bluuebunny/crossref_metadata_2025 huggingface dataset:
An Instrument with Internal Calibration for Monitoring Chlorine Residuals in Natural Waters
Authors: Marinenko George , Huggett Robert J. , Friend Dale G.
Published: April 2011

To increase the sensitivity of field instruments for measurement of low level chlorine concentrations in natural waters a new monitor was developed. Iodine, resulting from oxidation of potassium iodide by chlorine residual, is measured amperometrically in a system in which coulometrically generated iodine is used as a system calibrant. Laboratory tests, field tests, and comparisons of the new chlorine monitor with other instruments were performed. Data obtained with the new instrument show that chlorine concentrations down to a few parts per billion can be measured. The instrument is portable, and has built-in electrical calibration features and direct read-out display in either microamperes or parts per million of residual chlorine.
Cryopreservation of Fish Spermatozoa and Ova
Authors: Horton Howard F. , Ott Alvin G.
Published: April 2011

This paper summarizes historical and current attempts to cryopreserve the gametes of fish, and suggests future uses of cryogenics in fishery biology. Particular attention is given to the evaluation of procedures for collecting, freezing, thawing, and testing spermatozoa. Best methods entail manual stripping for semen, rapid freezing in the vapor of liquid nitrogen, rapid thawing of sperm cells, and fertilization tests with fresh ova. Assessment of the cryoprotective influence of common constituents of fish sperm extenders and life protectors is given. Based on current studies, a simple extender containing two salts and lecithin seems as adequate as more complex diluents. Dimethyl sulfoxide repeatedly provides best protection of salmomd spermatozoa from damage by freezing. Considering current developments, recommendations are made for improving cryoprotective procedures. The paper concludes with speculation on cryopreserving eggs, and on possible areas for further research.
Role of Mariculture in the Canadian Seaweed Industry
Authors: Neish Iain C.
Published: April 2011

Natural stocks of Canadian marine algae serve as sources of raw material for the alginate, carrageenan, and food seaweeds industries. The large stocks of seaweed on both coasts of Canada have stimulated investigations by workers involved in a wide range of disciplines. In recent years, the results of seaweed surveys and scientific investigations have led to the development of seaweed cultivation techniques which are assuming a commercial orientation. Commercial seaweed cultivation in Canada is in the early stages of development. Although Canadian cultivation techniques draw on Japanese cultivation techniques to some extent, the Canadian work has a number of characteristic features which stem from the economic and environmental features prevalent in the area. Canadian cultivation techniques tend to emphasize vegetative propagation in enclosures. The Canadian techniques tend to be intensive and have a low labor content. The significance of mariculture within the context of a total Canadian seaweeds industry is discussed.
Some Comments on Balon’s Terminology of Fish Development Intervals
Authors: Richards W. J.
Published: April 2011

Reasons are given for using established and simplified terms and definitions for describing the developmental stages offish rather than new and complicated terms and definitions. There are many more important aspects of the study of the early life history of fish than developing terminologies for them.
Free Fatty Acids and the Onset of Rancidity in Rainbow Trout (Salmo gairdneri) Flesh. Effect of Phospholipase A
Authors: Mazeaud F. , Bilinski E.
Published: April 2011

The relation between free fatty acid (FFA) formation and lipid autoxidation was studied in rainbow trout (Salmo gairdneri) using muscle homogenates incubated with or without added phospholipase A (PLA). In both white and red muscle, incubated for 2 h at 37 C, PLA induced a strong increase of FFA, but the thiobarbituric acid (TBA) number of PLA-treated homogenates was lower than in the untreated samples. This antioxidant effect was also observed after incubation at 20 or 4 C. However, a few days cold storage (4 C) of homogenates previously incubated with PLA at 37 C led to a progressive decrease of the antioxidant effect, although FFA liberation continued. The incubation of muscle homogenates with butylhydroxyanisole (0.02%) depressed the TBA number to the same extent as the treatment with PLA. It is suggested that the antioxidant effect of PLA is related to the liberation of polyunsaturated fatty acids and an hypothetical mechanism involving the formation of prostaglandins is proposed.
Recruitment: a Problem of Multispecies Interaction and Environmental Perturbations, with Special Reference to Gulf of St. Lawrence Atlantic Herring (Clupea harengus harengus)
Authors: Lett P. F. , Kohler A. C.
Published: April 2011

A stochastic model was developed to study effects of temperature perturbations, predation, and competition from Atlantic mackerel (Scomber scombrus) on the recruitment process for Gulf of St. Lawrence Atlantic herring (Clupea harengus harengus). Multivariate statistics were used to determine the structural equation for portions of the life history of herring. Temperature and the abundance of age-group 0 mackerel affected the herring growth rate, but neither total herring biomass nor total pelagic biomass had any measurable effect on herring growth rate. Herring growth rate, coupled with adult stock size and environmental effects, mediated through temperature were the prime determinants of larval abundance less than 10 mm. Density-dependent growth was found in the l1 stage but is argued as being anomalous in relation to age-group 0 herring maximizing their production to simultaneously stabilize both l1, (the 1st yr of life) and year-class size. Predation, tempered by available food density, is discussed as a major population stabilizing and a fine-tuning mechanism for year-class formation. The ramifications of variation in recruitment are discussed in relation to the Beverton and Holt and the Schaefer models. In addition, the Ricker recruitment curve is confirmed as being a viable fisheries management tool.
Review of the Rate of Growth and Mortality of Pacific Salmon in Salt Water, and Noncatch Mortality Caused by Fishing
Authors: Ricker W. E.
Published: April 2011

Mortality (other than landed catch) caused by pelagic gillnetting is estimated to be equal to the catch, for salmon in their penultimate year of life, and equal to about a quarter of the catch for salmon in their final year of life. Mortality caused by trolling for coho (Oncorhynchus kisutch) and chinook salmon (O. tshawytscha) averages about one fish killed (mostly below legal size) for every two that are boated. The natural mortality rate for sockeye salmon (O. nerka) in their final year of life averages about 0.015 per mo and is somewhat more in earlier years of pelagic life; the greater part of natural mortality after the smolt stage occurs during the downstream migration and early months of "coastal" life. For coho and chinook the best natural mortality estimate for the last year of life is 0.013 per mo, and that for pink (O. gorbuscha) and chum (O. keta) is of the same order. Growth rates during the final growing season vary from 0.26 per mo for pink and coho salmon to 0.06 per mo for chinook in their 5th ocean yr. Gains from ceasing to take immature salmon on the high seas range up to 300% of the catch now being taken in that category, while for fish taken in their final year they range up to about 70%, depending on the time of year at which the fishing is done. Gains from transferring existing pelagic net fisheries to the coastal region would be 76% (North American sockeye) and 86% (Asian sockeye) of the weight of fish now caught pelagically. Gains in total yield of existing salmon fisheries (pelagic and coastal) are estimated as 78% for Asian pink salmon and 72% for Asian sockeye. The increase in weight of the total catch from discontinuing ocean trolling for Columbia River chinook salmon and increasing river fishing correspondingly is estimated tentatively as between 63 and 98%.
An Index of Fish Movement with Statistical Techniques for Its Interpretation
Authors: Bergersen Eric P. , Keefe Thomas J.
Published: April 2011

A measure of the strength of association between two categorical variables (location of initial marking and location of recapture) is proposed as an index of the extent of fish movement in streams. Confidence intervals and tests of significance for interpretation of the strength of association are presented, along with their development and theoretical justification. The proposed methodology is applied to fish movement data collected before and after pollution-abatement periods in a river in northern Utah.
Delayed Recruitment Models and Their Application to the American Lobster (Homarus americanus) Fishery
Authors: Marchesseault Guy D. , Saila Saul B. , Palm William J.
Published: April 2011

A delayed recruitment model intended for use in developing dynamic strategies for fisheries management is proposed. The conceptual and analytical properties of the model are elaborated and compared with those of the instantaneous model of Schaefer and the delayed recruitment model recently suggested by Walter. Of the three models discussed, the delayed recruitment model proposed herein constitutes the more biologically meaningful tool for use in management decision making with fisheries characterized by a multiple year delay between spawning and recruitment. The proposed delay and Schaefer models are fitted to catch and effort data from the Rhode Island inshore pot lobster fishery, and the generated coefficients are examined with respect to their interpretation and relative importance. Values of optimum equilibrium catch and effort are calculated for the proposed delay and Schaefer models, and we show that the delay model’s estimates of these management indices are more conservative than those derived from Schaefer’s model. The proposed delay and Schaefer models are compared in a dynamic analysis of the fishery, in which perturbations in the stock level and fluctuations in the applied effort are simulated to predict the subsequent behavior of the stock.
Recent Measurements of Wind Stress on Arctic Sea Ice
Authors: Banke E. G. , Smith S. D. , Anderson R. J.
Published: April 2011

Eddy flux measurements of wind stress on the arctic pack ice have been made in summer and winter in terrain ranging from fiat to hummocked. Parameterization by a drag coefficient dependent on a surface parameter is suggested. Reduced values of the drag coefficient were observed in highly stable stratification. The coefficient for sensible heat flux is lower than the drag coefficient. Wind drag on ice ridges has been measured by a pressure differential method.
Mineral Metabolism During the Ontogenesis of Rainbow Trout (Salmo gairdneri)
Authors: Zeitoun Ibrahim H. , Ullrey Duane E. , Bergen Werner G. , Magee William T.
Published: April 2011

Rainbow trout (Salmo gairdneri) eggs were collected from three females, fertilized by the milt of two males per female, and incubated separately. Samples were taken before fertilization, at +0.5 h and on days 1, 1.5, 3, 4, 5, 13, 17, 21, at hatching (23 days), and on day 37, immediately after postyolk absorption. The water environment contributed an estimated minimum 26% of the Na, 30% of the Fe, and 13% of the Zn found at hatching. Derivation of Ca, Na, K, Fe, and Zn from the water environment at postyolk absorption was estimated to be at least 70, 76, 45, 68, and 2%, respectively. All the P and Cu at hatching and in the larva could have been derived from the unfertilized oocyte.
Environmentally Induced Precocious Sexual Development in the Male Pink Salmon (Oncorhynchus gorbuscha)
Authors: MacKinnon Colin N. , Donaldson Edward M.
Published: April 2011

Nine males within a group of approximately 200 pink salmon (Oncorhynchus gorbuscha) reared in heated sea water became sexually mature in October of the year of hatching. These mature males (average weight = 119.44 g; average length = 19.8 cm) were larger than the immature males (average weight = 92.22 g; average length = 18.9 cm but not significantly so. This is the first record of precocious development in pink salmon other than as a result of the use of exogenous gonadotropin.
Visual Observations of Phosphorus Movement Between Algae, Bacteria, and Abiotic Particles in Lake Waters
Authors: Paerl H. W. , Lean D. R. S.
Published: April 2011

The transfer of 33P-PO4 into plankton and the appearance of labeled colloidal material occurs within minutes in lake water. It is difficult to clearly separate the microscopic forms involved in phosphorus transfer by mechanical means since size ranges of algae, bacteria, detritus, and colloidal matter overlap. To circumvent this problem we used microautoradiography and scanning electron microscopy (SEM) to describe the sequence in which bacteria, algae, and suspended particles remove 33P-PO4 from solution and the physical appearance of excreted material suspected of containing labeled phosphorus.Bacteria initially showed much more dense labeling with 33P-PO4 but, since the algal biomass greatly exceeded the bacterial biomass, algal 33P-PO4 incorporation represented the most significant uptake pathway. After 2 h 33P accumulated in both the detrital aggregates which were harboring bacteria and the "capsular" material surrounding Anabaena. When these suspected extracellular release sites were examined by SEM, we observed fibrillar and amorphous particles of colloidal size (.05–0.5 μm). The possible ecological roles of these colloidal substances are discussed.
Phosphoglucomutase Polymorphism in the Green Crab, Carcinus maenas
Authors: Sherburne Stuart W.
Published: April 2011

Starch-gel electrophoresis revealed a polymorphic system for the enzyme phosphoglucomutase (PGM) in muscle extracts of 100 green crabs, Carcinus maenas, sampled from Boothbay Harbor, Maine, in 1970 and 1971. This system comprised six phenotypes, including three homozygotes and the corresponding heterozygotes. Each phenotype consisted of two or more isozyme bands. The inheritance of the observed phenotypes can be explained by the existence of three allelic autosomal genes, PGMa, PGMb, and PGMc. The PGM isozymes of the green crab are described with gene frequency data from the population at Boothbay Harbor. These data conform to the Hardy–Weinberg distribution.
Modification of the Whiteside–Williams Pattern Sampler
Authors: Brakke David F.
Published: April 2011

The construction and operation of a modified pattern sampler for littoral microcrustaceans is described. The sampler is lightweight and inexpensive, yet produces quantitative information on populations and their spatial array. The composition of collections made by net and pattern samplers was not significantly different. The pattern sampler, however, offers several advantages.
Differing Goals of Salmon Management on the Skeena River
Authors: Hilborn Ray , Walters Carl J.
Published: April 2011

In this paper we describe the use of a specific decision analysis tool, multiattribute utility analysis, to investigate conflicting goals in the management of salmon on the Skeena River. We used this technique to determine the preferences of 10 individuals representing several interest groups and different management agencies. It is shown how individuals differ in their preferences, how conflicts can be identified, and how decision analysis can be used to refine an individual's understanding of his preferences. Individuals assessed possible outcomes of different alternative enhancement proposals using two techniques, the decision analysis technique and an intuitive approach. These two methods produced different results. The use of these techniques in the management process is discussed.
Critical Swimming Speeds of Coho Salmon (Oncorhynchus kisutch) Fry to Smolt Stages in Relation to Salinity and Temperature
Authors: Glova G. J. , McInerney J. E.
Published: April 2011

Critical swimming speeds (fork lengths per second L/s) of early fry, advanced fry, and pre-smolt coho salmon, Oncorhynchus kisutch, surpassed those of smolts. Performances were inversely related to size, varying from a peak of 7.3 L/s in fry to 5.5 L/s in smolts. In early fry to pre-smolt stages, salinity had little effect whereas in smolts a distinct maximum performance occurred near 13‰. Swimming performances of all stages varied directly with temperature: maxima occurred between 20 and 23 °C. As temperature decreased, critical speeds of early fry declined at a faster rate than that of later stages, the values at 23 and 3 °C being 7.2 and 3.5 L/s in early fry and 5.5–3.5 in smolts. This study shows that on a size-related basis underyearling coho are capable swimmers in estuarine conditions. Thus, their apparent failure to survive premature seaward migrations cannot be explained by their inability to perform important locomotor-dependent behaviors.
Reliability of Laboratory Metabolic Measurements of Meiofauna
Authors: Vernberg Winona B. , Coull Bruce C. , Jorgensen Darwin D.
Published: April 2011

The interstitial copepod Hastigerella leptoderma respires significantly less when sand grains are present than when sand grains are absent and the mud-dwelling species Nannopus palustris requires significantly different amounts of oxygen depending on the extraction method. Since the use of a substrate significantly reduced the metabolic rate of H. leptoderma, most meiofauna literature respiratory values are probably inflated estimates of the true metabolic rate. One must be careful how animals are extracted from the sediment because N. palustris extracted by differential gradient centrifugation respired significantly less than those hand sorted. Laboratory manipulation can significantly alter the estimated energy loss due to respiration.
Species Diversity of Littoral Zone Fishes Along a Phosphorus–Production Gradient in Lake Memphremagog, Quebec–Vermont
Authors: Nakashima Brian S. , Gascon Dominique , Leggett William C.
Published: April 2011

The species diversity of littoral zone fish communities in four areas of Lake Memphremagog was positively related to known phosphorus and primary production gradients along the north–south axis of the lake and to the associated north–south differences in macrobenthic and fish biomass. The highest diversity values were found consistently in the highly productive southern areas of the lake and the lowest values in the least productive northern areas.
Validity of the Subspecies Designation for the Dwarf White Sucker (Catostomus commersoni utawana)
Authors: Beamish R. J. , Crossman E. J.
Published: April 2011

A reexamination of white sucker populations originally used to document the subspecies validity and biology of a dwarf white sucker, Catostomus commersoni utawana, provided no evidence of two separate populations of different-sized individuals. Small mature white suckers and larger or normal-sized white suckers still were present, but there was a continuous range of sizes after maturity. After maturity males grew slower than females and had a higher rate of annual mortality. If the size separation originally used to separate the two forms was applied to this study, then all normal-sized white suckers in this study were females and would have had to reproduce with smaller males. Also, no meristic or morphological evidence for justification of a subspecies designation for the dwarf form of white sucker in this lake was found. Because it was also known that considerable variation in the size of white suckers at maturity occurs throughout the range of this species, it was concluded that the existence of a distinct dwarf subspecies has not yet been demonstrated.
Survival of Two Bacterial Fish Pathogens (Aeromonas salmonicida and the Enteric Redmouth Bacterium) in Ozonated, Chlorinated, and Untreated Waters
Authors: Wedemeyer Gary A. , Nelson Nancy C.
Published: April 2011

Ozone and chlorine inactivation curves were determined in three water types at 20 °C for the destruction of the fish pathogens Aeromonas salmonicida, the etiologic agent of furunculosis, and the enteric redmouth bacterium (ERM). In phosphate-buffered distilled water, 0.01 mg/ℓ ozone inactivated 103 cells/ml of ERM and A. salmonicida in 1/2 and 10 min, respectively. Chlorine at this concentration had little effect on either pathogen and a residual of at least 0.05 mg/ℓ was needed to achieve a complete kill within a 10-min contact time. In soft lake water (30 mg/ℓ as CaCO3) a chlorine residual of 0.1 mg/ℓ rapidly [Formula: see text] inactivated A. salmonicida and ERM but in hard water (120 mg/ℓ) A. salmonicida was more resistant and 0.2 mg/ℓ chlorine was required. Ozonation of the two lake waters at 90 mg O3∙h−1∙ℓ−1 (equivalent to a 0.01 mg/ℓ residual in ozone demand-free water) was required to destroy both pathogens within 10 min.In untreated soft lake water 103 cells/ml of A. salmonicida survived only 2 days, while the ERM bacterium (103 cells/ml) survived even after 20 day s in soft and hard untreated lake waters.
Holding of Atlantic Mackerel (Scomber scombrus) in Refrigerated Sea Water
Authors: Lemon D. W. , Regier L. W.
Published: April 2011

Refrigerated sea water proved to be an improved method of holding Atlantic mackerel (Scomber scombrus). The uniform lower temperature and reduction in available oxygen retarded the development of oxidative rancidity. Textural deterioration was also retarded. The sodium uptake from and the potassium loss to the sea water was not excessive, and taste panelists could not consistently identify samples with elevated sodium content. The addition of carbon dioxide to the RSW did not regularly affect the level of spoilage as monitored by the measurement of trimethylamine. The values, however, were low for all holding systems, even after 9 days. The presence of dissolved carbon dioxide in the fish muscle made the fish unacceptable for canning.
Effects of Bovine Growth Hormone on Growth of Carp (Cyprinus carpio) and the Influences of Temperature and Photoperiod
Authors: Adelman Ira R.
Published: April 2011

Experiments were conducted on young-of-the-year or yearling carp (Cyprinus carpio) to determine the influence of temperature and photoperiod on the growth promoting ability of bovine growth hormone, and the dose–response relationship of bovine growth hormone on carp growth. There was relatively greater enhancement of growth due to bovine growth hormone at an above optimum temperature for growth, 35 °C, than at the optimum temperature, 30 °C. This was possibly due to decreased production or activity of endogenous growth hormone at the higher temperature, resulting in a greater relative response to the exogenous bovine hormone. Inhibition of endogenous growth hormone may be a major limiting factor to growth at above optimum temperatures. Daylengths of 9 and 16 h had no effect on the response of the fish to hormone injections. At a temperature of 35 °C fish receiving bovine hormone dosages of 12.5, 25, 50, and 100 μg/g per wk responded with increasingly greater growth rates over fish receiving sham injections. Condition factors of fish increased throughout most of the experiment with greater increases among hormone injected fish.
Oceanographic Features, Currents, and Transport in Cabot Strait
Authors: El-Sabh Mohammed I.
Published: April 2011

Seventy oceanographic sections across Cabot Strait, taken at various times of the year between 1950 and 1974, were utilized to describe the average oceanographic featues, currents, and volume transport patterns as well as their variations with depth and time. The water mass structure in Cabot Strait is a two-layered structure; the water in the upper 50–100 m is typically moving seaward, while below that depth it is commonly found to be moving into the Gulf. The character of the upper layer which is normally not of uniform thickness across the Strait, but is distinctly wedge-shaped, is subject to considerable seasonal variation, whereas that of the lower is quite uniform the year round. Seasonal and long-term variations of the physical properties in Cabot Strait are described.Outflow through Cabot Strait is shown to be concentrated in the upper layer off Cape Breton and is balanced by inflow at intermediate depths on the Newfoundland side and in the deep portions of the section. The maximum and minimum transports, both inflow and outflow, occur in August and June, respectively. The net outward volume transport through the Strait increases from 9 × 103m3/s in April to 25 × 103m3/s in August and decreases to about 0.1 × 103m3/s in February. The weighted mean value, 13 × 103m3/s agrees well with the value obtained from an estimate of net freshwater input rate (run-off plus precipitation minus evaporation) above the section. The maximum transport occurs at times of surface minimum salinity. Horizontal advective transport of salt is found to be more important than horizontal diffusive transport. Recommendations for future transport studies in Cabot Strait are presented.
Dissolution of Diatom Frustules and Recycling of Amorphous Silicon in Lake Michigan
Authors: Parker J. I. , Conway H. L. , Yaguchi E. M.
Published: April 2011

We measured the concentration of diatom frustules and amorphous silicon per gram of dry sediment at 5-m intervals in the upper water column (0–40 m), in sediment traps placed at 37 and 60 m below the surface, and in a sediment core. The average concentration of frustules per gram of dry suspended sediment in the water column was 3.14 × 108. The 37 and 60 m trap sample averages were 1.16 × 108 and 5.03 × 107 frustules/g dry sediment, respectively. Subsamples from the sediment core averaged 6.31 × 106 frustules/g dry surficial sediment. The average proportion of amorphous silicon/g dry sediment was 8.6% in the water column, 7.7% in the 37 m traps, 6.0% in the 60 m traps, and < 2.0% in subsamples from the sediment core. The major fraction of amorphous silicon produced annually as diatom frustules was decomposed before incorporation in the permanent sediment. A comparison of the annual silicon requirement for diatom production and silicon inputs showed that the watershed contributes < 5.0% of the dissolved reactive silicon required for annual diatom production. These observations suggest that recycling of biogenic silicon provides the major source of soluble reactive silicon required for diatom blooms in Lake Michigan. Key words: Lake Michigan, diatoms, sedimentation, sediment traps, dissolution, deposition, silicon, sources, sinks, recycling
Effect of Meiofauna on Incorporation of Aged Eelgrass, Zostera marina, Detritus by the Polychaete Nephthys incisa
Authors: Tenore Kenneth R. , Tietjen John H. , Lee John J.
Published: April 2011

The mineralization rate of detritus derived from carbon-14 labeled eelgrass, Zostera marina, was measured in the presence and absence of the polychaete Nephthys incisa and a mixed meiobenthic community dominated by nematodes. Oxidation rates (milligrams dry weight of eelgrass detritus per day) of fresh and 2 mo-old detritus were similar (ca. 20). However, the oxidation rate of 5 mo-old detritus was around 45 with only microbenthos and Nephthys, but 84 when both Nephthys and meiobenthos were present. The net incorporation rates (micrograms dry weight of detritus per milligram dry weight of worm per day) of labeled material by Nephthys cultured without meiobenthos for fresh, 2-, and 5-mo-old detritus was 0.08, 0.26, and 3.30, respectively. For Nephthys cultured with meiobenthos, the net incorporation rates of fresh and 2-mo-old detritus (0.07 and 0.19) were similar to those listed above with Nephthys but with 5-mo-old detritus was 7.2.The results illustrate the importance of the state of decomposition of detritus and the activity of meiobenthos on the availability of eelgrass detritus to Nephthys incisa. Key words: detritus, Zostera marina, Nephthys incisa, meiofauna–meiobenthos, net incorporation rate, oxidation rate, decomposition
Effects of Constant Temperatures and Diel Temperature Fluctuations on Specific Growth and Mortality Rates and Yield of Juvenile Rainbow Trout, Salmo gairdneri
Authors: Hokanson Kenneth E. F. , Kleiner Charles F. , Thorslund Todd W.
Published: April 2011

Specific growth and mortality rates of juvenile rainbow trout (Salmo gairdneri) were determined for 50 days at seven constant temperatures between 8 and 22 °C and six diel temperature fluctuations (sine curve of amplitude ±3.8 deg C about mean temperatures from 12 to 22 °C). For constant temperature treatments the maximum specific growth rate of trout fed excess rations was 5.12%/day at 17.2 °C. An average specific mortality rate of 0.35%/day was observed at the optimum temperature and lower. At temperatures in excess of the growth optimum, mortality rates were significantly higher during the first 20 days of this experiment than the last 30 days. The highest constant temperature at which specific growth and mortality rates became equal (initial biomass remained constant over 40 days) was 23 °C. The upper incipient lethal temperature was 25.6 °C for trout acclimated to 16 °C. A yield model was developed to describe the effects of temperature on the living biomass over time and to facilitate comparison of treatment responses. When yield was plotted against mean temperature, the curve of response to fluctuating temperatures was shifted horizontally an average 1.5 deg C towards colder temperatures than the curve of response to constant temperature treatments. This response pattern to fluctuating treatments indicates that rainbow trout do not respond to mean temperature, but they acclimate to some value between the mean and maximum daily temperatures. These data are discussed in relation to establishment of criteria for summer maximum temperatures for fish. Key words: constant temperature, fluctuating temperature, specific growth rate, specific mortality rate, yield, lethal temperature, zero net biomass, rainbow trout, thermal criteria
Concentration Pattern of Chemical Constituents in a Paper Mill's Effluent Plume: Dynamics and Model
Authors: Polak J. , Palmer M. D.
Published: April 2011

The variation of conductivity in the effluent plume for a paper mill discharge on Lake Superior was studied to provide data for predictive models. The study included measurements of local winds and currents which were analyzed and related to the plume's location. To determine the spatial distribution of the plume, a statistical one-dimensional model relating plume conductivity and distance from the outfall and a two-dimensional phenomenological model assuming eiliptically shaped isopleths were developed. It was found that chemical constituents of the plume can be expressed as linear functions of conductivity. The models thus enable the definition of the lake area affected by the effluent chemicals for different wind conditions.
Distribution of Some Organic Compounds in the Receiving Waters of a Kraft Pulp and Paper Mill
Authors: Brownlee B. , Strachan W. M. J.
Published: April 2011

Water, seston, sediment, and macrophyte samples were collected from Nipigon Bay, Lake Superior at distances up to 6.8 km from the effluent discharge of a kraft pulp and paper mill at Red Rock, Ontario. Fifteen compounds have been identified in mill effluent and six of these were found in samples from the Bay. Mill-related compounds were found most often in water and sediment samples, less often in seston samples, and in none of the macrophytes samples. Dehydroabietic acid, present in mill effluent in excess of 1 mg/ℓ, was found in most water and sediment samples and a few seston samples. This compound is a good indicator of the areal influence of the effluent. Palmitic acid and dioctyl phthalate were also widely distributed. Acetovanillone and sandaracopimaric acid were found in one water sample 1.0 km from the discharge. 7-oxodehydroabietic acid was found in five water samples at distances of up to 4.7 km from the discharge. This is apparently the first time that this compound has been reported in a mill effluent or in environmental samples.
Distribution of Dehydroabietic Acid in Sediments Adjacent to a Kraft Pulp and Paper Mill
Authors: Brownlee B. , Fox M. E. , Strachan W. M. J. , Joshi S. R.
Published: April 2011

Sediments adjacent to a kraft pulp and paper mill on western Nipigon Bay, Lake Superior, were examined for resin acids. Dehydroabietic acid was the predominant resin acid with surficial concentrations of less than 5–100 μg/g.The areal distribution indicated the mill to be the primary source of this compound. Depth profiles of the acid and core dating by 210Pb methods enabled the calculation of a mean sediment accumulation rate of 0.11 cm∙yr−1 and a half-life for the disappearance of dehydroabietic acid in the sediments of approximately 21 yr. A half-life of 0.12 yr was estimated for this compound in the water column. It appears, therefore, that the primary removal mechanism of dehydroabietic acid is degradation in the water column.
Effect of a Pulp and Paper Mill Effluent on the Productivity of Periphyton and Phytoplankton
Authors: Moore J. E. , Love R. J.
Published: April 2011

The short-term effect of a kraft mill effluent on the productivity of periphyton and phytoplankton in Nipigon Bay was examined. Addition of raw effluent at concentrations of 10−2 and higher consistently reduced photosynthesis of both periphyton and phytoplankton. Significant reductions were occasionally observed at effluent concentrations as low as 10−4. At high effluent concentrations pH change produced a major portion of the depression. Laboratory experiments with four compounds identified from the effluent showed dehydroabietic acid to be slightly toxic.
Filtering Rate Performance of Daphnia retrocurva in Pulp Mill Effluent
Authors: Cooley John M.
Published: April 2011

Laboratory experiments were carried out with radioactive Scenedesmus to determine the effect on filtering rate of Daphnia retrocurva of exposure to different dilutions of raw pulp mill effluent in lake water. Filtering rate decreased progressively as the exposure time in 5 and 10% effluent increased. Most animals seemed able to recover from brief exposures, but with increased time spent in effluent, larger proportions of the animals did not filter when the food was presented.
Swimming Stamina Differences Between Genotypically Distinct Forms of Rainbow (Salmo gairdneri) and Steelhead Trout
Authors: Tsuyuki H. , Williscroft S. N.
Published: April 2011

Rainbow trout (Salmo gairdneri) homozygous for liver lactate dehydrogenase alleles ldhHαA and ldhHαB were artificially propagated and their swimming stamina compared. The time required to fatigue 50% of the HαAHαA phenotypes in fixed water velocity tests was 2.3 times greater on the average than that of HαAHαB phenotypes.Likewise, LDH phenotypes HαAHαA, HαAHαB, and HαAHαB of steelhead trout from the Thompson River were artifically propagated and their swimming stamina compared. In contrast to the rainbow trout, significant differences in stamina among the three phenotypes of steelhead were not evident in the stocks from this river nor between phenotypes HαAHαB and HαBHαB from another stream, the Vedder River, which has a very low frequency of the ldhHαA allele. The stamina of young steelhead from the Thompson River was, however, 3.8 times greater than that of those from the Vedder River. Key words: stamina, LDH, rainbow trout, steelhead, phenotype, swimming, fatigue
Specificity of Protection Induced in Coho Salmon (Oncorhynchus kisutch) by Heat-Treated Components of Two Pathogenic Vibrios
Authors: Schiewe Michael H. , Hodgins Harold O.
Published: April 2011

A series of in vivo comparisons between two marine vibrios pathogenic to pen-reared salmon demonstrated that each organism possessed protection-inducing, heat-stable components that were unique and others that were cross-protective. In all instances, however, immunization with the components of the homologous bacterium produced the highest degree of protection in juvenile coho salmon (Oncorhynchus kisutch) against subsequent live-bacteria challenge. Antigenic competition was not detected when fish were immunized with both bacteria, indicating that a bivalent vaccine would be effective against infection by either vibrio. Key words: fish disease, vibriosis, immunization, Oncorhynchus kisutch
A Method for Finding the Limits of Application of the von Bertalanffy Growth Model and Statistical Estimates of the Parameters
Authors: Bayley Peter B.
Published: April 2011

The following expression is derived expressing the instantaneous growth rate (G) in terms of length (l) the power of the weight–length relationship (b), and the Bertalanffy growth parameters (K and L∞): G = bK(L∞/l − 1). Since this is valid for a length (or age) range in which growth conforms to the Bertalanffy model, a plot of G vs. 1/l should be linear with the intercept on the G axis being −bK and on the 1/l axis being 1/L∞. Since the variables can be measured independently, deviations of points from the regression can be tested and the limits of validity of the model ascertained. In addition, confidence limits of K and L∞ can be estimated. Two examples compare results with those using previous methods. Key words: method, Bertalanffy, growth, statistical, estimates, parameters
A Stochastic Model for the Management of the Northwestern Atlantic Harp Seal (Pagophilus groenlandicus) Population
Authors: Lett Patrick F. , Benjaminsen Terje
Published: April 2011

Advice from the scientific advisers under the auspices of ICNAF to the international commissioners for 1977 was that the total allowable catch (TAC) for harp seals (Pagophilus groenlandicus) should not exceed 170,000. This advice, in part, was based on the scientific arguments presented in this paper. A stochastic model is developed that takes into account the variations in natural mortality and the landsmen's high arctic and Greenland catches. The Canadian–Norwegian large vessel hunt is controlled under quota regulations. The model is nonlinear, a result of changes in fertility and fecundity rates in response to shifts in population size. The maximum sustainable yield (MSY) 1 + population size is determined to be 1.6 million seals, or a breeding stock size of 375,000 seals. The MSY is approximately 240,000 seals assuming the hunt continues its present pattern. The 240,000 can further be split into 200,000 pups and 40,000 1 + seals. Present stock size is approximately 1.2 million and a TAC of 170,000 seals will allow the population size to reach to MSY level in 10–15 yr. A number of other management strategies are considered, in addition to prospects for future research.
Intertidal Kelp Response to Seasonal Environmental Changes in a British Columbia Inlet
Authors: Druehl Louis D. , Hsiao Stephen I. C.
Published: April 2011

Sporophyte response of three kelp species, Laminaria saccharina (L.) Lamouroux, Alaria tenuifolia Setchell, Costaria costata (Turner) Saunders, in the intertidal zone of Burrard Inlet was correlated primarily with tidal and atmospheric conditions and not with salinity or nutrients. Young sporophytes first became evident in February and March when insolation was increasing and the lower low tides were shifting from night to day. These sporophytes were distributed from 1.3 m above 0 tide to below 0 tide. By April all plants above 0.7 m had died and the remaining plants achieved their maximum biomass in May. The subsequent decrease in biomass was related to prolonged daytime exposures to air. Costaria costata produced meiospores by July before dying and L. saccharina and A. tenuifolia persisted until autumn when they produced meiospores. Key words: kelp, Laminariales, phenology, environment, growth
Response of the Crayfish Orconectes virilis to Exploitation
Authors: Momot Walter T. , Gowing Howard
Published: April 2011

Life tables can aid in assessing the impact of exploitation of the crayfish Orconectes virilis by fish, invertebrates, and man. The major response of the population to exploitation comes through an adjustment of both the mx column (egg production) and lx (survivorship). Fish and invertebrate predation were directed towards modification of the early portion of the lx column. Survivorship did not change appreciably.Exploitation by man was directed toward males rather than females. An indirect result was an increase in the lx values for females. However, this was counteracted by a decrease in mx values leading to population stability as indicated by the Ro values. Both the exploitive strategies of fish and man failed to extract the maximum available biomass from the production of a given year-class. Key words: crayfish, exploitation, Orconectes virilis, life tables
Age Determination of Lingcod (Ophiodon elongatus) Using Dorsal Fin Rays and Scales
Authors: Beamish Richard J. , Chilton D.
Published: April 2011

Cross sections of the 4th–8th fin rays from the second dorsal fin provided reliable ages of lingcod (Ophiodon elongatus), although there was some difficulty interpreting the ages of 1- and 2-yr-old fish. Length was an acceptable indicator of age 1- and 2-yr-old fish. After a scale age of 5 or 6 yr, the scale annulus became difficult to identify. After age 7 or about 75–85 cm, fin-ray ages were older than scale ages. Some of the oldest fish averaged 8 yr older by the fin-ray method.Mature females attained much larger mean sizes than males of similar age, and there was considerable variation in size of similar-aged older fish. Key words: Age determination, fin rays, scales, Ophiodon elongatus, ageing errors.
Significance of Hypochlorous Acid in Free Residual Chlorine to the Avoidance Response of Spotted Bass (Micropterus punctulatus) and Rosyface Shiner (Notropis rubellus)
Authors: Cherry Donald S. , Larrick Stephan R. , Dickson Kenneth L. , Hoehn Robert C. , Cairns Jr. John
Published: April 2011

The spotted bass (Micropterus punctulatus) and rosyface shiner (Notropis rubellus), when exposed to successively doubling doses of total residual chlorine (TRC) from 0.025 to 0.80 mg/ℓ, generally avoided higher concentrations when acclimated and tested at five temperatures from 6 to 30 °C. Both species avoided 0.05 mg/ℓ TRC when acclimated and tested at 6 °C and avoided 0.20 mg/ℓ TRC at 24 and 30 °C. Variations in avoidance of the free residual chlorine (FRC) ranged from 0.017 to 0.091 mg/ℓ (0.05 to 0.20 mg/ℓ TRC) between 6 and 30 °C. After the initial avoidance response, the rosyface shiner continued to avoid the remaining higher residual levels, while spotted bass showed less avoidance or none at all. The same behavioral responses occurred when each species was exposed to a single concentration (0.05 or 0.10 mg/ℓ TRC) for three successive 10-min observations.The avoidance response was most closely associated with the calculated hypochlorous acid (HOCl) fraction of the TRC, which declined (relative to the percent of TRC) as the pH and acclimation temperature increased. Avoidance to HOCl occurred between 0.012 mg/ℓ (6 °C) and 0.031 mg/ℓ (30 °C) when TRC was between 0.05 and 0.20 mg/ℓ, respectively. Avoidances did not occur at the 12 and 18 °C acclimation temperatures until the HOCl content comprising the 0.10 and 0.20 mg/ℓ TRC doses surpassed the initial HOCl threshold level (0.012–0.014 mg/ℓ) calculated for 0.05 mg/ℓ TRC at 6 °C. The HOCl content may be the most important constituent within the TRC to influence the avoidance response of fish in unpolluted aquatic systems. Key words: avoidance response, hypochlorous acid, free residual chlorine, Micropterus punctulatus, Notropis rubellus
The Importance of Allochthonous Particulate Carbon Pathways in a Subalpine Lake
Authors: Wissmar R. C. , Richey J. E. , Spyridakis D. E.
Published: April 2011

Particulate carbon pathways in subalpine Findley Lake, Washington, were examined to assess the dependence of invertebrate consumer production upon allochthonous and autochthonous carbon. Results suggest that allochthonous carbon provides a food base for insect production (6.5 kg C∙ha−1) and autochthonous production of carbon appears to maintain zooplankton production (5.0 kg C∙ha−1). Annual inputs of allochthonous carbon from snow, fluvial, and litterfall sources amounted to 75 kg C∙ha−1. Autochthonous production totaled 51 kg C∙ha−1. Most of the allochthonous inputs were lost through sedimentation (63 kg C∙ha−1) and fluvial output (15 kg C∙ha−1). In contrast, most of the autochthonous carbon losses through grazing and respiration were retained in the water column. Total allochthonous and autochthonous inputs were 126 kg C∙ha−1∙yr−1 and outputs were 114 kg C∙ha−1∙yr−1. A pelagic carbon budget did not balance by 12 kg C∙ha−1∙yr−1, a number well within the propagated variation of 26 and 21% for input and outputs, respectively. Key words: allochthonous, carbon, subalpine, lake
Percids of Lake Constance, a Lake Undergoing Eutrophication
Authors: Hartmann J. , Nümann W.
Published: April 2011

A review of literature suggested that yield of Eurasian perch, Perca fluviatilis, in Lake Constance was greatest with moderate eutrophication. During eutrophication (1950–76), changes also took place in food, growth, distribution, and diseases of perch. Differences in perch between Lake Constance and other German or Alpine lakes of various degrees of eutrophy were found with respect to growth, yield, the relation of growth to yield, food, and the relation of food to growth. Similarities were apparent for perch in these lakes in terms of their age composition, age at maturity, and mortality. Only limited data were available for pikeperch, Stizostedion lucioperca, mainly on stocking success, yield, and growth. The status of percids in Lake Constance indicates that eutrophication has led to conditions favoring percids. Key words: Percidae, Lake Constance limnology, eutrophication, yield, Perca fluviatilis, food, growth, distribution, disease, Stizostedion lucioperca
Effects of Exploitation, Introductions, and Eutrophication on Percids in Lake Balaton
Authors: Biró Péter
Published: April 2011

Percid populations in Lake Balaton have undergone changes which are considered to have been caused by individual or combined effects of overfishing, interspecific competition from nonnative species, and loadings of nutrients and pesticides. Eurasian perch (Perca fluviatilis) has almost disappeared and the ruffe (Gymnocephalus cernua) population is declining, probably as a result of competition from the eel (Anguilla anguilla) and effects of cultural eutrophication. Growth rate of pikeperch (Stizostedion lucioperca) is declining while that of the bream (Abramis brama) is increasing. Production of cyprinids has increased up to 10% in recent years, apparently in response to accelerated eutrophication. The exploitation rate of pikeperch is far in excess of that considered necessary for maximum sustained yield. The environment in the most eutrophic part of the lake is now considered to be unfavourable for pikeperch. Key words: Percidae, Stizostedion, Perca, Gymnocephalus, exploitation, eutrophication, introductions, ruffe, Lake Balaton