) were correlated with cadmium concentration in filtered water (8–72 ng∙L −1 ), suspended sediment (0.61–16.8 μg∙L −1 ), and bulk sediment. The concentration of hepatic nonthionein cytosolic cadmium (cadmium not bound by metal-binding proteins, MBP) in fish exposed to the two most contaminated sediments exceeded that in controls. The mean concentration of hepatic MBP was correlated with cadmium concentration in filtered water, suspended sediment, bulk sediment, and whole fish. Whole-body cadmium concentration was the most sensitive indicator of cadmium exposure, with lowest observed effect concentrations of 1.9 μg Cd∙L −1 for suspended sediment and 13 ng Cd∙L −1 for filtered water. Sediment-associated cadmium was less available than waterborne cadmium for uptake by fish.

Mississippi River Basin↗
USGS1994

Dramatic decline of unionid bivalves in offshore waters of western Lake Erie after infestation by the zebra mussel, Dreissena polymorpha

Unionid bivalves and attached epizoic zebra mussels ( Dreissena polymorpha ) were collected at one index station in 1989, 1990, and 1991 and at 17 stations in 1991 in offshore waters of western Lake Erie of the Laurentian Great Lakes. Sampling at the index station revealed that the proportion of live unionids declined from 53% in September 1989 to 17% in May&ndash;June 1990 and to 0% in September 1990: this 100% mortality coincided with heavy infestation by zebra mussels. Quantitative sampling with a Ponar grab at the 17 stations in 1991 revealed a widespread and dramatic reduction in unionid populations. In 1982, five unionid species occurred at 35% of the stations at a density of 4/m 2 , whereas in 1991, no live unionid species were found. Qualitative sampling with an epibenthic sled at the 17 stations in 1991 yielded only 4 live specimens of 2 species ( Amblema plicata plicata and Fusconaia flava ) and 187 dead specimens of 10 species. These and other results indicate that unionid populations are being negatively affected by zebra mussels in the Great Lakes. Similar impacts on unionids are expected to occur where zebra mussels become abundant throughout North America.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Variation in mitochondrial DNA and allozymes discriminates early and late forms of Chinook salmon Oncorhynchus tshawytscha in the Kenai and Kasilof Rivers, AK

Genetic differences between early and late forms of Alaskan chinook salmon ( Oncorhynchus tshawytscha ) were identified using two genetic approaches: mitochondrial DNA (mtDNA) analysis, and protein electrophoresis. Study populations consisted of early and late runs in each of the Kenai and Kasilof rivers in Alaska, and a population from the Minam River, Oregon. Two segments of mtDNA were amplified using the polymerase chain reaction (PCR) and digested with 14–16 restriction enzymes. Results showed that early runs were genetically similar to each other but different from the late runs. The late runs were different from each other based on the frequency of the common haplotypes. Frequency differences in shared haplotypes together with the presence of a unique haplotype separated the Minam River stock from those in Alaska. In the protein analysis, each population was examined at 30 allozyme loci. Based on 14 polymorphic loci, Minam River salmon were genetically distinct from the Alaskan populations. Within the Alaskan populations, early runs were most similar to each other but different from the late runs; the late runs were also genetically most similar to each other. Both mtDNA and allozyme analysis suggest that chinook salmon may segregate into genetically different early and late forms within a drainage.

Alaska↗
USGS1995

Evidence of autumn nitrogen limitation and contribution of picoplankton to carbon fixation in Lake Tahoe

Water samples were collected from Lake Tahoe at midlake and nearshore stations at three depths (25, 50, and 75 m, corresponding to light intensities of approximately 10, 1, and 0.1% of surface light) in May and September. The water samples were evaluated to decide the following: (1) whether carbon fixation was N-limited and whether there were differences between picoplankton and larger phytoplankters and (2) the relative importance of picoplankton carbon fixation and related photosynthetic parameters. Evidence of N-limitation was observed only in September at the midlake station for the populations at 50 and 75 m, and to a lesser extent at the nearshore station at 75 m, but only for the nanoplankton fraction. The contribution of picoplankton to total carbon fixation ranged from 34 to 69% and did not increase with depth. Low values for I k , the photoadaptation parameter, for deep water populations (0.1% light level) in September, but not May, suggested that these populations were adapted to low light in the fall but not the spring.

California, Nevada↗