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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Environmental biology of fishes 23 (1988), S. 141-154 
    ISSN: 1573-5133
    Keywords: Cyanide ; Diversity ; Development ; Ecology ; Environment ; Fisheries ; Pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The biological diversity and productivity of Philippine coral reefs are threatened by siltation, destructive fishing methods, coral and shell collecting and overfishing. Destructive fishing includes: the widespread, illegal use of explosives; poisons such as sodium cyanide; muro-ami and kayakas fishing; and trawling. The recent decline in catch rates threatens the livelihood of 700 000 near-shore subsistence fishermen who catch 55% of the total landings. The new government under Corazon Aquino wishes to protect the marine environment through the creation of a viable marine conservation management plan, enforcement of existing laws and through cooperation between government, non-government and international agencies to provide education and research. The Department of Agriculture, which has the authority for fisheries, has designated the International Marinelife Alliance as the lead non-government agency involved with fund raising, net-training and finding alternatives to destructive fishing methods.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1009
    Keywords: Flushing ; Scouring ; Channel Maintenance ; Fisheries ; Trinity River
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract The operation of Trinity and Lewiston Dams on the Trinity River in northern California in the United States, combined with severe watershed erosion, has jeopardized the existence of prime salmonid fisheries. Extreme streamflow depletion and stream sedimentation below Lewiston have resulted in heavy accumulation of coarse sediment on riffle gravel and filling of streambed pools, causing the destruction of spawning, nursery, and overwintering habitat for prized chinook salmon (Salmo gairdnerii) and steelhead trout (Oncorhynchus tschawytscha). Proposals to restore and maintain the degraded habitat include controlled one-time remedial peak flows or annual maintenance peak flows designed to flush the spawning gravel and scour the banks, deltas, and pools. The criteria for effective channel restoration or maintenance by streambed flushing and scouring are examined here, as well as the mechanics involved. The liabilities of releasing mammoth scouring-flushing flows approximating the magnitude that preceded reservoir construction make this option unviable. The resulting damage to fish habitat established under the postproject streamflow regime, as well as damage to human settlements in the floodplain, would be unacceptable, as would the opportunity costs to hydroelectric and irrigation water users. The technical feasibility of annual maintenance flushing flows depends upon associated mechanical and structural measures, particularly instream maintenance dredging of deep pools and construction of a sediment control dam on a tributary where watershed erosion is extreme. The cost effectiveness of a sediment dam with a limited useful economic life, combined with perpetual maintenance dredging, is questionable.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1573-5133
    Keywords: Chondrichthyes ; Elasmobranchs ; Fisheries ; Ageing methods ; Growth rates ; Gestation periods ; Maturity ; Vertebral bands ; Weight-length relationships ; Life histories
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Synopsis The silky shark, Carcharhinus falciformis, and scalloped hammerhead, Sphyrna lewini, represent 〉80% of the shark by-catch of the winter swordfish/tuna longline fishery of the northwestern Gulf of Mexico. This catch represents a potential supplemental fishery, yet little is known of the life histories of the two species. This report relates reproductive biology data to age and growth estimates for 135 C. falciformis and 78 S. lewini. Unlike other regional populations, C. falciformis in the Gulf of Mexico may have a seasonal 12 month gestation period. Males mature at 210–220 cm TL (6–7 yr); females at 〉225 cm TL (7–9 yr). Application of age at length data for combined sexes produced von Bertalanffy growth model parameter estimates of L∞ = 291 cm TL, K = 0.153, t0 = −2.2 yr. Adult male S. lewini outnumbered adult females in catches because of differences in the distributions of the sexually segregated population. Males mature at 180 cm TL (10 yr); females at 250 cm TL (15 yr). von Bertalanffy parameter estimates for combined sexes of this species were L∞ = 329 cm TL, K = 0.073, to = −2.2 yr.
    Type of Medium: Electronic Resource
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