bluuebunny/crossref_metadata_2025 huggingface dataset:
Use of Hormones in Induced Spawning of Carps
Authors: Chaudhuri H.
Published: April 2011

The role of hormones in regulating the ovulation and spawning in fishes is still controversial and inconclusive. Although remarkable progress has been made during the last decade in studying the effect of various hormones on the reproductive physiology of a number of fishes, little information is available on the regulation of hormones in the spawning of the difficult-to-spawn carps, namely the major Indian and Chinese carps. These important cultivated species, although they attain maturity in ponds, fail to reproduce in that environment in the absence of external stimuli which are essential for the release of gonadotropins resulting in ovulation and spawning.Attempts made to breed these carps by injections of mammalian hormone preparations did not meet with much success. Administration of fish pituitary hormones, on the other hand, induced ovulation and successful spawning in these fishes. While extensive use of crude pituitary treatment for production of carp seed is in vogue in pisciculture all over the world, attempts are being made to replace it by purified gonadotropins from piscine pituitary glands. Recent work on the purification of salmon and carp gonadotropin marks the beginning towards achievement of success in the field.The paper describes the techniques of hormone administration in major Indian and Chinese carps and discusses the effects of various hormones on their spawning. It also reviews the progress made in the study of the reproductive physiology of some closely related species.
Optimum Level of Dietary Biotin for Growth, Feed Utilization, and Swimming Stamina of Fingerling Lake Trout (Salvelinus namaycush)
Authors: Poston H. A.
Published: April 2011

Triplicate lots of fingerling lake trout (Salvelinus namaycush) held at 9 C for 20 wk were fed a semipurified basal diet supplemented with 1% spray-dried egg white or d-biotin at concentrations of 0.1, 0.5, 1.0, or 5.0 ppm. Trout fed the basal diet, either alone or with egg white, grew more slowly and converted feed less efficiently (P < 0.05) than those fed supplemental biotin. Neither the growth rate nor feed conversion differed significantly among the four groups fed supplemental biotin. However, when forced to swim to exhaustion against controlled water currents, trout fed either basal diet, with or without egg white, or 0.1 ppm supplemental biotin, swam a shorter distance (P < 0.05) than those fed more biotin. Fish fed 0.5 ppm biotin swam as far as those fed 1.0 ppm, but not as far as those fed 5.0 ppm. These results indicate that young lake trout probably need no more than 0.1 ppm biotin for optimum growth and feed conversion, but require from 0.5 to 1.0 ppm for optimum swimming stamina.
Spectral Analysis of the Long-Term Oceanographic Time Series at Ocean Weather Station "P"
Authors: Ross C. K. , Needler G. T.
Published: April 2011

Oceanographic observations taken at Ocean Station "P" (50°N, 145°W) provide one of the few long oceanographic time series. The intermittent nature of the sampling program at Station "P," however, presents problems for a standard time-series analysis. In this paper the seriousness of this aspect of the data is discussed and spectral estimates are obtained for the potential temperature, potential density anomaly, and dynamic height anomaly at several depths. We found that the lowest frequency estimates of dynamic height anomaly are approximately an order of magnitude less than those obtained from a similar station in the North Atlantic. This is consistent with a more rapid falloff of energy with depth at Station "P".
Tidal Currents and Estuarine-Type Circulation in Johnstone Strait, British Columbia
Authors: Thomson Richard E.
Published: April 2011

Four months of current meter observations across the western basin of Johnstone Strait have been examined, with particular attention given to the mean flow and to variations at tidal frequencies. We show that the time-averaged motions are typical of a moderately stratified estuary driven by tidal mixing and nonlinear advection. Steady currents are nearly unidirectional at all depths with the net outflow in the upper layer essentially balanced by a net inflow in the lower layer to order 103 m3∙s−1. In addition, the relatively small variation in residual current speed is found to decrease with depth and to be associated mostly with the quasi-fortnightly tidal cycle. Near the surface the variance in the residual flow appears to be related to along-channel winds whose speeds and duration exceed 6 m∙s−1 and 24 h, respectively. Time-dependent motions are dominated by the tidal signal which is mixed, predominately semidiurnal. Maximum speeds of order 1 m∙s−1 are found at depth and are generally 1.5–1.7 times larger than in the upper layer. There is also a strong correlation between the tidal current speeds below 150-m depth and the local tide height lagged by 6 h. It is suggested that these large lower layer currents are associated with baroclinic motions being generated by the barotropic tide propagating over the rapidly shoaling bathymetry to the east of the observation region.
Coded Spine Clipping to Identify Individuals of the Spiny-Rayed Fish Tilapia
Authors: Rinne John N.
Published: April 2011

Clipping 1 or more spines in the dorsal and anal fins was used to identify individual Tilapia. In fish > 15 cm the mark was permanent. In smaller fish spine regeneration occurred, but clipped spines could be recognized both by their incomplete regrowth and abnormal appearance. This technique is applicable not only to experimental situations requiring recognition of individuals but also to group marking and to other Perciforms.
Uptake and Retention of Kuwait Crude Oil and Its Effects on Oxygen Uptake by the Soft-Shell Clam, Mya arenaria
Authors: Fong Wang C.
Published: April 2011

Mya arenaria gills are capable of removing finely dispersed oil globules of 1–30 μm diam from sea water along with food particles. Clams exposed to seawater concentrations of 90–380 μg oil/liter for 10 days at 18 C accumulated oil in their tissues. Concentrations incorporated are directly related to the lipid content of tissues. Approximately 6 mg oil/g lipid was observed within the tissue of individual clams. Respiration rates of small clams (shell length 3.75–4.50 cm) at 18 C are significantly increased after 3 wk of exposure to sea water containing 220–370 μg oil/liter.
Incorporation of Fatty Acids into Phosphatidylcholine by Acyl-CoA: l-acyl-sn-glycero-3-phosphorylcholine Acyltransferase in Liver of Rainbow trout, Salmo gairdneri
Authors: Holub B. J. , Piekarski J. , Cho C. Y. , Slinger S. J.
Published: April 2011

The formation of phosphatidylcholine by acylation of 1-acyl-sn-glycero-3-phosphorylcholine with fatty acids was demonstrated in microsomal preparations from the livers of rainbow trout (Salmo gairdneri). Maximum incorporation of fatty acids into phosphatidylcholine was highly dependent upon the addition of 1-acyl-sn-glycero-3-phosphorylcholine to the incubation medium when activated acids in the form of [14C]acyl-CoA esters were provided. The acyl-CoA: 1-acyl-sn-glycero-3-phosphorylcholine acyltransferase showed a selectivity for unsaturated (oleate) over saturated (palmitate) fatty acids when microsomes were prepared from rainbow trout acclimated to 7 or 15 C and assays conducted at both temperatures. The presence of an acyl-CoA hydrolase in the microsomal preparations is also reported. The possible function of the acyltransferase in rearranging the fatty acid composition of cellular phospholipid when fish are exposed to a change in environmental temperature is discussed.
Influence of Lipid Pool Size on Bioaccumulation of the Insecticide Chlordane by Northern Redhorse Suckers (Moxostoma macrolepidotum)
Authors: Roberts J. R. , deFrietas A. S. W. , Gidney M. A. J.
Published: April 2011

An effect of the lipid pool size on the accumulation and clearance of cis- and trans-chlordane by northern redhorse suckers (Moxostoma macrolepidotum) has been demonstrated. A technique was developed using 203Hg-labeled methylmercury as a tracer, which permits the direct determination of the assimilation efficiency from food and the biological half-life of chlorinated hydrocarbons in terms of individual fish. Tissue retention of the insecticide chlordane in fish was directly proportional to the adiposity of the fish. For a fish containing 2% lipid, the half-life of the cis-isomer was 60 days and for the trans-isomer, 33 days. The net assimilation efficiency from food to fish tissue was also influenced by adiposity. These results on uptake and clearance, when used in a simple model for pollutant bioaccumulation, indicate that the steady state concentration of chlordane in fish will not exceed the concentration of chlordane in the diet unless the adiposity of the fish is high.
Immunization of Pacific Salmon: Comparison of Intraperitoneal Injection and Hyperosmotic Infiltration of Vibrio anguillarum and Aeromonas salmonicida Bacterins
Authors: Antipa Ross , Amend Donald F.
Published: April 2011

Two methods of immunizing fish, intraperitoneal (i.p.) injection and hyperosmotic infiltration, were compared for control of vibriosis and furunculosis in pen-reared coho salmon (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha). Both methods provided significant protection against vibriosis under field test conditions. In coho salmon, hyperosmotic infiltration provided the best protection and fastest rise in antibody titer of seven treatments tested. In chinook salmon, hyperosmotic infiltration of Vibrio anguillarum and Aeromonas salmonicida vaccines resulted in 83.3% survival in comparison with 28.7% survival in controls. Both i.p. injection and hyperosmotic infiltration of V. anguillarum and A. salmonicida bacterins resulted in production of serum antibodies specific for each respective pathogen. Vaccination with bivalent V. anguillarum–A. salmonicida vaccines produced antibodies to both pathogens, and provided protection against vibriosis. Growth rates of vaccinated coho salmon were not significantly different from controls.
Differences in Swimming Performance Among Strains of Rainbow Trout (Salmo gairdneri)
Authors: Thomas Allan E. , Donahoo Michael J.
Published: April 2011

Swimming performance profiles, relating fish size to swimming time, were established for three strains of rainbow trout (Salmo gairdneri). No differences were found in slope of regressions; only in level at each size of fish. Swimming performances of New Zealand and Sand Creek strains did not differ, but were superior to the Manchester strain. In stamina results from 189-day-old fish from individual matings of seven strains and various crosses, similar strains and crosses had closely matching profiles whereas profiles of unrelated groups were variable. Comparison of slowest, average, and fastest growing fish within the New Zealand strain showed that swimming ability was not related to growth rate.
Pulp and Paper Mill Effluent in a Freshwater Environment
Authors: Kelso J. R. M. , Minns C. K. , Brouzes R. J. P.
Published: April 2011

Background and scope are provided for joint Ontario Ministry of the Environment and Department of the Environment studies of the effect of a pulp and paper mill effluent in a freshwater ecosystem. Brief descriptions of pertinent features of the pulp and paper mill and Nipigon Bay are given as related to studies presented in this volume.
Analysis of a Pulp and Paper Mill Effluent Plume
Authors: Minns Charles K.
Published: April 2011

Several chemical surveys of a pulp and paper mill effluent plume in Nipigon Bay, Lake Superior, are analyzed to determine the average area and volume contained by a range of isoconcentration boundaries. Sodium, dissolved organic carbon, particulate organic carbon, and particulate organic nitrogen are the chemical variables used to examine changes occurring in the plume. Data are analyzed from three sampling regimes: (1) dye-slug tracking which allows interpretation of time-related processes, (2) surface surveys which indicate the areal extent of the plume, and (3) vertical profile surveys which indicate the degree of depth penetration for effluent components.Dilution dominates in the plume, though the nonconservative substances undergo significant changes. The plume area enclosed in a contour of 1% effluent is approximately 1.5 km2. Mass balance calculations indicate exchanges occurring between the plume and the old fiber beds in the vicinity of the effluent outfall.
Electrophoretic Distinction of Rainbow Trout (Salmo gairdneri), West-Slope Cutthroat Trout (S. clarki), and Their Hybrids
Authors: Reinitz Gary L.
Published: April 2011

Rainbow trout (Salmo gairdneri), west-slope cutthroat trout (Salmo clarki), and their F1 hybrids were electrophoretically examined for 13 different proteins. Of the 13 proteins, only phosphoglucose isomerase (PGI) proved to be a reliable biochemical marker for the distinction of genetically pure samples of the two species. Only PGI provided an accurate means of identifying F1 hybrids between the species. This information could possibly be used to facilitate the stabilization and restoration of native populations of west-slope cutthroat trout in western Montana. Key words: rainbow trout, west-slope cutthroat trout, hybridization, electrophoresis, biochemical marker, phosphoglucose isomerase (PGI)
Thyroid Activity of Alewives (Alosa pseudoharengus) and Rainbow Smelts (Osmerus mordax) in the Great Lakes
Authors: Sonstegard R. , Leatherland J. F. , Moccia R.
Published: April 2011

Thyroid glands, collected in 1974 and 1976 from sexually mature prespawning alewives (Alosa pseudoharengus) captured in lakes Ontario, Huron, and Michigan and from sexually mature, spawning rainbow smelts (Osmerus mordax) from lakes Ontario and Erie, showed no evidence of the thyroid exhaustion described in these species collected from identical sites and seasons in 1952. The observations suggest a change in the apparent thyroid activity of these species from those in earlier studies, and that the annual mortality of alewives is not directly related to an inability to produce sufficient thyroid hormone. Key words: alewives, rainbow smelts, thyroid, mortality, Great Lakes
An Illustrated Key to Freshwater and Soil Amoebae.
Authors: Low C. J.
Published: April 2011

not available
A Review of Pikeperch (Stizostedion lucioperca), Eurasian Perch (Perca fluviatilis), and Ruff (Gymnocephalus cernua) in Finland
Authors: Lind Esko A.
Published: April 2011

Three percids occur in Finland: the Eurasian perch (Perca fluviatilis), the pikeperch (Stizostedion lucioperca), and the ruff (Gymnocephalus cernua). Perch occur throughout Finland, whereas ruff and pikeperch show a more southerly distribution. The pikeperch prefers lakes of medium or large area and the perch small lakes. A negative correlation was found between the size of the population of the perch and the number of fish species present. The growth rate for all species is higher in brackish water than in freshwater, and also has been higher in recent than earlier years.The correlation between the intensity of color of the water and the percentage of predaceous fish in catches, perch and pikeperch included, is negative. Perch lived longer in ponds with dark water than in those with clear and eutrophic waters. Ruff and small perch are typically prey species, while the pikeperch is a major predator.The environmental toxins cadmium, lead, DDT, and PCBs were found in only slight concentrations in percids. Highest concentrations of mercury were found in fish taken from waters near the main sites of the cellulose industry. Concentrations in the percids have decreased since 1968 due to the reduction in mercury output.Catches of pikeperch from freshwater showed a decrease and those from brackish water an increase during 1953–73. Perch catches have increased. Key words: Percidae, Finnish percids, Stizostedion, Perca, Gymnocephalus, life history, environmental toxins, heavy metals, distribution, water color, yield
Maintenance of a Walleye, Stizostedion vitreum vitreum, Fishery in a Eutrophic Reservoir
Authors: Momot Walter T. , Erickson Jack , Stevenson Frederick
Published: April 2011

Hoover Reservoir, a very eutrophic environment, produces a successful fishery for walleye. However the population can only be sustained by stocking due to the absence of high quality summer habitat, intensive exploitation, poor recruitment of most natural year-classes, and poor growth of adult walleye. The oxygen temperature regime brought about by eutrophication forces the adult walleye to live at an above optimum temperature regime for maximum growth during the summer months. Because of the climate and geographical location, the preferred temperatures of the desired prey, young gizzard shad, are far above that of the adult walleye. This makes the shad less accessable to predation for a large portion of the day further reducing the growth of older walleye. Poor recruitment of large natural year-classes results from the absence of gizzard shad fry which spawn much later than walleye, at the time larval walleye convert from a planktonic to a piscivorous feeding habit. Large year-classes of walleye are produced in years when fry were stocked. Stocked fry were produced in hatcheries from spawn obtained at the reservoir. Fry were stocked in the reservoir just at or in advance of shad spawning, whereas in most years naturally produced fry appeared well in advance of shad spawning. This delayed appearance of stocked walleye fry probably accounts for their successful year-class production. This walleye spawning stock had an estimated mean biomass of 13.6 kg/ha and a mean annual production of 2.2 kg/ha between 1967 and 1973. Key words: Hoover Reservoir — Ohio, Percidae, Stizostedion, management, fry stocking
Long-Term Toxic Effects of DDT Food and Water Exposure on Fathead Minnows (Pimephales promelas)
Authors: Jarvinen A. W. , Hoffman M. J. , Thorslund T. W.
Published: April 2011

Fathead minnows (Pimephales promelas) were exposed during a partial chronic toxicity test to two DDT concentrations in the water, one in the diet, and combinations of water and diet for 266 days through a reproductive period of their life cycle. Tissue residue analyses were performed at preset intervals throughout the exposure and also on embryos, larvae at hatch, and 30- and 60-day progeny. The contribution of DDT from each source was monitored with gas chromatography and liquid-scintillation techniques. The fish were fed a diet of clams that had accumulated 14C-DDT when exposed at a DDT water concentration similar to that in the high fish exposure. Higher total DDT tissue residues were accumulated from the water than diet. Residues contributed by dietary DDT were additive to those from the water. Mean concentration factors were 1.2 for the diet and 100,000 for the water. Fish exposed to DDT in both water and diet had higher mortality rates than those exposed to only one or the other of these sources. DDT in the diet significantly reduced the probability of survival of the test fish (P = 0.025). Estimated maximum acceptable toxicant concentrations for DDT are 0.9 μg/ℓ for fish exposed to DDT in the water only and 0.4 μg/ℓ for fish exposed to DDT in both water and diet. Embryo residue levels and larval mortality rates were about twice as great for those from parent fish that had been exposed to DDT in both the water and diet as for those from parent fish exposed to only DDT in the water. Key words: toxicity, DDT, pesticides, food chain, 14carbon, bioassay, minnows, clams, aquatic animals
Structure of Pelagic Food Chain and Relationship Between Plankton and Fish Production
Authors: Sheldon R. W. , Sutcliffe Jr. W. H. , Paranjape M. A.
Published: April 2011

Further observations on the standing stocks of pelagic organisms confirm the occurrence of approximately equal biomass over logarithmically equal size ranges. A simple theoretical framework is developed that shows that the structural elements of the pelagic ecosystem can be described in terms of the sizes of predator and prey and of the efficiencies of their interactions. In practice this means that if the standing stock at any size range is known, the standing stock at any other size can be estimated, and if the growth rate at this size is known, the production can be estimated. The theory is tested on three fisheries. For the Gulf of Maine and the North Sea, phytoplankton production is estimated from fishery production. For the area off Peru the fishery production is estimated from the plankton production. Key words: pelagic ecosystem, predator–prey relationships, plankton production, marine fisheries, Peru, North Sea, Gulf of Maine
Technique for Tagging Small Fish with I131 for Evaluation of Predator–Prey Relationships
Authors: FitzGerald Gerard J. , Keenleyside Miles H. A.
Published: April 2011

Experiments to test the feasibility of using radioactive I131 as a technique for evaluation of conspecifïc predation on fry by adult convict cichlids (Cichlasoma nigrofasciatum) are described. The technique is useful for short-term quantitative studies of predator–prey interactions where it is not possible to observe and quantify predation directly or where stomach content analysis of adults is not feasible. Key words: radioactive tagging, predator–prey interactions, Cichlasoma nigrofasciatum
Polarographic Studies on the Nature of Cadmium in Scallop, Oyster, and Lobster
Authors: Chou C. L. , Uthe J. F. , Zook E. G.
Published: April 2011

Free and bound forms of cadmium were determined in raw shellfish by use of differential pulse polarography and atomic absorption spectrophotometry. Free cadmium is defined by its polarographic peak potential of −0.62 ± 0.02 V (saturated calomel electrode) in solvent washed ammonium sulfate extracts. Bound cadmium was determined by subtracting the free cadmium from the total cadmium present in the meat. Both scallop (various species) and American lobster (Homarus americanus) muscle tissues contain no free cadmium. Oyster (various species), on the other hand, had a considerable percentage (~50%) of its total cadmium present as free cadmium, a phenomena as yet unexplained. The detection limit for free cadmium is approximately 0.05 μg/g raw tissue. Key words: cadmium, polarography; free cadmium, oyster, lobster, scallop
Comparaison des échanges branchiaux de Cl− en eau douce chez Salmo gairdneri in vivo et in vitro sur la tête isolée perfusée
Authors: Payan P. , Pic P. , Renzis G. De
Published: April 2011

The Cl− influxes are identical in vivo and in vitro providing that the gills are externally irrigated during the preparation of the isolated head. A net uptake of Cl− is observed. When no irrigation is used the Cl− influx is reduced by 66% and Cl− is lost by the preparation.
Distribution of Humpback Whales (Megaptera novaeangliae) in the Caribbean Determined by a Rapid Acoustic Method
Authors: Levenson Coleman , Leapley William T.
Published: April 2011

Humpback whale (Megaptera novaeangliae) distribution in the eastern Caribbean Sea was studied by means of solitary sonobuoys deployed from an oceanographic aircraft. Humpback whale sounds were detected on 33 of 82 sonobuoys deployed. It is estimated that 62 whales were detected in an area of 22 140 km2 by this method with whale density calculated at 2.8 × 10−3 whales/km2. For further experiments in selected areas we used a colinear array to obtain accurate counts of humpbacks. A total of 18 humpbacks were detected in this manner with a mean of 2.6 whales per array deployment. Combined acoustic and visual detections indicate a minimum of 119 humpbacks in the area surveyed. This rapid acoustic method could also be applied to detection of almost all odontocete cetaceans and to other marine mammals with distinctive vocal patterns. Key words: cetaceans, whales, acoustic detection, distribution, density, humpbacks, aircraft detectors, sonobuoys
Status of Exosphaeroma inornata Dow and E. media George and Stromberg (Isopoda: Sphaeromatidae) with Ecological Notes
Authors: Iverson Ernest W.
Published: April 2011

The sphaeromatid isopod Exosphaeroma media George and Stromberg 1968 from San Juan Island, Puget Sound, is synonymized with E. inornata Dow 1958 from California. Differences between the original descriptions of both species are attributed to author errors or variations in the phenotype. Variation in the relative position of the rostrum and clypeus, crenulation of the uropod rami, pleotelson shape, coxal plate suture lines, and body ratio (width/length) are discussed. Exosphaeroma inornata is reported to be a wide-ranging intertidal species which is commonly found in crevices, sand, and associated with various algae. Although the distribution is reported to be from San Diego, Calif., north to San Juan Island, Puget Sound, a large distribution gap exists between Humboldt Bay and Puget Sound. Key words: isopod synonomy, anatomical variations, distribution, habitat
Vulnerability of Arctic Zooplankton Species to Predation by Small Lake Trout (Salvelinus namaycush)
Authors: Kettle Dean , O'Brien W. John
Published: April 2011

The susceptibility of arctic zooplankton species to small lake trout (Salvelinus namaycush) was investigated by measuring both the reactive distance of fish to prey and the success with which prey were captured. Species common to ponds without fish were found to be more vulnerable to lake trout than lake species, several of which appear to have developed adaptations to reduce visual predation. Key words: lake trout, zooplankton, predation, reactive distance
Separation of Two Dissolved Reactive Phosphorus Fractions in Lakewater
Authors: Downes Malcolm T. , Paerl Hans W.
Published: April 2011

A method for the separation of two dissolved reactive phosphorus (DRP) fractions in unconcentrated lakewater is described. A reactive high molecular weight phosphorus (RHMW-P) fraction has been found in all waters studied and a second fraction, corresponding to orthophosphate (PO4-P) is frequently detected. The hydrolysis of RHMW-P to PO4-P by acid in the analytical reagents is shown to be the most likely reason for its determination as DRP. Key words: freshwater analysis, reactive phosphorus, orthophosphate, molybdenum blue method, gel filtration
Meristic Variation of Lycodapus mandibularis (Pisces: Zoarcidae) and Oceanic Upwelling on the West Coast of North America
Authors: Peden Alex E.
Published: April 2011

Total vertebral counts of Lycodapus mandibularis populations in Georgia Strait, British Columbia, are significantly lower than those of southern populations off Oregon and California. The highest temperatures and lowest salinities at 200 m or deeper, where the species is most abundant, are also in Georgia Strait and correlate with the lowest counts. The Strait's deep water originates from tidal mixing of intermediate and estuarine surface waters of lower salinities and higher temperatures, whereas the mechanism in southern latitudes, which instead provides unmixed cooler and saline deep waters, is oceanic up-welling. It is suggested that differences in environment associated with different degrees of upwelling and mixing may cause the lower counts in the Strait of Georgia. Key words: Lycodapus mandibularis, Zoarcidae, meristic variation, inlets, upwelling, temperature, salinity, northeast Pacific Ocean, zoogeography
Marine Ecology. Vol. III. Cultivation, part 2.
Authors: Lawrence S. G.
Published: April 2011

not available
Method, Validity, and Variability in the Age Determination of Yellowtail Rockfish (Sebastes flavidus), Using Otoliths
Authors: Kimura Daniel K. , Mandapat Ruth R. , Oxford Sandra L.
Published: April 2011

A method using otoliths is presented for the age determination of yellowtail rockfish (Sebastes flavidus). Most of the details of this method are applicable to other species of rockfish. The method is validated in younger fish by documenting growth of the otolith annular zone by month, and by comparison with ages read from scales. Further validation is provided by length-at-age data, which show monotone growth for both males and females. Age reader variability was analyzed for each age category using random effects analysis of variance. This analysis showed that within-reader variances were similar for the two readers. Although there were significant variance components due to between-reader differences for aging some age categories, the contribution of this variance component to total variability was negligible. The standard deviation for an age determination of an otolith was similar for both readers, ranging from about 0.6 at 8 yr to about 1.6 at 19 yr. For both readers, the coefficient of variation was approximately 0.08 at all ages. Key words: Sebastes flavidus, age determination, otoliths
Indices of Food Type Preference by a Predator
Authors: Paloheimo J. E.
Published: April 2011

The forage ratio and Ivlev's electivity index as measures of preference by predators of different prey or food types were shown by Jacobs to depend on their abundance. Modifications proposed by Jacobs are shown here to be similarly affected by the abundance. However, an index of the preference that is indeed independent of the prey abundance can be based on standardized forage ratios, standardized so that the forage ratios for the different prey species sum to one. Key words: index of preference, prey selection, food selection, predator–prey relationship
Pollutant Effects on Marine Organisms.
Authors: Addison R. F.
Published: April 2011

not available
A Coastal Marine Ecosystem. Simulation and Analysis.
Authors: Silvert William
Published: April 2011

not available
Phytoplankton Ecology of the Strait of Georgia, British Columbia
Authors: Stockner J. G. , Cliff D. D. , Shortreed K. R. S.
Published: April 2011

Observations of phytoplankton production, abundance, and distribution were made at 16 stations in the Strait of Georgia from 1975 to 1977. The discharge of turbid Fraser River water exerts a strong influence on phytoplankton production and distribution in surface waters by rapid light attenuation and horizontal advection. At plume boundaries and back eddies where light conditions improve, very high production occurs (> 4–5 g C∙m−2∙d−1), because of rapidly replenished nutrients supplied by the Fraser River. Advection, turbulence, zooplankton grazing, and summer nitrate depletion collectively impart a heterogeneous distribution pattern to phytoplankton in the surface waters of the Strait of Georgia. Mean annual production varies from lows of 150 g C∙m−2 in Fraser River plume to highs of over 500 g C∙m−2 in sheltered boundary waters of inlets. Recent increases in ammonia and nitrate from land drainage and domestic sewage, mainly through the Fraser River, are related to increases in phytoplankton standing stocks in the Strait. Key words: phytoplankton, primary production, eutrophication, coastal marine, phytoplankton distribution and succession, chlorophyll a, pelagic
Limited Entry: Experience of the British Columbia Salmon Fishery
Authors: Fraser G. Alex
Published: April 2011

In 1969 a program of limited entry was introduced in the B.C. salmon fishery; this indicates the near desperation of Fisheries managers at the apparent bankruptcy of more traditional management measures. Also, this introduction represents a significant break in traditional management orientation. The goals of management were broadened to encompass not only resource conservation, but also socioeconomic rationalization. Unfortunately, the program was ill-designed to achieve either objective. In spite of license limitation it appears that fishing costs and fishing capacity are still growing at a rapid rate. Although vessel numbers are declining, much of the potential benefits are being offset by increasing capacity and capital intensity in the individual vessels that now make up the limited fleet. While some benefits may remain from the program due to the rapid increase in the value of the salmon resource over recent years, the distribution of these benefits is somewhat anomalous. The public purse has gained little because license revenues represent a small proportion of the total management costs of the fishery. At the same time, it cannot be interpreted that fishermen will be the long run beneficiaries of the program. The only clear winners are the original group of license holders. Various adjustments in the structure of the licensing program have been considered to address these problems. While the most practical and effective of these is a system of landings royalties or taxes on output, it remains the least politically attractive. If the British Columbia licensing program is to become an effective vehicle for decreasing fishing costs and fishing capacity, some difficult decisions are required. Key words: overcapitalization, salmon management, fisheries economics, fisheries management, fisheries policy, fish licensing, license limitation, fish royalties, tax on fish landings
Alaska's Limited Entry Program: Another View
Authors: Rogers George W.
Published: April 2011

Viewed in an historical perspective, the 1973 Alaska limited entry law evolved from fisheries policies motivated by distributive (Alaska first) and social (maintenance of rural fishing communities) criteria more than the traditional economic criteria of efficiency. Fisheries economics research has been primarily concerned with such matters as dissipation of economic rent through excessive units of harvesting. There is a need to expand this research into employment, labor mobility, and the evaluation of opportunity costs as well as economic efficiency. Key words: fisheries management, limited entry; Alaska; economics; political science and government; public policy
Limited Entry in the Western Australian Rock Lobster and Prawn Fisheries: An Economic Evaluation
Authors: Meany T. F.
Published: April 2011

Limited entry was first introduced into the rock lobster and prawn fisheries in 1963. Both fisheries have been characterized by rapidly rising prices for species caught. Although some sectors of the rock lobster fishery have remained moderately profitable, excessive reinvestment in boats and equipment has greatly reduced potential profitability. No trend towards company ownership of boats has been evident in this fishery. The prawn fishery was initially developed with a high degree of company ownership and the proportion of company ownership has increased. Overcapitalization has not occurred to any great extent in this fishery and profitability has remained high. Key words: rock lobster, prawns, limited entry, Australia, economics, overcapitalization, monopoly
Responses and Adjustments of Foreign Fleets to Controls Imposed by Coastal Nations
Authors: Kaczynski Wlodzimierz
Published: April 2011

Foreign distant-water fishing fleets expanded quickly during the last 15 yr and in some ocean areas accounted for a larger portion of the coastal fishery resources harvest than neighboring coastal nations. Extention of national jurisdiction sharply decreased these activities. Catch and fishing effort limitations imposed by coastal states were of particular concern for foreign fleets. To attenuate adverse effects of these restrictions, distant-water fishing operators are considering three basic and mutually complementing solutions: better utilization of their own coastal resources until now frequently neglected, shifting a part of their fleets to the open ocean fishing operations, and continuing highly restricted and reorganized fisheries in coastal zones of other nations. Fishing activities within the 200-mile economic zone involve utilization of surplus quotas allocated by coastal states, quicker development of joint venture operations with coastal partners, increased purchases of fresh fish from local fishermen, and transfer of technology and know-how mainly to the developing coastal countries. Supplies of goods and services are also accepted by foreign fleets in exchange for access rights to the marine living resources of the coastal nations.However, all these adjustments of foreign fleets are considered an intermediate stage of the long-run trend in which the coastal state will be able to develop the resources without substantial participation of foreign fishermen. This trend is analyzed in the North Pacific distant-water fisheries development during recent years. Key words: distant-water fishing fleets, world fisheries, foreign fishery activities, 200-mile economic zone, marine fishery resources utilization, management of foreign fleets, quota allocations, North Pacific marine fisheries
Implications of Multipurpose Fleets and Mixed Stocks for Control Policies
Authors: Huppert D. D.
Published: April 2011

Management of harvests from mixed stocks and multipurpose fleets requires the use of concepts not discussed in single species fishery models. Optimum harvest of a group of mixed stocks implies that an aggregate objective pertaining to the multispecies catch is maximized. This usually prohibits the attainment of the maximum sustained yield or the maximum economic yield for each individual stock. Operation of a multipurpose fleet is economically justifiable when there are significant annual or seasonal fluctuations in fish stock abundance. A simple linear model is developed in this paper to demonstrate how the multipurpose fleet can be a necessary part of rational management. Key words: economics, management, multispecies
Hydroacoustic Estimates of Adult Sockeye Salmon (Oncorhynchus nerka) in Lake Washington, 1972–75
Authors: Thorne Richard E.
Published: April 2011

Hydroacoustic techniques were used on Lake Washington from 1972 to 1975 to estimate the potential escapement of sockeye salmon (Oncorhynchus nerka). Target strength measurements were used to establish a threshold which would separate the larger adult sockeye salmon from smaller resident fish. The acoustic estimates of escapement were very similar to those obtained from visual observations at the Hiram M. Chittenden ship canal locks, observations on the Cedar River, and spawning ground surveys. Key words: hydroacoustic, acoustic, methodology, sockeye salmon, escapement
Die Binnengewässer Band XXVI. Das Zooplankton der Binnengewässer. Teil 2.
Authors: Patalas K.
Published: April 2011

not available
Terrigenous Organic Matter in Sediments of the St. Lawrence Estuary and the Saguenay Fjord
Authors: Pocklington R. , Leonard J. D.
Published: April 2011

The proportion of land-derived organic matter in sediments of the upper St. Lawrence Estuary is unexpectedly low. In the Saguenay Fjord and the lower estuary, high organic carbon to nitrogen ratios and the presence of lignin indicate a substantial contribution of organic matter from terrestrial sources. The proportion of terrigenous organic matter decreases rapidly thereafter, approaching levels typical of marine sediments in the open Gulf. Key words: Organic matter, sediments, carbon to nitrogen ratio, lignin, St. Lawrence Estuary, Saguenay Fjord
Relationship of Cadmium-Induced Hypocalcemia with Mortality in Rainbow Trout (Salmo gairdneri) and the Influence of Temperature on Toxicity
Authors: Roch M. , Maly E. J.
Published: April 2011

Cold-acclimated (6 °C) rainbow trout, exposed to lethal concentrations of cadmium, survived longer than warm-acclimated (12 and 18 °C) trout. Ten-day lethal thresholds indicated that cold-acclimated trout could also resist greater concentrations of cadmium. Calcium concentrations in the plasma of fish, exposed to 0.3 mg Cd/L, declined steadily during the period of exposure when subjected to five thermal regimes, different combinations of acclimation and experimental temperatures. The rate of decline in calcium concentrations was correlated with the rate of mortality. Survival times of 12°-acclimated trout subsequently exposed to cadmium at 6, 12, and 18 °C were inversely dependent on temperature, whereas survival times of trout acclimated to 6, 12, and 18 °C and subsequently exposed to cadmium at acclimation temperatures do not show the same temperature dependence. Survival times of 12 and 18°-acclimated and exposed fish were similar, indicating that temperature compensation may promote longer resistance of 18°-acclimated and exposed fish than when they are acclimated to 12 °C and abruptly transferred and exposed to cadmium at 18 °C. Symptoms of cadmium poisoning of the fish are consistent with the effects of extreme hypocalcemia and are similar to those reported in the literature for various fish. The decline of calcium concentrations in the plasma may be the direct cause of mortality. Key words: Cadmium, temperature, hypocalcemia, rainbow trout, Salmo gairdneri, toxicity
Examination of Phosphorus Cycling and Control of Phytoplankton Dynamics in Lake Ontario with an Ecological Model
Authors: Scavia Donald
Published: April 2011

An ecological model of Lake Ontario was used to assist in interpretation of data collected during the International Field Year for the Great Lakes (March 1972–April 1973). The analysis indicated that in spring and fall phytoplankton biomass is controlled by the interaction of incoming solar radiation and vertical mixing, in summer by silica- and phosphorus-limitation, and in late summer by zooplankton grazing. The influence of CaCO3 precipitation on the light climate in late summer was also demonstrated. During the period of stratification, available phosphorus concentration is controlled by recycling within the epilimnion, primarily through plant and animal excretion. Comparison of simulated available phosphorus concentrations and concentrations of total dissolved phosphorus and soluble reactive phosphorus in the epilimnion suggest that the composition of the soluble unreactive phosphorus pool changes dramatically during the year and that the large pool of dissolved unavailable phosphorus during summer is composed of end products of material cycled several times through the food web. Key words: phytoplankton dynamics, phosphorus cycle, Lake Ontario, ecological model, nutrient recycling, phytoplankton production
Différenciation de populations anadromes et dulcicoles de Grands Corégones (Coregonus clupeaformis) par la composition minérale de leurs écailles
Authors: Moreau Guy , Barbeau Claude
Published: April 2011

The mineral composition in alkaline earth elements of whitefish scales from fresh- and saltwater of the La Grande River area were studied. While calcium and magnesium concentrations remained unchanged, regardless of site or age, the strontium concentrations changed markedly according to basin and water salinity. The variations in strontium are used to differentiate anadromous and freshwater populations, and to caracterize certain portions of La Grande River.
Intrusions and Vertical Mixing at the Shelf/Slope Water Front South of Nova Scotia
Authors: Herman Alex W. , Denman Kenneth L.
Published: April 2011

Intensive profiling of the shelf/slope water boundary south of Nova Scotia has been made with a Batfish vehicle measuring physical and biological parameters consisting of chlorophyll a, zooplankton, conductivity, temperature, and depth. Continuous profiling (~30 h) through the boundary zone revealed intrusions at the subsurface front consisting of plumes of ascending slope water overlying descending surface coastal water both moving vertically and horizontally. Movements of the intrusions were coherent with M2 tidal cycles and exhibited localized turbulent mixing ascribed to shear instabilities. This mixing gives rise to a potentially efficient mechanism for vertical transport of heat and salt particularly as input to the Scotian Shelf. These intrusions also form inversion layers consistent with earlier observations which showed that these layers can decay over longer time scales by double diffusion processes. The vertical mixing at the subsurface front may also account for the anomalously high productivity along the front by means of continual replenishment of nutrients from below. Key words: physical oceanography, biological oceanography, Scotian Shelf, profiling
Intercomparison of Niskin and Blumer Samplers for the Study of Dissolved and Dispersed Petroleum Residues in Seawater
Authors: Levy E. M.
Published: April 2011

A comparison of the data from Niskin and Blumer contamination-free samplers regarding the concentration of dissolved and dispersed petroleum residues in seawater demonstrated that equivalent information may be obtained if the appropriate procedures are used. Key words: petroleum, pollution, seawater, samplers
Occurrence of a Deep Nitrite Maximum in Lake Michigan
Authors: Mortonson J. A. , Brooks A. S.
Published: April 2011

A nitrite maximum with concentrations up to 10 μg NO2−-N∙L−1 was observed at depths between 30 and 60 m during summer in oxygen-saturated waters of Lake Michigan. The extracellular release of nitrite by phytoplankton concentrated below the thermocline appears to account for this maximum. In fall, when phytoplankton were no longer concentrated in this zone, no nitrite maximum was observed. It appears that the deep nitrite maximum in Lake Michigan is found only in association with high densities of phytoplankton.Key words: Lake Michigan, nitrite, nitrogen, phytoplankton
Maximum Tolerable Level, Digestion, and Metabolism of D-Glucose (Cerelose) in Rainbow Trout (Salmo gairdneri) Reared on a Practical Trout Diet
Authors: Hilton J. W. , Atkinson J. L. , Slinger S. J.
Published: April 2011

The maximum tolerable dietary level, digestion, and metabolism of D-glucose (cerelose) were investigated in rainbow trout (Salmo gairdneri) reared on practical diets containing optimum protein and lipid levels at two different water temperatures for 12 wk. Liver glycogen levels (LG) and liver:body weight ratios (LB) initially increased with increasing dietary glucose, but leveled off above 10–15% glucose. The plateauing of LB and LG was consistent with the plateauing of liver glucose-6-phosphate dehydrogenase activity (G6PD) and probably overall hexose monophosphate shunt (HMS) activity at high dietary levels of glucose. This indicates that there may be an optimum ratio of digestible carbohydrate to lipid in salmonid diets. LG and LB tended to be higher in trout reared upon the same dietary glucose level in fish reared at 11 °C as compared with those at 15 °C. This may have been caused by increased activity of the HMS as indicated by increased activity of liver G6PD in fish acclimated to 11 °C as compared to trout reared at 15 °C on the same dietary glucose level (when assayed at 15 °C). The digestion coefficient of glucose was uniformly high (96–99%) and not affected by either dietary glucose level (up to 25% of the diet) or water temperature (11 or 15 °C). The maximum tolerable level of glucose in salmonid diets appears to be dependent upon the protein, lipid, and overall energy content of the diet.Key words: trout, glucose digestion, glucose metabolism, maximum tolerable levels, water temperature, dietary energy
A Method for Predicting Winter Oxygen Profiles in Ice-covered Ontario Lakes
Authors: Jackson Michael B. , Lasenby David C.
Published: April 2011

A simple method is presented for predicting oxygen profiles under ice cover in selected Ontario lakes. The oxygen loss rate within individual lake strata over winter can be predicted from the oxygen concentration in each stratum about 5 – 15 d after freeze-up (at the time of maximum volume-weighted oxygen concentration for the lake). Shield lakes and limestone-transition lakes are described by two distinct relationships; the rate of oxygen loss per unit oxygen concentration is greater in the limestone-transition lakes.Key words: lake-oxygen concentration, limestone lakes, lake respiration, oxygen profile, lake depth, oxygenation/oxidation processes, ice cover, Shield lakes