bluuebunny/crossref_metadata_2025 huggingface dataset:
Population Dynamics of Yellow Perch (Perca flavescens), Sauger (Stizostedion canadense), and Walleye (S. vitreum vitreum) in Four Main Stem Missouri River Reservoirs
Authors: Nelson William R. , Walburg Charles H.
Published: April 2011

Percid populations have generally increased in abundance relative to other groups of fishes in the 15–25 yr four large reservoirs have been operational on the Missouri River in South Dakota. Saugers (Stizostedion canadense) were initially the most abundant percid, but their numbers gradually declined, probably because of the reduction in river spawning habitat and the increase in water clarity. Yellow perch (Perca flavescens) increased to high population levels as the reservoirs filled but later decreased in abundance. Walleye (S. vitreum vitreum) populations were the slowest to develop in the reservoirs, probably because of initial lack of suitable spawning habitat; they later became well established.The yellow perch was one of the most important forage species in the reservoirs, and walleyes and saugers the primary predator and sport fishes. Sportfishing quality 15–25 yr after impoundment was good, but harvest remained low because of the large size of the reservoirs, inadequacy of facilities for anglers, and the relatively sparse human population. Reproductive success was the primary factor regulating the abundance of percids. Year-class strength was primarily determined by climatic rather than biological factors. Above-average precipitation presumably enhanced reproductive success, both directly by increasing the quantity and quality of spawning substrate through higher stream flows and water levels, and indirectly by providing a larger forage supply, thereby apparently reducing predation on young percids, as well as cannibalism. Kew words: Percidae, reservoirs, Missouri River, Stizostedion, Perca, population dynamics, ecology, precipitation, water level
Effects of Intensified Fishing, Species Changes, and Spring Water Temperatures on Yellow Perch, Perca flavescens, in Saginaw Bay
Authors: Eshenroder R. L.
Published: April 2011

A combination of intensified effort and size limit removal in the mid-1960s resulted in exceptional landings of yellow perch, Perca flavescens, from Saginaw Bay. Though gillnet effort increased from insignificance to account for more than half of the annual catch, gillnet catch per unit of effort (CPE) did not decline during the period of intensified fishing (1964–71) despite severe depletion on some grounds. Trapnet landings and CPE peaked in 1966, when the size limit was removed, but by the early 1970s both statistics were only one-third of the 1966 peaks. A fishing-up sequence began in outer Saginaw Bay and the stocks there were depleted. The fishery then shifted to the inner bay, where the stocks also declined, but to a lesser degree. With intensification of the fishery yellow perch growth rate increased, age-groups V–VII were no longer prominent in the catch and females became relatively scarce shortly after attaining vulnerability. The low recruitment of the late 1960s and early 1970s may have been related to the reduced brood stocks.Within the past 35 yr those changes in the fish community which appeared to affect yellow perch most included loss of the walleye, Stizostedion vitreum vitreum, in the 1940s and proliferation of smelt, Osmerus mordax, and alewife, Alosa pseudoharengus, in the 1950s. However, these changes occurred well before the late 1960s, and were probably not involved in the recent yellow perch decline.A comparison of the rate and regularity of the spring warming with the strengths of the strongest and weakest year-classes for the years 1957–75 suggested that spring temperature had an important role in reproductive success. Key words: Percidae, Perca, yellow perch, exploitation, Saginaw Bay, Lake Huron, water temperature, fish community, population trends, history of fishery, Great Lakes
Biology of the Percids
Authors: Collette Bruce B. , Ali M. A. , Hokanson K. E. F. , Nagięć Maria , Smirnov S. A. , Thorpe J. E. , Weatherley A. H. , Willemsen J.
Published: April 2011

The structure, origin, and spread of the family Percidae are reviewed briefly, and its characteristics compared with those of other families of freshwater fishes. It is suggested that the percids, essentially riverine, have been restricted in their success in North America by the presence of the Centrachidae. Percids are defined as temperate mesothermal fish, and this physiological characteristic together with osmoregulatory capacity and swimming performance is shown to limit the ranges of the perches. The degree of development of the tapetum lucidum in Stizostedion spp. and of the lateral line in all percids is related to differences in pattern of development, feeding behavior, and habitat. Reproductive, feeding and migratory behaviour are also reviewed. Key words: Percidae, structure, origin, biology, morphology, systematics, migration
Tag Retention of the Spot Prawn, Pandalus platyceros, Injected With Coded Wire Tags
Authors: Prentice Earl F. , Rensel John E.
Published: April 2011

Juvenile spot prawns, Pandalus platyceros (initial carapace length 15.0–22.5 mm), were successfully tagged with Bergman–Jefferts coded wire tags in the thoracic sinus. Tagged prawns, prawns subject to tagging needle insertion but without tags, and a control group were tested. No significant differences in growth and survival within or between test groups occurred and no behavioral changes were observed among tagged animals. All tagged prawns molted at least twice during the 6-mo experiment. Average tag retention was 95%. Key words: Pandalus platyceros, tagging, tag retention, molting, survival
Selection of Prey by American Lobsters (Homarus americanus) When Offered a Choice Between Sea Urchins and Crabs
Authors: Evans Patricia D. , Mann Kenneth H.
Published: April 2011

American lobsters (Homarus americanus) were presented with various numerical combinations of sea urchins (Strongyhcentrotus droebachiensis) and rock crabs (Cancer irroratus) in long-term laboratory feeding experiments. They exhibited a 5:1 preference for crabs when the numerical ratio of urchins to crabs varied from 0.25:1 to 8:1. Lobsters presented with a superabundance of sea urchins (urchin:crab ratios of 16:1 and 100:1) maintained relatively constant proportions of urchins and crabs in their diet. Direct observation indicated that lobsters feed selectively. Their role as key predators in kelp–sea urchin communities is discussed. Key words: food preference, predation, Canadian Atlantic, bioenergetics
A Titration Apparatus for the Determination of Dissolved Oxygen in Seawater
Authors: Levy E. M. , Cunningham C. C. , Conrad C. D. W. , Moffatt J. D.
Published: April 2011

A novel titration apparatus for the Carritt/Carpenter modification of the Winkler method for determining dissolved oxygen in seawater is described. Routine quantitative analyses for oxygen are made more reliable and more convenient by reducing the human factor. Key words: analytical techniques, oxygen measurement, seawater, oceanographic expeditions
A New Digital Hydroacoustic Data Processor and Some Observations on Herring in Alaska
Authors: Thorne Richard E.
Published: April 2011

A new hydroacoustic data processor using a PDP 11/45 computer was developed and applied to some herring studies in southeastern Alaska. The new processor allows for analysis of up to 50 different depth intervals, has a threshold to eliminate noise, and has greater dynamic range than any previous hydroacoustic data processor. The new system was used to analyze some data previously recorded on analog magnetic tape, including a series of 20 replicate hydroacoustic surveys over a 4-day period in Carroll Inlet. Comparisons were made with an earlier model digital integrator and with results of oscilloscope (CRT) measurements. Results of replicate surveys and comparisons between different areas demonstrated that the distributional characteristics of the herring can greatly affect the results of hydroacoustic surveys. Key words: hydroacoustic, herring, Alaska, echo integration, digital processor, fish assessment
Seaward Migration of Hatchery-Reared Atlantic Salmon, Salmo salar, Smolts in the Penobscot River Estuary, Maine: Riverine Movements
Authors: Fried Stephen M. , McCleave James D. , LaBar George W.
Published: April 2011

Forty-six hatchery-reared Atlantic salmon, Salmo salar, smolts tagged internally with ultrasonic telemetry transmitters were tracked in the Penobscot River estuary, Maine. Travel times of six smolts tracked from head of tide 35 km seaward to the river mouth ranged from 29.4 to 44.5 h (mean 37.1 h). During 1975 and 1976 onset of increased movement of smolts occurred when hatchery and river water temperatures rose past 5 °C. Full expression of migratory behavior occurred above 9 °C. Earlier increased movement in 1976 coincided with earlier warming trends. Water current was the main factor influencing routes and rates of smolt movement. Smolts usually moved in the same direction as current flow during ebb and flood tides. This resulted in net seaward progress and fastest ground speeds (mean 56.4 cm/s) on ebb tide, and net upriver progress and slowest ground speeds (mean 37.4 cm/s) on flood tide. Swimming depth measured during portions of six tracks averaged 2.4 m. Simultaneous tracking of 1- and 3-m drogues together with smolts during five tracks showed that seaward progress of smolts was due mainly to passive drift. During times of current reversal or upon reaching shallow water, smolts often stopped moving, milled about, or apparently swam against the current. No meaningful correlations were found between travel speed and any environmental factors other than water current, except for influence of water temperature on initiation of migration. This study substantiates previous indications that smolt migration through the estuary is effected relatively quickly. Key words: Atlantic salmon smolts, drift, estuaries, migration, telemetry
Dechlorination of Water for Fish Culture: Comparison of the Activated Carbon, Sulfite Reduction, and Photochemical Methods
Authors: Seegert Gregory L. , Brooks Arthur S.
Published: April 2011

Activated carbon, ultraviolet radiation, and sodium sulfite were evaluated as dechlorinating agents. Activated carbon tested in a variety of commercial dechlorinators was not 100% effective in chlorine removal. The residual concentration remaining after carbon dechlorination varied from 5 to 70 μg/L depending on how long the carbon had been in service and on the flow rate through the carbon bed. Ultraviolet radiation effectively removed residual chlorine from water but compared with the other two methods was considerably more expensive. Sodium sulfite was 100% effective but required a fail-safe injection system. A system combining the reliability of carbon dechlorination with the effectiveness of sulfite reduction was developed and shown to be safe, effective, and reliable. Key words: water quality, toxic levels, system design, operating costs, new methods
The Price of Knowledge: Fisheries Management as a Research Tool
Authors: Silvert William
Published: April 2011

One of the side effects of fisheries management is the discovery of new scientific information. Since this information has economic value, in that it can be used to improve future management of the fishery, the information that can be gained through a particular management strategy should not be ignored in evaluating that strategy. This paper shows using a simple model, how the research component of fisheries management can be measured and used to plan an optimal strategy. The management objectives are taken to include avoidance of risk and maximization of yield. The results depend critically on the time horizon for management. Long-term management favors creative risk-taking and leads to optimal future exploitation, while management based on short-term considerations may freeze the fishery in a permanent pattern of suboptimal yields. Key words: fisheries management, optimal control
A Surplus Yield Model Incorporating Recruitment and Applied to a Stock of Atlantic Mackerel (Scomber scombrus)
Authors: Walter Gilbert G.
Published: April 2011

A modification of Schaefer's surplus yield model that takes into account variations in year-class strength is introduced. Expressions for long-term equilibrium yield under assumptions of both linear and density-dependent recruitment are derived and compared. Strategies for exploitation under nonequilibrium conditions are discussed and equations derived. The model is fitted to a stock of mackerel and projections for the stock biomass in 1980 under various levels of fishing mortality are made. Key words: mathematical model, fisheries management, stock biomass projections
Stability of Freshwater Sucker (Catostomus spp.) Flesh During Frozen Storage
Authors: Dawson L. E. , Uebersax K. L. , Uebersax M. A.
Published: April 2011

Freshwater suckers (Catostomus spp.) were harvested from Lakes Huron, Michigan, and Superior during different seasons of the year. Initial compositional analyses and storage stability of products held at −18 °C for periods of 1, 3, 6, and 12 mo were determined for coarsely ground (eviscerated) fish, minced flesh, and loin and belly flap muscles. Moisture levels ranged from 75.3 to 83.5%, showing no consistent differences among lakes, harvest dates, or fish portions. Calcium levels of minced flesh averaged 0.08%, only about one tenth of that from coarsely ground fish. Lipid analyses (2-thiobarbituric acid test, TBA) showed increased lipid oxidation with storage time. Those results indicate that untreated minced flesh may be stored frozen for at least 6 mo without serious lipid oxidation, since TBA numbers averaged < 2.0 at that storage time. Lipids in loin muscle were least oxidized, followed by minced flesh, belly flap, and coarsely ground fish, respectively. Key words: fish, mechanically deboned, storage stability, sucker, lipid oxidation
Laboratory Exercises in Oceanography
Authors: Parsons T. R.
Published: April 2011

not available
Concentrations of Nutrients and Chlorophyll on a Cross-Channel Transect in Juan de Fuca Strait, British Columbia
Authors: Lewis A. G.
Published: April 2011

Nutrient and chlorophyll values were measured hourly at one of four stations on a cross-channel transect, over a 25-h period during each of 5 mo. Nitrate values increased with depth, chlorophyll decreased, and phosphate remained essentially unchanged during most months. Chlorophyll and phosphate values did not show consistent cross-channel trends, while nitrate levels were frequently higher on the southern side of the Strait. The cross-channel nitrate pattern can be at least partially explained in terms of geostrophic flow; greater amounts of nitrate-rich oceanic water enter at depth on the southern side of the Strait, while nitrate poor inshore water exists near the surface on the northern side. Key words: nutrients, chlorophyll, Juan de Fuca Strait
Anesthetic and Handling Stress on Survival and Cortisol Concentration in Yearling Chinook Salmon (Oncorhynchus tshawytscha)
Authors: Strange Richard J. , Schreck Carl B.
Published: April 2011

Brief anesthetization with 50 mg/L buffered MS-222® (ethyl m-aminobenzoate methanesulfonate) of yearling chinook salmon (Oncorhynchus tshawytscha) during mild handling caused no change in plasma cortisol concentrations compared with levels in non-anesthetized fish. Prolonged exposure (180 min) to a depressing dose of buffered MS-222® (25 mg/L) elevated cortisol more than an immobilizing dose (50 mg/L), while 100 mg/L was lethal within 30 min. Fish anesthetized (50 mg/L MS-222®) during a severe 30-min handling stress had significantly lower mortality than controls to a second handling stress applied when the fish were no longer anesthetized. Anesthetization during the first stressor also prevented the cortisol stress response evident in the control fish. Anesthetic (with or without buffer) administered before initial capture was most effective at increasing survival during a second stressor, while anesthetic supplied after initial capture may have been slightly less effective. A 0.5% NaCl solution supplied after capture was less effective than any anesthetic treatment in increasing future survival, but was better than no treatment. Saline treatment did not attenuate the cortisol stress response. A rapid method of plasma sample preparation for competitive protein binding assay of cortisol was developed. Key words: chinook salmon, cortisol, stress, anesthetic, cortisol assay, survival
Facing the Long Term: An Inquiry into Opportunities to Improve the Climate for Research with Reference to Limnology in Canada
Authors: Vallentyne J. R.
Published: April 2011

Deterioration of the climate for research was the main concern expressed in individual interviews with 125 freshwater scientists. The principal problem cited in the Department of Fisheries and the Environment (DFE) was disruptions to the continuity and time frame essential to research; in universities, declining support for "basic" research; and in both, a perceived lack of attention on the part of governments and the public to measures for the resolution of problems in the long term. These perceptions are analyzed in terms of changing attitudes to environment, research, and science policy from 1957 to 1976. Specific suggestions to improve the climate for research in DFE were: implementation of a policy on research; 3–5 year continuity in funding; standardized evaluation of programs; periodic evaluation of committees; filling research manager positions with scientists on a temporary basis; mechanisms to ensure adequate representation of national–international research (long term) interests. In universities there is a need for a shift in accent from individual to cooperative work, including graduate theses. A strategy needs to be developed within the research community to facilitate communication with the public and senior managers on long-term issues. Without an increase in the forces causing senior managers to be more responsive to the long term, the climate for research will remain as a perennial problem. This is because managers are conditioned by their role to think and act "short" in space and time, whereas scientists are conditioned by their role to think and act "long" in space and time. Development of an independent "scientific auditing" function, possibly coupled with existing financial auditing functions, is needed to improve the credibility of governments and industries in regard to resource interests that are "long" in space and time. Key words: climate for research, limnology, management, environment, Canada, long term, basic research, applied research
Paralytic Toxins in the Dinoflagellate Gonyaulax excavata and in Shellfish
Authors: White Alan W. , Maranda Lucie
Published: April 2011

Paralytic toxins were examined quantitatively in a culture of Gonyaulax excavata and in shellfish by the standard mouse bioassay and by an alkaline peroxide oxidation–fluorometric assay for saxitoxin (STX). The dinoflagellate probably contains at least three toxins, including STX, which represents 3–20% of the total toxin load. During growth in culture the toxin content per cell decreased progressively; however, relative amounts of the three toxins remained roughly similar. In toxic shellfish from nature (Mya arenaria, Mytilus edulis, Modiolus modiolus) and in shellfish fed G. excavata under controlled conditions the relative amounts of toxins differed from those in G. excavata, suggesting toxin interconversions and interference with the chemical assay by toxins other than STX. The consistency in the relationships between bioassay and chemical assay results for clam samples was fair, although the chemical assay measured from 16 to 48% of the bioassay. The chemical assay is questionable as an indicator of total toxin content, and until further data are accumulated the mouse bioassay method is considered more reliable for measuring paralytic, G. excavata toxins in shellfish. Key words: Gonyaulax excavata, dinoflagellate toxins, paralytic shellfish poisoning, saxitoxin, toxin measurement
Isotopic Composition of Dissolved Inorganic Carbon in the Great Lakes
Authors: Weiler R. R. , Nriagu J. O.
Published: April 2011

Values for the δ13C of the dissolved total inorganic carbon in the Great Lakes are presented. The surface values are about two parts per thousand more negative than the values to be expected assuming equilibrium with the atmospheric CO2 reservoir. In the hypolimnion of Lake Erie, the values become more negative as the summer progresses due to the increasing amounts of CO2 from decaying organic matter. Although Lakes Erie and Ontario receive considerably larger amounts of organic carbon as domestic and industrial sewage effluents than the upper Great Lakes, their higher inorganic carbon concentrations evidently mask any isotopic effects from the decay of the organic pollutants. Models to explain the variation in the δ13C in the hypolimnion and epilimnion of a lake are presented. The agreement between predicted and observed δ13C trends for the hypolimnion model is reasonable, suggesting that the flux rates assumed in the model are reasonable for the processes occurring in the lakes. Key words: carbon isotopes, Great Lakes, inorganic carbon, models
pH-Induced Changes in Blood Lead of Lead-Exposed Rainbow Trout (Salmo gairdneri)
Authors: Hodson Peter V. , Blunt Beverly R. , Spry Douglas J.
Published: April 2011

Blood of juvenile rainbow trout (Salmo gairdneri) exposed to lead in water showed increasing lead concentrations as pH of the test water decreased from 10.0 to 6.0. A decrease in pH by 1.0 unit from any reference pH resulted in an increase of blood lead by a factor of 2.1. Since sublethal lead toxicity is related to uptake, these results suggest that toxicity increases as pH decreases. Control experiments indicated that reactions of lead with inorganic constituents of the test water were complete within 3 h and that blood lead was at equilibrium with water lead within 48 h. Therefore, at the time of blood sampling in the pH experiment, both lead complexation processes in the exposure system, plus lead uptake and release from the blood, were at equilibrium. Key words: pH, lead, toxicity, fish, Salmo, blood, equilibrium.
Toxicity of a Mixture of Metals on Freshwater Algae
Authors: Wong P. T. S. , Chau Y. K. , Luxon P. L.
Published: April 2011

Recommended levels of a number of metals for Great Lakes Water Quality Objectives were found to be very toxic to freshwater algae when these metals were present simultaneously in lake water and culture medium. The diatom tested was more sensitive to metal toxicity than the blue-green and green algae. Key words: metals, Water Quality Objectives, toxicity, algae, diatom, primary productivity
The Political Implications of North Sea Oil and Gas.
Authors: Armstrong F. A. J.
Published: April 2011

not available
Preliminary Ecological–Genetic Comparison Between Unperturbed and Oil-Impacted Urosalpinx cinerea (Prosobranchia: Gastropoda) Populations: Nobska Point (Woods Hole) and Wild Harbor (West Falmouth), Massachusetts
Authors: Cole Timothy J.
Published: April 2011

Catastrophes, whether natural or man-made, impinge on populations of organisms by increasing mortality, thus reducing population numbers. Recent theoretical studies indicate that demographic and genetic changes may result from such events. The 1969 oil spill at Wild Harbor offered an opportunity to obtain empirical data on this relationship between ecology and genetics. The organism studied was the oyster drill Urosalpinx cinerea (Say, 1822). Monthly samples (April to September) were collected for each of 3 yr (1973–75) from the recolonizing population at Wild Harbor and from a long-standing population at Nobska Point. Genotypes at two allozymic loci (ODH and LAP) were determined. Demographic information was obtained by mark–recapture experiments during 1973–75. Analyses of population dynamics indicated that a reasonably functioning population has been reestablished at Wild Harbor. However, genetic structure (as revealed by genotypic distributions) of Wild Harbor drills exhibited generally greater year-to-year variation than did Nobska organisms. This may have resulted from genetic change caused by gene migration from different coadapted gene complexes and from stochastic "founder" effects. More information on the interdigitation of ecology and genetics is needed, however, before implications of these findings are fully realized. Key words: electrophoresis, genetics, oiled population, oyster drill, petroleum, Urosalpinx cinerea
Water Temperature Fluctuations and Seasonal Periodicity of Cladophora and Potamogeton in Shallow Rivers
Authors: Wong S. L. , Clark B. , Kirby M. , Kosciuw R. F.
Published: April 2011

The influence of water temperature on nuisance plant species in seven river systems in southwestern Ontario was investigated. Nutrients were not limiting. The study period covered the low flow season from May to September, 1973–76. A community dominated by Cladophora glomerata in late spring is usually replaced by a Potamogeton pectinatus dominated community. The tolerance limits of C. glomerata and P. pectinatus at fixed values of the daily mean or daily maximum temperature change with the daily temperature range. Two methods of predicting daily range were derived. An intermediate seasonal temperature (18–22 °C, < 4 °C daily temperature fluctuation) supported a mixed plant community. Maintenance of appropriate temperature conditions could provide a management technique for controlling nuisance plant growths or for establishing a diverse community in shallow rivers. Key words: Potamogeton, Cladophora, temperature, seasonal periodicity, rivers
Spatial Distribution of Nearshore Fish in the Vicinity of Two Thermal Generating Stations, Nanticoke and Douglas Point, on the Great Lakes
Authors: Minns C. K. , Kelso J. R. M. , Hyatt W.
Published: April 2011

At Nanticoke, Lake Erie, 1974, mean fish density varied considerably, range 162–14 204/10 000 m3, as estimated by digital acoustic fish enumeration. At Douglas Point, Lake Huron, 1975, mean density varied less, range 108–671/10 000 m3. At both sites fish densities were generally greatest in the shallowest, 3–5 m, depths. At Nanticoke, where the nearshore has low relief, there were no distinguishable communities. At Douglas Point, where depth increases rapidly offshore, there was evidence of benthic and pelagic communities. There was no evidence of altered fish distribution in relation to temperature. At Nanticoke there was no vertical variation in temperature and no vertical response was to be expected. At Douglas Point there was thermal stratification present in the summer and there was no apparent response. The influence of incident radiation was uncertain because of the effects of diurnal migrations. At both locations fish were clustered horizontally to varying degrees in the spring and fall, while in the summer fish were distributed more evenly. Densest clusters were usually in the vicinity of the turbulent discharge at both locations. The lack of temperature response and the similarity of Nanticoke with situations at nearby streams on Lake Erie suggest that the fish are responding to currents and perhaps topography. Key words: temperature, acoustic enumeration, topography, light
Acute Effects of Underwater Construction Blasting on Fishes in Long Point Bay, Lake Erie
Authors: Teleki G. C. , Chamberlain A. J.
Published: April 2011

We detonated 201 blasts 22.7–272.4 kg per charge with a high explosive (Hydromex) in 4–8 m of water at Nanticoke, Lake Erie. Shortly after each blast turbidity and CO2 concentrations increased markedly, returning to ambient levels within 3 h of the blast. Postblast pressure and charge weight were directly related (r = 0.70, P < 0.05). Fatality radii ranged from 20 to 50 m for 22.7 kg per charge to 45–110 m for 272.4 kg per charge. Common blast-induced injuries were swimbladder ruptures and hemorrhaging in the coelomic and pericardial cavities. Laterally compressed species were more susceptible to blast pressure gradients than were the fusiform fishes. Temporally, surface mortalities were high only in the spring and late summer. Spatially, 47% of the total blast mortality was not visible from the water surface. Key words: blasting impact, hydraulic pressure gradients, fish mortality, species specific susceptibility
Precocious Sexual Maturation in Atlantic Salmon (Salmo salar) Postsmolts Reared in a Seawater Impoundment
Authors: Sutterlin A. M. , Harmon P. , Young B.
Published: April 2011

Female Atlantic salmon, Salmo salar, usually become sexually mature following a minimum of one winter at sea. Between 4 and 16% maturation was observed for both sexes in two different stocks of salmon placed in sea water as 1+ yr smolts and subsequently reared one summer. Only the larger females and the smaller males matured. Egg size and fertility appeared normal. Smoltification at an early age or accelerated growth rates may be responsible for this phenomenon. Key words: Salinity tolerance, pen-rearing, brood stock, growth rates
Adaptation to Environment: Essays on the Physiology of Marine Animals.
Authors: Davis J. C.
Published: April 2011

not available
Coelenterate Ecology and Behavior.
Authors: Vandermeulen John H.
Published: April 2011

not available
Lowering of Serum Thyroxine and Triiodothyronine Levels in Yearling Coho Salmon, Oncorhynchus kisutch, by Dietary Mirex and PCBs
Authors: Leatherland J. F. , Sonstegard R. A.
Published: April 2011

Yearling coho salmon, Oncorhynchus kisutch, were fed diets contaminated with PCBs (500 μg or 50 μg/g dry feed), Mirex (50 μg or 5 μg/g dry feed), or a mixture of Mirex and PCBs (5 μg Mirex + 50 μg PCB/g dry feed) daily for 2 or 3 mo. Serum T3 and T4 levels were significantly reduced in fish fed the high Mirex diet for 2 or 3 mo. Serum T3 levels were reduced in fish fed the high PCB diet for 3 mo. Serum T3 and T4 levels were significantly reduced in fish fed the mixed Mirex–PCB diet for 3 mo. The significant increase in serum T4/T3 ratios in fish given the high Mirex or high PCB diet was not evident in fish given the mixed Mirex–PCB diet, suggesting a synergistic effect that is different from the effect of individual contaminants. Fish given the high PCB or high Mirex diet had significantly lower body weights than the control fish. Key words: organochlorines, teleost fish, thyroid gland, hormones, endocrines, synergism, pituitary gland
Application of Antibiotics in the Cultivation of Dungeness Crab, Cancer Magister
Authors: Fisher William S. , Nelson Richard T.
Published: April 2011

In static cultivation of Cancer magister zoeae, duration of antibiotic treatment, effectiveness of various antibiotics, and therapeutic pretreatment of the live food were evaluated. Periodic treatment with antibiotics was necessary to maintain high zoeal survival, the greatest benefit occurring during the early zoeal period. Low concentrations (1–10 mg/L) of chloramphenicol were equally or more successful than 100 mg/L streptomycin plus 100 mg/L penicillin. Kanamycin (100 mg/L) and neomycin (50 mg/L) appeared toxic to the zoeae. Successful antibiotic treatment did not alter the development and increased the weight of cultivated zoeae, although these were all lighter than captured crabs of the same apparent age. There was indication that elimination of bacterial epibionts with antibiotics restricted the attachment of other microbial epibionts. Key words: aquaculture, mariculture, epibionts, Crustacea epibionts, zoeal survival, Artemia salina, antibiotics
Effect of Seasonal Photoperiod on Acute Toxic Responses of Juvenile Rainbow Trout (Salmo gairdneri) to Pulpmill Effluent
Authors: McLeay Donald J. , Gordon Michael R.
Published: April 2011

Acute toxic responses to bleached kraft pulpmill effluent were compared for groups of underyearling rainbow trout (Salmo gairdneri) reared under constant temperature and either a summer (16L:8D) or winter (8L:16D) photoperiod. Toxicity tests included a 96-h LC50 bioassay, a 4.5-h sealed-jar test, an 18-h temperature tolerance test, and a 4-h blood-sugar stress bioassay. For all tests the threshold-effect concentration of effluent was not affected by photoperiod. Median effective concentrations for the blood-sugar, temperature tolerance, and sealed-jar tests were, respectively, < 0.2, 0.4, and ~1.4 times the 96-h LC50 value for each fish group. Key words: Salmo gairdneri, photoperiod, BKME, acute toxicity tests, LC50, blood sugar, temperature tolerance, residual oxygen
Temperature Effects on Acceleration of Rainbow Trout, Salmo gairdneri
Authors: Webb P. W.
Published: April 2011

Acceleration performance during and immediately following fast-starts was measured at 5, 10, 15, 20, and 25 °C for rainbow trout (Salmo gairdneri) of mean mass 23.5 g. Fast-start responses were initiated by an electric shock stimulus. Temperature had little effect on fast-start kinematics. Response latency and duration of propulsion strokes decreased with temperature. Latencies decreased from 23 ms at 5 °C to 6 ms at 25 °C. Times to complete the first two principal acceleration strokes in a fast-start decreased from 116 ms at 5 °C to 65 ms at 25 °C. Distance traveled in a given time increased with temperature. For an elapsed time of 100 ms, the distance traveled was 3.5 cm at 5 °C increasing to 11.3 cm at 25 °C. Velocity increased with time at each temperature to reach maximum values by the end of the third propulsive stroke and thereafter declining. Maximum velocity increased with temperature from 0.99 m∙s−1 at 5 °C to 1.71 m∙s−1 at 15 °C. Maximum velocity was independent of temperature from 15 to 25 °C. Similar trends were found for maximum acceleration rate which increased from 16 m∙s−2 at 5 °C to 41 m∙s−2 over the 15–25 °C range. Temperature effects on acceleration performance would alter the ability of fish to traverse short areas of high velocity flow, the effectiveness of predators, and vulnerability of prey fish. Key words: trout, acceleration, swimming, fast-start, temperature, predation, locomotion
Latitudinal Variation in Reproductive Characteristics of American Shad (Alosa sapidissima): Evidence for Population Specific Life History Strategies in Fish
Authors: Leggett William C. , Carscadden James E.
Published: April 2011

The reproductive characteristics of five populations of American shad (Alosa sapidissima) on the Atlantic coast were studied. The proportion of repeat spawners increased with the latitude of the home river. Relative and absolute fecundities decreased as the proportion of repeat spawners increased. These reciprocal trends in reproductive characteristics are independent of growth parameters. The principal factor influencing reproductive strategies in shad appears to be variability in the thermal regime of the home river which influences egg and larval survival. Northern populations, spawning in environments that are thermally harsh and variable, allocate a greater proportion of their energy reserves to migration thereby ensuring higher postspawning survival. This is accomplished by reducing the energy allocated to gonads. The pattern of reproductive responses of shad to the thermal environment of the natal river is consistent with existing ecological theory concerning the evolution of reproductive strategies in response to differing environmental conditions. Available literature for several other fishes suggests that fine tuning of reproductive strategies to local environmental conditions may be widespread among fish and may be the ultimate basis for the evolution of homing. Key words: American shad, Alosa sapidissima, reproductive strategies, fecundity, frequency of reproduction, energy allocation, latitudinal variation, theoretical ecology
Feeding and Migratory Habits of Arctic Char, Salvelinus alpinus, Indicated by the Presence of the Swimbladder Nematode Cystidicola cristivomeri White
Authors: Eddy S. B. , Lankester M. W.
Published: April 2011

The presence of Cystidicola cristivomeri White 1941 in the swim bladder of char indicates the fish have fed on infected, freshwater Mysis relicta which is the essential intermediate host of this parasite. Char younger than 5 yr occur in shallow waters in Stanwell-Fletcher Lake and apparently feed rarely on Mysis as indicated by infrequent infection with C. cristivomeri. Older fish that adopt a migratory habit and go to sea for the summer appear to feed little on Mysis when they return to overwinter in the lake. Small, slow-growing char present in the lake during summer were commonly infected with C. cristivomeri indicating they feed heavily on Mysis. These small fish, which are as old as many migrants, may not participate regularly in the seaward migration. Key words: Arctic char, feeding, migration, nematodes, Cystidicola cristivomeri
Culture Studies on the Effects from Fluoride Pollution on the Growth of Marine Phytoplankters
Authors: Oliveira Luis , Antia Naval J. , Bisalputra Thana
Published: April 2011

The autotrophic growth of 12 species of marine phytoplankters, from eight classes of algae, was tested on axenic cultures with NaF additions of 0–100 mgF/L. All species showed good growth without indication of toxicity or adaptation lag. The highest fluoride concentration caused 25–30% growth-rate inhibition of a diatom, a dinoflagellate, and a haptophyte; other diatoms and species from other classes of algae were virtually unaffected. It is hypothesized that the unexpected lack of toxicity from F− ion may be due to the formation of innocuous complexes with one or more ions of seawater. The ecological inference is drawn that fluoride pollution may be readily tolerated by some marine phytoplankton under nutrient-sufficient conditions. Key words: marine phytoplankton, growth in culture, fluoride-pollution effects
Trading Off Environment, Economics and Energy.
Authors: Shaffer Edward H.
Published: April 2011

not available
The Petroleum-Inducible Mixed-Function Oxidase of Cunner (Tautogolabrus adspersus Walbaum 1792): Some Characteristics Relevant to Hydrocarbon Monitoring
Authors: Walton D. G. , Penrose W. R. , Green J. M.
Published: April 2011

The hepatic aryl hydrocarbon hydroxylase of the cunner (Tautogolabrus adspersus) is a sensitive indicator of petroleum contamination. This fish is a particularly favorable species because of its limited home range and ease of capture. Oil concentrations of 1–2 mg/L in water caused two- to sixfold induction of the enzyme above uninduced levels; induction decayed in < 7 d after exposure ceased. Feeding of crude oil or mussel tissue contaminated with oil at a concentration of 500 mg/kg caused up to fivefold induction. Males maintained a constant specific activity of aryl hydroxylase through the season, but females had a decreased activity before spawning. Starvation may also have reduced AHH activity. Correlations with liver and body weight were not observed. 2,5-Diphenyloxazole was found to be a safe substitute for benzo[a]pyrene in the assay. Key words: cunner, mixed function oxidase, aryl hydrocarbon hydroxylase, oil pollution, monitoring, biochemistry
The Lake Washington Ecosystem: The Perspective from the Fish Community Production and Forage Base
Authors: Eggers D. M. , Bartoo N. W. , Rickard N. A. , Nelson R. E. , Wissmar R. C. , Burgner R. L. , Devol A. H.
Published: April 2011

In Lake Washington, fish production through detritus-based food chains is substantially greater than fish production through the grazing food chain. The lack of significant grazing by fish on the zooplankton is a consequence of both piscivore predation and conditions in the planktivore spawning environment. At low planktivore abundance, squawfish may switch to benthos feeding, exploiting the abundant prickly sculpin. At high planktivore abundance, squawfish feed more heavily on planktivores. Thus, even when reproductive success of planktivores is good, swamping of the squawfish population does not occur and depensatory mortality due to squawfish predation prevents planktivore abundance from increasing to the point where zooplankton resource depletion would occur. Benthic–littoral species are vulnerable to predation essentially only as larva and juveniles. They avoid predation by occupying littoral and epibenthic refugia. Recruitment to the adult population from these refugia may be sufficient to account for the greater rate of benthos exploitation by fish relative to the rate of zooplankton exploitation by fish. Neomysis is an important component of the Lake Washington fish production, since potentially Neomysis is a regulating agent on the zooplankton, and reduction in Neomysis predation on zooplankton, due to decreasing abundance and a deeper vertical distribution, may be partly responsible for the recent reappearance of Daphnia. The response of the fish community to trophic changes in Lake Washington has been slight. No consistent trends in the growth of fish utilizing zooplankton were observed. However, annual growth increments of consumers utilizing the benthic detrital food chain have declined with sewage diversion. The insights gained from analyzing the Lake Washington fish community structure and the Lake Washington carbon budget corroborate the above response of the fish community to trophic changes. Planktivores are predator-controlled and not able to deplete zooplankton resources, and thus would be insensitive to alterations in standing crop of zooplankton. On the other hand, benthic–littoral fish are more resource-limited and would be expected to respond to alterations in their forage base. Key words: ecosystem, fish, production, Lake Washington, eutrophication, predation
Enhancement of Sockeye Salmon (Oncorhynchus nerka) by Lake Fertilization in Great Central Lake: Summary Report
Authors: LeBrasseur R. J. , McAllister C. D. , Barraclough W. E. , Kennedy O. D. , Manzer J. , Robinson D. , Stephens K.
Published: April 2011

Great Central Lake was treated with ca. 1001 of commercial grade fertilizer (ammonium nitrate and ammonium phosphate) annually from 1970 through 1973. Limnological parameters and sockeye salmon (Oncorhynchus nerka) juveniles and adults were monitored from 1969 through 1976 to test the hypothesis that increasing the supply of inorganic nutrients in an ultraoligotrophic lake would increase production at succeeding trophic levels. Rates of change and linkages between different elements of the food chain leading to juvenile sockeye salmon were identified. During fertilized years mean summer primary production increased fivefold, zooplankton standing stock increased 9 times, the percentage survival from estimated potential egg deposition to juvenile sockeye increased 2.6 times, while mean stock size of adult sockeye increased from < 50 000 to > 360 000. Adult sockeye returning to an adjacent untreated lake also increased in abundance. The data for the 8-yr period support the initial hypothesis, but the dominant processes affecting production and interrelationships between different trophic levels in different years remain masked. Key words: food chain, limnology, sockeye salmon, primary production, zooplankton, eutrophication, lake fertilization, enhancement
Ammonia Production Rates of Artemia salina Under Various Culture Conditions
Authors: Moffett William L. , Fisher William S.
Published: April 2011

Artemia salina are used as a live food in the cultivation of several Crustacea and their metabolites add to the metabolites of the cultured species. Because it is toxic, ammonia was monitored over 7-d periods while A. salina nauplii and adults were held in a variety of culture conditions. Ammonia production increased with increasing temperature between 15–25 °C according to the relationship[Formula: see text]Production of ammonia by nauplii was density dependent. No change in ammonia production was shown by adults with alteration of density (200–2000 A. salina/L), salinity (10–50‰), or pH (7.0–9.0), or when fed twice daily with 50 000–100 000 cells Platymonas sp./mL. Artemia salina fed ad lib. to cultured experimental lobsters would contribute about 46% of the total ammonia in the culture system. Key words: Artemia, aquaculture, ammonia, metabolism, excretion, Crustacea
An Automated Device (AGARS) for Studying Avoidance of Pollutant Gradients by Aquatic Organisms
Authors: Cripe C. R.
Published: April 2011

Most apparatus designed to detect avoidance of pollutants by aquatic organisms require visual observations of test organisms in steep pollutant gradients. AGARS (Aquatic Gradient Avoidance Response System) was developed to eliminate these limitations. This system allows animals to choose between one uncontaminated zone and three increasingly toxic zones in a gradient trough that is monitored for extended time periods by infrared light sources, sensors, and a microprocessor. Data are accumulated hourly and processed by a paper tape reader/calculator/plotter system that records the time test animals remain in each zone and compares behavior before and during test exposures. Initial tests indicate that pinfish (Lagodon rhomboides) tested in the apparatus will avoid chlorine-produced oxidants at concentrations of 0.02–0.04 mg/L. Key words: avoidance responses, behavioral bioassays, automated monitoring systems, chlorine-produced oxidants
Paralytic Shellfish Toxins in the Sea Scallop, Placopecten magellanicus, in the Bay of Fundy
Authors: Hsu C. P. , Marchand A. , Shimizu Y. , Sims G. G.
Published: April 2011

The paralytic shellfish poison of the giant sea scallop, Placopecten magellanicus (Gmelin), from the Bay of Fundy has been analyzed. Of eight toxins isolated, seven were identified with those previously recognized in various sources including the Atlantic toxic dinoflagellate, Gonyaulax tamarensis cells. The major components were gonyautoxin-I, gonyautoxin-II, and neosaxitoxin; saxitoxin was responsible for only a very small portion of the total toxicity. A minor toxin that was eluted between neosaxitoxin and saxitoxin in the chromatography system was found to be new and designated as gonyautoxin-VII. Key words: paralytic shellfish poisons, gonyautoxins, neosaxitoxin, Gonyaulax tamarensis
Deepwater Exchange Processes in the Saguenay Fjord
Authors: Seibert G. H. , Trites R. W. , Reid S. J.
Published: April 2011

Evidence is presented showing that the deep waters in the Saguenay Fjord are flushed at a rate that appears to be significantly higher than other sill fjords with comparable bathymetry. Interval waves in the St. Lawrence estuary, with magnitudes of up to 60 m, provide a mechanism for bringing up dense water, semidiurnally, to the level of the seaward sill. Providing the density of the deep water in the fjord's outer basin is less than that at sill depth, a density flow develops and descends into the basin. Estimates of volume and kinetic energy fluxes of the plume suggest that, by itself, this is insufficient to explain the high flushing rates observed. Other processes, such as internal waves, which must be operative in carrying energy into the deep basin, are discussed. Key words: estuaries, sill fjords, mixing, circulation, coastal