bluuebunny/crossref_metadata_2025 huggingface dataset:
Aspects of Predation of Seals by Polar Bears
Authors: Stirling Ian , Archibald W. Ralph
Published: April 2011

Data were collected from 227 ringed seals (Phoca hispida) and bearded seals (Erignathus barbatus) killed by polar bears (Ursus maritimus) in the western arctic and the eastern high arctic. During periods of high ringed seal productivity, pups constituted at least half of the seals killed in both areas during the spring. Bearded seals were taken less often than ringed seals in both areas but were more important as prey to polar bears in the western arctic. Carcass utilization was significantly higher in the eastern high arctic than in the western arctic although the reason was not apparent. Scavenging of unutilized seal remains is probably of great importance to the survival of large numbers of arctic foxes (Alopex lagopus) through the winter. Key words: Ursus maritimus, Phoca hispida, Erignathus barbatus, predation, interspecific relationships, Arctic Ocean mammals
A Simple Mechanism that Causes Collapsing Stability Regions in Exploited Salmonid Populations
Authors: Peterman Randall M.
Published: April 2011

Depensatory predation mortality on salmon when added to a Ricker production model can create a system with at least two stable equilibria and two domains of attraction. The behavior of such a fish system is different from a single equilibrium situation and a simple mechanism is described through which commercial exploitation changes the ability of such multiple-equilibrium fish populations to respond to perturbations in survival rates. Furthermore, it is shown that this change in size of stability regions is proportional to the exploitation rate and that classically defined maximum sustainable yield (MSY) exploitation rates are inevitably close to the rates that would cause a drastic decrease in the population. The uncertainties inherent in environmental effects on survival and in achievement of desired exploitation rates precipitate the need to back away from the usual MSY exploitation rates and set up (through enhancement) a system of stocks whereby feedback information is provided to the manager. This approach of adaptive management seeks reasonable yields while gaining information about the state (or changes in state) of the system. Some applications of catastrophe theory are discussed, especially with reference to harvesting multiple-stock salmon systems. Key words: stability, resilience, exploitation, salmon, depensation, multiple equilibria, adaptive management, enhancement, catastrophe theory
Evaluation of Tests with Early Life Stages of Fish for Predicting Long-Term Toxicity
Authors: McKim James M.
Published: April 2011

Partial and complete life-cycle toxicity tests with fish, involving all developmental stages, have been used extensively in the establishment of water-quality criteria for aquatic life. During extended chronic exposures of fish to selected toxicants, certain developmental stages have frequently shown a greater sensitivity than others. In 56 life-cycle toxicity tests completed during the last decade with 34 organic and inorganic chemicals and four species of fish, the embryo–larval and early juvenile life stages were the most, or among the most, sensitive. Tests with these stages can be used to estimate the maximum acceptable toxicant concentration (MATC) within a factor of two in most cases. Therefore, toxicity tests with these early life stages of fish should be useful in establishing water-quality criteria and in screening large numbers of chemicals. Key words: fish, embryos, larvae, chronic toxicity, early life stages
Simulation of Dispersal of Sockeye Salmon (Oncorhynchus nerka) Underyearlings in Babine Lake
Authors: Simms S. E. , Larkin P. A.
Published: April 2011

The movement of underyearling sockeye salmon (Oncorhynchus nerka) in Babine Lake was computer simulated using a grid array with reflection principles applied for the complex shoreline boundaries. Dispersal was in accord with bivariate density functions summed appropriately to give 25 discrete components, with the standard deviations related to observed swimming speeds. Directionally biased dispersal was simulated using the lognormal density function. Natural movement of sockeye underyearlings in Babine Lake suggests three seasonal periods: (1) May 25–June 12; (2) July 13–August 28; (3) August 29–October 12. For (1), natural movement is best simulated by assuming that 90% of the fish move with a 10:90 bias toward southward movement, while 10% of the fish move at random; for (2), the best assumptions are that 50% of the fish move with a 90:10 bias for northward movement and 50% move at random; for (3), the best simulation assumed that 100% of the fry move at random. Considering the simplicity of the model assumptions, the fit to the data for natural movements is good. To construct a better predictive model the directional bias mimicked by the lognormal density function should be divided into components related to physical circulation in the lake basin and components related to fry behavior. The architecture of the computer program is briefly described and could be applied to other salmon dispersal studies. Key words: sockeye salmon, simulation, natural movements, fry distribution
Simultaneous activity recording of multiple isolated marine organisms in an artificial saltwater recirculating system
Authors: Rebach Steve
Published: April 2011

Simultaneous activity recordings were obtained from individual organisms under identical conditions using a recirculating saltwater system containing a chamber with removable dividers to allow a maximum of 10 testing compartments. Ten infrared-sensitive photoresistor arrays beneath the testing area sensed activity in the individual compartments. Data were recorded on a 20 channel event recorder.Twenty common rock crabs, Cancer irroratus, were housed and tested for 5 mo under five different light regimes to ascertain the presence of daily or tidal periodicities. These crabs were tested simultaneously, but individually, in duplicate facilities permitting calculation of individual and total sample periodicity and allowing observation of differences in activity rhythms based on age, sex, stage of the molt cycle, or other factors. Key words: activity patterns, actograph, aquaculture, Cancer irroratus, circadian rhythms
Effects of Fisheries on Eurasian Perch (Perca fluviatilis) in Windermere
Authors: Bagenal T. B.
Published: April 2011

A review of literature indicated that a wartime (1941–48) trap fishery reduced the Eurasian perch (Perca fluviatilis) population very considerably. An experimental gillnet fishery for northern pike (Esox lucius) from 1944 to 1975 presumably contributed to keeping the perch population low through increased predation. The gillnet fishery reduced the average size of the pike, and their growth rate increased, in turn increasing the predation on younger perch. This predation controlled recruitment to the adult perch population. Pike predation is given as one factor in a model explaining year-class fluctuations. Key words: Percidae, exploitation, year-class fluctuations, Perca predation, year-class model
Niche Theory and Percid Community Structure
Authors: Kerr S. R. , Ryder R. A.
Published: April 2011

The Hutchinsonian definition of niche is conceptually attractive, but lacks a quantitative, operational basis for analysis. Fry's autecological theories remedy the deficiency by permitting the use of metabolic units of measure that are observable, common, and important to all organisms and ecological functional groups. Contouring the niche hyperspace in units of metabolic scope for activity enables analyses at both the autecological and synecological levels of organization. A simple analysis of four coexisting percid species illustrates some applications of the method. Key words: community ecology, theory, Percidae, niche theory, prey size, light intensity, limiting factors
Relationships of Fish Yield to Lake Phytoplankton Standing Crop, Production, and Morphoedaphic Factors
Authors: Oglesby Ray T.
Published: April 2011

Fish yield is related to annual primary production, summer phytoplankton standing crop, and the morphoedaphic index for lakes representing a wide variety of typologies by a series of models in the form of log-log regressions. Tentative boundary conditions are established by which lakes inappropriate to the models can be excluded. Confidence intervals for predicted values about the mean are given for the fish yield–phytoplankton standing crop regression. From this relation, potential yields for the lakes studied are reduced from a range of 10,000 to one of 25-fold. Efficiencies with which carbon is transferred from primary production to fish yield vary by 2 to 3 orders of magnitude and are highest for small, intensively managed ponds and lowest for large, deep, cold-water lakes. Models based upon fish yield as a function of phytoplankton production or standing crop are inherently more accurate and subject to fewer exceptions than are those related to morphoedaphic factors. The former appear to be capable of substantial refinement but even in their present state might be employed to make useful predictions for groups of lakes. A suggested supplement to existing approaches in fishery management involves the following sequence: (1) use of expectation-variability diagrams to obtain an overview of the problem, (2) selection of an appropriate model or models to predict yield, (3) prediction of a range of yields, and (4) implementation of regulations proved successful for other lakes in the same yield category. Key words: fish, lakes, phytoplankton, morphoedaphic index, fishery management
Recovery and Restoration of Damaged Ecosystems.
Authors: Fee Everett J.
Published: April 2011

not available
Inland Fishes of California.
Authors: Resh Vincent H.
Published: April 2011

not available
Variation in Age at First Spawning in Atlantic Salmon (Salmo salar)
Authors: Nævdal Gunnar , Holm Marianne , Ingebrigtsen Oscar , Møller Dag
Published: April 2011

Significant differences in the proportion of mature fish in groups of Atlantic salmon (Salmo salar) of different river origins maintained under the same conditions were observed during the 1st and 2nd yr of sea rearing. Nearly all fish in sib groups originating from grilse rivers matured during the 2nd sea year, while few or no mature fish were found in the groups originating from rivers producing mainly multi-sea-winter salmon. The observations were in accordance with the life histories of the different river populations, indicating that salmon inherit rather than acquire a tendency to mature at a certain age. Key words: Atlantic salmon, maturation age, cultured salmon, river populations
Protein and Lipid Content of Gonads, Liver, and Muscle of Northern Pike (Esox lucius) in Relation to Gonad Growth
Authors: Medford B. A. , Mackay W. C.
Published: April 2011

Northern pike (Esox lucius) were sampled at regular intervals from Lac Ste. Anne, Alberta, between May 1973 and July 1974. Gonad weight, liver weight, somatic body weight, and the total protein and total lipid content of gonads and liver were determined for a pike of 50 cm fork length to evaluate the deposition of nutrients into gonads and to assess areas of possible nutrient storage and depletion. Protein, lipid, and water concentrations in muscle, gonad, and liver were also measured. Gonad growth began in July and proceeded at a similar rate between sexes during late summer. Testicular growth was complete in September, whereas ovarian growth continued through fall and winter until April. Mature ovaries contained 14.5 times more protein and 10.5 times more lipid than did mature testes. Ovarian growth before March occurred without any depletion of body nutrients. Liver weight in both sexes increased 2.5-fold between May (after spawning) and March. In March, total liver protein of females was 163% that of males. Female liver size decreased significantly before spawning (March–April) coincident with final gonad growth. Male liver size decreased significantly over spawning (April–June). No fat storage depots were observed in either sex. Muscle and somatic body weight data indicate that a depletion of body energy can occur in spring. Key words: protein, lipid, water, gonad, liver, muscle, northern pike, Esox lucius, spawning
Method for Incubating Leaf Tissue to Study Decomposition in Streams
Authors: Eidt D. C. , Meating J. H.
Published: April 2011

Discs of leaf tissue in mesh bags were incubated inside black plastic tubes secured to the stream bottom. The method minimizes losses of samples due to severe winter conditions and is easier to use than leaf packs or decomposition boxes.
Outplant Method for Phenological Studies of Chondrus crispus in Mechanically Harvested Beds
Authors: Hanic L. A. , Pringle J. D.
Published: April 2011

A method is described employing a primary pottery unit for seeding and growing Chondrus crispus Stackhouse and a secondary concrete platform for support and protection. The combined units facilitate long-term studies where frequent removal of plants for observation is required and where field conditions are adverse. Key words: Chondrus crispus, Irish moss, seeding, outplanting method
Survey of Trace Metal Contents of Suspended Matter in the St. Lawrence Estuary and Saguenay Fjord
Authors: Cossa D. , Poulet S. A.
Published: April 2011

Trace metal contents (Mn, Zn, Pb, and Cd) of suspended particulate matter were measured in the upper St. Lawrence estuary and Saguenay fjord. In the estuary, elution of the trace metal fraction adsorbed on particles seems to be mostly responsible for the significant differences in concentrations observed at the freshwater–saltwater boundary. In the Saguenay fjord, particles from deep waters are enriched with trace metals, especially Mn, compared with those from surface waters. This enrichment is probably due to Mn oxidation and simultaneous scavenging of the other trace elements. High Pb and Cd levels in particles of surface waters of the fjord seem to depend mostly on their high affinity for the rich organic matter. Key words: trace elements, suspended matter, estuaries, manganese, zinc, lead, cadmium
Effect of Double Freezing and Subsequent Long-Term Refrozen Storage at −23 °C on the Quality of Inshore Male Capelin (Mallotus villosus)
Authors: Botta J. R. , Shaw D. H.
Published: April 2011

Whole inshore male capelin (Mallotus villosus) were stored at −23 °C for 2 mo (C2), or 6 mo (C6) prior to thawing, beheading and eviscerating, and refreezing. Though the quality of the twice-frozen product was in both cases inferior to a once-frozen sample, it was still quite acceptable after 2 yr of refrozen storage. As expected, quality was superior in the C2 samples, but in both sets of samples taste deteriorated to a greater extent than texture. Chemical measurement of peroxide value indicated a possible development of rancidity that could not be detected by sensory analysis. Considerable lipid hydrolysis occurred, with the free fatty acids (FFA) at least doubling during storage; increases were greater in C6. In both experiments FFA production correlated with texture, taste, and with extractable protein nitrogen (EPN). Dimethylamine (DMA), trimethylamine (TMA), hypoxanthine, and EPN appeared to be good indicators of storage time and sensory quality. Key words: capelin, dimethylamine (DMA), extractable protein nitrogen (EPN), free fatty acids (FFA), hypoxanthine, peroxide value, refrozen storage, taste, texture, trimethylamine
Environmental Toxicity of Aquatic Radionuclides. Models and Mechanisms.
Authors: Schindler D. W. , Brunskill G. J.
Published: April 2011

not available
Contribution of Chronic Petroleum Inputs to Narragansett Bay and Rhode Island Sound Sediments
Authors: Van Vleet Edward S. , Quinn James G.
Published: April 2011

Sediment cores from Narragansett Bay and Rhode Island Sound have been analyzed for petroleum hydrocarbons and compared with a relatively unpolluted sediment core from the Gulf of Maine. The sediments were analyzed for unbound hydrocarbons, hydrocarbons bound or closely associated with humic substances, and residual hydrocarbons bound or closely associated with the clay mineral or kerogen matrix. Results indicated that in general 90–100% of the hydrocarbons were in the unbound form and could be easily extracted with organic solvents. The petroleum hydrocarbons decreased with depth at all stations. Biogenic hydrocarbons (nC25, nC27, nC29, and nC31) made up an increasingly greater percentage of the total with increasing depth. The hydrocarbons in the Narragansett Bay sediments and near surface Rhode Island Sound sediments strongly resembled the hydrocarbons previously reported for the Providence River and upper Narragansett Bay. These petroleum-like hydrocarbons were shown to be largely introduced to the river and bay through chronic inputs from a municipal wastewater treatment plant. These hydrocarbons then undergo sedimentation throughout the entire bay and into Rhode Island Sound. Preliminary calculations indicate that over 0.2 million t (tonne) of petroleum hydrocarbons may be transported to the marine environment annually from municipal treatment plants. Most of these hydrocarbons appear to accumulate in estuarine and coastal sediments. Key words: hydrocarbons, petroleum, chronic pollution, Narragansett Bay, sediments
Bioavailability of Crude Oil from Experimentally Oiled Sediments to English Sole (Parophrys vetulus), and Pathological Consequences
Authors: McCain B. B. , Hodgins H. O. , Gronlund W. D. , Hawkes J. W. , Brown D. W. , Myers M. S. , Vandermeulen J. H.
Published: April 2011

English sole (Parophrys vetulus) were exposed to experimentally oiled (Alaskan North Slope crude oil) sediments over a 4-mo period to assess the bioavailability and tissue hydrocarbon distribution kinetics in flatfish. Data were also obtained on hydrocarbon related physiological changes and tissue pathology. Crude oil was mixed with aromatic hydrocarbon-free sediments to a concentration of 700 μg/g dry weight at the beginning of the experiment. During the 1st mo of the experiment this concentration decreased to 400 μg/g dry weight, and remained relatively stable during the remainder of the 4-mo period. Compositional changes were observed in the alkane and aromatic fractions, with a differential decrease in the substituted naphthalenes. Flatfish maintained in such oiled sediments readily took up alkane and aromatic petroleum hydrocarbons from these sediments, and accumulated these in skin, muscle, and liver; 1- and 2-methylnaphthalene and 1,2,3,4-tetramethylbenzene were accumulated to greater extent than other aromatics. Tissue hydrocarbons decreased with time, and after 27-d continuous exposure to oiled sediments only the liver contained detectable levels of hydrocarbons. After 2 mo < 2% of the initial aromatic hydrocarbon load could be detected, and only in the liver in flatfish that were continuously maintained on oiled sediments. Depuration of tissue aromatics differed for various aromatics, 1,2,3,4-tetramethylbenzene and 2-methylnaphthalene being most persistent. Depuration is thought to be due to induction of the aryl hydrocarbon hydroxylase system during initial exposure to oiled sediments. Concomitant with the high tissue hydrocarbon period were found enhanced weight loss and severe hepatocellular lipid vacuolization (HLV). Although the observations, on growth changes and liver pathology are preliminary, the data indicate the need for further detailed study of fish growth abnormalities and pathology in the presence of petroleum hydrocarbons. Key words: flatfish, crude oil, bioavailability, pathology, aromatic hydrocarbons, bottom sediments, depuration
Prevention and Treatment of Nitrite Toxicity in Juvenile Steelhead Trout (Salmo gairdneri)
Authors: Wedemeyer Gary A. , Yasutake W. T.
Published: April 2011

The efficacy of mineral salts, pH, and tetramethylthianine (methylene blue) treatment in reducing the acute toxicity of nitrite to fingerling steelhead trout (Salmo gairdneri) was determined using a static bioassay system at 10 °C. The acute toxicity (96-h LC50) was reduced by a factor of about 24 for 5-g steelhead and 13 for 10-g fish when the total water hardness was increased from 25 to 300 mg/L (as CaCO3). NaCl or CaCl2 additions (0–200 mg/L) reduced toxicity by a factor of up to 3 for NaCl and 50 for CaCl2. Increasing the pH from 6.0 to 8.0 decreased toxicity by a factor of about 8 for the smaller and 3 for the larger fish. Methylene blue at 0.1 or 1.0 mg/L was effective in decreasing acute toxicity. For alleviating methemoglobinemia, removing the fish to freshwater for 48 h was about as effective as 1.0 mg/L methylene blue. Chronic exposure in soft water to 0.03 mg/L NO2-N for 6 mo caused no significant growth reduction, gill histological changes, hematological dyscrasias, or impaired ability of the smolts to adapt to 30‰ seawater and grow for an additional 2 mo. Key words: nitrite, toxicity, fish, methylene blue, pH, salts, acute toxicity, chronic toxicity
Alternative Sampling Device for Aquatic Organisms
Authors: Brodie P. F.
Published: April 2011

Problems of obtaining quantitative samples of aquatic organisms via conventional devices are discussed and an alternative sampler based on the presumed mechanics of cetacean feeding is proposed. A polyethylene tube mounted on a light frame that minimizes the bow wave envelops a column of water and permits its filtration. Key words: avoidance, bow wave, plankton, quantitative sample, sampler, turbulence, water column
Aquaculture Practices in Taiwan.
Authors: Ayles G. Burton
Published: April 2011

not available
Acceptability of Rapeseed Proteins in Diets of Rainbow Trout (Salmo gairdneri)
Authors: Yurkowski M. , Bailey J. K. , Evans R. E. , Tabachek Jo-Anne L. , Ayles G. Burton , Eales J.G.
Published: April 2011

Weight gain and feed consumption results showed that rapeseed protein concentrate (RPC) and rapeseed meal (RM) can be substituted for soybean meal (SM) and perhaps partially for herring meal (HM) in rainbow trout (Salmo gairdneri) control (SM–HM) diet and thus have economic benefits. Rapeseed flour (RF) was a poor source of proteins due to its greater effect on thyroid function. Rapeseed proteins have little effect on liver weight, body moisture, liver and body lipid, liver and body sterol content, visual and histological appearance of liver, heart and visceral tissues, or on the flavor, but caused yellow pigmentation of the skin. The levels of individual fatty acids in the diets directly affected the levels of individual fatty acids in the liver and body, while the type and level of dietary rapeseed proteins appeared to have no effect. The levels of fatty acids, 20:1 and 22:1 (includes erucic acid), were lower in the body and even lower in the liver compared with the diets. All test diets, except RPC–HM diet, caused marked thyroid hyperplasia, believed to be due to glucosinolates (goitrogens). However, some compensation for this goitrogenic action must occur because plasma T4 levels indicated a hypothyroid state for only five test diets (highest RPC-containing diet; highest RM-containing diet; all three RF-containing diets). Key words: dietary rapeseed, glucosinolates, feed–gain ratios, growth, lipids, fatty acids, plasma T4, thyroid histology, flavor, weight gain
Distance Chemoreception and Vision in the Selection of Prey by American Lobster (Homarus americanus)
Authors: Hirtle R. W. M. , Mann K. H.
Published: April 2011

Lobsters responded positively to the waterborne odor of intact living crabs (Carcinus maenas), sea urchins (Strongylocentrotus droebachiensis), and mussels (Mytilus edulis). The frequency of response was higher and the response time shorter to crabs than to sea urchins or mussels. Lobsters also responded to the sight of moving crabs or moving sea urchins, but not to the sight of stationary specimens. Crabs are probably more attractive to lobsters because of their odor and their greater activity, compared with sea urchins or mussels. Key words: lobsters, prey, chemoreception, vision, crabs, sea urchins, movement, odor
Rates of Mortality, Growth, and Biomass Production of Lymnaea palustris During Chronic Exposure to Lead
Authors: Borgmann U. , Kramar O. , Loveridge C.
Published: April 2011

Lymnaea palustris, a freshwater snail, was exposed to lead in a continuous-flow system from newly laid eggs until reproductive maturity. Lead, at concentrations as low as 19 μg∙L−1, caused a significant increase in the mortality rate, although the growth rate was not affected. The lead-induced mortality was proportional to the lead concentration raised to the exponent 2.5. The analysis of mortality as a rate function was found superior to the use of the more conventional LC50 (concentration resulting in 50% mortality). A plot of the logarithm of the lead-induced mortality against log lead concentration is linear and has the same slope as plots of double logarithms of the inverse survival at any one time versus log lead concentration or log time versus log LC50 or log LT50 (time to 50% mortality) versus log lead concentration. The mortality rate, unlike the percent mortality, is independent of time and can be combined directly with the growth rate to estimate the biomass production rate. A 50% drop in the rate of biomass production was observed at 36 μg∙L−1 and a drop to 0 production at 48 μg∙L−1. Lead uptake in whole snails was found to be proportional to the lead concentration in the water, giving a concentration factor of 8500 on a dry weight basis. Key words: snails, lead, toxicity, biomass production, bioaccumulation
Natural Convection: A Mechanism for Transporting Oxygen to Incubating Salmon Eggs
Authors: O'Brien R. N. , Visaisouk S. , Raine R. , Alderdice D. F.
Published: April 2011

Respiratory exchange at the surface of developing fish eggs is influenced by two processes: diffusion and convection. The respiring egg acts as an oxygen sink, removing dissolved oxygen from the diffusion layer surrounding the outer surfaces of the egg capsule. To maintain the oxygen gradient in the diffusion layer, oxygen must be delivered to it by convection. This paper describes two components of convective transport: that provided by forced convection — the bulk transport of oxygenated water to the egg; and a newly recognized component, natural convection. Salmon normally spawn in gravel environments. Mass transfer of oxygen to incubating eggs, resulting from forced convection, is provided by subsurface water moving with a velocity related primarily to properties of the gravel and the hydraulic gradient. Egg-induced natural convection is seen as a component embedded in these relations. Acting as an emergency oxygen transport and metabolite disposal mechanism at low water velocities, natural convection could maintain perfusion of respiring eggs at some minimum water velocity in the event of diminution or interruption of natural water flow. The relevance of natural convection as a possible mechanism affecting several other respiring systems is discussed. Key words: respiration, forced convection, density of water, bulk transport, diffusion, diffusion layer, oxygen gradient
First Evidence for Even-Year Spawning Pink Salmon, Oncorhynchus gorbuscha, in Lake Superior
Authors: Kwain Wen-hwa , Chappel J. A.
Published: April 2011

Nine even-year spawning pink salmon, Oncorhynchus gorbuscha, were taken in Steel River, Lake Superior, Ontario, in 1976. The possible origin of these fish was from unknown plantings or spawning of 3-yr-old, odd-year spawning pink salmon. Key words: Great Lakes, distribution, salmon maturation, spawning age, introduced salmon
Coho Salmon (Oncorhynchus kisutch) and Herring Gulls (Larus argentatus) as Indicators of Organochlorine Contamination in Lake Ontario
Authors: Norstrom R. J. , Hallett D. J. , Sonstegard R. A.
Published: April 2011

Coho salmon (Oncorhynchus kisutch) and herring gulls (Larus argentatus) in the Great Lakes depend to a large extent on alewives (Alosa pseudoharengus) and smelt (Osmerus mordax) for their food. All of these species range widely in the lakes, and therefore provide an integrated measure of levels of organochlorine contaminants in the lakes. Organochlorine residues were determined in herring gull eggs from four eastern Lake Ontario colonies, coho salmon from western Lake Ontario, and pooled alewife and smelt from the stomach contents of the salmon. The mean apparent bioconcentration factor was 2.9 ± 0.7 for accumulation of PCBs, DDE, mirex, photomirex, HCB, dieldrin, and DDD in coho salmon muscle from alewives and smelt. The salmon had a mean weight of 2.4 kg and a mean lipid content of 8.2%. The bioconcentration factor was 50 ± 10 for accumulation of PCBs with more than five chlorines, DDE, mirex, and photomirex in herring gull eggs. PCBs with fewer than six chlorines, HCB, dieldrin, and DDD were concentrated to a lesser extent in herring gull eggs. Assuming an apparent bioconcentration factor from water of 5 × 105 for accumulation of PCBs, DDE, mirex, and photomirex in smelt and alewives, the corresponding values in coho salmon and herring gull eggs were 1.5 × 106 and 2.5 × 107. Key words: bioconcentration, residue, alewives, smelt, PCBs, DDE, mirex, photomirex, HCB, dieldrin
Origin of Deposited Material Sedimented in a Marine Bay
Authors: Hargrave B. T. , Taguchi S.
Published: April 2011

Suspended and sedimented particulate carbon, nitrogen, chlorophyll a, and phaeophytin were measured at various depths throughout the year in a small marine bay. Seasonal and vertical differences in sedimentation rates were not simply related to changes in concentration of suspended particulate matter. Chlorophyll a/total pigment, carbon/nitrogen, and carbon/chlorophyll a ratios in suspended and sedimented material were usually different. Sedimentation rates generally increased with depth with greatest increases during periods of low stratification. Resuspension and horizontal transport of sedimenting material was implied by discontinuities in sedimentation at particular depths. Annual sedimentation of particulate carbon at 20 m depth (below the seasonal thermocline) was equivalent to 15% of the estimated supply from photosynthetic and chemosynthetic production, river discharge, and sewage input. Material deposited during periods of stratification, however, which coincided with high rates of primary production and increased zooplankton biomass during the summer, contained high amounts of carbon and chlorophyll a with a low carbon/nitrogen ratio indicative of a supply from biological production. Thus, although a small fraction of the total suspended particulate matter annually available was deposited, large differences in the quantity and quality of sedimented material occurred seasonally. Key words: sedimentation, resuspension, suspended particulate matter, biological production, organic supply, coastal embayment
Phytoplankton Ecology of Vancouver Harbor
Authors: Stockner John G. , Cliff David D.
Published: April 2011

Phytoplankton production and distribution were examined over a 2-yr period in the Burrard Inlet system, which includes a true fiord (Indian Arm), a shallow blind inlet (Port Moody Arm), and a turbulent narrows region that is contiguous to the Port of Vancouver. Greatest annual production occurred in Port Moody Arm with a mean of 532 g C∙m−2∙yr−1 while the lowest values were in Indian Arm and the Narrows region, averaging about 260 g C∙m−2∙yr−1. Nitrate and zooplankton grazing were the main factors limiting phytoplankton production in Indian Arm, while flushing and poor light conditions influenced phytoplankton growth in the Narrows and outer Burrard Inlet. Most of the discharges of domestic and industrial wastes have been diverted to the Fraser River, and Vancouver Harbor can be considered relatively clean and pollution-free because of strong tidal mixing and seaward flushing. The only sign of eutrophication in the inlet is in Port Moody Arm where sufficient nutrients from sewage discharges and a relatively stable mixed-layer depth create near optimal conditions for phytoplankton growth. Daily production here is among the highest recorded in the literature for Pacific coastal marine waters. Key words: Phytoplankton, primary production, coastal marine embayment, fiord, phytoplankton succession and distribution, chlorophyll a
Periodicities in Atlantic Coast Striped Bass (Morone saxatilis) Commercial Fisheries Data
Authors: Winkle Webster Van , Kirk Bernadette L. , Rust Bert W.
Published: April 2011

Atlantic Coast striped bass (Morone saxatilis) commercial fisheries data are examined for periodicities in the appearance of dominant year-classes using autocorrelation and spectral-analysis techniques. Results obtained using maximum entropy and classical Fourier spectral-analysis methods are compared. Statistically significant periodicities of approximately 20 yr and of 6–8 yr are common to the time series for most states and regions. Since the periodicities are neither very pronounced nor simple, it is difficult to isolate the causative factors, which are more likely to be density-independent environmental factors enhancing survival of the young than intrinsic characteristics of the life cycle of striped bass. The spectra for Maryland landings and Maryland landings per unit gear are nearly identical, suggesting that at least for Maryland the landings and landings-per-unit-gear data are approximately equally reliable as indices of stock size. The structure of the North Carolina time series is unique, which supports the opinion that this stock does not mix appreciably with Chesapeake and Hudson stocks. Impact assessments and monitoring programs should not be predicted on the expectation of pronounced or simple periodicities of 6 years or any other time interval in the appearance of dominant year-classes in Atlantic Coast striped bass populations. Key words: autocorrelation analysis, commercial fisheries data, Fourier spectral analysis, maximum entropy spectral analysis, periodicities, striped bass
Comparison of a High Volume Pump and Conventional Plankton Nets for Collecting Fish Larvae Entrained in Power Plant Cooling Systems
Authors: Leithiser Ronald M. , Ehrlich Karl F. , Thum Alan B.
Published: April 2011

A high volume pump (2.5 m3/min capacity at 6 m head) and conventional plankton nets (0.5 and 1.0 m diam) were operated side by side in two tests to evaluate the efficiency of each gear for sampling fish larvae within the intake structure of a coastal power plant. At intake channel current velocities up to 40 cm/s (the maximum tested), the pump in one test caught significantly more fish larvae than the nets. Compared to the pump, both sizes of plankton nets in each test greatly undersampled large larvae (over 5.0 mm total length). Our findings suggest that conclusions regarding ichthyoplankton entrainment based on data obtained with conventional plankton nets may be of questionable validity. Key words: ichthyoplankton, entrainment, pump, nets
Maybe You Can't Get There from Here: A Foreshortened History of Research in Relation to Management of Pacific Salmon
Authors: Larkin P. A.
Published: April 2011

The standard religion of Pacific salmon research and management was developed by the 1930s and persists today: that adequate husbandry of the resource requires research on the biology of salmon, regulation to ensure sustained yield, protection of the environment to ensure the means of production, and enhancement measures to augment natural production and to mitigate effects of imperfect regulation and protection. Through the 1930s into the 1950s, there were substantial gains in understanding the biology of salmon and relating it to management. Salmon cultural techniques fell into disrepute. In the 1950s and 1960s, the pressures of other resource uses and international conventions greatly expanded perceptions of management and stimulated major discoveries about salmon biology. Economists began to seriously examine the salmon fisheries and perceived the need for limited entry. By the late 1960s the salmon fishery had become highly complex and there was a resurrection of the erstwhile hopes for salmon culture as an integral part of management. Planning exercises for the Salmonid Enhancement Program underlined that integration into a total system of management was crucial to success.For the future, for salmon to be doubled in abundance rather than halved, the manager's perspective must be more closely identified with that of salmon. In addition to the continuing needs for protection of environment and a broadly balanced enhancement program with an appropriate amount of research and evaluation, there are some necessary changes in attitude concerning regulation. Under no circumstances should the permissible harvest of any race of salmon be exceeded. Day-to-day regulation should be geared to salmon biology, not human convenience. Experimental regimes of regulation should be undertaken with suitable commitment to long-term research. Unless such measures are taken, it is realistic to speculate that "maybe we can't get there from here." Key words: Pacific salmon, resource management, salmonid enhancement
ATP as a Measure of Living Phytoplankton Carbon in Estuaries
Authors: Sinclair Michael , Keighan Edric , Jones Jerry
Published: April 2011

An attempt has been made to evaluate the accuracy of ATP as a measure of living phytoplankton carbon in estuaries. Phytoplankton carbon estimated from ATP was compared to estimates from cell counts. In high biomass samples the agreement between the two estimates was quite good. In the low biomass samples the cell count method underestimated phytoplankton carbon relative to the ATP estimate. This was interpreted to be due in part to low cell counts in these samples. Contamination by microzooplankton (essentially only tintinnids) was, in 14 out of the 18 samples, < 3% of the ATP estimated carbon. However, it was as high as 19% in one case. In the lowest biomass samples (< 0.5 μg chlorophyll a/L) bacterial populations may contribute as much as 50% of the total living carbon. It is concluded that, with caution, ATP is a useful measure of living phytoplankton carbon in estuaries during periods of moderate to high biomass (> 1 μg chlorophyll a/L for the St. Lawrence). Since carbon to chlorophyll ratios in the high biomass samples varied considerably, a constant ratio appears inapplicable for transforming chlorophyll to carbon. Key words: ATP, phytoplankton biomass, estuaries, carbon to chlorophyll ratio
The Intrusion of Fine Sediments into a Stable Gravel Bed
Authors: Beschta Robert L. , Jackson William L.
Published: April 2011

A rectangular flume was used to study variables affecting the intrusion of fine sands into a stable gravel streambed. The amount of intrusion by sand (median particle diameter 0.5 mm) was determined under varied conditions of discharge, depth, velocity, flume slope, and rates of sediment transport. During all experimental tests, sand particles were trapped in voids within the upper 10 cm of an initially clean gravel bed (median particle diameter 15 mm), forming a barrier to further intrusion. An analysis of flow variables showed that flow conditions, as indexed by Froude number, significantly (90% confidence level) affected intrusion amounts, possibly by influencing the rate and depth of formation of the sand seal. Intrusion amounts, expressed as a percent of total volume, varied from 2 to 8%. Two replications used a finer grade sand (median particle diameter 0.2 mm) that intruded more and, in one case, completely filled the gravel pore space (25% by volume), further indicating that particle size, and not hydraulic variables, may have a more important influence on the total amount of intrusion. Key words: sediment transport, intrusion, streambed, substrates, riffles, sedimentation
Control of Rancidity in Frozen Pacific Herring, Clupea harengus pallasi: Use of Sodium Erythorbate
Authors: Bilinski E. , Jonas R. E. E. , Lau Y. C.
Published: April 2011

The effectiveness of 1% sodium erythorbate (NaER) and other treatments for retarding the development of rancidity was studied in Pacific herring, Clupea harengus pallasi, fillets stored at −28 °C. Dipping of fillets in NaER significantly decreased fat oxidation. Glazing with NaER was more effective than a water glaze alone. The addition of NaER to water used for enclosing fillets in ice blocks increased the protection against rancidity. All tested NaER applications were less effective in retarding rancidity than the vacuum packaging. Erythorbic acid uptake by the flesh reaching 0.2% caused a deterioration of the flavor, whereas uptake of 0.05% or less led to no discernible alterations in flavor or appearance. Therefore, when used at low levels (uptake ≤0.05%), NaER has a potential value for extending the storage life of frozen herring. Key words: Pacific herring, Clupea harengus pallasi, control of rancidity, sodium erythorbate, frozen storage
An Introduction to the Aquatic Insects of North America.
Authors: Flannagan John F.
Published: April 2011

not available
Environmental Disturbance and Life Histories: Principles and Examples
Authors: Lehmkuhl D. M.
Published: April 2011

While many environmental disturbances have no readily detectable effect on aquatic invertebrates in the short term, they may prevent normal reproduction and cause eventual local extinction of a species. Small temperature changes may interfere with diapause signals and prevent completion of the life cycle. Heavy metals and toxic substances may drastically reduce reproduction rates in species exposed to sublethal levels. Dissolved salts and pH affect organisms at abnormally high or low levels but most mechanisms are unknown. It is concluded that relatively little information is available on the effects of environmental disturbances on life cycles. Available information, however, is sufficient to provide evidence of many problems that require attention. Key words: life histories, benthos, environmental disturbances, toxic substances, diapause, temperature, heavy metals
Timing and Magnitude of Energy Deposition and Loss in the Body, Liver, and Gonads of Northern Pike (Esox lucius)
Authors: Diana James S. , Mackay W. C.
Published: April 2011

Northern pike (Esox lucius) were sampled periodically from Lac Ste. Anne, Alberta, between March 1976 and September 1978. The yearly cycle of production and depletion was determined for individual 3-yr-old fish. Body growth in length was similar for both sexes, and occurred during the summer. Somatic caloric growth was completed during the summer by females, while male somatic growth continued over winter. Gonad growth began in August; testicular growth was completed by September while ovarian growth occurred mainly during winter. There was no loss of somatic energy during ovary growth. Energy requirements for testicular growth appeared to come from liver stores. Both sexes lost considerable somatic energy between March and May, the spawning period; this loss appeared to be due to spawning activity and not late gonad growth. Young-of-year fish did not mature sexually and all of their energy accumulation went into somatic tissue. Total production in females from May to March was twice as high as production in males. Both sexes had similar yearly somatic production, while females had approximately 15 fold higher gonadal production than males. Key words: calories, growth, liver, gonad, somatic, Esox lucius, production, spawning depletion
Detritus and Juvenile Salmon Production in the Nanaimo Estuary: I. Production and Feeding Rates of Juvenile Chum Salmon (Oncorhynchus keta)
Authors: Healey M. C.
Published: April 2011

Theories of food chain dynamics have important implications for the management of marine resources. As yet, however, there are few empirical studies of the food chain dynamics of resource species against which these theories can be judged. This paper compares the food requirements of juvenile chum salmon (Oncorhynchus keta) in the Nanaimo Estuary with the productivity of their principal food species. Chum were present in the estuary from March until June and the estuary population ranged up to 4.1 million in May 1975 and 2.4 million in April 1976. The average weight of chum was 0.66 g in 1975 and 0.65 g in 1976, and their rate of growth averaged ~6% body weight per day in both years. Food intake estimated by three independent methods ranged 4.4–18% body weight per day and was assumed to average 15% body weight per day. Annual fry production was 2381 kg in 1975 and 1122 kg in 1976. Food intake was 6184 kg in 1975 and 2815 kg in 1976. The principal dietary item in both years was harpacticoid copepods. In 1975 Harpacticus uniremis made up 50% of the diet overall, and >80% of the diet when fry were most abundant. The seasonal pattern of abundance of fry and H. uniremis on the estuary was the same, and the fry consumed most of the estimated production of H. uniremis. Juvenile chum production was potentially limited by food supply. Food chain dynamics were, therefore, important in the productivity of the chum population, but since both chum and its chief food were rare and ephemeral elements of the estuarine fauna, their interaction probably had little impact on the dynamics of the estuary as a whole. Key words: chum salmon, estuaries, food chains, populations, feeding rates
Physiological and Biochemical Aspects of Ozone Toxicity to Rainbow Trout (Salmo gairdneri)
Authors: Wedemeyer Gary A. , Nelson Nancy C. , Yasutake William T.
Published: April 2011

An acute toxicity curve for dissolved ozone (O3) in soft water at 10 °C, using 10–13-cm rainbow trout (Salmo gairdneri) as the test species was calculated. The 96-h LC50 (95%, confidence interval) was 9.3 (8.1–10.6) μg/L. The lethal threshold level was about 8 μg/L mandating that a conservative margin of safety be used if ozone is employed as a fish disease control agent. Death apparently results from massive destruction of the gill lamellar epithelium together with a severe hydromineral imbalance. In partial chronic (3-mo) testing, 2 μg/L caused no significant biological damage while 5 μg/L caused some gill pathological changes and reduced feeding behavior. Accordingly, 2 μg/L is suggested as a provisional maximum safe exposure level, pending completion of life cycle studies. Thus, if ozone-treated water is discharged into the environment, dissolved O3 should be reduced to at least the 2 μg/L level to minimize adverse impacts on salmonids in receiving waters. Key words: ozone, fish toxicity, acute ozone toxicity, chronic ozone toxicity, Salmo gairdneri
Role of Tubificid Worms on Nitrogen Transformations in Stream Sediment
Authors: Chatarpaul L. , Robinson J. B. , Kaushik N. K.
Published: April 2011

Sediments obtained from Swifts Brook were highly organic whereas those from Canagagigue Creek were coarse-textured with relatively little organic content. Columns of sediment were overlain with continuously aerated 10 mg/L nitrate-N solution or distilled water. When columns of Canagagigue sediment with tubificid worms (Tubifex tubifex and Limnodrilus hoffmeisteri) were incubated for 33 d they lost nitrate-N at a significantly higher rate (P < 0.01) than did columns without worms. Following the initial period of nitrate disappearance (resulting from denitrification in the sediment) nitrate-N increased again, this increase being greatest in the presence of worms. The increasing concentration of nitrate-N probably resulted from nitrification which was masked early in the experiment by rapid denitrification. In columns with Swifts Brook sediment, added nitrate disappeared rapidly but no significant difference was observed between the columns with worms and those without; nitrate-N concentration was never observed to increase. Possibly both nitrification and denitrification are also enhanced here by the presence of tubificids but the effects are masked. Key words: tubificids, denitrification, nitrification, stream sediment, nitrate, ammonium, fecal pellets