bluuebunny/crossref_metadata_2025 huggingface dataset:
Incidental Catch of Cetaceans with Salmon Gillnet
Authors: Ohsumi Seiji
Published: April 2011

Using data on number of cetaceans caught per 1000 "tans" (= approximately 50 m) of salmon drift gillnet, incidental catch rates by salmon research vessels of the Japanese Fisheries Agency averaged 0.476. The maximum was 1.42. The average ranged between 0.37 and 0.65 from 1962 to 1971, indicating negligible effect on porpoise populations. These figures are much lower than the average incidental catch rate (6.66) in the United States salmon drift net research. The main catch is Phocoenoides dalli.
Size Selective Predation by Juvenile Chum Salmon (Oncorhynchus keta) on Epibenthic Prey in Puget Sound
Authors: Feller Robert J. , Kaczynski Victor W.
Published: April 2011

Analysis of gut contents shows that juvenile (30–50 mm) chum salmon (Oncorhynchus keta) in Puget Sound select epibenthic organisms as their primary prey. Harpacticoid copepods numerically comprised over 80% of their natural diet in two areas studied, while terrestrial insects and cladocerans were most important in a third area. Calculation of Ivlev (1961) electivity coefficients indicated high selectivity factors for harpacticoids at one site (+0.59 to +0.94). Comparison of fish gut contents with quantitative epibenthic pump samples of available prey shows that prey selection was size related, but opposite that currently reported in the literature (e.g. Brooks and Dodson 1965); that is, the smaller of the available prey was preferred. This was true for both the total available prey size spectrum and the harpacticoid copepod fraction of the prey spectrum. Large numbers of prey eaten per fish suggest that juvenile chum salmon may exert high predation pressure on nearshore epibenthic organisms in Puget Sound during spring.
Temperature and Deteriorative Changes in Postrigor Cod Muscle Stored up to 14 Days in the Superchill Range, −1 to −4 C
Authors: Nowlan Sandra S. , Dyer W. J. , Keith R. A.
Published: April 2011

The effect of several storage temperatures in the superchill range (−1, −1.6, −2.3, −3, and −4 C) on bacterial and autolytic spoilage processes in postrigor cod muscle was assessed. Changes in trimethylamine, hypoxanthine, and pH, monitored as spoilage indicators, were slight during superchilling at all temperatures between −1 and −4 C for 3 and 6 days, and 14 days at −4, indicating inhibition of bacterial action. However, at −1.6 and at 0 C spoilage thresholds were reached in 10 and 6 days, respectively. Salt extractable protein remained unchanged, but mild lipid hydrolysis occurred at all temperatures.In samples superchilled for 3 or 6 days, then thawed and held at +5 or +10 C, spoilage processes resumed as judged by trimethylamine, hypoxanthine, and free fatty acid increases. Changes at +5 C in samples that had been held at −1 and at −1.6 were slightly slower than in controls at 0 C similarly treated, but in samples presuperchilled at −3 and −4 spoilage changes at +5 were markedly delayed. No deleterious effect on protein extractability was detected. Thus superchilling at −4 C for 3 and for 6 days was very effective, increasing the postfilleting storage life to 8 and 11 days, respectively, as compared to 5 days for controls held at 0 for 3 days before transfer to 5 C.
Genetics and Mutagenesis of Fish.
Authors: Hershberger William K.
Published: April 2011

not available
Heavy Metal Binding Components of River Water
Authors: Ramamoorthy S. , Kushner D. J.
Published: April 2011

Ion-specific electrodes were used to measure the heavy metal (HM) binding capacity of river waters near Ottawa. Binding capacity was measured in unfiltered water and in water passed through filters retaining particles (0.45 μm) and macromolecules of molecular weight (MW) 45,000, 16,000 and 1,400. In the most studied water samples, almost all the Hg2+-binding ability passed through the smallest filter. Filters of different pore sizes retained substantial fractions of the binding ability towards other HM ions. Binding strengths and conditional binding constants were calculated for each HM ion and low MW Ottawa River water components.Binding in Ottawa River water was not due to HCO3− or CO32− ions; in the Rideau Canal, and probably in other bodies of water, such ions caused a substantial amount of binding. After complete ashing of Ottawa River water and reconstitution with deionized water almost all the HM binding ability was lost; thus, an organic compound(s) is responsible for binding.The binding pattern towards different HM ions of fulvic acid isolated from soil was different from that of unfiltered or filtered Ottawa River water. Fulvic acid is not the sole binding component of this water. These experiments suggest a way of assessing the importance of fulvic acid and other humic substances in HM binding by natural waters.
Preservation of Inshore Male Capelin (Mallotus villosus) Stored in Refrigerated Sea Water
Authors: Shaw D. H. , Botta J. R.
Published: April 2011

Male spawning capelin (Mallotus villosus) from an inshore stock were preserved ungutted in refrigerated sea water, both with and without carbon dioxide. Contrary to results found with other small pelagic species, refrigerated sea water in both forms leads to a rate of degradation considerably faster than that for similar capelin held in ice. Major taste and texture changes were obvious as early as the second day, followed by rejection of the fish at day 3. Analysis indicated that in the samples stored without carbon dioxide, bacterial decay was fast, as was the hydrolysis of lipid to free fatty acid. Spoilage due to textural changes was faster when carbon dioxide was added to the sea water. It was concluded that carriage or storage of spawning inshore male capelin in either form of refrigerated sea water is not to be recommended over boxing in ice.
Biochemical Genetics of Lobsters: Genetic Variation and the Structure of American Lobster (Homarus americanus) Populations
Authors: Tracey Martin L. , Nelson Keith , Hedgecock Dennis , Shleser Robert A. , Pressick Mary Lou
Published: April 2011

Eight populations of American lobsters, Homarus americanus, were surveyed for genetic variation at 44 loci encoding electrophoretically detectable proteins. Rather low levels of genetic variability were found, the average proportion of heterozygous loci per individual being 3.8%. Genetic variation is concentrated at only eight loci, with just five loci — Acid phosphatase-1, Esterase-2, Phosphoglucose isomerase-4, Phosphoglucomutase-1, and Tetrazolium reductase-2 — having proportions of heterozygotes greater than 20%. Interpopulation differences are small; the genetic identity averaged over all loci, I, is above 0.99 in all but three comparisons. Differentiation between populations was found only at the Malic enzyme locus, but the degree of this differentiation supports the suggestion from previous migration and morphological studies that H. americanus is subdivided into a number of more or less geographically isolated inshore and offshore populations. These local populations are nonetheless genetically similar.
Influence of Social Rank and Size on Thermoselection Behavior of Bluegill (Lepomis macrochirus)
Authors: Beitinger Thomas L. , Magnuson John J.
Published: April 2011

Juvenile bluegill (Lepomis macrochirus) (95–110 mm TL) were given a choice between an environment at their preferred temperature (31.0 C) plus a social dominant (130–160 mm TL) or an environment either cooler (27.0 C) or warmer (34.0 C) than their preferred temperature, but without a large bluegill. During a 3-day control period, when 20 small fish were isolated in individual experimental aquaria, each spent more than 75% of its time at 31.0 C rather than warmer or cooler temperatures. After an adult was placed into the preferred temperature side of each aquaria, small fish spent nearly the entire 3-day experimental period at previously non-preferred temperatures on the side without the larger bluegill. No significant correlation (r = −0.03) was found between length and selected temperatures of 35 individual bluegill (70–140 mm) tested in a temporal temperature gradient.
Estimates of Potential Fish Yield for the Nasser Reservoir, Arab Republic of Egypt
Authors: Ryder R. A. , Henderson H. F.
Published: April 2011

Available biological and hydrographic information on Lake Nasser was examined to provide guidelines for future development of the fisheries. Not enough consistent data were available to allow precise estimates of fishing-stock interrelations; however, an approximation of potential yield was derived from subjective evaluation of limnological characteristics of the lake. Morphoedaphic factors were utilized to establish a numerical expectation of yield in relation to other tropical lakes and reservoirs. Two other models based on estimated zooplankton biomass and an assumed net gain in productivity in Lake Nasser at the expense of a yield loss to the Mediterranean fishery provided order-of-magnitude agreement. Potential yield estimates for Lake Nasser (including its southern portion, Lake Nubia, Sudan) were 23,000 metric tons (MT) of fish annually, providing the reservoir fills to its expected maximum (180 m), or 12,000 MT if it remains at its 1973 level of about 160 m. These estimates are considered sufficiently reliable to guide future development of the fishery.There is little evidence to support the existence of stock overexploitation. Tilapia nilotica, however, the major species entering the fishery, has been subjected to potentially damaging fishing practices on its breeding grounds. These practices combined with water level drawdown, inadvertently timed to perturb Tilapia fry inhabiting the shallow nursery areas, may unduly stress a prime species largely responsible for the current success of the fishery.Management recommendations for the Nasser–Nubia Reservoir include a regular program of monitoring both stocks and harvest, especially for Tilapia. Development emphasis should be placed on improving the logistics of the fishery rather than increasing the number of fishermen, at least until the lake area expands substantially.
Graphical Methods for Estimating Parameters in Simple Models of Fisheries
Authors: Walter Gilbert G.
Published: April 2011

A graphical method for calculating the coefficients for a Schaefer model of a fishery is introduced. It involves plotting catch per effort vs. effort data and then correcting the values for disequilibrium of the fishery. A hypothetical and a realistic example are presented.
Movements and Growth of Petrale Sole (Eopsetta jordani) Tagged off Washington and Southwest Vancouver Island
Authors: Pedersen Mark G.
Published: April 2011

Tagging studies indicate that spawning groups of petrale sole (Eopsetta jordani) from Cape Flattery Spit Deep and Willapa Deep were the most significant contributors to the summer inshore fishery for petrale sole off Washington and Vancouver Island. Spawning groups south of Willapa Deep contributed less than 5% to this fishery. The Willapa Deep group was estimated to be at least as large as the Cape Flattery Spit Deep, although the latter supported a much larger winter fishery. Fish tagged during winter on Cape Flattery Spit Deep ranged primarily from Esteban Point south to Quillayute during summer. Ninety-seven percent of the winter recoveries from tag releases in deepwater spawning areas were made in the area of release.Length composition data suggested that after spawning offshore, adult sole returned to inshore grounds during the summer.For mature sole, growth parameters estimated from tagged fish agreed with those calculated by other methods of ageing.
Minimal Dissolved Oxygen Requirements of Aquatic Life with Emphasis on Canadian Species: a Review
Authors: Davis John C.
Published: April 2011

This article reviews the sensitivity, responses, response thresholds, and minimum oxygen requirements of marine and freshwater organisms with strong emphasis on Canadian species. The analysis attempts to define low dissolved oxygen thresholds which produce some physiological, behavioral, or other response in different species.Oxygen availability is discussed with reference to seasonal, geographical, or spatial variation in dissolved oxygen. Factors affecting availability of dissolved oxygen include atmospheric exchange, mixing of water masses, upwelling, respiration, photosynthesis, ice cover, and physical factors such as temperature and salinity. Dissolved oxygen terminology is summarized and tables are included for both fresh and saltwater O2 solubility at different temperatures.Incipient O2 response thresholds are used in a statistical analysis to develop oxygen criteria for safeguarding various groups of freshwater and marine fish. These include mixed freshwater fish populations including or excluding salmonids, freshwater salmonid populations, salmonid larvae or mature salmonid eggs, marine anadromous and nonanadromous species. Criteria are based on threshold oxygen levels which influence fish behavior, blood O2 saturation, metabolic rate, swimming ability, viability and normal development of eggs and larvae, growth, circulatory dynamics, ventilation, gaseous exchange, and sensitivity to toxic stresses. The criteria provide three levels of protection for each fish group and are expressed as percentage oxygen saturation for a range of seasonal temperature maxima.Oxygen tolerances and responses of aquatic invertebrates to low oxygen are reviewed for freshwater and marine species according to habitat. No invertebrate criteria are proposed owing to the capacity for many invertebrate species to adopt anaerobic metabolism during low O2 stress. It is suggested that the criteria proposed for fish species will provide a reasonable safeguard to most invertebrate species. It appears likely, however, that a change in oxygen regime to one of increased O2 scarcity will probably influence invertebrate community structure.It is suggested that criteria for protection of aquatic life be implemented by groups of experienced individuals. The group should consider the natural oxygen regime for a specific water body and its natural variability, the aquatic life therein and its value, importance, relative O2 sensitivity, and the possibility of interactions with toxicants and other factors that may compound the stress produced by low O2 on aquatic life. Each water body and its aquatic life should be considered as a unique situation and criteria application should not encompass diverse areas, habitats, or biological associations as if they were identical.
Crustacean Plankton Communities of the Matamek River System and their Variation with Predation
Authors: Pope G. F. , Carter J. C. H.
Published: April 2011

The crustacean plankton communities of lakes with fish planktivores and low densities of Chaoborus larvae contained greater numbers of noncyclopoid crustacean predators but lower numbers of the larger herbivores. Lakes with brook trout (Salvelinus fontinalis) only and low densities of Chaoborus larvae, had plankton communities whose biomasses were dominated by the larger herbivores. The communities of lakes with no fish and high densities of larvae were dominated by the smaller herbivores, although the larger species were present in some. The noncyclopoid, crustacean predators were absent from almost all of these lakes.
The Blackbass in America and Overseas.
Authors: Christie W. J.
Published: April 2011

not available
Relation Between Yield and Fishing Mortality for Ricker’s Yield Equation
Authors: Jensen A. L.
Published: April 2011

A method is presented that can be applied to examine the relation between yield and magnitude of fishing mortality for Ricker’s dynamic pool yield equation. The magnitude of fishing mortality is measured by the norm of the vector of interval specific instantaneous fishing mortality coefficients. The method is applied to a bluegill sunfish (Lepomis macrochirus) population.
Selective Breeding and Hybridization in Fisheries Management
Authors: Ihssen Peter
Published: April 2011

Selective breeding of fish using quantitative genetic techniques is discussed. Fish offer advantages over other livestock for selective breeding procedures because of their relatively high reproductive potential and low reproductive barriers.Maintaining fish stocks in artificial environments can cause undesirable genetic changes such as loss in heterozygosity due to inbreeding and loss in fitness. Methods to minimize inbreeding are given. The study of cross breeds of inbred lines, and hybrids among strains or even species, to produce high levels of heterozygosity and heterosis or hybrid vigor is suggested.
Initiation of Sea Lamprey (Petromyzon marinus) Control
Authors: Sprules W. M.
Published: April 2011

Sea lamprey (Petromyzon marinus) control became a major undertaking, relative to many other programs in aquatic biology. In several respects, the history of the program, outlined here, provides an informative prototype that might be usefully considered by aquatic biologists. F. E. J. Fry played an influential role in the development of the program.
Distribution of Sound Scattering Layers Caused by Euphausiids and Their Relationship to Chlorophyll a Concentrations in the Gulf of St. Lawrence Estuary
Authors: Sameoto D. D.
Published: April 2011

A 3-yr study in the Gulf of St. Lawrence estuary using a 120-kHz sounder has shown the existence of a large population of euphausiids consisting of the species Thysanöessa raschii, T. inermis, and Meganyctiphanes norvegica. The sound scattering produced by these animals varied in intensity as the density and biomass m−3 of the animals. Chlorophyll a concentrations measured within 5 m of the surface at the same time as the sound scattering layers showed a significant correlation between the numbers of euphausiids m−3 and the concentration of chlorophyll a m−3.
Year-Class Formation in the Walleye (Stizostedion vitreum vitreum) Population of Oneida Lake, New York, 1966–73
Authors: Forney J. L.
Published: April 2011

Abundance of eight successive year-classes of walleyes (Stizostedion vitreum vitreum) was measured at intervals from hatching into the second year. Each year-class arose from an initial stock of 12–18 billion eggs. Population of pelagic larvae was augmented in some years by the release of hatchery-reared larvae but the effect on year-class size was obscured by mortality after young became demersal. Decrease in number of fingerlings was attributed to predation by older walleyes. Intensity of predation was influenced by abundance of alternate prey and duration of cannibalism by growth of young walleyes. Five year-classes that were monitored through age 4 contributed 12,000–478,000 walleyes to the adult stock.
Aquacultural Techniques for Creating and Restoring Beds of Giant Kelp, Macrocystis spp.
Authors: North Wheeler J.
Published: April 2011

Giant kelp (Macrocystis spp.) occurs as extensive beds along the coasts of Baja California and California. The kelp beds form desirable habitat for fishes and invertebrates. The kelp plants are harvested and processed to produce food additives and chemicals. Many Califorman kelp beds have dwindled or disappeared since 1940. We have developed a number of aquacultural techniques to reverse trends of deterioration. One important cause of kelp bed damage can arise from grazing by sea urchins or herbivorous fishes. Urchins can be controlled by quicklime or by crushing the animals with hammers. Fishes can be controlled by netting. In areas where kelp is sparse or has disappeared, stands can be recreated by transplantation techniques. Where reproductive processes are not adequate to maintain a stable population, mass cultures of microscopic gametophytes and sporophytes can be introduced.
Test of a Model for Predicting the Body Burden of Trace Contaminants in Aquatic Consumers
Authors: Elwood Jerry W. , Eyman L. Dean
Published: April 2011

A model for predicting the accumulation and retention of trace contaminants obtained through food ingestion in aquatic consumers was tested for short-term exposure conditions. Model parameters were determined in a single-feeding experiment using bluegill (Lepomis macrochirus) and food labeled with 137Cs. Independent of this single-feeding experiment, bluegill were allowed to ingest 137Cs contaminated food over a 16-day period and the predicted and measured body burden of the radionuclide were compared. The model realistically simulated the absorption of 137Cs from the gastrointestinal tract and its accumulation over the 16-day period. Average body burden of 137Cs in bluegill was within 25% of the predicted body burden when the experiment was terminated. Apparent equilibrium of 137Cs in bluegill by day 16 suggests that this two-compartment linear model does not apply to the long-term accumulation of cesium in fish. The model appears most applicable for predicting body burdens of trace contaminants under acute exposure conditions that simulate an accidental release.
Survival of Daphnia, Crayfish, and Stoneflies in Air-Supersaturated Water
Authors: Nebeker Alan V.
Published: April 2011

Daphnia magna, the crayfish Pacifastacus leniusculus, and nymphs of the stoneflies, Acroneuria californica, A. pacifica, and Pteronarcys californica were tested in the laboratory to determine their survival in different concentrations of air-supersaturated water. The mean 96-h LC50 value (lethal concentration, 50% mortality) for D. magna was 122.5% total air saturation. The 7-day LC50 was 120% and the 10-day LC50 was 117.5%. The mean 96-h LC50 for crayfish was 147% total air saturation. The 7-day LC50 was 145% and the 10-day LC50 was 133%. The 10-day EC50 values (effective concentration, 50% immobilized) for stoneflies were 135% for A. californica and greater than 125% for A. pacifica and P. californica. Bubbles (emboli) were observed in body fluids and tissues, and general body distention occurred before death in Daphnia, crayfish, and stoneflies. Lethal threshold concentrations for Daphnia and crayfish were near 111 and 127%, respectively.
A Note Concerning Dr Richards’ Comments
Authors: Balon Eugene K.
Published: April 2011

The terminology of fish ontogeny was proposed to clarify and unify the meanings of words for the same intervals and processes across the environmental, linguistic, ideological, and political boundaries irrespective of tradition, belief, or authority. The criticism of this proposal, while defending tradition and authority, failed to discredit the rationale for such a unified terminology.
Spatial and Temporal Patterns in Macrobenthic Stream Diversity
Authors: de March Brigitte G. E.
Published: April 2011

The relationship between the characteristics of a stream community and sediments were studied for 1 yr in a small unpolluted river with a morainal substrate. Recognizable faunal assemblages were associated with silt or silt fill, sand or sand fill, and large boulders. The fauna in sediments of mean particle sizes coarser than sand but finer than boulders was characterized by a high variability due largely to temporal successions of morphologically related species. It was found that the number of species was directly proportional to mean particle size (in [Formula: see text] units) in spring when the sediments were well sorted, but the relationship broke down as the sediment interstices filled in. In late fall when the sediments were badly sorted, the number of species is perhaps more related to the sorting coefficient of the sediments. The relevance of these findings to studies of pollution is discussed.
Physical Oceanography in Canada
Authors: Mann C. R.
Published: April 2011

The basic research program in physical oceanography in Canada is described. The use of physical oceanographic information in resource development, environmental assessment, prediction of climate, and other marine activities is examined. A major finding of the study is that the use of physical oceanographic information has increased and will continue to do so. Basic research in fisheries oceanography, ocean climatology, and numerical modeling is inadequate. Recommendations are formulated to improve basic research and services.
Numerical Modeling of Ocean Circulations
Authors: Pond S.
Published: April 2011

This report was prepared as background material for the Fisheries Research Board of Canada study on oceanography in Canada. Models of the large-scale or general circulation of the ocean are examined first. The general approach to such modeling and a series of models are described and the status of modeling is discussed. It appears that such models are another useful way to study the ocean. However, the resolution of present models is not sufficient to include all possibly important dynamic effects. Developments in computational techniques and computers suggest that these problems can be overcome. Besides the resolution problem, the lack of sufficient data, particularly of currents, makes it difficult to tell how well the models reproduce reality. Data collection programs, designed to use observational knowledge and results of analytical and numerical modeling, will be required for input and verification of numerical models. The use of models should reduce the effort to where it is practicable though difficult and likely to tax the oceanographic community’s resources to the limit. Modeling of coastal regions, semienclosed seas, and estuaries is described and some models of the ocean mixed layer are presented. The upper-layer models are required to provide better bottom boundary conditions for numerical atmospheric models to predict weather and climate in addition to the oceanographic results they produce.An assessment of the usefulness of numerical models for prediction is attempted. Models of rivers and coastal models of tidal amplitudes and currents appear to be quite useful. Models of other regions are not developed and verified well enough to use for prediction but by analogy with river and coastal models and atmospheric models there appears to be a good possibility for useful predictions in future. Finally, suggestions are made for further development of the Canadian program of numerical modeling. Clearly there is a need for the results of coastal and estuarine models, so present programs require some expansion. To get the desired results much faster computers are essential. Acquisition of such computers will make possible the development of a program of modeling the large-scale circulation which will be needed to provide boundary conditions for the coastal models, and could provide an important contribution to the world effort in modeling the general circulation of the ocean.
Effect of Temperature and Salinity on Extension of Siphons by Mercenaria mercenaria
Authors: Winkle W. Van , Feng S. Y. , Haskin H. H.
Published: April 2011

Extension of siphons was used as a criterion of activity to examine the response of the quahog clam, Mercenaria mercenaria, to various combinations of test and acclimation temperatures and salinities. A quadratic regression model for the percentage of clams active as a function of the test temperature and salinity was assumed, and response surface contours for various percentages of activity were calculated and plotted.The regression model accounted for 72–88% of the observed variability in the 13 experiments considered. The contours are hyperbolic instead of elliptical for five of the experiments; no biologically meaningful estimates of the lower and upper temperature and salinity limits can be obtained in such cases. Low levels of activity, even at optimal T–S combinations, occurred during the summer. Some of the observed shifts in the position and shape of the temperature–salinity response surfaces were expected in light of shifts in acclimation temperature or salinity. Other shifts in response surface could not be accounted for. The implications of these results for the purification of quahog clams harvested from polluted waters are discussed.
Azygokeras columbiae, a New Genus and Species of Marine Epibenthic Copepod (Calanoida: Aetideidae) from British Columbia
Authors: Koeller Peter A. , Littlepage Jack L.
Published: April 2011

Azygokeras columbiae n.gen., n.sp. can be distinguished from other genera of Aetideidae by the asymmetrical first antennae of the male, the setation of the first two segments of the second antennal exopod of the female, and by the spinulation on basipods and rami of the swimming legs of both sexes. The animal was found only in deep hauls from Bute Inlet and is probably an epibenthic form.
Autotrophic Production in Carnation Creek, a Coastal Rainforest Stream on Vancouver Island, British Columbia
Authors: Stockner John G. , Shortreed K. R. S.
Published: April 2011

Attached algal growth in Carnation Creek and its estuary were monitored in 1974 and 1975 as part of the Carnation Creek Experimental Watershed Project. Net production on the estuary was 17.8 μg organic matter (org)∙cm−2∙day−1, and in Carnation Creek the average was 3.4 μg org∙cm−2∙day−1. Algal growth in Ritherdon Creek, located in an adjacent logged watershed, was slightly higher (4.6 μg org∙cm−2∙day−1) than the Carnation Creek average. In a streamside nutrient enrichment experiment, nitrate and phosphate concentrations in one trough were increased to twice the normal Carnation Creek values present in the control. In 35 days the nutrient-enriched trough had a total algal volume 3 times that of the control. It is suggested that extremely low nutrient concentrations (especially phosphate), and secondarily, poor light conditions under the canopy, are responsible for the paucity of algal growth in Carnation Creek. Major loss of algae from the system is caused by periodic freshets which scour the stream bed. Losses by grazing herbivorous insects were considered negligible. Dominant diatoms in Carnation Creek were Achnanthes minutissima, Synedra ulna, Hannaea arcus, Diatoma hiemale, and Eunotia pectinalis. Ulothrix sp., Draparnaldia sp., and Mougeotia sp. were the dominant filamentous green algae. Net production and algal biomass (chlorophyll a) in Carnation Creek are among the lowest ever reported in the literature.
Temperature Selection of Juvenile Atlantic Salmon (Salmo salar) as Influenced by Various Toxic Substances
Authors: Peterson R. H.
Published: April 2011

Previous exposure to sodium pentachlorophenate (NaPCP), Guthion®, malathion, Dursban®, and Dibrom® lowered the preferred temperature for juvenile Atlantic salmon (Salmo salar) tested in a horizontal temperature gradient. Lindane, CuSO4, ZnSO4, CdSO4, Sevin®, heptachlor, and fenitrothion did not change the preferred temperature significantly. Comparison with other published results indicates that those substances that increase the preferred temperature are more toxic (based on relevant changes in 24-h LC50) at low temperatures and vice versa. It is suggested that such shifts in selected temperature may be of potential immediate, short-term, survival value to the fish.
Assessment of Winter Planting of Hatchery-Reared Brook Trout (Salvelinus fontinalis) in Small Precambrian Lakes
Authors: Fraser J. M.
Published: April 2011

Distinctively marked 8-mo-old brook trout (Salvelinus fontinalis) were planted in autumn, 14-mo-old in winter, and 16-mo-old in spring in 10 experiments conducted on five small Ontario lakes in 1970–73. Comparative recoveries were assessed by examining the anglers’ catch and by intensive sampling with gillnets 1 mo following the spring planting. Recovery of spring-planted trout (mean 39.7%) was significantly higher (P < 0.01) than for winter- (15.7%) and autumn-planted trout (7.7%). Although there was evidence in one lake of predation on winter-planted trout by large brook trout and splake (S. fontinalis × S. namaycush), the factors generally responsible for the large losses of winter- and fall-planted trout have not been identified.
Factors Affecting Winter Respiration in Ontario Lakes
Authors: Welch H. E. , Dillon P. J. , Sreedharan A.
Published: April 2011

Winter oxygen consumption was measured in 16 Ontario lakes. Whole lake respiration ranged from 0.08 to 0.39 g O2 m−2 day−1 and was positively correlated with mean depth, phosphorus m−2 at spring overturn, and summer chlorophyll a m−2. Morphological variables plus Secchi depth were explained over 80% of the variability in respiration rates.
Molt- and Growth-Enhancing Effects of Bilateral Eyestalk Ablation on Juvenile and Adult American Lobsters (Homarus americanus)
Authors: Mauviot Jean C. , Castell John D.
Published: April 2011

Growth rate of 20 juvenile lobsters (Homarus americanus) at the 7th or 8th stage (2 mo old) and 9 older juveniles (5 mo old) was greatly enhanced by bilateral eyestalk ablation. The average weight of 7th and 8th stage ablated lobsters was 5 times that of controls 200 days after the operation. This increased growth was the result of increased molt frequency and greater percent weight gain per molt. Dietary composition was more critical to the survival and growth of the ablated lobsters than it was to the controls. A low protein diet resulted in reduced growth and survival of ablated lobsters but had little effect on controls. Biochemical analyses revealed that although the fast growth of ablated lobsters resulted in decreased lipid deposition in whole tail, chelae, and hepatopancreas, the faster growth rate was the result of real tissue synthesis and protein deposition.
Contribution of Gut Contents to the Concentration and Body Burden of Elements in Tipula spp. from a Spring-Fed Stream
Authors: Elwood Jerry W. , Hildebrand Stephen G. , Beauchamp John J.
Published: April 2011

Larvae of Tipula spp., a detritus-feeding aquatic insect collected from an unpolluted spring-fed stream, were analyzed for 30 elements before and after gut evacuation to determine the contribution of gut contents to whole-body concentrations. Chromium and Al concentrations were inversely related to body size, suggesting surface contamination. All elements analyzed except Na, Cr, Hg, Zn, and Se were significantly lower (P < 0.01) in concentration after gut evacuation (18% decrease for K to approximately 70% for V, Mn, Hf, and some of the rare earths). Ratios of variances of mean concentrations in organisms with guts filled to those with guts evacuated indicate that gut contamination is a major source of variation in measured whole-body concentrations of many elements. Calculated percentage of element body burden associated with gut contents ranged from < 1% for Na to 89% for Zr, with a mean for all elements analyzed of 57 ± 8% (± 2 SE). Calculated trophic transfer factors (TTF = element concentration in larvae with guts evacuated/concentration in leaf detritus) for elements which are obtained primarily through the food chain were significantly > 1 only for Zn; TTFs for all other elements were [Formula: see text].
Improved Reagent Dispenser for the Determination of Dissolved Oxygen in Sea Water
Authors: Cunningham C. C. , Conrad D. D. W. , Moffatt J. D. , Levy E. M.
Published: April 2011

An improved dispenser for delivering the reagents used in the quantitative determination of dissolved oxygen in sea water is described.
Inbreeding in Rainbow Trout (Salmo gairdneri)
Authors: Kincaid Harold L.
Published: April 2011

Effects of inbreeding on rainbow trout (Salmo gairdneri) were evaluated by a comparison of differences between inbred and outbred half-sib families reared as contemporaries during the 1st yr of life. Attention was focused on two levels of inbreeding expressed as inbreeding coefficients: F = 0.25, one generation of brother–sister matings, and F = 0.375, two generations of brother–sister matings. Although inbreeding at the F = 0.25 level in fall-spawning populations had no effect on egg hatchability, it significantly increased the frequency of crippled fry by 37.6% and significantly decreased feed conversion efficiency (5.6%), fry survival to 147 days (14.6%), and growth rate to 147 days (6%) and 364 days (23.2%). Effects of inbreeding at F = 0.375 were more pronounced; significant differences included increased frequency of crippled fry (191.5%) and decreased feed conversion efficiency (14.9%), fry survival to 147 days (29.7%), and growth rate to 147 day s (13.4%) and 364 days (33.5%). Application of the total effects of inbreeding on the number of fish remaining and the weight of fish remaining in a production lot at 1 yr of age indicated losses of 17.4 and 36.6% after one generation (F = 0.25) and 47.9 and 65.4% after two generations (F = 0.375) of brother–sister mating. Similar studies on a spring-spawning population produced similar results. General breeding methods that minimize the rate of inbreeding accumulation are discussed.
Taxonomic Reevaluation of the Spiny Dogfish (Squalus acanthias L.) in the Northeastern Pacific Ocean
Authors: Jones Barry C. , Geen Glen H.
Published: April 2011

Morphometric ratios, vertebral counts, and electrophoretic analyses of spiny dogfish from east and west coasts of North America indicate that those in the northeastern Pacific Ocean comprise one of several discontinuous stocks of the cosmopolitan species Squalus acanthias L. Though the individual stocks exhibit statistically significant differences in meristic and biochemical characteristics, available data do not support subspecific status for any of the groups around the Americas. The inadequacy of certain morphometric data to distinguish between Squalus species is also discussed.
Natural Water and Chemical Budgets for a Small Precambrian Lake Basin in Central Canada
Authors: Schindler D. W. , Newbury R. W. , Beaty K. G. , Campbell P.
Published: April 2011

Results of a 4-yr study of the hydrology of the Rawson Lake watershed, as well as the chemistry of precipitation, streamflow, and the lake are presented. Inputs of water and most chemicals varied by as much as 2 times from one year to the next, illustrating that several years’ data are necessary to determine accurately average nutrient inputs and losses from an ecosystem. Precipitation appeared to be almost the sole source of P and N to lake and terrestrial ecosystems, although N2 fixation cannot be dismissed in the latter case. Significant proportions of Ca, Mg, Na, K, Cl, and SO4 were supplied directly from precipitation. The lake also received substantial quantities of these elements as well as silicon, from weathering of terrestrial geological materials. Although far from any major industrial sources of SO2, the pH of precipitation averaged < 5 for the years studied. Both terrestrial and lake systems retained a high proportion of entering P and N, and smaller proportions of other nutrients. Interpretation of relative retentions of nutrients revealed that the terrestrial ecosystem has well-balanced P and N supplies, while the lake was P limited. Rates of loss of chemicals from the terrestrial watershed of Rawson Lake are comparable to other sites in the Precambrian Shield, but lower than values from other geological settings.
Transatlantic Migrations of Spiny Dogfish (Squalus acanthias)
Authors: Templeman Wilfred
Published: April 2011

The first record of a west to east transatlantic migration of a tagged spiny dogfish (Squalus acanthias) is reported, 11 yr after liberation at St. Pierre Bank to recapture in the Shetland Isles–northern North Sea area. The most northward and eastward records of spiny dogfish in the northwest Atlantic are presented and discussed in relation to the probable frequency of transatlantic migration. It is concluded that transatlantic migration is not great but probably not highly unusual.
Volatile Ketones and Alcohols of Codworms (Terranova decipiens) from Axenic Culture and Fresh Fish Muscle
Authors: Ackman R. G.
Published: April 2011

Simple techniques for the gas–liquid chromatographic analysis of volatile ketones and alcohols from cultures or native codworms, Terranova decipiens, or from the axenic culture medium, are described. Three ketones (propanone-2, butanone-2, pentanone-3) and two alcohols (butanol-2, pentanol-3) were observed. The proportion of alcohols to ketones was different in culture medium and in native worms from cod, but the latter were qualitatively and quantitatively similar in fresh cod taken in March and September.
Flatfish Densities Determined with a Diver-Operated Flounder Sampler
Authors: Walton James M. , Bartoo Norman W.
Published: April 2011

Densities of four species of flatfish: rock sole (Lepidopsetta bilineata), English sole (Parophrys vetulus), C-O sole (Pleuronichthys coenosus), and the speckled sanddab (Citharichthys stigmaeus) were determined by using a flounder sampler designed for use by a scuba diver biologist on sand bottom habitats. Under semicontrolled conditions the overall estimate of flatfish numbers was 91.0 flatfish/1000 m2 with a 95% confidence interval of ± 17.5. Biomass was estimated at approximately 7.4 kg/1000 m2.
Rate of Conversion of 14C-p,p′ -DDT to p,p′ -DDE by Brook Trout (Salvelinus fontinalis): Absence of Effect of Pretreatment of Fish with Compounds Related to p,p′ -DDT
Authors: Addison R. F. , Zinck M. E.
Published: April 2011

Brook trout (Salvelinus fontinalis) fingerlings were given four injections at weekly intervals of either p,p′ -DDT, p,p′ -DDE, p,p′-DDD, or p,p′ -DDMU to yield tissue concentrations of 1–5 mg/kg wet wt. The effect of these treatments on the subsequent dehydrochlorination of an injection of 14C-p,p′ -DDT was investigated. The rate of dehydrochlorination of 14C-p,p′ -DDT by the trout was not influenced by these treatments and was more highly correlated with factors such as the weight of the fish and their lipid content. Of the compounds injected during the treatment of the fish, p,p′ -DDMU was cleared more rapidly than the others.
Back-Calculated Fish Lengths and Hg and Zn Levels from Recent and 100-Yr-Old Cleithrum Bones from Atlantic Cod (Gadus morhua)
Authors: Scott J. S.
Published: April 2011

Dimensions of cleithrum bones from recently caught Atlantic cod (Gadus morhua) were measured and plotted against observed fish lengths to back-calculate cod lengths from cleithra from a ship wrecked in 1865. Mercury levels in the historical bones were approximately the same as those in recent material and showed no increase with fish length, but zinc levels appearto have increased since 1865 and increased with fish length.
Changes in the Size Structure of Cichlid Populations of Lake Malaŵi Resulting from Bottom Trawling
Authors: Turner J. L.
Published: April 2011

A bottom trawl fishery, primarily for cichlids, was started in 1968 in southern Lake Malaŵi. Since then a dramatic change has occurred in the catch of cichlids from one dominated by large species to one dominated by small species. Rates of change in abundance and mean length were much greater in the southern end of the southeast arm (area A) which has been fished for a longer period using trawls with 25-mm codend mesh than in the central region of the southeast arm (area B) which has been fished for a shorter time using trawls with 38-mm codend mesh. The changes in area A suggest heavy fishing mortality with little recruitment for species over 200 mm maximum length, heavy fishing mortality with limited recruitment for the medium-sized species (180–200 mm maximum length), and light fishing mortality and excellent recruitment for the small species (140–180 maximum length). Changes in area B showed the same trends but were considerably less drastic. The number of species caught has declined over 20% in the heavily fished areas. The remaining common species have greatly expanded their distribution. The change in the relative abundance of large and small species in the catch, and the decline in the number of species, appear to be stabilizing. These changes are probably the result of the size-selective nature of the codend mesh of the trawl net resulting in excessive fishing mortality for the larger species.
Effect of Temperature and Feeding Rate on the Liver–Somatic Index of the Largemouth Bass, Micropterus salmoides
Authors: Heidinger Roy C. , Crawford Steven D.
Published: April 2011

At a controlled food intake level after 14 days at a given feeding regime, the liver–somatic index (liver weight as a percentage of body weight) of largemouth bass, Micropterus salmoides, was positively correlated with daily food intake. At temperatures of 20.0 and 28.0 °C there was no overlap in the ranges of the liver–somatic index of bass fed 0, 2, and 4% of their body weight in live green sunfish (Lepomis cyanellus) per day. Within a given feeding regime, increased temperature lowered the liver–somatic index.
Photoreceptors and Visual Pigments as Related to Behavioral Responses and Preferred Habitats of Perches (Perca spp.) and Pikeperches (Stizostedion spp.)
Authors: Ali M. A. , Ryder R. A. , Anctil M.
Published: April 2011

A review of the literature indicated contrasts in retinal structure and function between perches (Perca spp.) and pikeperches (Stizostedion spp.). Foremost among these were differences in size and distribution of rods, size and shape of cones, extent of retinomotor responses, possession or lack of reflecting material, and relative concentrations of melanin. The perches are primarily active by daylight, whereas the pikeperches are most active during twilight or at night. The coincidental occupancy of shoal areas by yellow perch (Perca flavescens) and walleye (Stizostedion vitreum vitreum) at twilight is related to decreasing visual acuity of the former and the approach of optimum visual performance in the latter species. On this basis the two species have a classic predator–prey relationship. Key words: histology, light, Perca sp., photopic vision, predation, retina, Stizostedion vitreum vitreum, symbiosis, tapetum lucidum
Development and Food of Age-0 Eurasian Perch (Perca fluviatilis) in Reservoirs near Moscow, USSR
Authors: Spanovskaya V. D. , Grygorash V. A.
Published: April 2011

Eurasian perch (Perca fluviatilis) spawned in Mozhaisky and Uchinsky reservoirs in early May when water temperatures were 5–10 °C. Larvae subsisted on the yolk sac until the mouth became terminal at 6.0–7.0 mm standard length. Larval development is illustrated by drawings and discussed. As young perch grew they fed on cladocerans in preference to copepods, later switching to insect larvae. Daily ration of larvae in June was 12–16% body weight and of fingerlings 5–28% body weight, in different months and years. Most feeding was crepuscular. In the years when food was abundant fast-growing young-of-the-year matured as precocious males in autumn. They spawned with larger females the following spring. This is considered to be an adaptive response to increased food supply and low population densities. Key words: Percidae, Perca, food, development, spawning, Mozhaisky Reservoir, Uchinsky Reservoir
Relations Between Exploitation, Yield, and Community Structure in Polish Pikeperch (Stizostedion lucioperca) Lakes, 1966–71
Authors: Bonar Alina
Published: April 2011

A review of official fishery records maintained on 43 Polish pikeperch (Stizostedion lucioperca) lakes during 1966–71 showed that yield was dependent on exploitation intensity and community structure. Community structure was studied on the basis of three groups of fish: predatory, undesirable, and valuable nonpredatory. The percent of predatory fish was used as an index of community structure. An increase of 1 unit of exploitation intensity increased yield by 0.42–0.50 kg/ha and a 1% increase in predatory fish decreased yield by 0.45–0.49 kg/ha. Undesirable fish predominated in lakes with high yields and predatory fish predominated in lakes with low yields. The largest catches of predatory fish species occurred when their percentage in the total catch reached 25. A more effective regulation of predatory and nonpredatory fish populations may be achieved through controlled exploitation. Key words: Percidae, European pikeperch, Poland, community dynamics, methodology, predators, exploitation, yield