bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors Affecting the Behavior of Five Chlorinated Hydrocarbons in Two Natural Waters and their Sediments
Authors: Oloffs P. C. , Albright L. J. , Szeto S. Y. , Lau J.
Published: April 2011

Water samples from the Fraser River and Georgia Strait, British Columbia were treated with different chlorinated hydrocarbons and incubated for up to 12 weeks at 13 C. 1) In the presence of bottom sediments from the same locations as the waters, no residues were found to escape into the atmosphere. 2) With the exception of lindane in ocean water, all detectable residues had moved into the sediments after 6 weeks. 3) Most of the lindane was metabolized. 4). Sterilization of the waters and sediments prevented the metabolism of lindane but had little effect on DDT and DDD. 5) Agitation of water samples containing γ-chlordane, incubated without sediment, had no effect on its disappearance, but the presence of 0.01% of a nonionic surfactant retarded this almost completely.
Distribution of Udonella caligorum Johnston, 1835 (Monogenea: Udonellidae) on Caligus elongatus Nordmann, 1832 (Copepoda: Caligidae)
Authors: Kabata Z.
Published: April 2011

A large number (2933) of Caligus elongatus (Copepoda: Caligidae) removed from the buccal cavities of cod, Gadus morhua, off the west coast of Scotland, were examined for presence and distribution of Udonella caligorum (Monogenea: Udonellidae). Distribution of worms was not consonant with space available for attachment. Eggs and young worms were found primarily on the posterior half of the copepod, whereas adults occupied predominantly the lateral margins of the cephalothoracic shield. It was concluded that U. caligorum has a feeding area and a nursery area on the copepod and carries out migrations between them. Location of the feeding area strongly suggests that the worm feeds directly on the epithelial tissues of the fish.
Captan Toxicity to Fathead Minnows (Pimephales promelas), Bluegills (Lepomis macrochirus), and Brook Trout (Salvelinus fontinalis)
Authors: Hermanutz Roger O. , Mueller Leonard H. , Kempfert Kenneth D.
Published: April 2011

The toxic effects of captan on survival, growth, and reproduction of fathead minnows (Pimephales promelas) and on survival of bluegills (Lepomis macrochirus) and brook trout (Salvelinus fontinalis) were determined in a flow-through system. In a 45-week exposure of fathead minnows, survival and growth were adversely affected at 39.5 μg/liter. Adverse effects on spawning were suspected but not statistically demonstrated at 39.5 and 16.5 μg/liter. The maximum acceptable toxicant concentration (MATC), based on survival and growth, lies between 39.5 and 16.5 μg/liter. The lethal threshold concentration (LTC) derived from acute exposures was 64 μg/liter, resulting in an application factor (MATC/LTC) between 0.26 and 0.62. LTC values for the bluegill and brook trout were 72 and 29 μg/liter, respectively. The estimated MATC is between 44.6 and 18.7 μg/liter for the bluegill and between 18.0 and 7.5 μg/liter for the brook trout.The half-life of captan in Lake Superior water with a pH of 7.6 is about 7 hr at 12 C and about 1 hr at 25 C. Breakdown products from an initial 550 μg/liter of captan were not lethal to 3-month-old fathead minnows.
Effects of Illumination on Behavior of Wild Brown (Salmo trutta) and Rainbow Trout (Salmo gairdneri) Exposed to Black and White Backgrounds
Authors: Ritter John A. , MacCrimmon Hugh R.
Published: April 2011

Wild brown (Salmo trutta) and rainbow trout (Salmo gairdneri) placed in a circular tank illuminated at 10−2 lx immediately selected black rather than white background. Preference for black fluctuated with activity during the first 2 hr while both selection of black and activity gradually decreased with habituation over the following 84 hr. A sudden increase in illumination to 200 lx reestablished the strong selection of black which decreased rapidly with rising activity. Selection of black was inversely correlated with activity of the fish and was greater under moving than nonmoving water conditions. Differences in activity levels between rainbow and brown trout caused minor differences in response to background.Temporal preference for black background is interpreted as a protective response to the fright stimuli of initial handling, unfamiliarity with the experimental tank, and sudden increase in illumination. Duration of the response after the sudden increase in illumination was less in brown than rainbow trout. Because of its influence on activity and selection of light or dark backgrounds, light is an important ecological factor for trout.
Contributions to the Biology of the Bering Cisco (Coregonus laurettae) in Alaska
Authors: Alt Kenneth T.
Published: April 2011

Taxonomic and biological data are presented on Bering cisco, Coregonus laurettae Bean, from the South Fork of the Kuskokwim River; Hess Creek and the Porcupine River in the Yukon System; and the Koyuk River and Port Clarence–Grantley Harbor area of western Alaska. Gill raker counts ranged from 31–40 with means of 33.8–36.6, those on the lower arch 18–24 with means of 20.4–23.6.Potential spawners were found 1610 km up the Yukon River in mid-June and 262 were taken at the mouth of Hess Creek in the Yukon River 1270 km upstream from the mouth June 10–14, 1972.Bering cisco from Hess Creek grow faster than cisco from Port Clarence–Grantley Harbor, reaching a maximum length of 480 mm and 8 years of age. Growth rates for males and females are similar.
Effect of a Reciprocal Photoperiod Regime on Standard Rate of Oxygen Consumption of Postsmolt Atlantic Salmon (Salmo salar)
Authors: Withey Kathryn G. , Saunders Richard L.
Published: April 2011

Postsmolt Atlantic salmon (Salmo salar) subjected to a reciprocal photoperiod regime (decreasing daylength from early March and increasing daylength from late June) had significantly lower standard rates of oxygen consumption than those subjected to a simulated natural photoperiod regime when both were tested in total darkness in sea water in late summer. A reduced metabolic level, as indicated by the low standard rate of oxygen consumption, in the test fish is consistent with earlier observations of reduced feeding and growth rates and food conversion efficiencies in similarly treated fish following transfer to sea water.
Dependence of Recruitment on Parent Stock
Authors: Cushing D. H.
Published: April 2011

Observations on the relation of recruitment to stock suggest that there is a lightly convex curve for herring and a dome-shaped one for gadoid fishes, in contrast to flatfishes where a flat-topped curve is well established for several species. Theoretical examination of potential mechanisms lead to a suggestion that natural mortality rate decreases with age down to a minimum, then increases among the older, senescent, fish. This has been incorporated into yield curves for the North Sea plaice and Arcto-Norwegian cod, which have maxima at rates of fishing (F) of 0.22 and 0.26, respectively.
The Role of Aquaculture in Fishery Development and Management
Authors: Pillay T. V. R.
Published: April 2011

Although historically there have been different patterns of development of aquaculture, present-day interest is mainly directed toward the establishment of viable industries. Emphasis in the major aquaculture areas of the world continues to be on the cultivation of species that are within the reach of most consumers. Aquaculture is also practised for the improvement of natural stocks through artificial recruitment and transplantation or for the production of bait, sport, or ornamental fish. The different types of aquaculture include culture of fish and shrimps in ponds, tanks, cages, enclosures, raceways, and recirculating systems, and "bottom" and "hanging" methods of mollusc culture.World production through aquaculture (excluding bait, sport, and ornamental fish and production through stocking of open waters) is over 5 million tons. This has an important role in the food and nutrition of many countries and is particularly significant in integrated rural development.Aquaculture can contribute significantly to meeting the demand for animal proteins in developing countries and increase the production of luxury foods. It can also serve as an efficient convenor of low-grade fishery products to high quality fish. The employment potential is high and well-managed installations yield favorable returns on investment.Besides contributing to relieve pressure on intensively exploited stocks, aquaculture enables the development of resources within national boundaries. There is considerable potential for stock improvement through artificial recruitment and transplantation in certain areas. Possible adverse effects of aquacultural development can be eliminated by the adoption of appropriate remedial measures.Although a world-wide survey has not yet been undertaken, it is known that extensive areas are readily available for aquaculture in many developing countries. In 11 countries of Asia alone, about 22 million ha have been identified as potential areas for fish culture. Sites for other types of aquaculture are much more extensive. An increase of up to 10 times in production through aquaculture by the year 2000 has been predicted.Some of the existing misconceptions about aquaculture have acted as constraints to the development of the industry. Due to the lack of adequate planning, financing, and shortage of trained personnel, the existing knowledge is not being fully utilized. Besides better research facilities to fill the gaps in our knowledge, there is an urgent need to evolve suitable development strategies in the framework of national fishery development plans, to achieve targets of production in different countries.
Alternatives in Aquacultural Development: Consideration of Extensive Versus Intensive Methods
Authors: Neal R. A.
Published: April 2011

For animal species having apparent potential for economical culture, the alternatives of developing extensive or intensive cultural practices are compared. Extensive culture is defined as raising fish or shellfish in natural bodies of water with few modifications of the environment, while intensive culture is defined as rearing animals in man-made ponds, raceways, or tanks where environmental control is exercised. A discussion of legal, biological, economic, environmental, and social implications of each approach is presented. It is concluded that, for most carnivorous and omnivorous species of interest to aquaculturists, expenditures for the development of extensive culture methods are not justified.
Fisheries Planning to Meet Economic and Social Objectives with Special Reference to Countries Bordering the Eastern Central Atlantic
Authors: Hamlisch R.
Published: April 2011

Planning responsibilities for fisheries should be entrusted to specially trained staff, not to economic and agricultural planners or even to fishery specialists with a technical, scientific, or general administrative background. Characteristics of fishery resources ("invisibility," mobility, and nonexistence of ownership rights) and of fish production (the large range of input/output combinations, technical and managerial requirements, fishing labor remuneration, and fish utilization) elevate such essential features of planning as inventory-taking and supply- and demand-projecting to an "art," which a planner unfamiliar with fisheries cannot be expected to have mastered. Fisheries specialists lack the know-how for selecting projects, and their record in planning is generally no better than that of nonspecialists.Basic techniques of sectoral planning are summarized, and the methods of adjusting them to overall economic and social plans are described. Examples relating to countries bordering the eastern central Atlantic are presented, listing the types of questions planners might raise in initiating or evaluating programs.Two proposals for improving fisheries development planning are mentioned — workshops on fisheries planning; and appointment of fisheries planning experts to give advice, set up planning units, and train counterpart personnel.
Myxosoma cerebralis: Isolation and Concentration from Fish Skeletal Elements — Sequential Enzymatic Digestions and Purification by Differential Centrifugation
Authors: Markiw Maria E. , Wolf Ken
Published: April 2011

An effective sequential procedure for recovery of Myxosoma cerebralis spores from infected trout was developed, and quantification of spores was carried out at each step of release and concentration. Methods are described for fresh and frozen material. Effective concentration of from 1100- to 9000-fold and an estimated efficiency of recovery of about 80% has been achieved. Tabular and graphic data are presented with recommendations for diagnostic applications. The immediate applications of these procedures are in implementing more effective detection and in preparing antigen for the immunologic studies that should provide the most sensitive detection.
Availability, Size Composition, Age Composition, and Growth Characteristics of Pacific Ocean Perch (Sebastes alutus) off the Northern Washington Coast During 1967–72
Authors: Gunderson Donald R.
Published: April 2011

Cruises were conducted off the northern Washington coast each year during 1967–72 to study trends in the availability and biological characteristics of Pacific Ocean perch (Sebastes alutus).There were marked differences in catch rate between cruises, and corresponding differences in age composition and age–length structure indicated that they resulted from differential availability of an old, slow-growing segment of the population to on-bottom trawling. Females from this segment of the population were particularly available when the cruise coincided with the period of peak spawning, and both sexes were available during the 1972 summer cruise.Within cruises, adults from different portions of the bathymetric range showed similar age composition, but there was an inverse relationship between depth and size attained by age 15. Size compositions consequently contained a smaller proportion of large fish as depth increased.Juveniles were confined to the shallow portions of the bathymetric range. There were obvious between-year changes in the length and age composition of juveniles, caused by the temporal progression of a dominant 1961 year-class.Fluctuations in availability make it difficult to monitor changes in mortality and since age composition also varies with availability, the problem is compounded further. Unless all segments of the population are located and sampled in proportion to their abundance, estimates of mortality can be made only between those cruises where the old, slow-growing component of the population is equally available.
In Vitro and In Vivo Efficacy of a Potentiated Sulfonamide in Control of Furunculosis in Salmonids
Authors: Bullock G. L. , Stuckey H. M. , Collis Diane , Herman R. L. , Maestrone G.
Published: April 2011

In vitro and in vivo efficacy of a potentiated sulffonamide, Ro5–0037, for inhibition of Aeromonas salmonicida, causative agent of fish furunculosis was determined. The components of the potentiated sulfonamide, sulfadimethoxine, and ormetoprim were tested alone and in combination. In vitro results showed that both sulfonamide-resistant and sensitive strains of A. salmonicida had greater sensitivity to Ro5–0037 than to either of its components. Also, sulfonamide-sensitive strains developed resistance to ormetoprim and sulfadimethoxine more rapidly than to Ro5–0037. Efficacy studies with small numbers of artificially infected trout revealed that Ro5–0037 effectively controlled furunculosis at 50 mg/kg of fish/day, one fourth the usual sulfonamide dosage level. Extensive field trials also showed the 50 mg/kg level of Ro5–0037 gave effective control of hatchery outbreaks of furunculosis. As found in the in vitro studies, all in vivo trials indicated the combination of ormetoprim and sulfadimethoxine was more efficient in inhibiting A. salmonicida than either component alone.
Preliminary Feeding Trials Using Artificial Diets to Study the Nutritional Requirements of Oysters (Crassostrea virginica)
Authors: Castell J. D. , Trider D. J.
Published: April 2011

Oysters (Crassostrea virginica) showed positive growth response when fed artificial diets of known nutrient composition; differences in growth rate, meat weights, and glycogen content corresponded with differences in dietary composition. High levels of dietary carbohydrate resulted in greater oyster glycogen production. The type and level of lipid in the diet was also important. Cod liver oil was of higher nutritional value for the oysters than corn oil; increasing the dietary lipid from 5 to 18% of the dry weight, resulted in greater meat production and earlier total weight gains considered to be associated with earlier gonadal ripening.Oysters held in Malpeque Bay in floating trays grew 10 times faster than those held in tanks of continuously flowing filtered sea water and fed artificial diets.
Immature Insects (Plecoptera, Trichoptera, and Ephemeroptera) Collected from Deep Water in Western Lake Superior
Authors: Selgeby James H.
Published: April 2011

Five species of aquatic insects — two plecopterans, two trichopterans, and one ephemeropteran — usually found in streams or ponds were collected in water 32–100 m deep in western Lake Superior. All appear to be new records for the lake and all were collected from far greater depths than previously recorded for these forms.
Spatial and Temporal Distribution of Chlorophyll a and Pheopigments in Surface Waters of Lake Erie
Authors: Glooschenko Walter A. , Moore James E. , Vollenweider Richard A.
Published: April 2011

Chlorophyll a analyses including pheopigments were made on water samples taken on 10 cruises on Lake Erie between April and December, 1970. The highest mean chlorophyll a values of approximately 11 μg/liter occurred in the mid-Western Basin, with a second maximum of 6 μg/liter off Erie, Pennsylvania. The southern shore is also characterized by high values of chlorophyll to the east of Cleveland, Ohio. The lowest yearly means were found in the eastern portion of the Central Basin and most of the Eastern Basin (approximately 3 μg/liter.) Ratios of chlorophyll a between the Eastern, Central, and Western basins have a yearly mean of 1:1.4:2.8, respectively; with maximum differences in the summer, i.e. late August, the ratio was 1:1.5:7.2.Pheopigment concentration in the surface waters reached a maximum in late October corresponding to the fall overturn of the lake and subsequent resuspension of organic matter containing degradation products from the bottom of the lake. No significant correlation was found between zooplankton abundance and pheopigment concentration as in other water bodies studied. This may indicate that zooplankton food chains are primarily detrital in Lake Erie, with grazing of living phytoplankton playing a lesser role compared with more oligotrophic water bodies.
In Situ Measurement of the Settling Velocity Profile of Particulate Organic Carbon in Lake Ontario
Authors: Burns N. M. , Pashley A. E.
Published: April 2011

Depth profiles of calm water settling velocities were measured in situ using specially constructed sampling bottles. Samples of water were taken at specific depths and the settling process commenced as soon as the samples were taken. Just before retrieval of the bottles, the samples were subdivided into upper and lower portions so that settling velocities could be calculated; these varied between − 0.4 and + 2.0 m day−1. Net settling velocities measured at the top of the thermocline were used to estimate net settling fluxes from the epilimnion; these varied between − 0.074 and + 0.336 mmoles of phosphorus m−2 day−1. Net settling flux can differ from sedimentation flux out of the epilimnion and the necessity for a clear distinction between these two values is emphasized.
Exchange of Carbon Dioxide Between the Atmosphere and Lake Ontario
Authors: Weiler R. R.
Published: April 2011

The calculated flux of carbon dioxide between Lake Ontario and the atmosphere ranged from about 0.1 gC m−2 day−1 during the summer to about 3 during a winter storm. During the summer, the amount of carbon supplied from the atmosphere was from 5 to 30% of the estimated amount utilized in primary production. Also Lyman's dissociation constants for carbonic acid were found applicable to the carbonate system of the lake.
Marking Atlantic Salmon (Salmo salar) with Oxytetracycline
Authors: Odense P. H. , Logan V. H.
Published: April 2011

The marking of Atlantic salmon (Salmo salar) by feeding oxytetracycline has been investigated. Fluorescent marks, readily visible for up to 2 yr postfeeding have been observed in centrum and rib with the former being superior for gross observation. Best results were obtained with fish more than 1 yr old. Sampling, storage, and observation techniques are discussed.
Mercury in Some Canadian Atlantic Coast Fish and Shellfish
Authors: Freeman H. C. , Horne D. A. , McTague B. , McMenemy M.
Published: April 2011

All species of North Atlantic fishes studied, with the exception of two groups of offshore lobsters, had total mercury levels less than the 0.5 ppm limit allowed for fish of commerce in Canada and the United States. There appeared to be no relationship between mercury levels and the sex and/or weight of fish of any one species.The first indication that mecury was a threat to public health came from the Japanese mercury poisoning epidemics in the early 1950s (Löfroth 1969; Berglund et al. 1971). This initiated many studies. Apparently increased industrial and agricultural use and the broad dissemination of mercury compounds had caused mercury contamination in fish (Nuorteva 1971).
Muscle Arylamidase Activity of Several Marine Species
Authors: Bauer Beverly A. , Eitenmiller R. R.
Published: April 2011

Arylamidase activity in muscle extracts of mackerel, mullet, whiting, blue crab, quahog clam, and shrimp was investigated. The optimum pH for activity was between 7.0 and 7.5 for each species using alanyl-β-naphthylamide as substrate. Enzymes of the three species of fish exhibited maximum activity against alanyl-β-naphthylamide, whereas the clam showed maximum activity with leucyl-β-naphthylamide and the crab and shrimp with lysyl-β-naphthylamide. Puromycin inhibited each of the arylamidases. Acrylamide gel electrophoresis of the crude extracts suggested the presence of one arylamidase in muscle of the fish, crab, and clam. The shrimp muscle extract contained two active enzymes. Upon electrophoresis, the faster moving enzyme from shrimp muscle was active against lysyl-, alanyl-, and leucyl-β-naphthylamides, but the slower moving enzyme was active only against lysyl-β-naphthylamide.
Color and Some Composition Changes in Ocean Perch (Sebastes marinus) Held in Refrigerated Sea Water With and Without Carbon Dioxide
Authors: Longard A. A. , Regier L. W.
Published: April 2011

Skin color of ocean perch (Sebastes marinus), measured instrumentally, was at least as good when the fish were held up to 12 days in refrigerated sea water (RSW) at −1 C as when they were held in ice. Adding carbon dioxide to the RSW generally enhanced skin color retention. The loss in total extractable carotenoid pigments was not much affected by the storage conditions. The fish stored in RSW with CO2 were kept in better condition, as measured by trimethylamine production in the fillet tissue, than in ice or RSW. The ionic diffusion, sodium uptake, and potassium loss between the fish and the RSW did not appear excessive but did not reach equilibrium in 12 days storage.
Toxicity of Various Formulations of 2,4-D to Salmonids in Southeast Alaska
Authors: Meehan William R. , Norris Logan A. , Sears Howard S.
Published: April 2011

To determine acute toxicity to juvenile (1) pink, chum, coho, and sockeye salmon, (2) Dolly Varden char, and (3) rainbow trout, 2,4-D acid, butyl and isooctyl esters were tested in southeast Alaska. A comparable test was made in Oregon using coho salmon fingerlings. The mean percent mortality after 96 h and the highest concentration of herbicide that did not produce any mortality were determined for each formulation tested.At less than 50 ppm 2,4-D acid produced no mortality except in pink salmon fry. The butyl ester was most toxic causing nearly complete mortality in all species at concentrations > 1.0 ppm and the isooctyl ester least toxic of the ester formulations. Alaskan and Oregon coho fingerlings were similar in their responses to 2,4-D acid, butyl and isooctyl esters. The toxicities of three different formulations of isooctyl ester, a PGBE ester, and butyl ester to Alaskan coho fingerlings were also determined. There were few or no differences in toxicity among isooctyl ester formulations. The butyl and PGBE esters were similar in toxicity.
Trout Production in Prairie Ponds
Authors: Lawler G. H. , Sunde L. A. , Whitaker J.
Published: April 2011

Experimental plantings of rainbow trout (Salmo gairdneri) in prairie winterkill lakes commenced in 1968 to test the feasibility of their commercial production. These trials were highly successful and by 1970 a small but rapidly expanding trout farming industry had been established. Trout planted early in the spring as 5- to 8-cm long fingerlings grew to marketable size (200 g minimum), without supplementary feeding, in the 6-mo period of open water that prevails in this region. Recoveries as high as 86% of the fingerlings stocked have been achieved and the quality of the trout produced is usually excellent in flavor and color. These experiments are continuing to improve management techniques and to determine the long-term productive capacity of pothole lakes. Three serious problems — summerkill, muddy flavor, and harvest inefficiency — are also subjects of continuing investigations. Use of prairie winterkill lakes as nursery ponds for production of advanced fingerlings of walleye and whitefish for use in resource-enhancement programs has also been tested with considerable success.
Experimental Lakes Area: Whole-Lake Experiments in Eutrophication
Authors: Schindler D. W. , Fee E. J.
Published: April 2011

The following whole-lake experiments are described:Lake 227, fertilized for 5 yr with phosphate and nitrate, has shown an enormous increase in phytoplankton, in spite of low carbon concentrations. The carbon necessary for production of algal blooms was found to invade from the atmosphere.Lake 304, eutrophied by fertilization with phosphorus, nitrogen, and carbon in 1971 and 1972, recovered rapidly when phosphorus fertilization was terminated.Lake 226 was split in half with a curtain. One half was fertilized with carbon and nitrogen and the other was fertilized with phosphorus, carbon, and nitrogen. The half of the lake receiving phosphorus developed an algal bloom and the other half did not.Lake 302, which had carbon, nitrogen, and phosphorus added to the hypolimnion, did not develop algal blooms in summer. Small phytoplankton blooms were found under ice in early December, but all nutrients were efficiently sedimented and unavailable the following year.The above studies illustrate clearly that phosphorus control is an efficient primary step in preventing or checking eutrophication problems.A review of other published and ongoing studies in the Experimental Lakes Area is given, illustrating the role which large-scale experiments can play in interpreting environmental problems.
A Review of Research on the Limnology of West Blue Lake, Manitoba
Authors: Ward F. J. , Robinson G. G. C.
Published: April 2011

An interdisciplinary research program on the West Blue Lake ecosystem is reviewed. The composition, seasonal occurrence, abundance, and primary productivity of the phytoplankton are reported. In spring "net" phytoplankton diversity and abundance were highest with diatoms predominating. In summer Anabaena spiroides and Aphanizomenon flos aquae were a major component. During winter both cell numbers and species diversity declined. Cyclotella bodanica became dominant. Average summer phytoplankton primary productivity approximated 320 mg C m−2 day−1 in both 1971 and 1972. Average daily estimates (exclusive of zooplankton) of organic carbon in the euphotic zone during summer periods in 1971 and 1972 were, respectively, 5 and 8 g C m−2.Kinetic parameters for the bacterial uptake of 11 dissolved organic substrates are reported. Values Vmax ranged from 0.003 mg C m−3 h−1 for formic acid to 0.115 mg C m−3 h−1 for lactic acid; turnover times from 8 h for malic acid to 950 h for glycolic acid, and (Km + S) values from 0.288 mg C m−3 for malic acid to 47.883 mg C m−3 for glucose. A relation between Vmax values and plated bacterial counts is described for six organic acids. Evidence for proliferation and adaptation of bacteria in sample bottles is presented and the absence of photoheterotrophy described. Potential bacterial production during the summer of 1972 ranged from 18.24 mg C m−2 day−1 to 67.44 mg C m−2 day−1. The relationship between this production and temperature (Q10 = 3.129) is described. "Filtration effect," as a source of error, in measuring glucose uptake is probably an artifact.Generally, Cyclops bicuspidatus was more abundant than Diaptomus siciloides. Both were relatively scarce in summer. Daphnia pulicaria were usually most abundant in spring and early summer, and persisted at low levels during winter. Largest animals (over 2.0 mm long) with high relative caloric content [Formula: see text] predominated in fall, winter, and early spring when reproduction was minimal. No fish species reside permanently in the pelagic zone of West Blue Lake, but age 0 fry of Perca flavescens inhabited the epilimnion during July and early August and fed almost exclusively on D. pulicaria. In contrast, age I and older perch consumed a variety of, principally, littoral organisms. Walleye, Stizostedion vitreum vitreum, over 25 cm in length put on most of their annual growth in length and weight during the summer, when maximum production also occurred. Perch fry and larger perch were an important food for walleyes.
Plankton, Chemistry, and Physics of Lakes in the Churchill Falls Region of Labrador
Authors: Duthie H. C. , Ostrofsky M. L.
Published: April 2011

Of 10 lakes and a reservoir in the Churchill Falls region of western Labrador studied in 1970–71, nine lakes were 12 m or less deep, humic, thermally unstratified, and had Secchi disc transparencies between 3.5 and 8.25 m. Maximum surface temperatures of 16–17 C in the nine lakes were generally reached by mid-August. Michikamau Lake (area 1980 km2, depth 84 m) rarely exceeded 12 C and had a Secchi disc transparency of 13 m. Conductivities and alkalinities (as CaCO3) ranged from about 13 μmho/cm and less than 6.5 mg/liter, for lakes draining granite, gneiss, or quartz bedrock, to about 30 and 15, for those draining gabbro or slate. Maximum live phytoplankton biomasses in 1970 ranged from 70 mg/m3, in Michikamau Lake, to 739 mg/m3, in Ossokmanuan Reservoir, and, in general, there was a positive correlation with conductivity. Diatoms were the most abundant group, in particular Asterionella formosa, Tabellaria fenestrata, and Rhizosolenia eriensis; however, flagellated Chrysophyta, mainly species of Dinobryon, were more abundant in the reservoir than in the natural lakes. Predominant zooplankters included Diaptomus minutus, Cyclops scutifer, Holopedium gibberum, Daphnia longiremis, D. galeata mendotae, and Bosmina coregoni. Maximum seasonal standing crops ranged from 1600 to 8910 individuals/m3, with the highest densities being found in the reservoir. The chemical and biological data suggested that the reservoir 8 yr after filling, showed little evidence of trophic upsurge and was possibly entering a period of trophic depression.
Lymphocystis in Age 0 Bluegills (Lepomis macrochirus) Relative to Heated Effluent in Lake Monona, Wisconsin
Authors: Petty Lorna L. , Magnuson John J.
Published: April 2011

The viral disease lymphocystis was more common in age 0 bluegills (Lepomis macrochirus) in an area of Lake Monona heated by a power plant outfall than in unheated reference areas. Approximately 14,000 fish collected from July through October 1971 were examined. The infection became prevalent in mid-September and attained a maximum incidence in early October, when 11.6% of age 0 bluegills in the heated area had lesions in comparison with 5.5% in unheated areas in late September.Infected fish were longer than uninfected fish and usually exceeded 50 mm TL. Fish >50 mm long in the heated and in the unheated areas had similar lymphocystis incidence. Thus, higher lymphocystis incidence in heated than in unheated waters was largely explained by the greater percentage of bluegills longer than 50 mm TL in the outfall area.Leeches (Piscicolaria reducta) also were more prevalent in the heated area and may have increased lymphocystis incidence by creating foci for viral penetration or by acting as vectors.Slightly higher condition factors of infected than of uninfected bluegills were unexplained.
Effects of Prey Abundance on Density and Territorial Behavior of Young Rainbow Trout (Salmo gairdneri) in Laboratory Stream Channels
Authors: Slaney P. A. , Northcote T. G.
Published: April 2011

When rainbow trout (Salmo gairdneri) fry (underyearlings) were introduced into laboratory channels at three different prey levels and permitted to emigrate voluntarily, their density remained highest at the highest prey level. The distribution of fry was positively associated with a gradient in prey abundance. Both territory size and frequency of aggressive encounter varied inversely with prey level; the higher the prey level, the smaller the territory and the lower the frequency of aggressive encounter. Emigration from the channels was neither as rapid nor as marked when prey level was reduced, compared to when fry were initially introduced to different prey levels. However, frequency of aggressive encounter significantly increased when the prey level was decreased and significantly decreased when the prey was increased.
Effect of ACTH and Salmon Gonadotropin on Interrenal and Thyroid Activity of Gonadectomized Adult Sockeye Salmon (Oncorhynchus nerka)
Authors: Donaldson Edward M. , McBride J. R.
Published: April 2011

Injection of a chinook salmon (Oncorhynchus tshawytscha) gonadotropin preparation into gonadectomized sockeye salmon (Oncorhynchus nerka) did not result in any increase in the plasma concentration of cortisol or cortisone, nor did it stimulate the activity of the interrenal tissue. On the other hand, injection of mammalian ACTH (Acthar) did result in an increase in the plasma concentration of cortisol and cortisone, and stimulated the interrenal tissue. The salmon gonadotropin preparation, however, elicited an increase in thyroid activity. The results suggest that in the salmon, ovulation is not caused by gonadotropin induced interrenal corticosteroidogenesis.
Estimation of Bluegill (Lepomis macrochirus) Proximate Composition with Regression Models
Authors: McComish Thomas S. , Anderson Richard O. , Goff F. Glenn
Published: April 2011

Dry weight, protein, fat, and ash proximates were determined for 100 individual laboratory reared bluegill (Lepomis macrochirus). Regression analysis using forms of length and weight provided models for prediction of proximates. Percent dry weight was a linear function of coefficient of condition (r = 0.866). Natural logarithm of ash was a linear function of natural logarithm of length (r = 0.997). Percent fat was a function of coefficient of condition and natural logarithm of length (r = 0.796). Percent protein was a function of coefficient of condition and natural logarithm of length times natural logarithm of weight (r = 0.768). The regression models, based only on length and live weight of fish, allowed accurate prediction of bluegill proximate composition for a laboratory fish population raised on chironomid larvae.
Physiological and Ecological Significance of the Chemical Instability of Uric Acid and Related Purines in Sea Water and Marine Algal Culture Medium
Authors: Antia Naval J. , Landymore Arthur F.
Published: April 2011

The chemical instability of uric acid and related purine bases in a seawater phytoplankton culture medium was evaluated spectrophotometrically from concentration changes incurred on aseptic incubation at about 20 C under cool-white light or complete darkness. Uric acid showed slow degradation in darkness, which was increased severalfold by illumination. Xanthine showed a small degree of degradation only from illumination, but adenine, guanine, and hypoxanthine appeared to be stable under both test conditions. The degradation of uric acid was traced to three factors differing in intensity of effect: 1) pH of sea water (minor effect), 2) photolysis (additional minor effect), 3) trace-metal cation content of sea water (major effect), whereas that of xanthine could be traced only to photolysis.These results cast doubt on previous reports of utilization of uric acid as N-source for phototrophic growth of marine planktonic algae in that the compound actually utilized may be degradation product(s) rather than the intact purine. Ecologically, the results signify that uric acid could undergo rapid chemical turnover, without biological intervention, in the marine environment.
Gravel Incubators: a Second Evaluation on Pink Salmon, Oncorhynchus gorbuscha, Including Adult Returns
Authors: Bams Robert A.
Published: April 2011

A hatchery method designed for mass production of unfed Pacific salmon fry and utilizing a gravel medium during most of the incubation period is being evaluated on successive cycles of a stock of pink salmon, Oncorhynchus gorbuscha, of the Tsolum River, B.C. Possible treatment effects are studied at emergent fry and returning adult stages in artificially and naturally propagated populations. Average growth rate and, hence, efficiency of yolk conversion were unimpeded in the hatchery environment, but fry emerged 11 days prematurely. Survival from green egg to emergent fry averaged 74.9% in the hatchery and 20.6% in the creek, for a gain ratio at emergence of 3.63. Recovery of selectively marked populations of hatchery and creek fish demonstrated almost identical survival rates from fry to adult stages and a final gain ratio of 3.46. Adult lengths and weights, fecundity, and timing of migrations were unaffected generally by the hatchery treatment.
Effects of Reduced Oxygen on the Embryos and Larvae of Lake Trout (Salvelinus namaycush) and Largemouth Bass (Micropterus salmoides)
Authors: Carlson Anthony R. , Siefert Richard E.
Published: April 2011

At 7 and 10 C lake trout (Salvelinus namaycush) development from fertilization through first feeding was inhibited at all reduced oxygen saturations tested (50% and lower). Survival was adversely affected at all reduced concentrations although only slightly at 50% saturation at 7 C.At 20 and 23 C oxygen concentrations as low as 35% saturation were adequate for largemouth bass (Micropterus salmoides) survival. However, even at the highest reduced oxygen saturation (70%) growth was reduced, and at saturations of 50%) and below hatching was premature and first feeding was delayed.
Liver Damage in Rainbow Trout (Salmo gairdneri) Fed Cyclopropenoid Fatty Acids
Authors: Malevski Y. , Wales J. H. , Montgomery M. W.
Published: April 2011

Histological changes in livers of rainbow trout (Salmo gairdneri) repeatedly fed diets containing cyclopropenoid fatty acids (CPFA) revealed that these fish were unable to develop resistance to liver damage caused by CPFA. One group of trout was fed 150 ppm CPFA in the basal diet for 49 days followed by the basal diet for the remainder of the experimental period. Another group of trout was fed 150 ppm CPFA for 49 days, basal diet for 65 days, and 150 ppm CPFA for 45 days. At this time this group was divided into two subgroups; one received basal diet for 15 days, the other for 30 days, after which both subgroups were placed on a diet containing 360 ppm CPFA for 36 days. Analysis of the livers for histological changes showed that the parenchymal cells underwent cyclic changes of injury and recovery each time the trout were fed CPFA. Complete recovery of parenchymal cells occurred after the fish were removed from the diets containing CPFA for 30 days. Bile duct and blood vessel hyperplasia was observed for as long as 7 mo after CPFA was eliminated from the trout diet.
Fish Sporozoa: Extraction of Antigens from Myxosoma cerebralis Spores Which Mimic Tissue Antigens of Rainhow Trout (Salmo gairdneri)
Authors: Pauley Gilbert B.
Published: April 2011

This is the first report of an antigenic preparation from the spore stage of any histozoic sporozoan parasite. The method for successful extraction of the antigens is presented. This antigenic preparation is active in rabbits, but not salmonid fish. The detection of asymptomatic carrier fish using the spore antigens was not successful and evidence is presented to show that the parasite is successful because its antigens mimic those of trout. Immunoelectrophoresis indicates the parasite and trout antigens are different proteins.
Partial Replacement of Herring Meal with Soybean Meal and Other Changes in a Diet for Rainbow Trout (Salmo gairdneri)
Authors: Cho C. Y. , Bayley H. S. , Slinger S. J.
Published: April 2011

Growth rate, feed efficiency, and mortality were not adversely affected by reducing the level of herring meal in an open formula dry-pellet diet fed to rainbow trout (Salmo gairdneri) in aquaria through which 80–90% of the effluent water was recirculated. The herring meal was reduced from 35 to 18%, and the level of soybean meal increased from 10 to 39%. The fish gained 5.5 and 5.4 kg/100 fish from 8 to 40 wk of age on the high and low herring meal diets, respectively. Deletion of brewers' yeast, corn fermentation extractives, and whey powder from the diet with the higher level of herring meal increased weight gain to 7.0 kg/100 fish. When the fermentation by-products were removed from the diet with the lower level of fish meal the gain was reduced to 4.8 kg/100 fish. All the diets contained 4% of soybean or rapeseed oil or a marine oil; the type of oil did not influence the gains, but the conversion of feed to gain was most efficient for the diet containing the marine oil. The apparent digestibilities of the proximate components of three of the diets suggested that the fermentation by-products were not as digestible to the fish as the other components of the diet.
Spectrophotometric Determination of Dissolved Oxygen Concentration in Water
Authors: Duval W. S. , Brockington P. J. , Melville M. S. von , Geen G. H.
Published: April 2011

A modification of the Winkler method which increases precision while decreasing time required for oxygen analysis is described. The technique involves colorimetric determination of liberated iodine concentration at 287.5 nm.
Relationship of Fishing Mortality to Natural Mortality at the Level of Maximum Sustainable Yield Under the Logistic Stock Production Model
Authors: Francis Robert C.
Published: April 2011

The often-used approximation that, for a stock of fish under exploitation, the instantaneous fishing mortality rate equals the instantaneous natural mortality rate at the point of the maximum sustainable yield is examined with respect to its mathematical roots and practical utility. Examples from two diverse fisheries are utilized.
Is Morpholine an Effective Olfactory Stimulant in Fish?
Authors: Hara Toshiaki J.
Published: April 2011

Morpholine was designated as olfactorily nonstimulatory in rainbow trout as studied electrophysiologically. The morpholine-effect caused by 1% solution differs in many respects from the normal olfactory bulb response, suggesting a mechanism not directly associated with the normal olfactory function. Furthermore, 1% morpholine inhibits the olfactory sensitivity.
The Biological Half-life of Inorganic Mercury in the Dungeness Crab (Cancer magister)
Authors: Sloan J. P. , Thompson J. A. J. , Larkin P. A.
Published: April 2011

The biological half-life of inorganic mercury in the Dungeness crab, Cancer magister, has been determined experimentally to be about 25 days. Three theoretical models to explain the mode of elimination were tested by computer program. From results obtained, the validity of the widely used negative exponential "biological half-life" is left in some doubt.
Fish-to-Fish Attraction and the Facilitation of Feeding Behavior as Mediated by Visual Stimuli in Striped Mullet, Mugil cephalus
Authors: Olla Bori L. , Samet Carol
Published: April 2011

Single juvenile striped mullet, Mugil cephalus, tested in a specially designed experimental tank system, were allowed visual contact with a group of fish located in one of four adjacent tanks. Attraction of mullet isolates was greatest to a group of species mates, and less to bluefish, Pomatomus saltatrix, and Atlantic mackerel, Scomber scombrus, groups, respectively.To study the role of visual stimuli in feeding behavior, responses of mullet isolates were measured under three different test conditions: 1) absence of a group of species mates, 2) presence of a feeding group, and 3) presence of a nonfeeding group. Isolates tested in the absence of a group began feeding only after some delay, although the total number of subsequent feeding responses remained high. When isolates viewed a feeding group, the initiation of feeding was greatly facilitated, with the total number of feedings remaining high until the latter part of a test. Isolates viewing a nonfeeding group showed inhibition in the latency to feed as well as a low number of grazing responses. The significance of these observed responses is discussed.
Seasonal Succession of Free-Swimming Perciform Larvae in Lake Opinicon, Ontario
Authors: Amundrud James R. , Faber Daniel J. , Keast Allen
Published: April 2011

Free-swimming larvae of five perciform species were collected with tow nets in large numbers in Lake Opinicon from May to August of 1969 and 1970. The species appeared in the same seasonal sequence during the 2 yr: first yellow perch (Perca flavescens) followed by logperch (Percina caprodes), black crappies (Pomoxis nigromaculatus), and pumpkinseeds and bluegills (Lepomis gibbosus and L. macrochirus). Peaks of larval abundance, and also hatching, occurred earlier in 1970, when nest-site temperatures from early May to mid-June showed faster lake warm-up than in 1969.
Predator–Prey and Competition Models with State Variables: Biomass, Number of Individuals, and Average Individual Weight
Authors: Jensen A. L.
Published: April 2011

Applying the identity that biomass equals number of individuals multiplied by average individual weight, simultaneous equations for change with respect to time in biomass, number of individuals, and average individual weight are obtained for Kostitzin's predator–prey equations and for the Lotka–Volterra competition equations. By the same procedure applied here, simultaneous equations for these three variables can be obtained for other predator–prey and competition equations. These equations can be applied to determine the biomass, number of individuals, and average individual weight of interacting fish populations under different rates of exploitation.