bluuebunny/crossref_metadata_2025 huggingface dataset:
Food Availability and Consumption by Young Connecticut River Shad Alosa sapidissima
Authors: Levesque Raymond C. , Reed Roger J.
Published: April 2011

Food habits of young American shad (Alosa sapidissima) were studied in the Connecticut River above Holyoke, Massachusetts, 1969. Diurnal feeding data revealed a peak in stomach content volume at 8:00 PM during midsummer. Larval shad fed mainly on aquatic crustaceans and tendipedid larvae and pupae. Juveniles ingested the most abundant organisms: crustaceans, tendipedid larvae and pupae, hydropsychid larvae and adult insects. Electivity data indicated positive selection for tendipedid pupae and crustaceans and negative selection for hydropsychid larvae and tendipedid larvae. Selection of Trichoptera larvae by young shad in significant amounts was documented for the initial time.
Antibiotic Toxicity, Efficacy, and Teratogenicity in Adult Spring Chinook Salmon (Oncorhynchus tshawytscha)
Authors: DeCew Mark G.
Published: April 2011

Antibiotics were tested for toxicity and efficacy in adult spring chinook salmon (Oncorhynchus tshawytscha) infected with bacterial kidney disease and furunculosis. The complex of penicillin G procaine, dihydrostreptomycin sulfate, and oxytetracycline-HCl was not toxic and it effectively controlled both diseases, producing a three-fold increase in adult survival and production of viable eggs.Mandible and fin teratogenesis occurred in progeny of adults treated with the above antibiotic complex, but could be reduced by providing a 32 day interim between injection and spawning.
Methylmercury in Northern Pike (Esox lucius): Distribution, Elimination, and Some Biochemical Characteristics of Contaminated Fish
Authors: Lockhart W. L. , Uthe J. F. , Kenney A. R. , Mehrle P. M.
Published: April 2011

Northern pike heavily contaminated with methylmercury were captured from Clay Lake, Ontario, and released in Heming Lake, Manitoba, an area relatively free of mercury. Mercury levels in muscle biopsy samples at the time of transfer and at subsequent recaptures indicated that only 30% was eliminated in one year. Distribution among various body tissues was essentially unchanged, those organs most heavily contaminated being lens, kidney, and liver in decreasing order. Biochemical profiles of blood serum constituents showed several differences between samples from the two lakes, especially in levels of inorganic phosphate, total protein, alkaline phosphatase, and cortisol. Serum values for transplanted fish tended toward those in the clean lake and we have concluded that biochemical profiles were sensitive to the environmental change.
Voltage and Pulse Rates for Inducing Electrotaxis in Twelve Coastal Pelagic and Bottom Fishes
Authors: Klima Edward F.
Published: April 2011

Laboratory observations on fish reactions to different voltages and direct current pulse rates provided information on the electrical characteristics needed for inducing electrotaxis for use in a proposed automated harvesting system. Optimal electrical combinations for 12 species of coastal pelagic and bottom fishes varied according to species and length, and ranged from 1.5 to 3.0 v/10 cm at 15–45 pulses/sec with a pulse duration of 1.0 msec.
Acidification and Bubbling as an Alternative to Filtration in Determining Phytoplankton Production by the 14C Method
Authors: Schindler D. W. , Schmidt R. V. , Reid R. A.
Published: April 2011

Acidification and bubbling was found superior to membrane-filtration for post-incubation treatment of 14C-productivity samples. The method eliminates errors associated with filtration. Results are compared with those of conventional and corrected filtration procedures, and application of the method is discussed.
Comparison of the Efficiency of Various Aeration Devices for Oxygenation of Water in Aquaria
Authors: Scott K. R.
Published: April 2011

Efficiencies of aeration of five different combinations of Venturis, air stones, and sprays were measured in a 1.8-m3 tank. Results showed that the venturi method discharging through a nozzle near the tank bottom had the highest efficiency. Air stones were 53% as effective and sprays directed at the surface 41% as effective as the venturi method. Details are given for fabrication of the PVC (polyvinyl chloride) venturi. The unit is reliable, inexpensive, and eliminates the need for a separate air supply.
Population Biomass, Number of Individuals, Average Individual Weight, and the Linear Surplus-Production Model
Authors: Jensen A. L.
Published: April 2011

The identity [Formula: see text], where Bt is the population biomass, Nt is the population size, and [Formula: see text] is the average individual weight for all ages, is applied to develop simultaneous equations for change in biomass, number of individuals, and average individual weight for the linear surplus-production equation. It is shown that equations for all three variables cannot be simultaneously logistic. The relation between logeNt and [Formula: see text] predicted by the linear surplus-production model is compared with observations of bluegill population densities and average weights estimated from 10 years of cove rotenone sampling in five large TVA reservoirs. The fit of the model to the data is fairly good, but it accounts for only a small amount of the total variation observed.
Effect of Cations on the Interaction Between Paralytic Shellfish Poison and Butter Clam (Saxidomus giganteus) Melanin
Authors: Price R. J. , Lee J. S.
Published: April 2011

The interaction between paralytic shellfish poison (PSP) and butter clam (Saxidomus giganteus) melanin was strongly influenced by the presence of cations. The amount of PSP bound by the melanin decreased by 68% in the presence of Al+++, 62 and 57%, respectively, with Ca++ and Ba++, and 17 and 15% with Na+ and K+. Salt solutions containing 0.01-M Al+++, Mg++, Ca++, Ba++, Na+, or K+ induced the desorption of PSP bound to melanin by 54, 34, 28, 19, 11, and 4%, respectively. These results confirm our earlier conclusion that the PSP–melanin interaction is reversible and electrostatic in nature.
Morphological and Meristic Variation in Northwest Atlantic Sand Lances (Ammodytes)
Authors: Scott J. S.
Published: April 2011

Morphological characteristics of Ammodytes species from Greenland to New England showed little variation from area to area, except for mean and maximum lengths which increased offshore from north to south and from inshore to offshore. Meristic numbers (dorsal and anal fin rays, vertebrae) were fairly uniform for offshore stocks, but reduced values in Gulf of St. Lawrence and off Cape Cod bridged the gap between offshore (A. dubius) and inshore (A. hexapterus) values which had previously been used to differentiate the species.Weight–length relations conformed to the standard weight–length equation and were similar over the Nova Scotia and Newfoundland grand banks. There was a considerable difference between prespawning and postspawning fish, indicating a 30% loss in weight during spawning.There appeared to be a close relation between morphological and meristic variation, and environment. Changes in fish size and meristic numbers corresponded to changes in water temperature, but observed ranges in meristic numbers were much greater than experimentally induced changes in other species, and genetic variation between stocks is difficult to discount.
Morphological Differences in Male Gonads Among Nine Genera of Gadidae (Pisces)
Authors: Vladykov V. D.
Published: April 2011

Among 12 species of Gadidae, which belong to nine genera and three subfamilies six basic types of male gonads are observed. In the freshwater genus, Lota, gonads are simple nearly cylindrical m shape, and not subdivided into lobes. In the marine genera of cold waters, such as Melanogrammus and Gadus, the other extreme in gonad structure, consisting of numerous, rather uniform convolutions, is found. In the marine genera Urophycis and Merluccius of more temperate waters, the male gonads consist of several lobes, rather irregular in shape and size. Among genera inhabiting brackish and sometimes fresh water, such as Microgadus, Boreogadus, and Eleginus, the gonads are subdivided into lobes which are not very numerous. In the genus Arctogadus, distributed in salt and brackish Arctic waters, the gonads are intermediate m their complexity between the typical marine genera of cold water, Melanogrammus and Gadus, and those three genera inhabiting brackish waters. The explanation for the morphological differences in male gonads of Gadidae appears to be associated principally with the respective type of waters (salt or fresh) which they inhabit and their spawning requirements and to a much lesser degree with their systematic relationships.
Size at Maturity, Fecundity, and Embryonic Growth of the Spiny Dogfish (Squalus acanthias) in British Columbia Waters
Authors: Ketchen K. S.
Published: April 2011

Information on the biology of dogfish in British Columbia waters, none of it previously reported, is compared with similar information from other areas of the North Pacific as well as the North Atlantic.Males and females on both sides of the Pacific have an approximate maximum size of 100 and 130 cm, respectively, or at least 10 cm greater than in the North Atlantic. Females in the North Pacific mature at an average length of 92–100 cm depending on region, as compared to 77–82 cm in the North Atlantic. Males likewise mature at a larger size in the North Pacific.Observations in Canadian west coast waters show a weak correlation between number of embryos and length of the mother (r = 0.57).Female dogfish produce 2–17 young with an average of 6–7 in the North Pacific off the British Columbia coast; 3–25, averaging 12 in the Sea of Japan; 1–9, averaging 4 in the northwest Atlantic; and 1–10, averaging 3–5 in the northeast Atlantic. Size at birth is about the same throughout the northern hemisphere being between 23 and 30 cm with an average of 25–27 cm.Intrauterine growth rate is essentially the same in all regions, but at any given time of year differences is size are substantial and are determined largely by differences in time of conception.
Social Interaction Between Juvenile Coho (Oncorhynchus kisutch) and Fall Chinook Salmon (O. tshawytscha) in Sixes River, Oregon
Authors: Stein Roy A. , Reimers Paul E. , Hall James D.
Published: April 2011

Spawning and emergence of coho and fall chinook salmon overlapped in timing and location in Sixes River, Oregon. In early spring both species were distributed throughout most of the river system. Underwater observations during this period indicated that both species occupied the same habitat. As temperatures increased, coho disappeared from the main river, but continued to occupy cool tributaries. Fall chinook were found primarily in the main river until early summer, when they moved to the estuary.In flowing-water observation troughs coho assumed social dominance and defended space near the source of incoming food. In allopatry in the troughs, both grew at similar rates, but coho maintained lower population densities than did chinook. In sympatry in the troughs or in cool tributary streams, coho grew faster than chinook. Coho had brighter fin and body colors, greater fin development, deeper bodies, and were heavier than fall chinook of the same length.Our study suggests that the population of fall chinook salmon in Sixes River might be adversely affected by an increase in numbers of coho. Our evidence suggests that ecology of native fishes should be examined closely before widespread manipulation of fish stocks is encouraged.
Some Physiological Consequences of Handling Stress in the Juvenile Coho Salmon (Oncorhynchus kisutch) and Steelhead Trout (Salmo gairdneri)
Authors: Wedemeyer Gary
Published: April 2011

The stress of handling juvenile coho salmon (Oncorhynchus kisutch) and steelhead trout (Salmo gairdneri) in soft water and in water with added salts was evaluated using blood and tissue chemistry fluctuations as indices of metabolic and endocrine function. Changes in plasma glucose, chloride, calcium, and cholesterol levels indicated that significant osmoregulatory and metabolic dysfunctions can occur and persist for about 24 hr after handling in soft water. Pituitary activation, as judged by lack of interrenal ascorbate depletion, did not occur. Increasing the ambient NaCl and Ca++ levels to about 100 milliosmols and 75–120 ppm, respectively, partially or completely alleviated the hyperglycemia and hypochloremia indicating that the stress of handling had been reduced.
Food of Pacific Hake (Merluccius productus) on an Offshore Bank Southwest of Vancouver Island, British Columbia
Authors: Outram Donald N. , Haegele C.
Published: April 2011

In 1196 adult Pacific hake (Merluccius productus) stomachs from off the British Columbia coast euphausiids occurred in 94%; Pacific sandlance (Ammodytes hexapterus) in 26%; Pacific herring (Clupea harengus pallasii) and eulachon (Thaleichthys pacificus) each 5%; and lanternfish, young rockfish, northern anchovy (Engraulis mordax), and pandalid shrimp each in 3% or less. Fish, particularly herring, were of greater importance in the diet of larger hake. The extent of stomach fullness and the stage of digestion of stomach contents were similar for all sizes of hake taken in daylight tows. The presence of fresh to near-fresh organisms in only 9% of the stomachs, coupled with large numbers (52%) of empty to near-empty stomachs, indicated low feeding activity during daylight hours.
The Effects of Starvation and Subsequent Feeding on Survival and Growth of Fulton Channel Sockeye Salmon Fry (Oncorhynchus nerka)
Authors: Bilton H. T. , Robins G. L.
Published: April 2011

In the laboratory 8 groups of Fulton River channel fry were starved for periods ranging from 1 to 7 weeks, then offered food ad libitum for 8 weeks. Fry withstood up to 4-weeks starvation with less than 10% mortality; beyond this point mortality increased sharply to 90% at 7-weeks starvation. At 5-weeks starvation both fry length and weight decreased significantly. Mortality continued when fish were offered food ad libitum after being starved. Among fish starved for 1 and 2 weeks, mortalities continued to be low, 0 and 6.6%, respectively; but, among fish starved from 3 to 5 weeks, mortalities rose considerably, ranging from 42 to 99%.
Etude du métabolisme de l’eau et de l’azote dans l’hépatopancréas et l’ovaire de Carcinus maenas
Authors: Martin J.-L. M.
Published: April 2011

Measurements were made of variations in water, protein, and soluble nitrogen in the hepatopancreas of Carcinus maenas during the intermolt cycle and in the ovary during ovogenesis. Analyses of hepatopancreas show three reasons for the variations in protein and soluble nitrogen contents: entry of water into the organism during and after exuviation and a corresponding dilution of the constituents, alternation of fasting and feeding during the intermolt cycle, and heavy demands of ovogenesis resulting in a decrease in nitrogen in the hepatopancreas. Variations in the metabolism of water and nitrogen are shown in the ovary during ovogenesis.
Hexose Monophosphate Accumulation and Related Metabolic Changes in Unfrozen and Thawed Adductor Muscle of the Sea Scallop (Placopecten magellanicus)
Authors: Hiltz Doris Fraser , Dyer W. J.
Published: April 2011

The hexose monophosphates (glucose-6-phosphate (G6P), fructose-6-phosphate, and glucose-1-phosphate) accumulate postmortem in scallop adductor muscle (meats) during chill storage, increasing from only traces at death to levels totalling about 10 μmole/g after 8–10 days. In both unfrozen and thawed meats, G6P accounted consistently for 80–85% of the total hexose monophosphate, over a wide range of actual concentrations. Quick freezing at any time postmortem did not affect the concentrations of hexose monophosphates or related metabolic constituents. Thawing of the prerigor-frozen muscle, however, either slowly or rapidly, resulted in considerable G6P formation, and accelerated markedly the subsequent rate and extent of G6P production. The exceptionally high levels (− 20 μmole/g) reached in the thawed meats after 1–2 days at 5 C are implicated in the development of burned flavors, odors, and discolorations (i.e. Maillard browning reactions) observed in these thawed meats when cooked. While thawing of the prerigor-frozen muscle led to some hypoxanthine (Hx) and octopine formation, the subsequent rate of Hx accumulation at 5 C was three times faster in the thawed meats than in unfrozen meats. In meats frozen postrigor, thawing resulted in negligible change in concentrations of the metabolites; subsequent patterns of change during storage differed little from those in unfrozen muscle, although Hx accumulation was more rapid. Hx content showed potential as an index of quality in thawed scallop muscle.
Effects of Bunker C Oil on Intertidal and Lagoonal Biota in Chedabucto Bay, Nova Scotia
Authors: Thomas Martin L. H.
Published: April 2011

In February 1970, a large spill of Bunker C oil occurred in Chedabucto Bay, Nova Scotia. The incident was of particular interest since large spills of this type of oil had not previously been studied. Further interest was added by the unusually cold temperatures and by the nonuse of detergents in cleanup. The effects of the oil on intertidal and lagoonal biota have been followed since the accident. Many rocky shores and lagoons were heavily oiled. On exposed shores, oil has decreased steadily since oil stopped coming ashore in mid-1970 and by August 1971 only small amounts remained. In sheltered areas, particularly lagoons, heavy oil contamination remains. The summer remobilisation and subsequent redeposition of oil added a chronic aspect to the pollution. Initial effects of oil involved minor smothering of fauna and tearing loose of algae. Longer term effects involved extensive mortalities of Fucus spiralis on rocky shores and Mya arenaria and Spartina alterniflora in lagoons. Other biota were not visually affected. In all three affected species, mortalities took place either continuously or only in the second year of pollution. Causes of death are unknown. It is recommended that in all intertidal areas very heavy oil deposits should be mechanically removed and the remainder of the oil left to natural degradation.
Hunters, Trappers, and Gatherers of the Sea: a Comparative Study of Fishing Strategies
Authors: Cove J. J.
Published: April 2011

This study is a comparison of fishing strategies in three areas: the Newfoundland offshore fishery, the inshore salmon fishery of British Columbia, and an oyster fishery of Cornwall, England. From the Newfoundland fishery, a model was developed to account for differences in risk-taking by fishing captains. The model specified relations between reward structure, technology, and environment that influence captains’ evaluations and, hence, decision-making.The model was then tested in the other fishing contexts. The results indicate that the situational approach to risk-taking can be used for the problem of understanding short-term production strategies. This particular model, however, requires the addition of an historical dimension in order to adequately account for decision-making in all three fisheries.
Annual Life Cycle and Production of the Chaetognath Sagitta elegans in Bedford Basin, Nova Scotia
Authors: Sameoto D. D.
Published: April 2011

In Bedford Basin, Nova Scotia, Sagitta elegans has two main generations per year, one in the spring and one in the fall. The biomass of S. elegans per 100 m3 of water was an order of magnitude greater in the Basin than that reported previously for St. Margaret’s Bay, N.S. The growth rate and the number of degree days needed to mature were similar to those found for S. elegans in St. Margaret’s Bay. Annual turnover rate for S. elegans in the Basin was 5.6 and yearly production was estimated at 27.0 kcal per year or 9.0% of the yearly copepod production. It was calculated that the species used 90.4 kcal per m2 per year in respiration. The percentage of the total yearly production of copepods consumed by S. elegans was estimated at 36%.
A Quantitative, Semiroutine Method for Determining Algal and Sedimentary Chlorophyll Derivatives
Authors: Daley Ralph J. , Gray C. B. J. , Brown S. R.
Published: April 2011

An integrated, quantitative method is described for the determination of chlorophylls and chlorophyll degradation products in freshwater phytoplankton and sediments. Prior to extraction, algal samples were concentrated by filtration through glass fiber filters while sediment samples were lyophilized. All materials were extracted in a mixture of acetone, methanol, and water (80:15:5) by ultrasonication in a glass extraction chamber refrigerated at −10 C. Extracts were filtered through solvent-resistent membrane filters, rather than centrifuged, and then fractionated without prior drying by reverse-phase thin-layer chromatography on oil-impregnated layers of kieselguhr G. Using three chromatographic systems consisting of different developing solvents and oil phases (triolein, parrafin oil, and castor oil), rapid, artefact-free separations of chlorophylls a, b, and c and 18 of their derivatives were obtained. Individual pigments were estimated by direct, in situ thin-layer scanning with a filter fluorometer. The sensitivity and reproducibility of the procedure are ca. 2 ng and 11%, respectively. In routine operation, the method is fast and relatively simple, a complete analysis being accomplished in 1.5 hr.
Diet, Time and Place of Spawning, and Environments Occupied by Creek Chub (Semotilus atromaculatus) in the Mink River, Manitoba
Authors: Moshenko Robert W. , Gee John H.
Published: April 2011

Creek chub (Semotilus atromaculatus) are omnivorous with a diet consisting of berries, insects, crayfish, noncyprinid fishes, and frogs. In 1971, in the Mink River, most spawning occurred between the middle and end of May in shallow (< 25 cm) fast-flowing (> 15 cm/sec) waters. Fecundity varied from 1146 to 7539 ova per female. In summer most chub in their 1st and 2nd years occupied moderately deep waters (< 50 cm) with little current (0–30 cm/sec), while most older chub occupied deeper waters. In autumn chub were most abundant in deep (> 50 cm) sheltered pools, where they overwintered.
Inheritance of Thermal Resistance in Hybrids of Salvelinus fontinalis and S. namaycush
Authors: Ihssen Peter
Published: April 2011

The two reciprocal F1 hybrids of brook trout (Salvelinus fontinalis) and lake trout (S. namaycush) had similar times to death on exposure to several lethal high temperatures for a series of acclimation temperatures. These hybrids resembled the brook trout, the more resistant parent, more than the lake trout. The F2 hybrids were intermediate in resistance to the parent species, and the backcrosses intermediate between the F2 hybrids and the respective parents. After acclimation to 5 and 10 C, F2’s and backcrosses arising from the F1 hybrid of brook trout maternal origin were consistently higher in resistance than the F2 and backcrosses arising from the F1 hybrid of lake trout maternal origin. After acclimation to 20 C and above, differences associated with the maternal origin of the F1 hybrid were not found.The number of effective factors segregating was estimated using the techniques of variance component analysis. A genetic model with two codominant factors was found to fit the data for 5 and 10 C acclimation, and one with five factors and dominance of the brook trout factors was found to fit the data for the higher acclimation temperatures.
Total Mercury and Methylmercury Content of the American Eel (Anguilla rostrata)
Authors: Freeman H. C. , Horne D. A.
Published: April 2011

In American eels (Anguilla rostrata) caught in Nova Scotia, the total mercury content was found to be 0.72 ± 0.05 ppm and the methylmercury content was 0.40 ± 0.06 ppm (mean ± SE for 23 fish). Since the mean total mercury content was less than 1 ppm and the toxic methylmercury content was 50% of this, or less than the 0.5 ppm guideline, such eels may be acceptable for human consumption.
Additional Notes on Polychaetes as Intermediate Hosts of Helminth Parasites of Vertebrates
Authors: Margolis L.
Published: April 2011

Additions and corrections to the records of larval helminths in polychaetes reviewed by Margolis (1971) are summarized.
Effects of Sublethal Concentrations of Sodium Pentachlorophenate on Growth Rate, Food Conversion Efficiency, and Swimming Performance in Underyearling Sockeye Salmon (Oncorhynchus nerka)
Authors: Webb P. W. , Brett J. R.
Published: April 2011

Tests were performed at 15 C, pH 6.8, and dissolved oxygen values of 90–100% air saturation. Growth rate and conversion efficiency were measured by feeding a ration level of 15% body dry weight/day to underyearling sockeye salmon (Oncorhynchus nerka) held at sodium pentachlorophenate (PCP) concentrations of 0, 1.14, 1.99, 3.49, 7.16, 13.60, 27.73, 31.57, and 47.18 ppb. Swimming performance was measured at PCP concentrations of 0, 7.21, 19.00, and 50.00 ppb. The 96-hr LC50 was 63 ppb PCP. Growth rate and conversion efficiency were almost equally affected by PCP, the EC50 values being 1.74 ppb for growth rate and 1.80 ppb for conversion efficiency. This is approximately 2.8% of the 96-hr LC50. Swimming performance was unaffected by PCP at the concentrations used.
Crustacean Plankton and the Eutrophication of Lakes in the Okanagan Valley, British Columbia
Authors: Patalas Kazimierz , Salki Alex
Published: April 2011

In early September 1969 and late August 1971, the vertical and horizontal distribution of temperature, Secchi disc visibility, some chemical components, and zooplankton abundance in lakes Okanagan, Skaha, and Osoyoos were investigated. In addition, lakes Kalamalka and Wood were sampled only in late August 1971. Four different basins could be distinguished in Lake Okanagan: the Penticton-Summerland basin, the Peachland-Kelowna basin, a basin north of Kelowna, and one formed by the northern end of the lake. Total dissolved solids, calcium, and electrical conductivity within the lake decreased gradually from north to south. Macroelement values within lakes Okanagan, Skaha, and Osoyoos were apparently not substantially different but Kalamalka and Wood lakes were about twice higher in sodium, potassium, magnesium, and about 1.5 higher in total dissolved solids. Four species of copepods and nine species of cladocerans were found with Cyclops bicuspidatus thomasi and Diaptomus ashlandi dominant in all five lakes. Diaphanosoma leuchtenbergianum and Daphnia longiremis were the most common cladocerans in all five lakes. Also, Daphnia thorata was common in all except Wood Lake. Eighty-nine percent of the total plankters in Lake Okanagan were located in the upper 50-m layer. Relatively little horizontal variation was found within the lake but two areas, near Kelowna and in the northern end showed in both years of investigation greater abundance of plankton than the remaining areas. Crustaceans were usually less abundant inshore than offshore. Volume of settled net plankton varied from 8 mm3/cm2 in Okanagan Lake to 31 mm3/cm2 in Wood Lake. No substantial changes in species composition of zooplankton, Secchi disc visibility, and dissolved oxygen in the hypolimnion were found relative to the data of 1935 reported by Rawson. However, in 1969 and 1971 net plankton volumes were about five and three times larger, respectively, than in 1935. Calculations of total phosphorus load from two independent sources of data provided similar results and indicated that lakes Okanagan and Kalamalka are still in the oligotrophic range but close to mesotrophy. Lake Wood is moderately eutrophic and lakes Skaha and Osoyoos showed a marked degree of eutrophy, higher than in Lake Washington, U.S.A. before sewage diversion, or in Lake Erie. The estimates for lakes Wood, Skaha, and Osoyoos were supported by the values of the hypolimnetic areal deficits characteristic for highly eutrophic lakes. The trend of changes in phosphorus load during the past century is presented and predictions are made about the load in 1990 in situations with and without phosphorus removal from sewage.
Fecundity of Resident and Anadromous Dolly Varden (Salvelinus malma) in Southeastern Alaska
Authors: Blackett R. F.
Published: April 2011

Fecundity of resident Dolly Varden (Salvelinus malma) in an isolated population of southeastern Alaska averaged 66 eggs per female in comparison with 1888 eggs for anadromous Dolly Varden from two nearby streams. A relatively large egg size, averaging 3.6 mm in diameter and overlapping the range for the anadromous char, has been retained by the females in the resident population. Curvilinear regressions between egg number and fish length and linear regressions between egg number and body and ovary weights show that resident females have fewer eggs per unit of length, approximately the same number of eggs per gram of body weight, and more eggs per gram of ovary weight than anadromous females. The resident char attain sexual maturity a year earlier in life and at a smaller size than the migratory char. Development of a larger left ovary containing more eggs than the right was a common occurrence for both resident and anadromous Dolly Varden.
Notes on the Whitefish of the Colville River, Alaska
Authors: Alt Kenneth T. , Kogl Dennis R.
Published: April 2011

Five whitefish species are present in the Colville River. Least cisco (Coregonus sardinella) was the most common species in the Colville Delta, while the broad whitefish (C. nasus) was most abundant at test net sites near Umiat.Limited age and growth data indicate slower growth than in interior Alaska waters.
Occurrence of Hybrids Between Longnose Sucker (Catostomus catostomus) and White Sucker (C. commersoni) in Upper Kananaskis Reservoir, Alberta
Authors: Nelson Joseph S.
Published: April 2011

Hybrids between longnose sucker (Catostomus catostomus) and white sucker (C. commersoni), identified on the basis of intermediacy in several scale counts and in morphometric data, are recorded for the first time from Canada. The weakening of isolating mechanisms permitting hybridization was attributed to environmental factors, particularly species introduction and habitat disturbance. There was no evidence of swamping.
Acute and Long-Term Accumulation of Copper by the Brown Bullhead, Ictalurus nebulosus
Authors: Brungs William A. , Leonard Edward N. , McKim James M.
Published: April 2011

Brown bullheads (Ictalurus nebulosus) were exposed to constant concentrations of copper ranging from 6.5 to 422 μg/liter. Copper concentrations in gill, opercle, liver, and kidney tissues of live fish did not differ from those that died during the acute exposure. Exposure of fish to sublethal concentrations for 20 days before exposure to lethal concentrations resulted in higher tissue levels in the dead fish than in fish not previously exposed. A distinct increase in liver and gill tissue copper concentrations occurred at exposure levels of 27 μg/liter and above. Equilibrium tissue levels of copper in the liver and gill were reached within 30 days. Copper levels in red blood cells and plasma after 20-months exposure did not differ from the controls. Red blood cells analyzed after 6-days and 30-days exposure to copper also showed no increased copper residues.
Variation of Organochlorine Residue Levels with Age in Gulf of St. Lawrence Harp Seals (Pagophilus groenlandicus)
Authors: Addison R. F. , Kerr S. R. , Dale J. , Sergeant D. E.
Published: April 2011

Blubber samples from 18 harp seals taken near the Saguenay River in the Gulf of St. Lawrence were analysed for DDT metabolites, PCBs, and dieldrin. The concentration of total DDT and metabolites [Formula: see text] ranged from 3.1 to 22.6 ppm, PCBs (as Aroclor® 1254) from 2 to 22 ppm, dieldrin from 0.1 to 0.3 ppm of blubber. Rank correlation of residue level and age indicated that significant portions of the [Formula: see text] and PCB variance could be assigned to increased residue levels with age. Within the [Formula: see text] group, DDE alone showed a strong proportional increase in concentration with age. Dieldrin concentration was not appreciably correlated with age. Among factors other than age, changes in blubber thickness did not account for any significant amount of the variance in blubber residue concentration. Examination of other published data suggested that parturition and/or lactation may cause reductions in blubber residue concentrations.
Sea Lamprey (Petromyzon marinus) Predation on Freshwater Teleosts
Authors: Farmer G. J. , Beamish F. W. H.
Published: April 2011

The incidence of attack by the sea lamprey (Petromyzon marinus) was studied on freshwater teleosts of similar and different size. Splake (Salvelinus namaycush × Salvelinus fontinalis), carp (Cyprinus carpio), and white suckers (Catostomus commersoni) were attacked a significantly greater number of times than lake whitefish (Coregonus clupeaformis), burbot (Lota lota), shorthead redhorse suckers (Moxostoma macrolepidotum), and brown bullheads (Ictalurus nebulosus). Lampreys rarely preyed upon walleye (Stizostedion vitreum vitreum). Most attacks occurred between the head and caudal peduncle below the lateral line and particularly in the region behind the pectoral fins. Lampreys attacked the largest individuals of any species more frequently than the smaller representatives. The presence of lampreys on a fish did not further the incidence of attack on that fish. None of the species of fish appeared to avoid lamprey attacks, nor did they avoid fish on which lampreys were attached. Only rarely were fish observed to dislodge lampreys.
An Outbreak of Columnaris Disease in White Suckers (Catostomus commersoni) in Saskatchewan
Authors: Wobeser G. , Atton F. M.
Published: April 2011

Columnaris disease, due to Chondrococcus columnaris, was diagnosed during a die-off of white suckers (Catostomus commersoni) in a lake in Saskatchewan. The pathology of the disease in white suckers is described. This is the first known report of columnaris disease from the prairie region of Canada.
Recent Changes in Stock Composition of Atlantic Salmon (Salmo salar) in the Miramichi River, New Brunswick
Authors: Ruggles C. P. , Turner G. E.
Published: April 2011

Data collected from 1954 to 1971 show that the recent decline in Miramichi River Atlantic salmon (Salmo salar) abundance has been accompanied by changes in the ratio of grilse to large salmon (2-sea-years and older) entering the river. From 1954 to 1962 trap samples were composed of about equal numbers of grilse and large salmon. Since 1963 the grilse catch has averaged 87%. Large declines in abundance of the fall-run grilse portion of the spawning stock occurred in 1968 and similar declines occurred in the fall-run large salmon component in 1969. An increase in commercial fishing mortality of large salmon is believed responsible for shifting the river escapement in favor of grilse. The result has been a reduction in reproductive potential and declines in the fall-run stocks of both large salmon and grilse.
An in situ Method for Measuring Primary Productivity of Arctic Sea Ice Algae
Authors: Clasby R. C. , Horner Rita , Alexander Vera
Published: April 2011

With the use of SCUBA diving and a new 14C incubation chamber, the rates of carbon fixation by the algal community that lives within the undersurface of sea ice have been measured. Rates of primary productivity ranged from 7.67-mg C/m2∙hr near the peak of the bloom to a low of 0.30-mg C/m2∙hr just prior to the thaw period.
Temperature Selection of Atlantic Salmon (Salmo salar) and Brook Trout (Salvelinus fontinalis) as Influenced by Various Chlorinated Hydrocarbons
Authors: Peterson R. H.
Published: April 2011

The effects of previous exposure to p,p′-DDT, o,p′-DDT, p,p′-DDD, p,p′-DDE, and methoxychlor on temperature selection by juvenile Atlantic salmon (Salmo salar) in a horizontal temperature gradient were similar. Exposure to low concentrations resulted in no change or a decrease in selected temperatures as compared to control values of about 16 C. Exposure to higher concentrations raised selected temperatures. The concentrations of the substances required to produce a given effect varied as: p,p′-DDT≥p,p′-DDD> methoxychlor >o,p′-DDT>p,p′-DDE. Exposure levels of p,p′-DDA≤ 8 ppm did not alter temperature selection nor did exposure to Aroclor® 1254, a polychlorinated biphenyl (PCB) preparation at 2 ppm. Aldrin lowered temperature selection at 0.1–0.15 ppm. In a vertical gradient, brook trout (Salvelinus fontinalis) previously exposed to p,p′-DDT and p,p′-DDD selected higher temperatures than controls.
Effect of Lime Neutralized Iron Hydroxide Suspensions on Survival, Growth, and Reproduction of the Fathead Minnow (Pimephales promelas)
Authors: Smith E. J. , Sykora J. L. , Shapiro M. A.
Published: April 2011

The long-term effect of lime neutralized suspended iron on fathead minnow (Pimephales promelas) survival, growth, and reproduction was assessed in a flow-through environment with a modified proportional diluter. Results of 12 months of testing reveal lower survival and declining growth of fathead minnows with an increase in lime neutralized suspended iron concentration. Hatchability and growth of fathead minnows were appreciably reduced in the lowest insoluble iron concentration tested, 1.5 mg Fe/liter. Reduced hatchability was attributed to the higher percentage of smaller particles in low lime neutralized iron concentrations. A comparison of data on survival, growth, and hatchability indicates that the safe level of suspended iron for fathead minnows presumably lies between the control and 1.5 mg Fe/liter.
Metabolism and Biliary Excretion of Sulfobromophthalein by Rainbow Trout (Salmo gairdneri)
Authors: Schmidt Dana C. , Weber L. J.
Published: April 2011

The plasma half-life of sulfobromophthalein (BSP) for rainbow trout (Salmo gairdneri) was 13 min for doses of 5 and 10 mg/kg and 29 min for a dose of 15 mg/kg. The biliary BSP transport maximum (Tm) averaged 9.6 μg/min per kg for five fish while the blood clearance averaged 1.7 ml/min per kg for two fish. Normal bile flows of 0.87 μliter/min per kg in trout were increased upon anesthetization but were unaffected in fish allowed to recover from spinal transection. Spinal transection did not affect the plasma half-life of BSP.The data presented support the conclusion that the transport of BSP from liver cells to bile is the rate-limiting step in the excretion of this dye. When the BSP Tm of trout was compared to literature values for mammals and dogfish (Squalus acanthias), large differences were found which were probably caused by effects of different temperatures and blood flows. When the Tm values of the various species were based on blood clearance of BSP (reflecting liver blood flow) the differences were greatly reduced, suggesting similar abilities of the liver of the various species to excrete this dye.
Trout Production and Eels in Bill Lake, Saguenay County, Quebec
Authors: O’Connor J. F. , Power G.
Published: April 2011

Competition and predation by American eels (Anguilla rostrata) is believed to have substantially reduced trout population and production in Bill Lake. Brook trout (Salvelinus fontinalis) occurred at densities of 7/ha; biomass of 0.34 kg/ha and annual production was estimated at 0.21 kg/ha. This is considerably less than values for trout density, biomass, and production in other lakes in the Matamek watershed from which eels appear to be absent. Eels in Bill Lake are old and large but not numerous, in keeping with their apparent position as top carnivores.
Fish Viruses: Isolation and Identification of Infectious Hematopoietic Necrosis in Eastern North America
Authors: Wolf Ken , Quimby M. C. , Pettijohn L. L. , Landolt M. L.
Published: April 2011

Infectious hematopoietic necrosis virus (IHNV) was isolated from diseased fingerling rainbow trout (Salmo gairdneri) from a hatchery in West Virginia. Clinical signs, histopathologic findings, and origin of eggs provided a basis for diagnosis, and virus was isolated and presumptively identified by plaque characteristics. Serum neutralization tests provided positive identification of the agent as IHNV, and electronmicroscopy showed its rhabdovirus morphology. Experimental infections resulted in signs of IHNV and death; test fish had characteristic histopathologic alterations and appropriate virus titers. This is the first completely documented occurrence of IHNV beyond the Pacific Northwest.
The Skate, Raja richardsoni Garrick 1961, Assigned to Bathyraja
Authors: Templeman Wilfred
Published: April 2011

The deepwater skate, Raja richardsoni Garrick 1961, is assigned to the genus Bathyraja on the basis of studies of 18 specimens from the northwest Atlantic including 10 mature males. It is similar to other Bathyraja species and distinguished from Raja and Breviraja species especially by having in the clasper tip a ventral terminal cartilage completely enclosed within the skin of the ventral lobe and lacking a free sharp edge, and a sentinel (accessory terminal cartilage no. 1) in the form of a hatchet-shaped knife with a sharp distal edge. Its clasper also has a projection, whose support is the distal process of the ventral marginal cartilage, always found in Bathyraja but not in Raja of the northeast Atlantic. It differs also from Raja in having an uncalcifled or little calcified anterior part of the rostral cartilage, in the freedom of the appendices of the rostrum from the shaft and in the more anterior extension of the pectoral radiais toward the snout.
First Records, Description, Distribution, and Notes on the Biology of Bathyraja richardsoni (Garrick) from the Northwest Atlantic
Authors: Templeman Wilfred
Published: April 2011

Eighteen Bathyraja richardsoni (Garrick 1961), 95–174 cm in total length were taken by bottom longline from southern Labrador to Georges Bank, 17 at 1810–2360 m, and one at 1370–1500 m. These are the first records for the western Atlantic. Studies of morphometries, of numbers, of form, and arrangement of spines, dermal denticles, and teeth, and of body color in these skates amplify the description of the species, known previously only from New Zealand (the holotype) and the northeast Atlantic (eight specimens). There is, however, appreciable variation in the distribution and abundance of dermal denticles between the new specimens and the holotype. These specimens also have middorsal caudal spines instead of the middorsal caudal row of fleshy oval structures (some with a central tubercle of enamel) of the holotype, which are related in this paper to scar areas from lost spines.Some information is provided on weight–length, liver weight, and fatness, vitamin A of liver oil, and length at sexual maturity. Food was mainly fish.The trematode Otodistomum veliporum occurred in 5 of 16 stomachs and the cestode Onchobothrium pseudouncinatum in 6 of 16 intestines. A copepod, tentatively identified as Lernaeopodina longimana, was found on the gills of one of five specimens.
Objectives and Problems of Managing Aquatic Living Resources
Authors: Alverson D. L. , Paulik G. J.
Published: April 2011

In the management of aquatic living resources a wide range of objectives has emerged, associated with maintenance of renewable resources at productive levels, socioeconomic goals, and national and international political interest. Conservation objectives are largely concerned with "rational use" concepts, while socioeconomic goals may be associated with economic efficiency, resource development, allocation of resources between user groups, etc.A number of problems confront managers of aquatic living resources. They include the rapidity of the changes occurring in fisheries, conflicting objectives, the fragmented and limited jurisdiction of management agencies, adequacy of scientific input into management decisions, difficulties of enforcement, and multiple use interest. Improved management of aquatic living resources will require decision-making machinery that is responsive to the dynamic character of modern fisheries, systems to resolve potential conflicts in human values, a commitment of governments, managers and scientists to assume the responsibilities delegated to them, including the promulgation and enforcement of appropriate regulations, and a recognition on the part of management that they cannot expect scientific unanimity or certainty regarding the status of fish stocks and the nature of the actions required to ensure their productivity. Although the responsibility to manage is clearly the mandate of the administrator, the scientific community has the responsibility to effectively communicate its findings to managers, to evolve methods of providing quick and reasonably cheap diagnoses of the status of stocks, and to contribute to the development of the theory and application of the total systems approach to management of renewable resources.
Marine Aquaculture: Problems and Prospects
Authors: Idyll C. P.
Published: April 2011

Aquaculture is the technique of raising useful aquatic species under some control of the organism and its environment. It is expected to supplement fishing by adding significantly to supplies of protein food, but it is unlikely that it will ever replace fishing as the principal means of exploiting the sea.Discussions are often confused because there are a number of distinctly different procedures embraced by the term aquaculture, with different chances of development into major industries. One type involves raising fish and other animals in hatcheries for release in the sea with the expectation of increasing commercial catches. For most of the very large number of mature animals cultured in this way proof is lacking that any benefits have accrued. Capture and confinement of young is a second kind of aquaculture. This can involve various degrees of supplemental feeding. A third kind involves production of young from eggs obtained from wild parents. The last kind of aquaculture, and the one that is equivalent to land farming, involves hatching of young from eggs obtained from brood stock maintained by the farmer. Not many examples of the last two types exist yet.The areas at the edge of the sea suitable for aquaculture are very large; e.g. perhaps at least 1.5 million ha in Asia and perhaps half a million ha in Nigeria alone among African countries. Potential production depends on many imponderables, but is believed to be very large — perhaps 10 times present production.Aquaculture has developed with very little help from scientists, and the solution of technical and engineering problems would advance its rate of development greatly. The kinds of problems that should be solved include : the search for species suitable for culture; research on nutrition of cultured animals and development of suitable food; pathology of cultured animals; studies on the behavior of cultured animals; engineering studies; studies of pollution and the use of waste substances and heat; legal research; economic and social research.It is proposed that a small number of regional centers for aquaculture be established to study the most pressing problems.
Prospects for the Development of Brackish-Water Fish and Shrimp Culture in India
Authors: Jhingran V. G. , Gopalakrishnan V.
Published: April 2011

Brackish-water fish and shrimp culture exists in several localities in India, but the total area used was only 10,000 ha in 1968 and might reach 15,200 ha by 1973. Some of this is in paddy fields used alternately for crops.Natural sources of seed (fish fry and shrimp larvae) are used exclusively. Usually these simply enter the ponds from the estuary during high tide periods. Production averages about 200 kg/ha per year.The potential for increasing brackish-water culture is great. Capital requirements are not excessive, and a return of 15% per annum is suggested under average conditions. Development can be encouraged by surveys of suitable areas, by experimental work on capturing and transporting seed, by artificial spawning for the production of fry of the most desirable species, and by pilot projects to test methods of supplementary feeding and other practices.