bluuebunny/crossref_metadata_2025 huggingface dataset:
Tidal and Diurnal Effects on Zooplankton Sample Variability in a Nearshore Marine Environment
Authors: Sameoto D. D.
Published: April 2011

Two 26-h series of duplicate and replicate vertical zooplankton samples taken at two stations at two different times of the year showed that a periodic fluctuation correlated to the tide was present in the biomass of zooplankton and in the numbers of animals of several copepod species. Diurnally migrating species of zooplankton did not show a tidal correlation. The hour to hour fluctuations in zooplankton were generally more important than the difference between stations 1.6 km apart. Similar relations were found between the zooplankton and the tide in May and August even though there were significant differences in the composition of the zooplankton community during the two periods.Correlation coeficients between all species in all samples showed the presence of a diurnally migrating predator community and a nonmigrating prey community consisting of copepods.An experiment using sample data suggested that to obtain a reasonably accurate estimate of the mean numbers of a given species, one should make at least two vertical tows on a station at a 6-h interval.
Perfusion Fixation of Whole Fish for Electron Microscopy
Authors: Hinton D. E.
Published: April 2011

A method for obtaining uniform fixation of whole bodies of fish for electron microscopic study is described. The procedure employs vascular perfusion of aldehyde fixatives through the proximal aorta of anesthetized fish. Light microscopic examination of semi-thin (0.5–1 μ) sections of Epon embedded material, stained with toluidine blue, showed near to complete removal of blood cells from vessels of gill, bone, skin, skeletal muscle, heart, exocrine pancreas, mesentery, glomerulus, and brain. Electron microscopic examination of liver and kidney, fixed by whole body perfusion, showed excellent preservation of cell ultrastructure.
The Management of Marine Fisheries.
Authors: Iles T. Derrick
Published: April 2011

not available
Temperatures Selected and Avoided by Fish at Various Acclimation Temperatures
Authors: Cherry Donald S. , Dickson Kenneth L. , Cairns Jr. John
Published: April 2011

Temperatures selected and avoided by 13 fish species, evaluated at decreasing increments of 3 C from 30 to 6 C, declined as the acclimation temperature decreased from summer to winter. As acclimation levels declined the difference between acclimation and selected temperatures increased for centrarchids and cyprinids, whereas the difference between these two temperatures increased for trout above and below the 18 C level of acclimation. Bluegill (Lepomis macrochirus) and spotted bass (Micropterus punctulatus) selected the highest temperatures at all acclimation levels, followed by channel catfish (Ictalurus punctatus), green sunfish (Lepomis cyanellus), smallmouth bass (Micropterus dolomieui), spotfin shiner (Notropis spilopterus), and other cyprinids. Rainbow (Salmo gairdneri) and brook (Salvelinus fontinalis) trout selected the lowest temperatures. A linear regression of the selection vs. the acclimation temperatures was plotted for cyprinids, centrarchids, and salmonids.As the acclimation temperature was lowered, temperatures avoided decreased and the difference between the upper and lower avoidance range increased at each acclimation level. Eurythermal species, centrarchids, ictalurids, and most cyprinids, generally had a range difference of at least 10 C or more between the upper and lower avoidance temperature at each acclimation level.
Effects of Temperature on Development and Survival of Rainbow Trout, Salmo gairdneri, in Acid Waters
Authors: Kwain Wen-hwa
Published: April 2011

Differences in mortality of rainbow trout (Salmo gairdneri) embryos were significant (P < 0.05) when the eggs were exposed to 5, 10, and 15 C and pH levels from 3.0 to 6.0. No embryos survived at pH values below4.49, regardless of the temperature. The median lethal pH values for rainbow embryos were 4.75 and 5.52 at temperatures of 10 and 5 C, respectively.Differences in lethal pH values for fingerling rainbow trout were significant (P < 0.05) when trout were exposed to four test water temperatures (5, 10, 15, and 20 C) and two acclimation temperatures (10 and 20 C). The median lethal pH values of fingerling trout were positively related to the test water temperatures and ranged from 3.86 to 4.49. Resistance of yearling trout to acid waters was higher than that of fingerlings.
Practical Aspects of Survival and Destruction of Infectious Pancreatic Necrosis Virus
Authors: Desautels Denise , MacKelvie R. M.
Published: April 2011

The survival of infectious pancreatic necrosis (IPN) virus under conditions of practical import and its susceptibility to destruction by two common disinfecting agents were examined. An indigenous strain of virus, shed to trough water at a concentration of 105 TCID50 per milliliter during an epizootic, lost 99% of its infectivity in fresh water at 4 C in 10–12 wk. There was residual infectivity after 24 wk. Survival was prolonged in sea water where loss of activity of an ATCC strain after 10 wk incubation at either 4 or 10 C was negligible. The loss in 5–6 mo was under 99%.IPN virus (107 TCID50/ml) survived drying in air at laboratory temperature and humidity for 5 but not for 6 wk. Under reduced humidity, residual infectivity was still evident after 8 wk.At a titer of 105.0 TCID50/ml, IPN virus was completely inactivated by exposure to 25 ppm available chlorine in 30 min. A concentration of 40 ppm available chlorine was required to inactivate 107.5 TCID50 of virus/ml in the same period of time. IPN virus, at a titer of 105.5 TCID50/ml, was totally destroyed by 30 ppm active iodine (Wescodyne) in 5 min. An increase in virus concentration, to 106.6 TCID50/ml increased the iodine requirement to 35 ppm to achieve the same result.The implications for salmonid culture of the persistence of IPN virus in an aqueous environment and its resistance to destructive agents are discussed.
Multichannel Toxicant Injection System for Flow-Through Bioassays
Authors: DeFoe David L.
Published: April 2011

A mechanical injection system needing little maintenance is described which offers a dependable and flexible method for maintaining multiple toxicant concentrations in flow-through bioassays. Falling water from a series of water-metering cells similar to those of a proportional diluter, activates a series of mechanical syringe injectors. The system dispenses equal amounts of toxicant dispersants (solvents, wetting agents, or additives) to all toxicant concentrations and to a dispersant control and allows changing unlimited toxicant concentrations independently of each other.
Chemical Changes During the Seasonal Cycle of Growth and Decay in Eelgrass (Zostera marina) on the Atlantic Coast of Canada
Authors: Harrison P. G. , Mann K. H.
Published: April 2011

In a submerged bed of eelgrass, newly formed leaves in winter and spring had their maximum levels of total organic matter (90% of dry weight), soluble organic fraction (45%), carbon (42%), and nitrogen (4.8%). These components all decreased as the leaves matured, aged, and died. Soon after death, a leaf had only 70% total organic matter, 28% soluble organic matter, 30% carbon, and 1.5% nitrogen. Intact dead leaves showed little further change in chemical composition. The commonly used crude protein determination (6.25 × nitrogen content) overestimated true protein by up to 180%. The carbon to nitrogen ratio (C:N) was an unreliable index of the nutritional value of the plant. Two growth forms were present, most probably in response to wave action and substrate composition. Daylength, not temperature, most probably controls the seasonal cycle of growth.
Pectoral Fin and Opercular Movements of Atlantic Salmon (Salmo salar) Alevins
Authors: Peterson Richard H.
Published: April 2011

The pectoral fins of Atlantic salmon (Salmo salar) alevins change in shape and orientation as development proceeds. They flutter rhythmically at 100–150/min whereas opercula move infrequently in newly hatched alevins. Ablation of pectoral fins induces increased opercular movements. Rhythmic movements of the pectoral fins displace water from the posterior edge of the opercula to the area immediately behind the fins. The frequency of pectoral movements is influenced by changes in ambient PO2. The pectoral movements are probably useful in generating water currents around the alevin in the gravel interstices.
New Coccidia from the Spiny Dogfish Shark (Squalus acanthias) and Great Sculpin (Myoxocephalus polyacanthocephalus)
Authors: Fitzgerald Paul R.
Published: April 2011

New coccidia from the spiny dogfish shark, Squalus acanthias, and the great sculpin, Myoxocephalus polyacanthocephalus, from waters around the San Juan Islands, Puget Sound, Washington, are described and named. Thirty-one species of bony and two species of cartilaginous fishes were examined. Twenty-eight of 71 dogfish and one of four sculpins were infected with coccidia.
Preferences of Juvenile Coho Salmon (Oncorhynchus kisutch) and Cutthroat Trout (Salmo clarki) Relative to Simulated Alteration of Winter Habitat
Authors: Bustard David R. , Narver David W.
Published: April 2011

Winter habitat preferences of juvenile coho salmon (Oncorhynchus kisutch) and cutthroat trout (Salmo clarki) were tested by simulating conditions before and after stream disturbance such as might result from logging: (1) sidepools with or without an overhanging bank and roots, and (2) sidepools with clean or silted rubble substrate. Both coho and cutthroat demonstrated a strong preference for sidepools offering overhanging bank cover as opposed to those without bank cover. Similarly they preferred sidepools with clean rubble substrate as opposed to silted rubble. In both the bank and rubble tests, when given the option of either remaining in the sidepools or of moving into the stream, a greater percentage of the total number of coho and cutthroat originally in the sidepools remained in the pools with cover as opposed to those without cover. Coho utilized bank cover more readily than rubble cover whereas cutthroat used both bank and rubble cover.
Chemical Attraction of some Marine Fish in their Natural Habitat
Authors: Sutterlin A. M.
Published: April 2011

Using underwater television, photography, and fish traps the attractiveness of a number of natural baits and pure compounds to four species of marine fish was examined directly in their natural habitat. Winter flounders (Pseudopleuronectes americanus), mummichog (Fundulus heteroclitus), and Atlantic silversides (Menidia menidia) were each attracted by specific amino acids. Only flounders and killifish exhibited biting and digging behavior in the vicinity of the odor source. Hagfish (Myxine glutinosa) could be trapped using a variety of natural baits but no single amino acid or a variety of combinations of amino acids or amines was effective. The active principle(s) in cod muscle accounting for its attractiveness to hagfish was found to be heat stable, of small molecular weight and extractable with ethanol. Chromatographic separation of the ethanol extract resulted in only one active fraction consisting of several compounds. This fraction, however, accounted for only a small amount of the total activity in the ethanol extract, suggesting a multicomponent system.
Selenium Toxicity on the Early Life Stages of Zebrafish (Brachydanio rerio)
Authors: Niimi A. J. , LaHam Q. N.
Published: April 2011

Embryos at four stages of development and the newly hatched larvae of zebrafish (Brachydanio rerio) were exposed to selenium concentrations between 0.5 and 10 μg/ml to establish the toxic levels at the different stages. Embryo mortality was negligible at all selenium concentrations. Following hatching, mortality among the larvae sharply increased at concentrations of 3 μg/ml or greater irrespective of the embryonic stage when exposed. For most treatments, over 90% of the larvae died within 10 days of hatching. The mortality rate for larvae exposed to selenium after hatching was slightly less.
Identity, Abundance, and Present Status of Populations of White Whales, Delphinapterus leucas, in North America
Authors: Sergeant D. E. , Brodie P. F.
Published: April 2011

White whales, Delphinapterus leucas, in the North American arctic number at least 30,000 animals. Largest herds identified are about 10,000 animals in western Hudson Bay, at least as many in Lancaster Sound, and at least 5000 summering in the Beaufort Sea. Hunting in the Canadian arctic has decreased in the last decade from 1000 or more to about 500 annually and is clearly well below sustainable yields except in one locality, Cumberland Sound, where the local population of white whales has never recovered from historic depletion. The species is most vulnerable when concentrated in river estuaries in summer, probably for reproduction. The species’ range has shrunk in the St. Lawrence estuary, a change that can be associated with hydroelectric developments in the last decade. The effects of oil exploration, drilling, and island building in shallow water in the Mackenzie Delta are under study, and developments in oil and gas could have an influence on other populations in the Canadian arctic. Tourism related to this species is increasing, without undue disturbance to date.
Ecological Aspects of Smaller Cetaceans, with Emphasis on the Striped Dolphin (Stenella coeruleoalba)
Authors: Nishiwaki Masaharu
Published: April 2011

The striped dolphin (Stenella coeruleoalba) is captured by drive fisheries as it migrates along the coast of Japan. The largest school of striped dolphins captured contained 2838 individuals. Annual catches have reached approximately 20,000 striped dolphins, and it is estimated that the population fished must number 400,000–600,000 animals. Recent variations in catch levels have resulted from economic and environmental fluctuations, not from a decrease in population size.
Progress Report on Small Cetacean Research in Chile
Authors: Aguayo L. Anelio
Published: April 2011

The geographic distribution is plotted, and where known, the seasonal occurrence with new data on sightings is given for the smaller Cetacea of Chile. Species documented are: Cephalorhynchus commersonii, C. eutropia, Delphinus delphis, Lissodelphis peronii, Lagenorhynchus australis, L. obscurus, L. cruciger, Tursiops sp., Grampus griseus, Orcinus orca, Globicephala melaena, and Phocoena spinipinnis. Several small dolphin fisheries exist. The pilot whale may be exploited in the future in Chile.
Pollution Ecology of Freshwater Invertebrates.
Authors: Hynes H. B. N.
Published: April 2011

not available
Optimal Harvest Strategies for Salmon in Relation to Environmental Variability and Uncertain Production Parameters
Authors: Walters Carl J.
Published: April 2011

A method is developed for incorporating the effects of environmental variability and judgmental uncertainty about future production parameters into the design of optimal harvest strategies; these are expressed as curves relating stock size and exploitation rate. For the Skeena River sockeye, the method suggests that optimal strategies are insensitive to judgmental uncertainty about the Ricker stock production parameter, but are very sensitive to management objectives related to the mean and variance of catches. Best possible tradeoffs between mean and variance of catches for the Skeena River are developed, and a simplified strategy is suggested for improving mean catch while reducing year to year variation.
Effects of Brief Temperature Increases on Larvae of Mulinia lateralis (Mollusca: Bivalvia)
Authors: Diaz Robert J.
Published: April 2011

Temperature increases of 10, 15, and 20 C for 30 min significantly increased 48-h mortality of Mulinia larvae. Growth of surviving larvae was temporarily decreased only by a 20-degree temperature increase. No interaction was found between age of larvae when exposed and mortality after brief temperature increases.
New Techniques for Policy Evaluation in Ecological Systems: Methodology for a Case Study of Pacific Salmon Fisheries
Authors: Peterman Randall M.
Published: April 2011

The complexity of exploited ecological systems creates difficulties for the manager who must decide among alternative policy options. Some methods for overcoming these difficulties are presented, using examples from the salmon fishery of the Skeena River system in British Columbia. The described methods produced a "desk-top optimizer," a tool that permits decision-makers to perform fairly sophisticated "optimization" operations at their desks instead of having to rely on decision theorists or operations researchers. Also discussed are various system indices which should become part of the information used by managers. These indices include measures of resilience (ability to absorb the effects of unexpected events), costs of failures in management policies, and costs of uncertainty of various types.
Increased Opercular Rates of Pink Salmon (Oncorhynchus gorbuscha) Fry after Exposure to the Water-Soluble Fraction of Prudhoe Bay Crude Oil
Authors: Thomas Robert E. , Rice Stanley D.
Published: April 2011

The opercular rates of pink salmon (Oncorhynchus gorbuscha) fry were measured during 24-h exposure to sublethal concentrations of the water-soluble fraction of Prudhoe Bay crude oil. Opercular rates increased significantly for as long as 9 and 12 h after exposure to water-soluble fractions prepared from oil–water solutions of 2.83 and 3.46 ppm. The increases in rates were proportional to increases in dose. Recording changes in opercular rates appears to be a suitable method for detecting sublethal physiological effects of stress, because the observed changes occurred at approximately 20% of the 96 h-LC50.
Culture Studies on the Effects from Borate Pollution on the Growth of Marine Phytoplankters
Authors: Antia Naval J. , Cheng Joseph Y.
Published: April 2011

The autotrophic growth of 19 species of marine phytoplankters, from 10 classes of algae, was tested on axenic cultures with boric acid additions of 0–100 mg/liter B to a nutrient-enriched, pH-controlled seawater medium. All the growth rates were virtually unaffected by the incorporation of 5–10 mg/liter B, while 26% of the species were strongly inhibited by 50 mg/liter B and this proportion was increased to 63% species inhibited at 100 mg/liter B. Several species required prolonged periods of adaptation before exponential growth with 50–100 mg/liter B. Both the adaptation period and the degree of inhibition were gradually mitigated on sequential transfer of certain species from lower to higher boron concentration. Such sequential transfer tests showed that the majority of initially inhibited species could recover good growth at 50 mg/liter B but not at 100 mg/liter B, which concentration appeared to be lethal to 37% of the species tested. These results predict that, in the absence of stress from nutrient deficiency and pH adversity, inorganic borate pollution would be facilely tolerated by phytoplankton up to 10 mg/liter B; higher borate concentrations up to 100 mg/liter B are expected to cause species redistribution tending to favor growth of some forms by suppressing that of others.
Physiological Changes During the Course of Blooms of Aphanizomenon flos-aquae
Authors: Healey F. P. , Hendzel L. L.
Published: April 2011

Several aspects of the cellular composition and metabolism of Aphanizomenon flos-aquae (L.) Ralfs were measured during the course of four blooms in small prairie lakes. Much larger changes were observed in these than in the nutrient concentrations of the water, suggesting the former to be more sensitive indicators of the progress of the bloom. These changes were reminiscent of the changes in batch cultures growing into nutrient deficiency. All four blooms developed characteristics of P deficiency, and to a lesser extent of N deficiency. In spite of their similar characteristics, three blooms collapsed dramatically, while the fourth did not. While P deficiency seems to play an important part in setting conditions for a collapse, it is not the factor that triggers the collapse.
Preferred Temperatures of F3 to F5 Hybrids of Salvelinus fontinalis × S. namaycush
Authors: Goddard C. I. , Tait J. S.
Published: April 2011

Preferred temperatures were determined for samples of four generations, F3, F4, "F4.5" (F4 × F3), and F5 of yearling splake (Salvelinus fontinalis × S. namaycush), acclimated 4, 8, 12, 16, and 20 C. Final preferenda for the four generations were 16.3, 15.9, 15.7, and 14.8 C, respectively, decreasing as generation number increased. Although these values are close to the 16 C preferendum of S. fontinalis, they show a trend towards the lake trout preferendum of 11.7 C. The hybrids are like S. namaycush in having preferred temperatures that are virtually unaffected by changes in acclimation temperature or season.
Effects of Antibacterial Agents on Nitrification in an Aquatic Recirculating System
Authors: Collins M. T. , Gratzek J. B. , Dawe D. L. , Nemetz T. G.
Published: April 2011

Treatment of recirculating systems with a single dose of erythromycin (50 mg/liter) resulted in nitrate reduction and stopped nitrification for 14 days as evidenced by changes in pH and ammonia, nitrite and nitrate concentrations. Treatment of systems with 2-chloro-6-(trichloromethyl) pyridine, a known nitrification inhibitor, inhibited nitrification similarly. Treatment with chloramphenicol (50 mg/liter), oxytetracycline (50 mg/liter), sulfamerazine (50 mg/liter), or nifurpirinol (1 mg/liter) had no effect on nitrification.
Mercury in the Surficial Sediments of Lake Erie
Authors: Thomas R. L. , Jaquet J.-M.
Published: April 2011

In 259 samples of the topmost 3 cm of sediment taken from Lake Erie in 1971, total mercury values ranged from 8 to 2929 ppb [Formula: see text]. The highest levels were in the Western basin adjacent to the Detroit River, the rest of the lake showing increasing concentration from the coarser sediments of the Inshore Zone and cross-lake moraine sills out into the basin muds. A quartz correction was applied to compensate for texture and dilution by an inert constituent. The distribution of quartz-corrected mercury confirmed that the Detroit River is the predominant source of industrial mercury to the Western basin with subsequent transport across the Central basin to final sink in the Eastern basin. Further possible inputs were indicated from Erie, Pennsylvania and Buffalo, New York. Analysis of suspended sediment in the Detroit River showed no change in concentration between 1970 and 1974 with a mean 1974 level of 1060 ppb. Mercury loading was estimated at 7.2 m.t./yr to the sediments of the Western basin. A relationship was observed between total mercury and organic carbon, showing two distinct regressions: ’A’ with lower organic-bound mercury, is taken to represent the levels related to industrial and natural loadings existing prior to the introduction of mercury cell chlor-alkali plants; ’B’ applicable to highly contaminated sediments, is believed to be indicative of loadings derived from the chlor-alkali industry.
Sediment Yields and Nutrient Loadings From Canadian Watersheds Tributary to Lake Erie: an Overview
Authors: Ongley Edwin D.
Published: April 2011

Mean annual loadings and unit yields for sediment, phosphorus, nitrogen, and chloride have been calculated for 19 river-mouth locations on the Canadian side of Lake Erie for the period 1967–72. Data, drawn from routine monitoring data files of Federal and Provincial agencies, are discussed in terms of biases inherent in such monitoring programs. Unit yields are only marginally related to basin substrate texture but show pronounced storage characteristics within basins for sediment and sediment-bound nutrients. It is suggested that there is a minimum threshold size of basin below which nutrient runoff is relatively unaffected by basin storage and uptake.
Nutrient Budgets for Lake Erie, 1970
Authors: Burns N. M.
Published: April 2011

Budgets for the quantities of water, chloride, and phosphorus entering and leaving Lake Erie during the year of 1970 have been developed. The phosphorus budget was broken down into basin budgets which were further subdivided into epilimnion budgets for the Central and Eastern basins. Epilimnion budgets for soluble inorganic nitrogen (SIN) and soluble reactive silica (SRS) were also developed. The average coefficients of elimination by sedimentation of the phosphorus within each basin were 4.0, 0.38, and 0.18%/day for the Western, Central, and Eastern basins, respectively. The phosphorus elimination was found to be inversely related to mean basin depth but directly related to the phosphorus concentration of the water. The epilimnion budgets showed that during the summer the internal loading of SRS to the epilimnion was greater than the uptake of SRS by phytoplankton growth. The epilimnion budget of SIN demonstrated a massive uptake of the material during the summer, which was only partially replenished. The loss rate of phosphorus from the Central and Eastern basin epilimnia decreased as the summer progressed, to the extent that there was a net gain of phosphorus in the Eastern basin epilimnion toward the end of the summer. It is believed that this resulted from significant upward transport of phosphorus from the hypolimnion to the epilimnion by flagellate species of phytoplankton.
Hormones and the Control of Reproduction in Aquaculture
Authors: Fontaine M.
Published: April 2011

The role of hormones and compounds probably intervening by hormonal mechanisms in the reproduction of teleosts are considered. First of all, the fundamental part played by the pituitary and its gonadotropic hormone or hormones in the control of reproduction are stressed by discussing problems which are still outstanding. The zoological specificity of gonadotropic hormones, the mechanism of their action, and the possibilities of using mammalian hormones are examined. The intervention of pituitary hormones other than gonadotropins is then considered. The actions of organs, tissues, and hormones secreted before the pituitary (hypothalamus, epiphysis) and that of the same formations and hormones beyond the pituitary, whose intervention is certain or under discussion (sexual steroids, hormones of the interrenal and the chromaffin tissue, ultimobranchial body and calcitonin, thyroid, urophysis) are discussed. Mention is also made of the prostaglandins.The endocrine control of reproductive behavior and the intervention of pheromones in the reproduction of teleosts are discussed. Then the effects in reproduction of certain extrabiological substances are briefly examined (for example, clomiphene citrate, copper acetate, asphalt, petrichor, methallibure).Final emphasis is given to the importance of ecophysiological studies in the endocrine control of reproduction, which should lead to much more natural and less costly techniques by applying data presently at our disposal, regarding hormonal control of reproductive function.
Formulating Practical Diets for Fish
Authors: Halver J. E.
Published: April 2011

Formulas for balanced fish diets must include an energy source plus sufficient indispensable amino acids, essential fatty acids, and specific vitamins and minerals to support life and to promote adequate growth. Tentative requirements for the 10 indispensable amino acids and evaluation of the sparing effect of several others have been reported for only a few species of fish held under specific experimental conditions. These findings must be confirmed for other species and other rearing conditions, since the protein requirement and amino acid balance is the major determinant for growth, and is the greatest food source problem. Essential fatty acid needs for fish reared indicate that this component may be the second limiting factor for future practical diets. Water-soluble and fat-soluble vitamin needs have been reported for only a few fish and these data must be extended to include other species and fish reared in different waters. Digestion coefficients of diet ingredients, measured for terrestrial animals, must be confirmed in fish before data banks of nutrient ingredient sources can be translated into least-cost computer diet formulas. Specific nutrient requirements vary with species, size, water temperature, stress, and nutrient balance; thus, economical rations must be programmed accordingly. Techniques that have been developed for determining metabolizable energy and digestibility of diet components for several species can be expanded to develop diets and rations for scientific fish husbandry.
Antimycin: Uptake, Distribution, and Elimination in Brown Bullheads (Ictalurus nebulosus)
Authors: Schultz Donald P. , Harman Paul D.
Published: April 2011

Radioactive antimycin was readily taken up in bile and tissues of brown bullheads (Ictalurus nebulosus) exposed to 0.045 μg/ml of 14C-antimycin for as long as 48 h. Bile contained the most and blood the least radioactivity at all sampling periods. The highest concentration of 14C-antimycin in muscle was 0.12 μg/g, after 12 h of exposure. The average amount of 14C-antimycin per fish was 0.94 μg/g. The 14C-antimycin concentration decreased with the elapse of time in the muscle and in samples of combined head, skin, and viscera. The concentration of l4C-antimycin in the exposure solution decreased from 0.045 μg/ml to 0.015 μg/ml after 12 h and 0.010 μg/ml after 48 h. The initial half-life of 14C-antimycin in the exposure solution was about 6.5 h. A second group of fish was exposed to 0.045 μg/ml of l4C-antimycin for 48 h and then transferred to antimycin-free, flowing water for up to 96 h. The 14C-activity decreased in muscle tissue from 0.11 μg/g to 0.05 μg/g in 96 h. Half-life of 14C-antimycin was about 75 h in muscle and 61 h in the combined head, skin, and viscera.
A Further Note on Sampling Research Trawl Catches at Sea
Authors: Westrheim S. J.
Published: April 2011

An additional 108 empirical tests (19 species) have corroborated the validity of a method, described in 1967, for estimating total weight of individual species in trawl catches. Mean error was −0.6%, and in 97% of the tests, error was no more than ±4%.
Viral Hemorrhagic Septicemia: Comparative Susceptibility of Rainbow Trout (Salmo gairdneri) and Hybrids (S. gairdneri × Oncorhynchus kisutch) to Experimental Infection
Authors: Ord Wilma M. , Berre Monique Le , Kinkelin Pierre de
Published: April 2011

Rainbow trout (Salmo gairdneri) fry and yearlings were compared with hybrids of rainbow trout and coho salmon (Oncorhynchus kisutch) for susceptibility to viral hemorrhagic septicemia (VHS). In three trials, exposure to waterborne infectivity consistently resulted in a 77% mortality of rainbow trout fry while loss among the hybrid fry averaged only 11%. Tests showed survivors might be carriers of virus. Hybrid yearlings infected by gill brushing were fully refractory to VHS whereas mortality (3:8) and viremia were recorded among gill-infected rainbow trout yearlings.
Seaward Nutrient Transport in the Lower St. Lawrence Estuary
Authors: Sinclair Michael , El-Sabh Mohammed , Brindle Jean-Rock
Published: April 2011

A transect across the lower St. Lawrence estuary was occupied to estimate volume transport and nutrient distributions (total dissolved nitrogen and phosphorus, and silicate) during February and May through September. Seaward transport was restricted to the upper 50 m and varied from 17 × 103 m3/s (August) to 129 × 103 m3/s (May). Nutrient and volume transport data are combined to estimate seasonal variability in monthly surface nutrient transport towards the Gulf of St. Lawrence. The estimates vary as follows: 0.72–6.72 × 103 tons N/mo, 0.05–0.48 × 103 tons P/mo and 0.50–6.73 tons Si/mo. Ratios between monthly freshwater input into the estuary and the corresponding values for net seaward transport, which varied from 1.1 to 9.4, are combined with annual data (1960–73) on monthly freshwater input into the estuary to estimate potential annual variability in seaward transport for each of the above months. Observed nutrient data, with the above transport estimates, suggest the possible range in monthly seaward nutrient transport that would be associated with the annual variability in monthly freshwater input into the estuary. Seaward nitrogen transport from May through September, estimated at 2.3 × 104 tons, is considered in relation to published data on the primary production in the western part of the Gulf of St. Lawrence. The estuary supplied a smaller amount of nutrients to the Gulf than has previously been assumed.
Specimen Weight and M.S. 222
Authors: Houston A. H. , Corlett J. T. , Woods R. J.
Published: April 2011

The influence of specimen weight upon induction of and recovery from Stage I M.S. 222 (ethyl m-aminobenzoate methanesulphonate) was examined in goldfish (Carassius auratus), brook (Salvelinus fontinalis), and rainbow trout (Salmo gairdneri) exposed to various anesthetic concentration–temperature combinations. Both induction and recovery times varied inversely with weight, the influence of weight being particularly pronounced among smaller specimens. These observations are consistent with the hypothesis that attainment of "critical" internal anesthetic concentration is influenced by weight-specific variation in the relationship between gill area and extracellular phase volume.
Marine Mortality of Puget Sound Coho Salmon (Oncorhynchus kisutch)
Authors: Mathews Stephen B. , Buckley Raymond
Published: April 2011

A model for natural mortality over the 18 mo of marine life of Puget Sound coho salmon (Oncorhynchus kisutch) is proposed, wherein the natural mortality rate M continuously decreases with increasing weight. Weight closely follows an increasing exponential function of marine age. The model is extended to account for ocean troll and sport fishing mortality and applied to data from marking studies of Puget Sound coho. The survival curve for marine life with only natural mortality declines rapidly for early ocean life and is quite flat over the ages fished. Recent high survival rates for hatchery coho released at a larger than normal size could be partially explained by this mortality model, although additional marking experiments are needed to separate the effects upon survival of size at release and time of release. The model applied to hatchery release-size strategy indicates that 70 g/fish might be optimal.
Measurements of a Small Near-Bottom Cyclonic Circulation Near the Gulf Stream Axis
Authors: Clarke R. A.
Published: April 2011

Data from near-bottom current meters moored in a small triangular array (25 km/side) plus hydrographic sections reveal the presence of a near-bottom cyclonic circulation with a radius of 50 km and velocity of 10 cm/s just north of the Gulf Stream near 50°W. The circulation extends to at least 1350 m from the ocean floor and was observed over a period of 9 days during which time it moved southward toward the Stream with speeds of 0.5–15 cm/s. The strength of the circulation decreases somewhat with distance from the bottom.
Spectrum of Small-Scale Oceanic Temperature Gradients
Authors: Elliott J. A. , Oakey N. S.
Published: April 2011

The spectrum of the vertical temperature gradient is computed for a number of "typical" 50-m long profiles from the upper 200 m of the ocean. Most of the variance occurs in the microstructure range, between approximately 1 and 100 cycles/m; there is normally a spectral maximum near 10 cycles/m. The shape of the spectra for the range 10–100 cycles/m agrees well with that predicted for sharp interfaces that have been smoothed by thermal diffusion.
A Method for the Automatic Measurement of Wave Frequency
Authors: Donelan M.
Published: April 2011

The idea is advanced that the dominant wave frequency in a locally wind-generated sea may be accurately estimated from the ratio of root-mean-square surface vertical velocity to root-mean-square surface deviation. Field and laboratory data are used to establish the relationship between this ratio and the frequency of the peak of the spectrum as a function of inverse wave age. Wave age and the nondimensional fetch parameter are shown to be uniquely related in the fetch-limited case. Finally a procedure is given for estimating the appropriate one-dimensional spectrum from automatic field measurements of average wind speed, root-mean-square surface deviation, and root-mean-square surface vertical velocity.
Spectra and Coherence of Wind-Generated Internal Waves
Authors: Käse R. H. , Tang C. L.
Published: April 2011

On the basis of a model for an internal wave field that is generated by a randomly varying isotropic wind stress and in which energy is transferred to small-scale turbulence, we derive the two-dimensional energy density function. The coherence scales are determined by the highest order internal wave mode that is not affected by virtual friction in the main thermocline, provided the curl of the wind stress has a white noise wave number spectrum. In general, this mode number scale is increasing monotonically with frequency. As a result of such a frequency dependent mode bandwidth, the vertical coherence drops with increasing frequency.
Seiches, Circulation, and Storm Surges of an Ice-Free Lake Winnipeg
Authors: Hamblin P. F.
Published: April 2011

Predictions of numerical hydrodynamical models of seiches, steady circulation, and water level setup and time-dependent motions known as storm surges are compared to limited amounts of water level data during the ice-free season on Lake Winnipeg. Two-dimensional gravitational seiches are computed by minimizing an expression for the total energy. The fundamental inviscid period is 39 h which is considered to be a maximum for any inland water body. Four higher modes of oscillation have been detected in spectra of water level fluctuations at three stations on Lake Winnipeg. Frictional effects are shown to have appreciable influences on the seiches. Predicted water level setup has an asymmetrical distribution with the largest excursions occurring in the southern basin. A number of observations of water level setup are in accordance with model predictions at Winnipeg Beach if a drag coefficient of 1.0 × 10−3 is assumed. Setup is relatively insensitive to vertical eddy diffusivities in the range 10–100 cm2/s. A modeling strategy utilizing the previously obtained solutions for the free oscillations and for the steady state setup results in a simple prediction scheme for arbitrary forcing in time involving the convolution of the time history of the wind stress components with the response of the lake. Predicted storm surges are in reasonable agreement with two storm surges measured at two locations in the southern basin, considering the imperfect knowledge of the forcing obtained from winds at a single station in the northern basin.
Performance of Lake Trout (Salvelinus namaycush) Backcrosses, F1 Splake (S. fontinalis × S. namaycush), and Lake Trout in Lake Huron
Authors: Spangler G. R. , Berst A. H.
Published: April 2011

This paper presents the results of plantings in Lake Huron waters of lake trout (Salvelinus namaycush), F1 splake (S. fontinalis × S. namaycush), and the progeny of the backcross between splake males and lake trout females.The planted fish were piscivorous throughout age-groups II – V with rainbow smelt (Osmerus mordax), sticklebacks (Pungitius [?]), and alewives (Alosa pseudoharengus) the dominant food organisms. Hybrid stocks grew more rapidly but attained a somewhat smaller asymptotic length than did lake trout. The F1 hybrids were the earliest to mature with 34% of the males and 4% of the females spawning at age II. Earliest maturity occurred in the backcrosses at age III, in contrast to lake trout which matured predominantly at ages VI and VII. The backcrosses demonstrated a slightly broader thermal and bathymetric distribution during summer than did lake trout, while the F1 hybrids tended to concentrate in the thermocline. Total annual mortality rates (attributed mostly to predation by sea lampreys, Petromyzon marinus) ranged from 62 to 95% for all of the planted stocks.
Effects of Dry Pellet Diets on the Metabolic Rates of Bluegill (Lepomis macrochirus)
Authors: Schalles John F. , Wissing Thomas E.
Published: April 2011

Experiments were designed to evaluate the effects of five dry pellet diets containing various protein levels on metabolic rates and energy cost of food utilization of bluegill (Lepomis macrochirus). In the 48-h period after feeding metabolic rates increased an average of 57% above base levels established prior to food presentation. The energy cost of food utilization, estimated as a percentage of ingested food energy, was [Formula: see text] (range 7.5–32.3%). Positive correlation was found between protein and caloric intakes and the increases in O2 consumption observed after feeding. Percent protein in the diet had no significant effect on mean values of O2 consumption after feeding or the estimates of the energy cost of food utilization. Probably the calorigenic effect of protein in fishes, which are principally ammonotelic, is considerably lower than that observed in ureotelic and uricotelic vertebrates. The mean estimate (14.90% of ingested energy) for the bluegill could reflect a low specific dynamic action of protein in conjunction with the calorigenic effect of the carbohydrate and lipid components of the diets.
Behavior and Growth of Juvenile Atlantic Salmon (Salmo salar) and Three Competitors at Two Stream Velocities
Authors: Symons P. E. K.
Published: April 2011

In a laboratory stream juvenile Atlantic salmon (Salmo salar), common shiners (Notropis comutus), blacknose dace (Rhinichthys atratulus), and white suckers (Catostomus commersoni) apparently preferred habitats that simulated their natural ones. Only salmon and one sexually mature male shiner defended territories. Dace were gregarious and nomadic, shiners tended to school in open water, and suckers were asocial bottom browsers.No competitive advantage or disadvantage was apparent between species in capturing drift food and growing at fast and slow stream velocities. However, salmon, because of their aggressive territorial behavior, successfully competed for and reduced presence of other species in their preferred boulder habitat.
Notholca laurentiae and N. michiganensis, New Rotifers from the Laurentian Great Lakes Region
Authors: Stemberger Richard S.
Published: April 2011

The descriptions of two new planktonic rotifers, both cold stenotherms, is presented. Notholca laurentiae n.sp. is a predominant winter rotifer of the Laurentian Great Lakes, but to date has not been found in inland lakes of the region. Morphologically its closest relative is the European brackish water species, N. salina Focke.Notholca michiganensis n.sp. has been recorded only in the oligotrophic inland lakes of the northern portion of Michigan’s lower peninsula during winter and early spring (water temperatures 0.5–5.2 C). Morphologically, N. michiganensis is similar to, but distinctly smaller than N. frigida Jaschnov.
Correlations of Fish Catch and Environmental Factors in the Gulf of Maine
Authors: Sutcliffe Jr. W. H. , Drinkwater K. , Muir B. S.
Published: April 2011

In an investigation of catches of 17 commercial marine species of fish and shellfish from the Gulf of Maine, 10 showed statistically significant correlations with sea temperatures at St. Andrews, N.B., or Boothbay Harbour, Maine. Most fish records contained at least 40 yr of data. Descriptive equations are produced for four species based first on the correlation between catch and sea temperature and second on the correlation between catch and sea temperature allowing for fishing effort. Inclusion of fishing effort, not surprisingly, improved the correlations for all of the species so examined. The equations permitted the "prediction" of later parts of the records from earlier parts.Considering the fish species collectively, the Gulf of Maine system from 1940 to 1959 appeared to be in equilibrium with little fluctuation in the total commercial biomass. We interpret the large fluctuations in individual species abundance as resulting from a combination of fishing pressure and to a significant degree oceanic climate as represented by sea temperature. The small fluctuations in the total biomass displays the species variation, with their differing climatic "preferences," as well as possible predator (including man)–prey relationships. Environmentally imposed patterns underlie at least 50% of the fluctuations in catch of many species and the understanding of these fluctuations is basic to effective management.
Age Determination of an Elasmobranch (Squalus acanthias) by X-ray Spectrometry
Authors: Jones Barry C. , Geen Glen H.
Published: April 2011

Ages of spiny dogfish (Squalus acanthias) in the Strait of Georgia, B.C., have been estimated by an X-ray spectrometric technique which involves measuring variations in the element composition within vertebrae.
Estimates of Tag Extrusion and Initial Tagging Mortality in Atlantic Herring (Clupea harengus harengus) Released with Abdominally Inserted Magnetic Tags
Authors: Winters G. H.
Published: April 2011

Returns of Atlantic herring (Clupea harengus harengus) tagged internally with magnetic tags along southwest Newfoundland and in the southern Gulf of St. Lawrence in 1970–71 were analyzed for biases due to initial tagging mortality and to tag extrusion during the reproductive act. Initial tagging mortalities calculated by two methods ranged from 4 to 49% and increased with the duration of impoundment of the fish prior to tagging. Estimates of tag loss during the spawning season indicated that most of the tags inserted in ripening herring were extruded with the reproductive products, whereas those applied to recently spent or recovering herring had sufficient time to become attached to internal organs and hence had a high retention rate. The results indicate that the effectiveness of tagging herring internally will be greatly improved if conducted on recovering or spent fish impounded for only short periods of time before tagging.
On the Variability and Taxonomy of Pleuroxus denticulatus Birge (Cladocera: Chydoridae)
Authors: Flössner Dietrich , Kraus Karl
Published: April 2011

Comparative morphological investigation of extensive series of Pleuroxus denticulatus Birge from North America and Europe revealed considerable variability in certain characters. These are quantitative (body dimensions), qualitative (structure of postabdomen), and meristic (number of ventro–caudal shell denticles). With regard to the postabdomen, two morphotypes, connected by transitional forms, can be distinguished in both sexes, which, however, are not separated geographically. Nevertheless, there are certain field populations (e.g. from Indiana and southern Germany) that are so strongly divergent in certain characters they would satisfy the taxonomic requirements for assigning them to different geographic races. The North American population s are distinguished by having significantly more denticles on the ventro–caudal angle of the valves, the frequency distribution of which satisfied the 75% rule for the separation of subspecies. However, we do not consider the distinctness in this single character of a single west European population sufficient to justify the establishment of two geographic subspecies. Trunk limb morphology, which yields important conclusions concerning the systematic affinities of Pleuroxus denticulatus, is also described. The species, along with Pleuroxus truncatus (O. F. Müller) and Pleuroxus proauvus Birge, form a group of closely related species, characterized by the sperm ducts opening on the lateral surfaces of the postabdomen and by the relatively small structural differences between the male and female postabdomen. Finally, differentiation of characters within the truncatus group is analyzed in detail. Key words: Cladocera, Chydoridae, Pleuroxus, taxonomy, morphological variation, geographical distribution