bluuebunny/crossref_metadata_2025 huggingface dataset:
Protective Effect of Chloride on Nitrite Toxicity to Coho Salmon (Oncorhynchus kisutch)
Authors: Perrone Stephen J. , Meade Thomas L.
Published: April 2011

Tolerance of coho salmon (Oncorhynchus kisutch) to nitrite was increased when the concentration of chloride ion in the environment was high. The results of flow-through bioassays revealed that no mortality occurred when yearling coho salmon were subjected to nitrite-nitrogen (NO2−–N) of 29.8 mg/ℓ and chloride (Cl−) of 261.3 mg/ℓ for 48 h. When yearling coho salmon were exposed to 3.8 mg/ℓ NO2−–N and 2.5 mg/ℓ Cl− for 12 h, the resultant mortality was 58.3%. Possibly, chloride competes with nitrite for transport across the gills and integumental tissues, thereby interfering with the onset of nitrite-induced methemoglobinemia.
Seasonal Periodicity of Diatoms, and Silicon Limitation in Offshore Lake Michigan, 1975
Authors: Parker J. I. , Conway H. L. , Yaguchi E. M.
Published: April 2011

Diatom biomass maxima occurred in spring and fall and produced a bimodal bloom sequence at an offshore Lake Michigan station. The maximum in May was preceded by rapid growth as indicated by increased values of primary productivity and pigment concentration. As the spring bloom progressed, decreasing nutrient levels apparently slowed diatom growth. The diatom-biomass accumulation rate declined, assimilation quotients were minimal, and soluble reactive silicon was reduced from 13 to 6.8 μmol/ℓ. In summer, after the bloom, diatom biomass and silicon reached seasonal minima of < 250 mg C/m2 and ~ 1.0 μmol/ℓ, respectively. Diatom biomass increased again in October when silicon supplies were replenished and the concentration exceeded 6.6 μmol/ℓ. A critical silicon concentration of ~ 6.5 μmol/ℓ, may control the development and timing of offshore diatom populations in Lake Michigan. Key words: Lake Michigan, diatoms, growth, biomass, periodicity, silicon, uptake, limitation
Egg Hatchability and Tolerance of Brook Trout (Salvelinus fontinalis) Fry at Low pH
Authors: Trojnar John R.
Published: April 2011

Hatchability of brook trout (Salvelinus fontinalis) eggs incubated at pH 4.6, 5.0, 5.6 and 8.0 ranged from 76 to 91%. Differential mortality was experienced when subsequent swim-up fry were exposed to a different pH indicating an acclimation effect. This suggests that brook trout fry incubated at lower, but sublethal, pH levels are less likely to experience acid-induced mortality upon emergence than those incubated in spring upwellings. Key words: low pH, brook trout, egg and fry mortality, acclimation, acid precipitation, lake acidification
Caloric Changes Along Pulp and Paper Mill Effluent Plumes
Authors: Johnson M. G.
Published: April 2011

Eight pulp and paper effluent plumes in Nipigon Bay were tracked with Rhodamine dye to determine dilution and nondilution losses of calories with distance and time. Dilution, as determined by Na+ decrease, accounted for 98.5% of the decrease in caloric concentration along centerline trajectories of plumes over 2000 m in 7.5 h; mean caloric concentration decreased from 1583 cal∙ℓ−1 in effluent to 50 cal∙ℓ−1 at background stations. Nondilution caloric changes were estimated by two methods, first by examination of the main processes (respiration, settling of particles, and primary production) and, secondly, by interpretation of time series of direct measurements of caloric concentrations. By the first method, measurement of respiration indicated loss of 2.1 cal∙ℓ−1, while particle loss from plumes was 25.5 cal∙ℓ−1 and accrual of calories by primary production was 0.5 cal∙ℓ−1. Integration of these results yielded an estimate of 27.1 cal∙ℓ−1 net nondilution loss in caloric concentration along centerline trajectories over the average distance of 2000 m. By the second method, direct measurement of decrease in caloric concentration gave an estimate of nondilution loss of 45 cal∙ℓ−1 over 2000 m. Approximately 17% of effluent calories were used in biodegradation and lost in sedimentation from the plume within 2000 m of the source. Environmental degradation, in terms of dissolved oxygen conditions and deposition of particles, apparently was only locally significant.
Effect of Pulp Mill Effluent on the Surficial Sediments of Western Nipigon Bay, Lake Superior
Authors: Sandilands R. G.
Published: April 2011

Bottom sediment samples were obtained in June 1974 to determine the zone of influence of a point source discharge from the kraft paper mill at Red Rock Ont. The composition of the samples were described by particle-size distribution, organic and inorganic carbon, major elements and trace element analyses. Correlation coefficients and cluster analysis were used to determine any characteristic associations. The results showed that the mill discharge decreased pH and increased organic matter in the sediment. Above average concentrations of total sulphur and mercury appeared to be associated with this organic matter. These effects were localized around the point source (1.5 km) and were detectable to about 5 km downstream from the mill outfall.
Distribution and Abundance of Seals in the Eastern Beaufort Sea
Authors: Stirling Ian , Archibald W. Ralph , DeMaster Douglas
Published: April 2011

The objectives of this study were: (1) to design a statistically reliable method for surveying ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus) that could be repeated and, (2) to obtain baseline information on the distribution, abundance, and general biology of ringed and bearded seals in relation to other mammals in the pack-ice ecosystem of the eastern Beaufort Sea.Because of the limitations encountered in aerial surveying during the period of optimum haul out, and the heterogeneous environment, we employed a stratified design incorporating a weighted linear regression model. Identical surveys, conducted from June 15 to 29, 1974 and from June 12 to 20, 1975, showed a significant decline in numbers of both seal species in 1975. This conclusion was supported by other independent observations. Observer bias in sighting and identifying the species of seals was tested for and rejected. Neither species was distributed randomly over the heterogeneous habitat but the degree of clumping was different. In general, bearded seals preferred shallower areas and ringed seals deeper ones.When the seal population declined, the reproductive rates of both species dropped markedly and young of the year virtually disappeared from the population. The reduction in numbers of seals stimulated a major change in reproductive rates of the polar bears (Ursus maritimus) and arctic foxes (Alopex lagopus) that depend upon them for food, and the bear and fox populations decreased in size.Some possible causes of the decline are discussed. This unprecedented variability in the stability of the marine ecosystem has serious management implications. Key words: census techniques, Phoca hispida, Erignathus barbatus, seals, interspecific relationships, Beaufort Sea
Circulation and Temperature Structure in Large Marine Enclosures
Authors: Steele J. H. , Farmer D. M. , Henderson E. W.
Published: April 2011

Certain physical measurements intended to shed light on the circulation in large plastic enclosures (60–2000 m3) induced by the changing environment in which they are moored are described. Layers of dye were generally seen to diffuse vertically although some important advection effects were also observed. Estimates of an average coefficient of turbulent diffusivity yielded values in the range.05–.26 cm2∙s−1.Measurements taken with recording thermistor chains both inside and outside the enclosures show strong damping of external fluctuations with periods significantly less than 1 day. Various possible sources of mixing energy are considered and it is concluded that thermal forcing through the wall may be significant and could account for the observed range of coefficients.The significance of the observed mixing and circulation to the ecology of the enclosures is discussed. Of particular importance is the vertical mixing of nutrients that influences phytoplankton sinking rates and thus plays a crucial role in determining variations in algal concentration at different depths. Key words: mixing, enclosures, controlled ecosystem pollution experiment, circulation, temperature profiles
A Leukocytolytic Factor Isolated from Cultures of Aeromonas salmonicida
Authors: Fuller D. W. , Pilcher K. S. , Fryer J. L.
Published: April 2011

A substance characterized as a glycoprotein, isolated from the supernatant fluids of broth cultures of Aeromonas salmonicida by a combination of ammonium sulfate and ethanol precipitations followed by chromatography on DEAE-cellulose, was cytolytic for rainbow trout (Salmo gairdneri) leukocytes, and antigenic when injected into rabbits. The ratio of protein to hexose determined by analysis of the purified fraction was between 0.35 and 0.45, and small amounts of amino sugars were detected. A virulent strain of A. salmonicida produced much more of this factor than an avirulent strain. This factor was cytolytic for leukocytes in vitro and also produced a pronounced leukopenia when injected intravenously in adult rainbow trout. When injected in small coho salmon (Oncorhyncus kisutch) 8–13 cm long together with about one LD50 of live A. salmonicida 36 of 40 fish succumbed to the combination, whereas only 14 of 40 died from an injection of the bacterium alone. Thus, the pathogenicity of the organism was enhanced, presumably by increasing the susceptibility of the host. Hence, this glycoprotein apparently is one of the virulence factors of this bacterium. Key words: leukocytolytic factor, Aeromonas salmonicida, glycoprotein, virulence factor
A Multiple Opening and Closing Plankton Sampler Based on the MOCNESS and N.I.O. Nets
Authors: Sameoto D. D. , Jaroszynski L. O. , Fraser W. B.
Published: April 2011

A multiple net zooplankton sampler with 10 1-m2 nets was designed and built using the principles incorporated in the N.I.O. and the MOCNESS zooplankton samplers. The main differences between this net and others are the use of a depressor as part of the design of the sampler and the use of a ridge frame and cables to form the sampler body. The depressor enabled the sampler to be towed at speeds up to 6 knots while still maintaining a wire angle of < 45°. Key words: multiple net zooplankton sampler, net depressor
Carbon Budgets in Lake Ontario
Authors: Charlton Murray N.
Published: April 2011

A previous carbon budget for Lake Ontario appeared to balance because primary production was included as an input to the lake. Actually, the calculated CO2 losses to the atmosphere cause yearly outputs to be much higher than inputs. The assumption that these CO2 losses are a direct result of primary production is not consistent with other data. Key words: carbon budget, primary production
Water Resources of the World. Selected Statistics.
Authors: Low C. J.
Published: April 2011

not available
Reproduction and Embryonic Development of Spiny Dogfish (Squalus acanthias) in the Strait of Georgia, British Columbia
Authors: Jones Barry C. , Geen Glen H.
Published: April 2011

Lengths at 50% maturity of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., are 78.5 and 93.5 cm, corresponding to ages 19 and 29 yr, for males and females, respectively. Modal lengths of mature males and females are 85 and 100 cm, respectively.Mating occurs from October to January, with a peak in December. Males are capable of mating every year, with smaller dogfish mating earlier in the year than larger ones. Females mate every 2nd yr. Ovulation of 4 cm diam eggs closely follows mating. The fertilized eggs are enclosed in gelatinous capsules for 4 mo after which the embryos are released into the uterine cavity. The external yolk supply of the embryos is totally absorbed by parturition, although the internal yolk is not fully utilized until 2 mo later. Parturition occurs from September to January, with a peak in November. Gestation is roughly 23 mo. Breeding females produce a mean of 7.14 progeny.These population characteristics indicate that regulation of a future fishery should be by total catch limit rather than net mesh size selection. Key words: spiny dogfish, reproduction, length distribution, survivorship, fecundity, fishery regulation
Evidence of a Genetic Basis for Absence of the Pelvic Skeleton in Brook Stickleback, Culaea inconstans, and Notes on the Geographical Distribution and Origin of the Loss
Authors: Nelson Joseph S.
Published: April 2011

Laboratory and field crosses show that the absence of the pelvic skeleton in a brook stickleback population is under partial genetic control. Some offspring of parents lacking the pelvis possess a complete pelvic skeleton, while some offspring of parents with a complete pelvic skeleton lack the pelvis. Although a wide range of morphologically intermediate states exists, intermediates do not predominate in the crosses.Loss of the pelvic skeleton occurs in Ontario, Saskatchewan, and Alberta. Within Alberta, 23 localities are known where 20% or more of the sticklebacks lack a complete pelvic skeleton. In some localities 95% or more of the individuals lack all trace of the pelvis. Variation in predation is inferred to be the environmental variable causally associated with the presence or absence of the pelvic skeleton. The absence is postulated to have arisen independently in the various localities. Key words: Culaea inconstans, brook stickleback, pelvic skeleton absence, genetic control.
Influence of Water Temperature on the Growth Rate of the Landlocked Sea Lamprey (Petromyzon marinus) and the Associated Rate of Host Mortality
Authors: Farmer G. J. , Beamish F. W. H. , Lett P. F.
Published: April 2011

Groups of sea lampreys (Petromyzon marinus) of 10–90 g initial weight were held at temperatures of 1–20 °C for 30 days and allowed to feed ad lib. on white suckers (Catostomus commersoni). Increases in water temperature and in lamprey size caused the rate of host mortality to increase in agreement with observations that mortality in the Great Lakes is seasonal. Instantaneous growth rates were maximal at 20 °C for lampreys of 10–30 g, the optimal temperature for growth shifting to 15 °C for larger lampreys of 30–90 g. Growth rates were intermediate at 10 °C and lowest at 4 °C for lampreys of all size. Accordingly, host mortality increased with temperature over the 4–20 °C range. At all experimental temperatures, increases in lamprey weight were accompanied by an exponential decline in instantaneous growth rates, a phenomenon also observed for teleosts. Laboratory growth rates at temperatures of 5–15 °C were comparable to rates observed for lampreys in Lake Huron between April and November and agree with the observation that lampreys feed in deeper waters between April and June before moving to warmer, shallower waters during the summer when growth rate increases. Key words: sea lamprey, white sucker, host, temperature, growth, Great Lakes, mortality
Sealed-Jar Bioassays for Pulpmill Effluent Toxicity: Effects of Fish Species and Temperature
Authors: Gordon Michael R. , McLeay Donald J.
Published: April 2011

To standardize the sealed-jar bioassay for optimum sensitivity to whole bleached kraft pulpmill effluent, experiments were designed to assess the effects of test temperature, acclimation temperature, and fish species. Coho salmon (Oncorhynchus kisutch) conformed to a previously recognized test paradigm by showing progressively decreased oxygen utilization with increasing toxicant concentrations; however, rainbow trout (Salmo gairdneri) did not. In concentrations of effluent < 1.5 LC50, rainbow trout used significantly more oxygen than control groups, while coho salmon used significantly less oxygen. The sensitivity of these responses was influenced by test temperature and acclimation temperature. Results for coho confirmed that this species was most sensitive to effluent when tested at ambient room temperature. Both species showed significantly decreased oxygen utilization in effluent concentrations > 1.5 LC50 irrespective of test temperature or acclimation temperature. The significance of these responses is discussed, and the applicability of sealed-jar bioassays for assessing the acute toxicity of pulpmill effluents is reviewed. Key words: residual oxygen bioassay, sealed-jar bioassay, pulpmill effluent toxicity, temperature, hyperthermia, respiration, hypoxia, species-specific response
Identification of Golden Shiner, Notemigonus crysoleucas, Spotfin Shiner, Notropis spilopterus, and Fathead Minnow, Pimephales promelas, Larvae
Authors: Snyder Darrel E. , Mulhall Snyder Maryann B. , Douglas Susan C.
Published: April 2011

The various proportional length measurements and myomere counts for each larval phase of the cyprinid fishes golden shiner, Notemigonus crysoleucas, spotfin shiner, Notropis spilopterus, and fathead minnow, Pimephales promelas, are generally quite similar and typical of the family. Mean snout to vent lengths for protolarvae and mesolarvae ranged from 58 to 60% of total length and decreased to 54 to 59% for metalarvae. Mean total myomere counts for all phases overlapped among the species and ranged from 34 to 37.Identification of protolarvae and mesolarvae depends largely on melanophore distribution and patterns, while fin ray counts and position are applicable to metalarvae. Later protolarvae and mesolarvae of Notemigonus crysoleucas exhibit a distinctive midventral line of pigment anterior to the vent, while metalarvae are readily distinguished by an anal ray count of over 10 and pelvic fins well anterior to the dorsal fin origin. The later protolarvae, mesolarvae, and metalarvae of Notropis spilopterus are distinguished by a lack of melanophores on the ventral surface of the gill covers.These and other distinguishing features discussed are not necessarily unique to the cyprmids studied. Unless potentially similar species (undescribed or inadequately described) in a study area can be eliminated, identifications based on these characters should be considered tentative. Key words: Notemigonus crysoleucas, Notropis spilopterus, Pimephales promelas, Cyprinidae, fish, larvae, development, identification, taxonomy
Year-Class Abundance, Population, and Production of Walleye (Stizostedion vitreum vitreum) in Clear Lake, Iowa, 1948–74, with Varied Fry Stocking Rates
Authors: Carlander Kenneth D. , Payne Philip Michael
Published: April 2011

Year-class abundance of walleye, Stizostedion vitreum vitreum, in Clear Lake from 1948 to 1974 was significantly correlated (r = 0.613) with annual fry stocking, which was varied from 0 to 6070 fry/ha. Abundance of young walleye seined along shore was even more highly correlated with fry stocking (r = 0.819) but not significantly correlated with year-class abundance (r = 0.179) indicating that year-class strength may change between the first summer and later years. No correlation was found between year-class abundance and temperature in summed degree-days, water levels, or abundance of yellow perch, Perca flavescens, as effects were probably masked by the fry stocking. Growth of age 0 and I walleye were negatively correlated with fry stocking (r = −0.42 and r = −0.41, respectively), but growth of age V walleye was positively correlated (r = 0.70). Growth was also correlated with water levels (r = 0.79). Annual mortality rate averaged 42%. Standing crop ranged from 2.63 to 16.52 kg/ha and annual production from 1.01 to 9.31 kg/ha. Production per biomass was low when water levels were low. Key words: Percidae, walleye, Stizostedion vitreum vitreum, population dynamics, productions, Clear Lake, Iowa, stocking
Responses of Percids to Exploitation
Authors: Spangler G. R. , Payne N. R. , Thorpe J. E. , Byrne J. M. , Regier H. A. , Christie W. J.
Published: April 2011

Conventional exploitation is described as an opportunistic process directed initially toward the largest members of the fish community and preferentially selecting those species for as long as the fishery persists. Some responses of percid communities to exploitation stress are similar to those previously described for marine stocks and salmonid communities. The most conspicuous responses of percids are changes in variability of recruitment, increases in growth rate, and reductions in the ages of first spawning. The least tractable and potentially most malefic responses are changes in genetic stocks and in interspecific relationships within the aquatic community. Three models are proposed for early detection of exploitation stress in fish stocks or communities. Key words: Percidae, exploitation, community ecology
Growth of Rock Bass, Ambloplites rupestris, in Relation to the Morphoedaphic Index as an Indicator of an Environmental Stress
Authors: Ryan Patrick M. , Harvey Harold H.
Published: April 2011

Atmospheric contamination by sulfur dioxide in the Sudbury region and the associated acidification has reduced population densities of fishes in the La Cloche Mountain lakes, 33–90 km away. Surviving rock bass (Ambloplites rupestris) responded to decreased abundance with increased growth rate. Variation in abundance among surviving populations could be monitored by means of individual growth rates and mean lake depth. Our findings suggest that growth rate of fishes, in conjunction with the morphoedaphic index, may serve as an indicator of environmental stress. Key words: environmental indicator, environmental stress, lake acidification, fish growth rate, morphoedaphic index, population density, rock bass
Spawning Time and Egg Size of Atlantic Mackerel, Scomber scombrus, in Relation to the Plankton
Authors: Ware D. M.
Published: April 2011

The mean date of peak spawning of Atlantic mackerel (Scomber scombrus) in the southwestern Gulf of St. Lawrence is July 1 ± 1 wk. This coincides with the maximum abundance of the summer plankton. Mackerel eggs average 1.3 mm in diameter at the beginning of the spawning season in June and decrease steadily to 1.1 mm by mid-August. There is a corresponding trend in the mean size of the plankton, which reach a minimum length in midsummer, and a maximum in winter. This recurring size cycle is as important as the seasonal change in plankton biomass in determining the abundance of suitable food organisms for newly hatched larvae. In an evolutionary sense, the observed reproductive characteristics of mackerel ought to be adaptive since the accurate timing of spawning and the progressive decline in egg size will tend to ensure that the parent stock produces larvae of a suitable size and at the correct time, so they encounter an abundant supply of appropriately sized food organisms. Key words: reproduction biology, plankton size composition, larval feeding, adaptive behavior, recruitment
Seawater Adaptation and Parr–Smolt Transformation of Juvenile Atlantic Salmon, Salmo salar
Authors: Farmer G. J. , Ritter J. A. , Ashfield D.
Published: April 2011

Seawater adaptation of 1- and 2-yr-old Atlantic salmon, Salmo salar, presmolts and smolts was assessed during exposure to salinity increasing from 0.1 to 31‰ by examining changes in the osmotic concentration of their serum, urine, and intestinal fluid. Both age-classes adapted to seawater equally well; the marine osmoregulatory mechanisms apparently function before completion of parr–smolt transformation. Adaptation was possible during the parr stage for fish exceeding 12–13 cm fork length. The timing of transformation was synchronous for 1- and 2-yr-old juveniles as demonstrated by changes in their lipid and moisture content and condition factor (K). Condition factor of juveniles at the Mactaquac Hatchery, New Brunswick (45°58′N), decreased from February until the second half of May, while lipid content decreased from February until the second half of June. Migratory activity of juveniles at this location was maximal during the second half of May coincident with attainment of minimum K values and decreased during the first half of June as K values increased. While timing of changes in lipid and moisture content and K values were similar for juveniles at the Mersey Hatchery, Nova Scotia (44°10′N), lipid content of fish at the more southerly station decreased at a greater rate and migratory activity was apparent earlier. This was probably attributable to the advanced temperature cycle at that location. Smolt-release dates are discussed in terms of the development of the marine osmoregulatory mechanisms and the timing of parr–smolt transformation. Key words: Atlantic salmon, seawater adaptation, parr–smolt transformation, migration, hatchery management
Baeoctenus bicolor (Diptera: Chironomidae) Parasitic in Unionid Bivalve Molluscs, and Notes on Other Chironomid–Bivalve Associations
Authors: Gordon M. J. , Swan B. K. , Paterson C. G.
Published: April 2011

Parasitic association of Baeoctenus bicolor Sæther with the bivalves Anodonta cataracta and A. implicata in Morice Lake, New Brunswick, is described. An intimate relationship was also found between an undescribed genus of orthoclad (near Phycoidella) and A. cataracta but not A. implicata. Neither chironomid species was found in the other two genera of unionids that occur in the lake. Key words: Baeoctenus bicolor, Chironomidae, parasitism, Unionidae, Anodonta cataracta
Bias in Using an Age–Length Key to Estimate Age-Frequency Distributions
Authors: Westrheim S. J. , Ricker W. E.
Published: April 2011

Consider two representative samples of fish taken in different years from the same fish population, this being a population in which year-class strength varies. For the "parental" sample the length and age of the fish are determined and are used to construct an "age–length key," the fractions of the fish in each (short) length interval that are of each age. For the "filial" sample only the length is measured, and the parental age–length key is used to compute the corresponding age distribution. Trials show that the age–length key will reproduce the age-frequency distribution of the filial sample without systematic bias only if there is no overlap in length between successive ages. Where there is much overlap, the age–length key will compute from the filial length-frequency distribution approximately the parental age distribution. Additional bias arises if the rate of growth if a year-class is affected by its abundance, or if the survival rate in the population changes. The length of the fish present in any given part of a population's range can vary with environmental factors such as depth of the water; nevertheless, a sample taken in any part of that range can be used to compute age from the length distribution of a sample taken at the same time in any other part of the range, without systematic bias. But this of course is not likely to be true of samples taken from different populations of the species. Key words: age–length key, bias, Pacific ocean perch, Sebastes alutus
Calculating Mortality Rates and Optimum Yields from Length Samples
Authors: Marten Gerald G.
Published: April 2011

An equation is derived for yield per recruit of a fishery (or other exploited animal population) as a function of fishing intensity and age of first capture. The equation has the advantage that it does not require explicit estimates of natural mortality or individual growth rate parameters. Linear length growth is assumed until maximum size is reached, and mortality parameters are expressed relative to growth rate. Mortality parameters are estimated from average length samples of separate populations experiencing different fishing efforts in the same fishery. The equation may be used to compare existing fishing efforts and age of first capture with optimal values. Samples of the catfish Bagrus docmac from Lake Victoria (East Africa) are used to illustrate the method. Key words: yield equation, Beverton–Holt, fish lengths, Lake Victoria, Bagrus docmac, fishing effort, recruitment age
Bioenergetics of Pelagic Fish: Theoretical Change in Swimming Speed and Ration with Body Size
Authors: Ware D. M.
Published: April 2011

It is shown from hydrodynamics theory and the size composition of particles in marine food chains that there are two unique swimming speeds of importance to pelagic fish: (1) the optimal cruising speed, which maximizes the distance traveled per unit energy expenditure and (2) the optimal foraging speed, which maximizes the rate of flow of surplus energy, or production in its broadest sense. With sockeye salmon (Oncorhynchus nerka) as an example, the optimal cruising and foraging speeds were found to be proportional to the body length raised to the 0.4 power. By analogy, if pelagic fish in general tend to move at either of these speeds, their ration and growth rates relative to the body weight should be proportional to a power that varies between 0.7 and 0.8. These predictions are consistent with field growth measurements for several pelagic species. Therefore, the necessary conditions for a theory of optimal foraging exist since (1) all adaptive swimming speeds are physiologically possible and (2) there is evidence that some juvenile fish feed by moving at the appropriate speed to maximize their production rate. Key words: bioenergetics, swimming speed, optimal foraging
The Economics of Fisheries Management.
Authors: Sinclair William F.
Published: April 2011

not available
Mineral Cycling in Southeastern Ecosystems.
Authors: Pharo C. H.
Published: April 2011

not available
Principles of Oceanography.
Authors: Parsons T. R.
Published: April 2011

not available
Buoyancy Response to Changes in Water Velocity and Its Function in Creek Chub (Semotilus atromaculatus)
Authors: Berezay Gordon , Gee John H.
Published: April 2011

Creek chub (Semotilus atromaculatus) reduce buoyancy by decreasing swim-bladder volume when exposed to water current. Fish were near neutral buoyancy (0.956–0.997 mL∙g−1) in still water but in current small fish (< 73 mm) were more buoyant (0.668 mL∙g−1) than larger fish (0.540 mL∙g−1). Extent of buoyancy alteration was influenced by acclimation temperature, water velocity, and an interaction of both these factors. Reduction of buoyancy on exposure to water current required 3–6 h and the rate of decrease (0.035–0.068 mL∙g−1∙h−1) was independent of acclimation temperature and water velocity. The hypothesis that creek chub reduce buoyancy when exposed to water current to compensate for the lift created due to deflection of water over the dorsal surface of the body was supported by the following findings. When initially exposed to current, fish lowered the head assuming an angle of attack of 9–12° from horizontal. A horizontal (< 1°) angle of attack was gradually assumed during buoyancy adjustment. Fish acclimated to moderate current for 12 or 24 h tired less readily in strong current (80% took 43 and 44 min, respectively) than those not acclimated or acclimated for 6 h (80% took 33 and 25 min, respectively). Fish induced to swim in still water reduced buoyancy to a similar extent as those in current. Key words: swim-bladder volume change, temperature, hydrodynamic lift, swimming angle of attack, time to fatigue
Concentrations and Kinetics of Phosphorus Fractions in Water from Streams Entering Lake Memphremagog
Authors: Peters Robert Henry
Published: April 2011

This study examines the possibility that the proportions of different P fractions may vary among rivers, and hence, that the P supplied to lakes may differ in its availability for algae regardless of any similarities in the total P concentration of river waters. Surface water from eight streams and groundwater was collected at roughly monthly intervals from June 1975 to September 1976 and analyzed to determine the concentrations of P fractions and the interrelations between these forms and orthophosphate. Despite differences in total P concentration, (18–64 μg/L) the proportions of P in different fractions were relatively constant seasonally and geographically. Soluble P formed about one third and PO4 < 10% of the total P. These values were not greatly affected by urban drainage but both were increased in small headwater streams during periods of low water. Soluble P was divided into two roughly equal fractions by gel filtration: a large molecular weight fraction (> 5000 mol wt) which eluted at void volume and a small molecular weight fraction (< 400 mol wt) which eluted with 32P-PO4. This latter fraction also included some small organic phosphates. Soluble reactive phosphate consistently overestimated PO4. The exchange of P between PO4 and suspended material was slow in winter and more rapid in summer, although only rivers draining lakes, embayments, or bogs reached the very rapid values reported from lakes. As in lakes, soluble organic P entered into the short-term P dynamics of streams as indicated by the labeling of large molecular weight P during equilibration of river water with radioactive phosphate. This exchange shows that at least a portion of the soluble organic and particulate P is available to the plankton once the river water enters a lake. The uncertainty as to the size of this portion leads to uncertainty in predicting the impact of P loading on lakes. Key words: nutrient budget, P loading, orthophosphate, soluble organic P, drainage basins
Biological Monitoring of Water and Effluent Quality.
Authors: Clarke R. McV.
Published: April 2011

not available
Impact of Acid Precipitation on Forest and Freshwater Ecosystems in Norway. Research Report 6/76.
Authors: Beamish R. J.
Published: April 2011

not available
Editor's note:
Authors: Scott D. P.
Published: April 2011

not available
Fish Cell Culture: Properties of a Cell Line from the Sheepshead, Archosargus probatocephalus
Authors: Law W. M. , Ellender R. D. , Wharton J. H. , Middlebrooks B. L.
Published: April 2011

A cell line designated SHF-1 was established from fin tissue of the sheepshead, Archosargus probatocephalus. Cells were fibroblastlike and grew best at 26 °C in Leibovitz (L-15) medium containing serum supplements and a final sodium chloride concentration of 0.150 M. The 2N number of primary sheepshead cells was 48 but the SHF-1 line at passage levels above 11 was heteroploid. SHF-1 cells did not replicate any of seven viruses tested. Species confirmation of SHF-1 was accomplished by the cytotoxic antibody test and was attempted with isoelectric focusing of lactic dehydrogenase isoenzymes. Plating efficiency and freeze viability studies were also performed. Key words: fish cell culture, sheepshead, Archosargus probatocephalus, microbiology
Alterations in Growth and Physiology of Soft-Shell Clams, Mya arenaria, Chronically Oiled with Bunker C from Chedabucto Bay, Nova Scotia, 1970–76
Authors: Gilfillan E. S. , Vandermeulen J. H.
Published: April 2011

Two populations of soft-shell clam, Mya arenaria, one from a chronically oiled lagoon (since the Arrow oil spill in 1970) and the other from a nonoiled lagoon, were compared as to population structure, growth, and metabolism. The oiled lagoon sediments contained up to 3800 μg/g oil (UV determination), and clams up to 200 μg/g hydrocarbon in their tissues (fluorescence). The oiled population of clams differed from the nonoiled population in lower total numbers with fewer mature adults, a 1–2-yr lag in tissue growth, a lower shell growth rate, and a reduced carbon flux with a lower assimilation rate. Results are interpreted to indicate that the recovery potential of M. arenaria in these oiled sediments is low and that these oiled populations remain under continued stress 6 yr after the Arrow spill. Key words: physiology, petroleum, growth, carbon flow, clams, recruitment
Long-Term Effects of an Oil Spill on Fucus Macrofauna in a Small Baltic Bay
Authors: Notini Mats
Published: April 2011

On October 6, 1970, the small tanker Irini ran aground in the southern part of the Stockholm archipelago, releasing about 1000 t of medium and heavy fuel oil. Approximately 400 t drifted into a small bay, Gästviken, wiping out nearly the entire littoral fauna. Most of the oil was collected mechanically during the winter, and by May 1971 cleanup operations were completed. The recruitment of the bladder wrack (Fucus vesiculosus) community in the bay was observed at intervals over a 5-yr period. Significantly increased macrofauna population densities were found for a number of species in the 1974 and 1976 samples compared to those of 1971 and 1972. From June–July 1971 to June 1976, the mean numbers of individuals for all species rose from about 280 to 1000/100 g Fucus dry weight (d.w.). The bivalve Mytilus edulis increased in number from 0 to about 45, the gastropod Theodoxus fluviatilis from 0 to about 160, the amphipod Gammarus spp. from about 40 to 580, the isopods Idotea spp. from about 5 to 35, and Iaera spp. from almost 0 to about 10/100 g Fucus. Larvae of Chironomidae were the only group found with a decreased density between the first and sixth summers after the spill, with 240 and 145 individuals, respectively. The data obtained are discussed in relation to conditions in a nearby unpolluted bay and to normally occurring cyclic variations. Key words: algae, Fucus vesiculosus, littoral community, petroleum, pollution
Acidic Precipitation in South-Central Ontario: Recent Observations
Authors: Dillon P. J. , Jeffries D. S. , Snyder W. , Reid R. , Yan N. D. , Evans D. , Moss J. , Scheider W. A.
Published: April 2011

Precipitation in south-central Ontario, with mean pH between 3.95 and 4.38 and frequent event pH's of < 4.0, is more acidic than that in the Sudbury, Ontario, region and in Scandinavia, and as acidic as that in the northeastern USA. As in New England, a major component of the total acidity is strong mineral acid. Because most lakes in south-central Ontario have very low buffering capacities (10–200 μeq∙L−1), high acid loadings are likely to lead to acidification of many lakes and streams in the forseeable future. Although it is not yet possible to estimate the time required for this to happen, there is already some evidence of declining buffering capacity in a few lakes. Key words: acidic rain, buffering capacity, acidic lakes, precipitation, alkalinity
Metabolic Rate and Energy Expenditure of the Spiny Dogfish, Squalus acanthias
Authors: Brett J. R. , Blackburn J. M.
Published: April 2011

The metabolic rate of spiny dogfish, Squalus acanthias, was determined in both a tunnel respirometer and a large, covered, circular tank (mass respirometer). Swimming performance was very poor in the respirometer, so that a power–performance curve could not be established. Instead, resting metabolic rates were determined, with higher rates induced by causing heavy thrashing (active metabolism). Routine metabolic rates were measured for the spontaneous activity characterizing behavior in the circular tank. For fish of 2 kg mean weight, the metabolic rates at 10 °C were 32.4 ± 2.6 SE (resting), 49.2 ± 5.0 SE (routine), and 88.4 ± 4.6 SE (active) mg O2∙kg−1∙h−1. Assuming that the routine rate represents a general energy expenditure in nature, this is equivalent to metabolizing about 3.8 kcal∙kg−1∙d−1 (15.9 × 103 J∙kg−1∙d−1). Key words: dogfish, metabolic rates, energetics, respiration
Relationship Between Cytoplasmic Distribution of Mercury and Toxic Effects to Zooplankton and Chum Salmon (Oncorhynchus keta) Exposed to Mercury in a Controlled Ecosystem
Authors: Brown D. A. , Parsons T. R.
Published: April 2011

Fish and zooplankton were simultaneously exposed to trace, 1, and 5 μg Hg/L. In fish and zooplankton, pathological effects appeared to coincide with saturation of metallothionein and "spillover" of Hg into the high molecular weight protein (enzyme-containing) pool. Coincidental with increases of Hg in tissue were decreases of Cu and Zn. Pathological effects of Hg are explained in terms of tertiary and quaternary structural changes in metalloenzymes resulting from replacement of Cu and Zn by Hg. Decreases in tissue Cu and Zn with increasing Hg concentration are discussed as an intracellular displacement of Cu and Zn by Hg and as duodenal and cellular exclusion processes. Key words: CEPEX, Oncorhynchus keta, zooplankton, mercury, copper, zinc, metallothionein, enzymes, metal tolerance
Elevated Heavy Metals: A Stress on a Population of White Suckers, Catostomus commersoni, in Hamell Lake, Saskatchewan
Authors: McFarlane G. A. , Franzin W. G.
Published: April 2011

This study examined populations of white suckers (Catostomus commersoni), in two physically and chemically similar lakes in the vicinity of, and receiving heavy-metal fallout from, a base-metal smelter complex near Flin Flon, Manitoba. The white suckers occupying Hamell Lake, Saskatchewan, which is contaminated by Zn, Cu, and Cd, showed signs typical of a population under stress when compared with the population in Thompson Lake, Manitoba, which contains much lower levels of these metals. Hamell Lake white suckers showed greatly increased growth in length and weight, increased fecundity, and earlier age of maturation, but reduced spawning success, reduced larval and egg survival, smaller egg size, and reduced longevity compared with Thompson Lake white suckers. We attribute these differences to elevated heavy metals in Hamell Lake waters, particularly in early spring, a most critical period in the reproductive cycle of these fish. Effects of the metals on other species of fish in Hamell Lake are also discussed. Key words: heavy metals, fish, population, stress, white sucker
Larvae and Pelagic Juveniles of Blackgill Rockfish, Sebastes melanostomus, Taken in Midwater Trawls off Southern California and Baja California
Authors: Moser H. Geoffrey , Ahlstrom Elbert H.
Published: April 2011

Examination of 217 midwater trawl samples from the coastal basins off southern California and Baja California revealed a recurring group of rockfish species. The late larvae and pelagic juveniles of the blackgill rockfish, Sebastes melanostomus, constituted 16% of the total number of rockfish specimens. The life-history stages of this species are described, with emphasis on the pelagic juvenile stage. Late stage larvae and pelagic juveniles develop a distinctive pattern of melanophore bands which, by disrupting the body outline, may help conceal the young during their midwater existence. Evidence from midwater trawl collections suggests that 30-mm pelagic juveniles migrate or are carried shoreward at a depth of ~ 200 m to the appropriate habitat for settling. The high relative abundance of blackgill rockfish pelagic juveniles in midwater trawl samples suggests that this species may represent a potential resource. Key words: blackgill rockfish, Sebastes melanostomus, larvae, pelagic juveniles, midwater trawls, developmental stages, melanophore patterns, life-history strategy, head-spine development
Ionization of Ammonia in Seawater: Effects of Temperature, pH, and Salinity
Authors: Bower Carol E. , Bidwell Joseph P.
Published: April 2011

Previous studies have shown that the toxicity of ammonia to freshwater fishes depends on the ambient concentration of the un-ionized fraction (NH3) and have quantified the percent NH3 in solution as a function of temperature and pH. If NH3 is also toxic to marine fishes, the effect of salinity on the ionization of ammonia must also be considered. The percent NH3 over ranges of temperature, pH, and salinity common in seawater-culture situations is presented here. Key words: ammonia, ammonia analysis, ammonia ionization, ammonia toxicity, pH, salinity, temperature
The Need for Human Sciences Research in Atlantic Coast Fisheries
Authors: Andersen R.
Published: April 2011

Canada's coastal fishing industry is changing in response to recent international agreement permitting coastal states to extend jurisdiction over fish and fishing to 200 miles from their shores, the appreciation that renewable aquatic resources can be harvested easily to a point of nonrenewability, the current economic conditions in the world giving rise to spiralling prices, inflation and unemployment, and political developments specific to Canada. I argue that by controlling changes in the fishing industry it is possible to optimize the social benefit to the nation and that two routes are available to attempt this, by additions to existing structures and by qualitative restructuring. But, above all else, I stress that fishing, as a modern enterprise, cannot be isolated from the livelihood and benefits of those most dependent on the harvest from the sea. In order that the results of change can work to optimize the social good, I indicate where lack of knowledge in human and social terms precludes rational decisions or policy shifting towards qualitative restructuring of the fishing economy. The results of additive changes are summed up — "Additions call for more of the same, with temporary improvements possible for some, until our growth prospects meet the limits of renewed stocks available to us under preferential fishing within the 200 mile management zone."
Evaluation of an Aerial Survey of Pacific Walruses (Odobenus rosmarus divergens)
Authors: Estes James A. , Gilbert James R.
Published: April 2011

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. Key words: aerial survey, aggregation, Chukchi Sea, estimation, population, stratification, walrus