bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparison of Skin Tumors in Three Species of Flounders
Authors: McArn G. E. , Wellings S. R.
Published: April 2011

A study of the natural history of skin tumors occurring on two species of Pleuronectidae was conducted in the waters of Bellingham Bay, Washington. Twelve collections at monthly intervals indicated that 4.8% of 1977 English sole (Parophrys vetulus) and 2.4% of 2946 starry flounders (Platichthys stellatus) were tumorous. Three types of tumors were observed, and were classified as angioepithelial nodules, epidermal papillomas, or angioepithelial polyps, according to nomenclature previously established by other workers. The angioepithelial nodule was found on fish in the 1st year of life but not on fish older than 1 year. Epidermal papillomas usually occurred on fish that were 1 year or older, as did the angioepithelial polyps. The incidence of tumor-bearing fish, and the average number of tumors on a single specimen was greatest during the 1st year of life and decreased progressively in older age-groups. Tumors were more likely to occur on the pigmented side than on the nonpigmented side of the fish. The results of this study were compared and contrasted with a similar disease previously described on Hippoglossoides elassodon, the flathead sole.
An Expression for the Variance of Abundance Estimates Using a Fish Echo Integrator
Authors: Moose Paul H. , Ehrenberg John E.
Published: April 2011

A mathematical model of the fish echo integrator, an acoustic device for measuring the abundance of pelagic fish, is presented. This model is analyzed and general expressions for the mean and variance of the integrator output are obtained. The integrator output can be scaled to provide an estimate of the total number of fish in the volume of water surveyed. The effect of each system parameter on the variance of the estimate is investigated and optimum operational procedures are suggested.
Age and Growth of the Giant Pacific Sea Scallop, Patinopecten caurinus, from the Strait of Georgia and Outer Washington Coast
Authors: Haynes Evan B. , Hitz Charles R.
Published: April 2011

At any given age, giant Pacific sea scallops, Patinopecten caurinus, from an inner coastal area of Washington (Strait of Georgia) were about 1.5 times as large as those from an outer coastal area (near Destruction Island). Annuli were apparently formed during the winter. Lee's phenomenon, i.e., a slower estimated growth for young animals when calculated from successively older individuals than the true average growth, occurred m the outer coast data but not in the Strait of Georgia data. Differences in size between populations at the same ages apparently resulted from differences in the amount of growth during early years of life, because growth rates in later years differed little. Differences in growth rate were more likely to be due to hydrographic conditions than to infestations by boring annelids. Growth rate of the scallops in the Strait of Georgia was similar to that reported for the species off Kodiak Island, Alaska, to about 135 mm; thereafter, Strait of Georgia scallops grew more slowly.
Redescription of the Spionid Polychaete Malacoceros (Malacoceros) indicus (Fauvel 1928)
Authors: Foster Nancy M.
Published: April 2011

The co-type of Malacoceros (Malacoceros) indicus has been redescribed. Several discrepancies have been noted with regard to various characters. It is pointed out that use of modern optics in descriptions of setal characters makes it desirable to redescribe certain older species, in order to avoid the establishment of new species that will later have to be synonymized. It is also pointed out that specific characters commonly used for spionids are not necessarily valid for all genera, even though they have been used in the past.
Production Potential of a Seaweed–Lobster Community in Eastern Canada
Authors: Miller R. J. , Mann K. H. , Scarratt D. J.
Published: April 2011

An energy-flow diagram for the bottom community in the seaweed zone of St. Margaret's Bay, Nova Scotia, has been constructed, using previous estimates of seaweed production and observations on animal biomass and respiration rates. Annual seaweed production exceeded the annual consumption by herbivores by a factor of more than 10 (7000 vs. 572 kcal/m2 per year). This fact, plus observations of physical processes in the seaweed zone, indicate that most of the seaweed production is exported as particulate matter in suspension. Production rates of the American lobster (Homarus americanus) prey species exceed lobster ingestion rates, also by a factor of more than 10 (84 vs. 6 kcal/m2 per year). The difference is presumably consumed by lobster competitors. The available information suggests lobster production in the seaweed zone could be increased by reducing predation and competition for food, together with an increase in suitable shelter.
Some Factors in Susceptibility of Juvenile Rainbow Trout and Chinook Salmon to Chondrococcus columnaris
Authors: Fujihara M. P. , Olson P. A. , Nakatani R. E.
Published: April 2011

Susceptibility of juveniles of chinook salmon (Oncorhynchus tshawytscha) and rainbow trout (Salmo gairdneri) to Chondrococcus columnaris disease appeared to be influenced by age offish, crowding, and water temperature. Rainbow trout of about 1 g and chinook salmon of about 3 g were less susceptible than smaller fish, and tests with chinook salmon suggested that age was more important than weight. When chinook salmon averaging 4.3 g were exposed from July to October to the pathogen in river water, mortality ranged from 1.0% in a trough with 50 fish to 12% in one with 900. Mortality of rainbow trout averaging 2.4 g that were exposed to the pathogen in trough river water averaged 4.7–22% after 4 weeks, at temperatures from 17.2 to 17.8 C; the survivors, however, were generally resistant to subsequent infection, suggesting development of an immune response. Times to 100% mortality of sibling chinook salmon averaging 3.9 g that were exposed for 25 min to about 2.5 × 105 organisms per liter of sterile river water were about 19 hr at 10 C and 8 hr at 22 C. Survival of rainbow trout was higher when they were held at 2.2 degrees C below than when held at 2.2 degrees C above seasonal river temperatures.
Distribution of Radioactive and Stable Zinc in an Experimental Marine Ecosystem
Authors: Cross Ford A. , Willis James N. , Baptist John P.
Published: April 2011

The distribution of radioactive and stable Zn in an experimental marine ecosystem is described. We added 1 mCi of 65Zn to 2000 liters of sea water and a mixed community of planktonic and benthic algae in a fiberglass tank, after which the ecosystem was left undisturbed for 9 months. We then measured the 65Zn specific activities for (1) particulate Zn (0.45 μ filterable), (2) extractable Zn (from water passed through a 0.45-μ filter and then treated with dithizone), (3) total dissolved Zn (from samples passed through a 0.45-μ filter and treated with acid prior to extraction with dithizone), and (4) dialyzable Zn. Zinc-65 specific activities were not significantly different among the extractable, dialyzable, or acid-treated samples of the water. Further, absolute concentrations of 65Zn and total Zn were no higher in the acid-treated samples than in the extracted or dialyzed samples, which indicates that nearly all of the soluble Zn in the water was dithizone-extractable and dialyzable. Zinc-65 specific activities were significantly less, however, in the particulate material than in the water. This difference indicates that equilibrium of Zn between particulate material and water had not been reached after 9 months. Three months later (December 1969) 65Zn specific activities were determined again for particulate material and total dissolved Zn. The mean specific activity of 65Zn in the particulate samples showed a small but significant increase, but it was still less than in the water. Concentration factors in the particulate matter were 980 for 65Zn and 1400 for total Zn. Samples of benthic algae taken in March 1970 had a mean specific activity of 65Zn similar to the mean 65Zn specific activity of water samples taken 3 months earlier.
Mobilization of Mercuric Sulfide from Sediment into Fish under Aerobic Conditions
Authors: Gillespie D. C. , Scott D. P.
Published: April 2011

A system for studying the aerobic mobilization of mercury from aquatic sediments into fish was described. Using this method, it was shown that mercuric sulfide in sediment was very slowly mobilized and picked up by fish.
Survival of Some Freshwater Fishes in the Alkaline Eutrophic Waters of Nebraska
Authors: McCarraher D. B.
Published: April 2011

Of 14 species of freshwater fishes held in cages in one or more of 13 alkaline lakes and ponds in Nebraska, few species survived more than a month where carbonate alkalinity, mostly as compounds of Na2CO3 and KCO3, was above 300 mg/liter. Of the 14 species tested, Sacramento perch (Archoplites interruptus), fathead minnow (Pimephales promelas), northern pike (Esox lucius), and the black bullhead (Ictalurus melas), were the most tolerant of alkaline environments. Most centrachid fishes except A. interruptus and the green sunfish (Lepomis cyanellus), did not survive more than a month in alkaline waters greater than 950 mg/liter total alkalinity. A lake classification index for slightly alkaline to strongly alkaline environments is presented, along with suggested fish species for introduction into such waters.
Chloramine Toxicity to the Amphipod Gammarus pseudolimnaeus and the Fathead Minnow (Pimephales promelas)
Authors: Arthur John W. , Eaton John G.
Published: April 2011

The amphipod Gammarus pseudolimnaeus was subjected to 96-hr and 15-week exposures, and the fathead minnow (Pimephales promelas) to a 21-week exposure, to various chloramine concentrations under continuous-flow conditions. The most marked sublethal effects were reductions in the number of young produced by the amphipod and in egg production by the minnow. The 96-hr median tolerance limit for the amphipod was 220 μg/liter total chloramine. Fathead minnows in the long-term study were all killed at the highest concentration, 154 μg/liter total chloramine, within 3 days. The lowest measured total chloramine concentration in the long-term tests having no significant effect was < 3.4 μg/liter for the amphipod and 16.5 μg/liter for the fathead minnow.
Accumulation and Persistence of DDT in a Lotic Ecosystem
Authors: Dimond J. B. , Getchell A. S. , Blease J. A.
Published: April 2011

DDT persisted in streams of several small watersheds in Maine for at least 10 years following light applications to the forest. Residues declined sharply within 2 or 3 years after application, but after 10 years were still well above concentrations detected in untreated streams. This was true of all components studied: muds, plants, invertebrates, fish, and fish-eating birds. The prolonged persistence led to cumulative residue levels in streams sprayed more than once. Concentration of residues through the food chain was evident.
The Stress of Formalin Treatments in Rainbow Trout (Salmo gairdneri) and Coho Salmon (Oncorhynchus kisutch)
Authors: Wedemeyer Gary
Published: April 2011

Changes in gill function, acid–base balance and pituitary activation occurring during standard 200 ppm formalin treatments of juvenile rainbow trout (Salmo gairdneri) and coho salmon (Oncorhynchus kisutch) were compared. Plasma Cl−, Ca++, total CO2, and interrenal vitamin C in the trout declined continuously and in proportion to the exposure time, but the salmon were able to maintain these metabolic parameters at approximately initial levels. Blood pH and alkaline reserve regulation of the salmon was also less affected by formalin treatments, especially during prolonged exposures. The oxygen consumption of both species was depressed, but substantially more so in the trout than could be accounted for by decreased ventilation rates. Little frank hemolysis occurred in either species, but there was a significant bilirubinemia in the trout.
Abnormal Body Curvatures of Rainbow Trout (Salmo gairdneri) Inbred Fry
Authors: Aulstad Dag , Kittelsen Arne
Published: April 2011

In an inbreeding experiment with rainbow trout (Salmo gairdneri), a special type of deformed fry was found. The deformity appeared after one generation of fullsib mating in one of nine fullsib groups. The deformed fry were observed soon after the resorption of the yolk sac and showed different forms of body curvatures. The deformity was lethal. Significant differences between inbred groups and the noninbred control groups indicate that the deformity is at least partly heritable.
A Record of Pacific Herring (Clupea harengus pallasi) Feeding on Juvenile Chinook Salmon (Oncorhynchus tshawytscha) in a British Columbia Estuary
Authors: Ito Jun , Parker R. R.
Published: April 2011

An occurrence of Pacific herring (Clupea harengus pallasi) predation on juvenile chinook salmon (Oncorhynchus tshawytscha) is described. This is the first recorded incidence of this particular predator–prey relation.
Fertilization of Pink Salmon (Oncorhynchus gorbuscha) Ova by Spermatozoa from Gonadotropin-Injected Juveniles
Authors: Donaldson Edward M. , Funk James D. , Withler F. C. , Morley R. B.
Published: April 2011

Sexual maturation in male pink salmon (Oncorhynchus gorbuscha) from Jones Creek, a tributary of the Fraser River, British Columbia, was accelerated by intraperitoneal injections of partially purified chinook salmon (O. tshawytscha) gonadotropin. The treated pinks produced milt 1 year earlier than normal. Milt from these fish was compared with milt from wild Lower Babine River pinks with respect to its ability to fertilize the ova of Lower Babine River females. There were no marked differences in proportions of ova fertilized, in survival to hatching, or in numbers of deformed larvae. Densities of sperm in the milt from treated males ranged from 0.15 × 109 to 7.35 × 109 per ml; sperm densities in the milt from wild males ranged from 19.3 × 109 to 38.6 × 109 per ml. Two stages in testicular development were identified among the treated males and found to be directly related to the success of fertilization. The significance of induced early maturation in attempts to establish pink runs in the "off" year rivers is discussed.
Determination of the Spectra of Empirical Wave Force Coefficients
Authors: Bell W. H.
Published: April 2011

A method is proposed for obtaining frequency-dependent values of wave force coefficients for marine structural forms. If orbital velocity (or acceleration) components and wave force measurements are directly available, the coefficients are obtained without recourse to any particular wave theory. However, linearity of the wave-force process is implicit in the use of the Morison force equation. Modifications of the method are indicated for use when velocities must be inferred from measurements of wave parameters other than velocity, or from their power spectra, by means of a chosen wave theory. The feasibility of the method for obtaining wave force coefficients as a function of frequency is demonstrated using data reported by another worker for force measurements on a sphere.
Oxygen Consumption of the Euryhaline Fish Aholehole (Kuhlia sandvicensis) with Reference to Salinity, Swimming, and Food Consumption
Authors: Muir B. S. , Niimi A. J.
Published: April 2011

Active and standard metabolism of Kuhlia sandvicensis increase with fish weight to a power of about 0.8 and active is nine times standard. No significant difference was found between experiments in fresh water and 30‰ sea water at 23 C. At low swimming speeds the fish may be unable to physically take up as much oxygen as at higher speeds. Swimming activity may be essential to circulatory adequacy.Elevated oxygen consumption lasted for 42 hr following a ration of 2.3% of body weight and for 60 hr after one of 4.5%. It amounted to about 76 mg O2/g ration, equivalent to about 16% of the energy of the ration, in both cases. For a nonswimming fish the highest oxygen consumption observed following the maximum daily ration is no more than half of the difference between active and standard rates.
Observations on the Migration of Sockeye Salmon Fry (Oncorhynchus nerka) in the Lower Babine River
Authors: Clarke W. Craig , Smith H. D.
Published: April 2011

No distinct length, weight, or behavioral differences associated with place of capture in the river were observed, indicating that all fry are susceptible to downstream displacement. A minimum of 7.5 million (18%) of the fry produced passed through a counting fence below the spawning grounds. Others reached quiet waters inshore, where they progressively developed behavioral characteristics that enabled them to ascend the river and reach lake nursery areas above. Two million fry ascended an improvised ladder spanning an area of turbulence at the base of the fence. Construction of leads and baffles at strategic places below the fence could help fry reach shore sooner and increase numbers reaching the lake.
Exposure Times Necessary for Antimycin and Rotenone to Eliminate Certain Freshwater Fish
Authors: Gilderhus Philip A.
Published: April 2011

In laboratory flowing-water troughs exposure required to induce 100% mortality, regardless of time to death for antimycin and rotenone against selected freshwater fish species was determined. Carp and white suckers required shorter exposures to antimycin (6 hr) than to rotenone (18–24 hr) at field-use concentrations of 5 and 50 ppb respectively. Bullheads were killed by 3–10 hr exposure to 100–250 ppb rotenone at 17 C or higher. However, the long exposure time necessary in colder water (25 hr at 100 ppb in 12 C water) made elimination of bullheads with rotenone difficult in cold seasons. Exposure time was influenced more by water temperature than by the toxicant concentration. The effects of rotenone were often reversible even after fish had been on their sides in the toxicant solution for 4–5 hr but irreversible for antimycin after fish showed the first signs of distress.
Change in Body Weight Caused by Handling and Exercise in Fish
Authors: Stevens E. Don
Published: April 2011

Either handling or exercise cause an increase in body weight in fish acclimated to fresh water, and a decrease in body weight in fish acclimated to sea water.
Morphometries of Three Sympatric Arctic Codfishes of the Genera Arctogadus and Gadus
Authors: Boulva Jean
Published: April 2011

Three populations of codfishes inhabit the waters of Cambridge Bay: two belong to the genus Arctogadus, the third is Gadus ogac. In spite of phenotypic resemblances of some Arctogadus specimens to Gadus, the two genera are well separated as indicated by significant (P < 0.05) differences in otolith shape. Significant differences in 15 out of 27 morphometric characters and in two out of 10 meristic characters, and a different sexual dimorphism indicate that the separation of the Cambridge Bay Arctogadus stock in two populations is valid; these populations correspond respectively to the described species A. borisovi and A. glacialis.
Reversible Changes in Adrenal Cortical Cell Morphology and Plasma Hydroxycorticosteroids During Freshwater Portion of the Spawning Journey of Atlantic Salmon (Salmo salar)
Authors: Heyl Henry L. , Carpenter Stanley J.
Published: April 2011

Adrenal cortical tissue taken from Atlantic salmon netted in the estuary of the Miramichi River, New Brunswick, at three stages of gonadal activity showed increasing hyperplasia from July to October, with varying degrees of regression or degeneration by the following April. Adrenal cortical cells in April fish contained a characteristic paranuclear dense body, the light and electron microscopic appearances of which are described and discussed. Levels of 17-hydroxycorticosteroids in the plasma almost doubled from July to October and returned to July values by the following April. The presence of these cyclic changes in Atlantic salmon and their absence in Pacific salmon are discussed. Data indicate that genetic factors may be important in determination of the capacity for multiple spawning journeys by some Atlantic salmon.
Use of Continuous Recording Salinity–Temperature–Pressure Instrumentation at Ocean Station P (50N, 145W)
Authors: Collins C. A. , Healey D. A.
Published: April 2011

The operational precision of STP instruments for salinity and temperature was estimated as 0.07 ppt and 0.07 C, respectively. Correction of electronically digitized data for instrument response constants failed to improve the quality of the data. However, a response constant of 1 sec would remove the salinity inversions associated with large temperature gradients. Smoothing of STP data with a numerical taper about 2-db wide and decimation to 2-db intervals seemed appropriate for 0.2 sec sampling rates.
A Diver-Operated Plankton Collector
Authors: Ennis G. P.
Published: April 2011

A plankton collecting apparatus was devised by strapping together two diver-towing vehicles and mounting a 50-cm plankton net ahead of them. It can be operated at the surface by a snorkel diver or under water by a scuba diver.
Residues of Organochlorine Pesticides and Polychlorinated Biphenyls in Some Commercially Produced Canadian Marine Oils
Authors: Addison R. F. , Zinck M. E. , Ackman R. G.
Published: April 2011

Herring oils produced in the late 1960s from Gulf of St. Lawrence fish generally contained 7–17 ppm DDT complex, 0.1 ppm dieldrin, and up to 11 ppm PCBs. In spring, oils were richer in residues than in autumn. Seal oils contained up to 8 ppm DDT complex, and about 4 ppm PCBs, but no dieldrin. Residue levels showed no marked change from the mid-1950s to mid-1960s. North Atlantic whale oils contained up to 40 ppm DDT complex, and (in a few samples only) about 7 ppm PCBs; no dieldrin was found. Some Antarctic whale oils produced about 1950 contained 0.1 ppm DDT complex and no detectable PCBs.
Molluscan Sterols: A Review
Authors: Idler D. R. , Wiseman P.
Published: April 2011

Many studies on mollusc sterols were made before the advent of modern techniques such as gas chromatography and mass spectrometry, and several structures ascribed to such sterols were incorrect because the preparations lacked homogeneity.The Monoplacophora are extremely rare and the sterols have not been investigated. Cephalopods are believed to contain cholesterol but they have not been investigated in recent years. Among the Amphineura, Aplacophora have not been studied while Polyplacophora contain Δ7-cholestenol sometimes accompanied by cholesterol and brassicasterol.Among the least evolved pelecypods, two protobranchs studied contained cholesterol and one also had cholestenol. Septibranchia have not been investigated. A dozen species of filobranchs and eulamellibranchs have been found to have complex mixtures with the same predominant sterols. All sterols of the sea scallop have now been identified and the most recent are 22-trans-24-norcholesta-5,22-dien-3β-ol, and a novel C-30 compound, 29-methylisofucosterol, neither of which has been found elsewhere in nature. A primitive bivalve, the lamp shell, has an almost identical sterol composition to the modern pelecypods.Gastropods contain predominantly cholesterol and sometimes its precursor, desmosterol.
Physiological Responses of Three Species of Fishes to Various Salinities
Authors: Brocksen Robert W. , Cole Ronald E.
Published: April 2011

The effects of varying salinity on parameters such as growth, food consumption, food conversion efficiency, and respiration were determined for three species of fish inhabiting the Salton Sea, California. Bairdiella (Bairdiella icistia), orangemouth corvina (Cynoscion xanthulus), and sargo (Anisotremus davidsoni), were subjected to salinities ranging between 29 and 45‰. The optimal range of salinity was between 33–37‰ for all three species. Growth, food consumption, food assimilation, and respiration were adversely affected at the extreme salinities of 29 and 45‰. The results indicate that the fish inhabiting the Salton Sea will experience difficulty in maintaining populations of the current size when the salinity reaches 40‰.
Effects of the Floy Anchor Tag on the Growth and Survival of Brook Trout (Salvelinus fontinalis)
Authors: Carline R. F. , Brynildson O. M.
Published: April 2011

We conducted two field trials to determine the effects of the gun-injected, Floy anchor tag (FD-67) on growth and survival of 10-month-old domesticated brook trout (Salvelinus fontinalis) in a 0.7 ha pond. Trials ran from October to the following June. In 1968 we stocked 106 tagged trout and 1005 controls, and in 1969, 300 tagged trout and 500 controls. We removed different fins from each group to determine tag loss. In both trials we sampled the trout twice through the ice and twice during open water. The tags retarded growth of the trout from October to January; differences in growth rates between tagged and controls were 18 and 28% for the 1968 and 1969 trials, respectively. After January both groups grew at similar rates. Thetags did not affect survival, and tag losses were 5.7 and 2.0% for the two trials.
Effects of Introductions of Salmonids into Barren Lakes
Authors: Nilsson Nils-Arvid
Published: April 2011

There are still many lakes in the Palearctic that are barren of fish because of deglaciation history. Early transplantations of fish into such lakes have been documented, and there is a continuous activity of that kind going on for example in Scandinavia and at the North American west coast. Introductions of fish into barren lakes produce noticeable responses in the invertebrate fauna. For example, in a large mountain lake in northern Sweden the fairy shrimp Polyartemia forcipata disappeared after the introduction of Arctic char, and after a period of spectacular growth the fish now tend to get stunted. Changes in the invertebrate fauna after the introduction of new species of fish have been recorded also in many lakes with more complicated species compositions, and also in very large lakes such as Lake Michigan. In the Scandinavian mountain lakes there seems to be a correlation between the composition of fish species and the crustacean plankton. Further studies of introductions into barren lakes should provide a better understanding of predator–prey relations on the whole and, in the long run, of management of fish populations.
Limnology and Fish Ecology of Sockeye Salmon Nursery Lakes of the World
Authors: Hartman W. L. , Burgner R. L.
Published: April 2011

Many important, recently glaciated oligotrophic lakes that lie in coastal regions around the northern rim of the Pacific Ocean produce anadromous populations of sockeye salmon, Oncorhynchus nerka. This paper describes the limnology and fish ecology of two such lakes in British Columbia, five in Alaska, and one in Kamchatka. Then we discuss the following general topics: the biogenic eutrophication of nursery lakes from the nutrients released from salmon carcasses wherein during years of highest numbers of spawners, lake phosphate balances in Lakes Babine, Iliamna, and Dalnee are significantly affected; the use of nursery lakes by young sockeye that reveals five patterns related to size and configuration of lake basins and the distribution of spawning areas; the interactions between various life history stages of sockeye salmon and such resident predators, competitors, and prey as Arctic char, lake trout, Dolly Varden, cutthroat trout, lake whitefish, pygmy whitefish, pond smelt, sticklebacks, and sculpins; the self-regulation of sockeye salmon abundance in these nursery lakes as controlled by density-dependent processes; the interrelations between young sockeye salmon biomass and growth rates, and zooplankton abundance in Babine Lake; and finally, the diel, vertical, pelagial migratory behavior of young sockeye in Babine Lake and the new hypothesis dealing with bioenergetic conservation.
Keller Lake: Characteristics of a Culturally Unstressed Salmonid Community
Authors: Johnson Lionel
Published: April 2011

Keller Lake, with an area of 413 km2, is an essentially unexploited lake in the Northwest Territories. Results of an experimental fishery and a commercial fishery of short duration are described. Effects of gillnet selection are discussed for the two major species, lake trout and humpback whitefish, and it is concluded that the sample obtained represents the actual population, at least for sizes over 350 mm in length. There were very few fish in the 350–500 mm size range, or in age-groups 9–13; but size and age were not closely correlated. The population structure is likened to a forest climax condition. A mechanism for the dynamics of the system is proposed, which can be tested. Size distribution of the population is considered to be in the form of a standing wave with the shape of a normal distribution for the main body of the population; age structure changes with time but will retain a bimodal condition continuously. The effect of cropping on a population structure of this type is discussed.
Windermere: Effects of Exploitation and Eutrophication on the Salmonid Community
Authors: Cren E. D. Le , Kipling Charlotte , McCormack Jean C.
Published: April 2011

Windermere is a lake of 14 km2 divided into two glacially excavated basins. It is essentially mesotrophic but, about 1840, Asterionella became the dominant planktonic diatom and small changes towards eutrophication have recently occurred, all as a result of increases in population, water borne sewage, and agricultural fertilization in the catchment.Windermere has five salmonid taxa belonging to the three species: Salmo salar, S. trutta, and Salvelinus willughbii. Perca fluviatilis, Esox lucius, Anguilla anguilla, and Phoxinus phoxinus are abundant, and there are two other small fish species.A successful net fishery for the char, perch, pike, and trout operated for several centuries until overfishing for the char and an ascending interest in sport fishing for salmon and trout brought it to an end in 1921. There was then no significant exploitation until 1941.The Freshwater Biological Association has experimented with the fish populations since 1941 by intensive trapping of perch from 1941 to 1964 and gillnetting of pike from 1944 to the present. Perch were reduced to less than 20% of their former abundance and have not recovered since trapping ceased; their growth rate has increased. The larger pike have been reduced but young pike are more numerous. Char have increased. Most of the population changes of these three species can be attributed to pike netting, but fluctuations caused by variations in year-class strength contribute.The recent establishment of small local populations of Rutilus rutilus, Scardinius erythrophthalmus, and Tinca tinca are probably the only effects on the fish of slight eutrophication.
The Bodensee: Effects of Exploitation and Eutrophication on the Salmonid Community
Authors: Numann W.
Published: April 2011

The upper basin or Obersee of the Bodensee still retains all the fish species described more than four centuries ago, though rapid changes have recently been noted in many aspects of the fish community and of the Bodensee ecosystem. Though a variety of non-native species have been introduced, including a number of European and North American salmonids, none has become a prominent part of the community. The famous Blaufelchen, a pelagic coregonine, has recently been threatened by a combination of increasingly intensive exploitation, beginning at a low minimum size, compounded by an increasing growth rate of the species due to low population density, and due to increased planktonic food as a result of eutrophication. Consequently, by the early 1960s, the fishery came to exploit large yearlings, and few Blaufelchen survived to spawn. Eutrophication has reached a stage that is marginal to a number of deeper, benthic coregonines and char. Cyprinids, usually inshore, have expanded greatly, have invaded the pelagic habitat, and are subject to periodic mass mortalities. Other of man's effects are identified as are management measures now in practice.
Kootenay Lake: Man's Effects on the Salmonid Community
Authors: Northcote T. G.
Published: April 2011

A synopsis and evaluation is made of man's impact on Kootenay Lake salmonids since their first significant contact, perhaps less than 300 years ago. Exploitation of stocks for food by native Kootenay Indians was heavy in the late 1700s, probably surpassing present sport-fishery exploitation estimated at about 35 tons annually. Exploitation for fish-culture purposes never exceeded 7 tons annually, but because of restriction to a few spawning streams had serious effects on some local populations. Introduction of non-native fishes apparently was of little consequence to salmonids, whereas mysid introduction probably has produced growth enhancement in some stocks, especially kokanee. A similar but less obvious effect may be due to the marked cultural eutrophication occurring via heavy phosphate enrichment from a fertilizer plant. More serious and deleterious changes have been effected by stream habitat alteration resulting from mining, agriculture, and logging practices as well as from dam construction.
Lake Huron: Effects of Exploitation, Introductions, and Eutrophication on the Salmonid Community
Authors: Berst A. H. , Spangler G. R.
Published: April 2011

Lake Huron is a large, deep, oligotrophic lake, centrally located in the St. Lawrence Great Lakes system. Manitoulin Island and the Bruce Peninsula divide the lake into the relatively discrete water masses of the North Channel, Georgian Bay, and Lake Huron proper. Water quality in Lake Huron has deteriorated only slightly since the early 1800s. The only significant changes are confined to areas adjacent to centers of human activity, chiefly Saginaw Bay and various harbours and estuaries in Georgian Bay and the North Channel. The lake has supported a commercial fishery which has produced annual catches as high as 13000 metric tons. A dramatic decline in landings of commercially valuable species and an instability in fisheries resources has occurred in all areas of the lake since the 1940s. This depression of populations of valued species was associated with the accidental introduction of the sea lamprey, instances of overfishing and deterioration of water quality in Saginaw Bay. The present depressed state of the fisheries will undoubtedly persist until sea lamprey control is achieved and climax predators are reestablished. Governments are proceeding toward the establishment of water quality criteria and fishery management practices which, hopefully, will stabilize the fisheries and prevent further deterioration of the aquatic environment.
Lake Ontario: Effects of Exploitation, Introductions, and Eutrophication on the Salmonid Community
Authors: Christie W. J.
Published: April 2011

Commercial catch statistics were analyzed to follow the sequence of events in the deterioration of the major fish stocks of Lake Ontario. Atlantic salmon (Salmo salas), lake trout (Salvelinus namaycush), burbot (Lota lota), deepwater ciscoes (Coregonus sp.), and whitefish (Coregonus clupeaformis) have all disappeared or declined seriously in abundance. Only the colonists alewife (Alosa pseudoharengus), smelt (Osmerus mordax) and white perch (Morone americana) are currently abundant. Abundance of deepwater ciscoes is thought to have been controlled originally by the piscivores lake trout and burbot. Three deepwater cisco species are inferred to have been progressively eliminated by overfishing, leaving only the smallest and least valuable present when the fishery collapsed. The effects of the sea lamprey (Petromyzon marinus) on the Lake Ontario fishes are held to have increased with the reduction of the number of dams in the watershed, and as fishing reduced numerical abundance and average size of the prey fishes. The early colonists alewife and carp (Cyprinus carpio) were thought to have stabilized early. It was suggested smelt were suppressed for many years by trout and burbot predation, and after the release of this constraint, the smelt in turn caused the collapse of the deepwater ciscoes and other species through predation. The white perch invasion of the Bay of Quinte was thought particularly swift and successful because of the absence of predators. Yellow perch (Perca flavescens) abundance may have increased because of eutrophication effects in the nearshore areas. Recent deterioration of water quality appears so extreme as to ensure that the last premium species which used the inshore areas cannot return. Overfishing is thought to have been the major destabilizing influence. The role of the open lake predators in the vectoring of energy and materials through the system is discussed.
The Future of Salmonid Communities in North American Oligotrophic Lakes
Authors: Ryder R. A. , Johnson L.
Published: April 2011

Predictions are made pertaining to the status of salmonid communities in North American oligotrophic lakes about the year 2000. It is assumed that man-induced effects such as eutrophication, exploitation, and introduction of exotic species will continue to increase at an exponential rate. The influence of forest fires, domestic and industrial water pollution, road development, pulp mills, mines, pipe-lines, air pollution, agriculture, power development, summer resorts, angling, commercial and subsistence fishing, diversions and introductions of both salmonids and other species is discussed. It is concluded that at the present rate of interference of the oligotrophic environment by man, salmonid communities will be reduced to insignificant levels within the next 30 years.
The Future of Salmonid Communities in the Laurentian Great Lakes
Authors: Smith Stanford H.
Published: April 2011

The effects of human population growth, industrialization, and the introduction of marine fishes have reduced the suitability of each of the Great Lakes for oligotrophic fish communities. The ultimate consequence has been a reduction of fishery productivity that has ranged from extreme in Lake Ontario to moderate in Lake Superior. If measures are not taken to alleviate the adverse effects of marine invaders and trends in environmental quality, a major reduction in fishery productivity can eventually be expected throughout the Great Lakes.Prospects for the next century will be improved if the lakes can be intensively managed. More stringent control of the sea lamprey (Petromyzon marinus), and subsequent reduction of the alewife (Alosa pseudoharengus), by the reestablishment of populations of large piscivores, should permit the recovery of some of the previous predator and prey species, or the development of populations of new species that are more compatible with a reduced number of lampreys. Even if marine species can be reduced greatly, the full restoration of the former fishery productivity remains uncertain and will require a high degree of coordination among all management and research agencies that have responsibilities on the Great Lakes.Unfavorable trends toward progressive degradation of water quality pose the greatest threat to restoration of the fishery resources of the Great Lakes. Where changes in water quality have been the greatest, oligotrophic species have become scarce or absent, and in the deepwater regions no other species have reoccupied the vacated niches.
Yearly Respiration Rate and Estimated Energy Budget for Sagitta elegans
Authors: Sameoto D. D.
Published: April 2011

The respiration rate of Sagitta elegans in Bedford Basin, Nova Scotia, was found to be significantly different at different times of the year. Respiration rates were lower in summer and fall than during spring because the animals acclimated to warmer temperatures as the year progressed. The annual energy expenditure by respiration of the S. elegans population in St. Margaret's Bay, Nova Scotia, was equal to the net yearly production of the population; the calculated minimum ingested energy for this population was estimated to be between 13.2 and 20.0 kcal 100−3 year−1, or about 0.7–1.1% of the estimated total energy produced annually by copepods in the Bay. S. elegans probably has its greatest impact on the zooplankton community in St. Margaret's Bay during winter and early spring, when its biomass is greatest and its energy of respiration per unit volume of water is highest.
Food Resource Division Among Northern, Marine, Demersal Fishes
Authors: Tyler A. V.
Published: April 2011

The division of food resources among 13 demersal fishes was examined over a 16-month period in an area of Passamaquoddy Bay, New Brunswick. Though over 100 prey species were found in the stomachs of the predators, each predator took only three or four principal prey, and these prey made up 70–99% of the mass of the food for each predator species. Which species that a predator took as principal prey depended on prey body size, whether the prey were nekton, epi-fauna, or in-fauna; and whether or not they had a hard test or shell. Within predator species there was significant heterogeneity in diet related to size of predator individual.The seasonal predators did not feed as a group on their own set of prey species. Most principal prey species of the seasonal predators were taken simultaneously by one or two of the regulars.Data were compared with published results from two other northern marine areas. Within Irish Sea, Sea of Okhotsk, and also Passamaquoddy winter and summer communities, only 10–24% of the possible recurrences of principal prey among predators actually occurred, i.e. there was relatively little overlap among diets. Such specialization would have adaptive significance in a food-limited production system.
Survival of Hatchery-Reared Rainbow Trout (Salmo gairdneri) in Relation to Stamina Tunnel Ratings
Authors: Horak Donald L.
Published: April 2011

No conclusive evidence was found in tests from 1966 to 1969 in either lentic or lotic environments to support the hypothesis that hatchery-reared rainbow trout (Salmo gairdneri) with a high-stamina index had a higher survival potential than those whose stamina index was low. Physical stamina was measured by determining the length of time each fish could withstand sustained swimming in a specially constructed stamina tunnel. For high-stamina rating, fish swam in the tunnel for 80 min; for low stamina, 1–10 min.In tests of reproducibility of stamina ratings, improved swimming ability of low-stamina fish was demonstrated upon retesting in the tunnel. In 1970, with retested fish, still no evidence was found to indicate higher survival of fish rated as high in stamina. Additional studies are needed to determine if performance of hatchery-reared salmonids in a stamina tunnel is a valid indicator of their survival potential in the wild.
Migratory Movements of Adult Sockeye Salmon (Oncorhynchus nerka) in Coastal British Columbia as Revealed by Ultrasonic Tracking
Authors: Madison D. M. , Horrall R. M. , Stasko A. B. , Hasler A. D.
Published: April 2011

Individual courses, obtained by ultrasonic tracking nine sockeye in 1969 and nine in 1970, ranged up to 130.8 km (24.2 median) and 66.6 hr (9.6 median). Course directions were mainly to the north and west in 1969 and to the south and east in 1970. This difference may have arisen from differences in home river affiliation of the tracked sockeye. Swimming speeds showed a pronounced diel rhythm with higher values at 1400 hr and lower values at 0200 hr. The average speed of 53 cm/sec was consistent with rate of movement estimates obtained previously from tagging–recapture studies. A 13 cm/sec greater average speed in 1970 than in 1969 was observed, and possible reasons for the difference were discussed. Differences in speed within or beyond 2 km from land were not observed for either year. A diel rhythm in the magnitude of course change appeared, with a decrease in the frequency of large angular changes occurring in the afternoon. An orientation mechanism involving a daily reorientation process is hypothesized.
Temperature Control System for Recirculation Fish-Holding Facilities
Authors: Scott K. R.
Published: April 2011

The self-contained conditioning unit included heating, refrigeration, filtration, and aeration devices on a caster-mounted frame. Heating and cooling were performed in a stainless steel combination cooler-heater unit. Heating is produced by an electric resistance element and cooling by a water-cooled hermetic refrigeration compressor. Temperatures were maintained within ± 0.06 C degree of set point between 2 and 20 C in two 200-gal tanks using a modulating electronic temperature controller.
The First Record of Anguilla rostrata From Alberta
Authors: Radford D. S.
Published: April 2011

The first record of an American eel (Anguilla rostrata) is reported for Alberta. The specimen was collected in the South Saskatchewan River and probably originated from elvers stocked in Lac Pelletier in Saskatchewan in 1953.
Subcutaneous Hemorrhage in Captive Sablefish (Anoplopoma fimbria): A Possible Link to Mortality
Authors: Thorson Kenneth N.
Published: April 2011

During the spring of 1971 two groups of sablefish (Anoplopoma fimbria) were captured by pot fishing gear off the Washington coast. Within three days subcutaneous hemorrhages occurred in both groups and the more extensively hemorrhaged fish soon died. It appeared that the hemorrhages were a delayed reaction to injury sustained at capture. Impact against the pot walls or embolism arising from rapid decompression are suggested as possible causes.
Effect of Intertidal Exposure on Survival and Embryonic Development of Pacific Herring Spawn
Authors: Jones Barry C.
Published: April 2011

Eggs of Pacific herring were exposed to air for different periods of time to simulate tidal effects on spawn deposits at varying beach heights on the British Columbia coast. Prehatching mortality changed from 13% unexposed to 31% at 8-hr exposure twice daily. Significantly higher mortality occurred among eggs of smaller fish and eggs in smaller clumps. Incubation time decreased from 19.2 to 18.2 days with 2-hr exposure twice per day, and thereafter declined 0.4 days with greatest exposure. Larval length at hatching for unexposed eggs was 7.7 mm; lengths for all degrees of exposure were similar (7.2 mm). Larval weight was greatest (0.099 mg) for eggs exposed between 4 and 6 hr twice per day, decreasing with either greater submergence or exposure (7 and 12%, respectively). Hypoxia, desiccation, and the air-water temperature differential are considered as possible causal agents. A field survey indicated that deposition of larger eggs occurred at upper beach levels. These results suggest that a high fishing intensity could detrimentally affect future spawn and thereby reduce population recruitment.
Sound-Scattering Layers in the Northeastern Pacific
Authors: Donaldson Henry A. , Pearcy William G.
Published: April 2011

Temporal and spatial variations in the depth, thickness, and vertical movement of scattering layers were studied using a 38.5 kHz echosounder in waters off Oregon and between Hawaii and Adak, Alaska.Off Oregon one or two layers migrated toward the surface at dusk and descended into deeper water at dawn. Although individual scattering layers migrated at a fairly constant rate during a twilight period, rates of ascent and descent varied from day to day. Average rates were 2–3 m/min. During the night the depth of the top of the scattering layer averaged 40 m, and it varied between 50–245 m during the day. The bottom of the deepest recorded layer was 450 m deep.Regardless of intensity, the thickness of the scattering layers in the water column was usually greater during night than day. It was greater over the continental slope than abyssal depth, and in some years it was greater during the summer than during other seasons.Between Hawaii and Adak, Alaska, central waters had large amounts of scattering but low midwater trawl catches, transitional waters had high-intensity scattering layers and high biomass, and subarctic waters had very reduced scattering layers but high biomass.