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  • 1995-1999  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied ichthyology 15 (1999), S. 0 
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: The lake sturgeon (Acipenser fulvescens) is resident in the North and South Saskatchewan rivers of Alberta. Because of their confined distribution, low abundance, and vulnerability to anthropogenic impacts, lake sturgeon in Alberta have been the focus of specific management actions for nearly 60 years.Lake sturgeon harvest was prohibited in Alberta from 1940 to 1968, after which a limited harvest was again permitted, but only as a hook-and-line sport fishery. After being reopened the fishery was primarily managed as a “trophy” fishery. Sport fishery harvest statistics have been compiled annually since 1968, through mail-out questionnaires sent to all holders of sturgeon angling licenses.Few research studies have been undertaken on the life history or habitat requirements of lake sturgeon in the province, and biologists have relied primarily on anglers to provide information for management decisions. Preliminary population information for the South Saskatchewan River, from mark-recapture data, suggests a population size of about 3700 fish. Recent studies in the North Saskatchewan River indicate a population of about 1300 fish. Studies indicate that a portion of the population in both rivers is trans-boundary, moving between the waters of the adjoining provinces of Alberta and Saskatchewan, and creating concerns because of differences in angling regulations. During recent decades, major consumptive uses of water have also contributed to depletion of lake sturgeon habitat in the province.After reviewing past management strategies and actions, Alberta Environmental Protection implemented a number of regulatory changes in 1987 to further protect lake sturgeon populations in the province while continuing to provide angling opportunities and maintaining a controlled harvest.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of applied ichthyology 15 (1999), S. 0 
    ISSN: 1439-0426
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: White sturgeon (Acipenser transmontanus) in the Columbia River in Canada have recently been listed as Endangered/Critically Imperiled, based on a shift in size and age-class composition from a population dominated by juveniles in the early 1980s to one presently dominated by adults. This shift has been attributed to a poor survival of early life stages. To determine the causes for this poor survival, investigations conducted annually since 1990 have focussed on identifying white sturgeon movement patterns, population dynamics, reproductive biology, and critical habitats. The reasons for the low recruitment remain poorly understood but river regulation and reservoir formation due to dam construction and pollution from municipal and industrial effluent inputs are suspected as contributing factors.The history of dam development on the Columbia River and implications to white sturgeon are discussed from a historical perspective. A synopsis of post-1990 study results is provided and discussed in the framework of management strategies that include: 1) angling regulations, 2) flow enhancement strategies during spawning, 3) development of a population stabilization plan, 4) investigations into the feasibility of artificial stock supplementation, and 5) proposed future study programs to identify factors limiting recruitment.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 376 (1995), S. 669-672 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The oscillations that we observe are resonant acoustic waves, called p modes. The eigenfunction of a mode varies in the horizontal approximately as a spherical harmonic Y"' of degree / and azimuthal order ra, and is characterized also by a principal quantum number n, called the order, which is ...
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A novel method for the direct determination of mercury species at the ng l−1 level in natural waters is described. Methyl-, ethyl- and inorganic mercury are preconcentrated on a sulphhydryl cotton microcolumn incorporated in a flow injection system. Retained mercury species are then eluted with hydrochloric acid solution (3 mol/l) and subjected to phenylation before determination by gas chromatography-microwave induced plasma-atomic emission spectrometry. Limits of detection for mercury species are 10 ng l−1 for methyl- and ethyl-mercury and 16 ng l−1 for inorganic mercury based on processing 200 ml of sample. Application of the methodology to waters of the Manchester Ship Canal revealed elevated levels of methylmercury and inorganic mercury.
    Type of Medium: Electronic Resource
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