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0 (hodnocen0 x )

BK

Praha : Academia, nakladatelství Československé akademie věd, 1987

64 s.

Monografické číslo seriálu: Přírodovědné práce ústavů Československé akademie věd v Brně nova ser., t. 21 (1987), fasc. 12

Downstream fish migration were studied in two Czechoslovakian reservoirs. The Mostiště reservoir is of a submontane type, the depth near the dam being about 30 m and the coefficient of water exchange about 5. The Věstonice reservoir is situated on a plain, the depth at the dam being some 3.2 m and the coefficient of water exchange 50. In the deep reservoir the frequent migrants were those fish species inhabiting the pelagic and profundal-pelagic complex (perch, pike-perch, ruffe and eel). The highest migration occurred in the cool seasons of the year. The sharp decrease of hydrostaticpressure inflicted injuries or death of practically all migrants. In the shallow reservoir with a large discharge stream originating in the sublittoral zones the migration intensity was much higher in both fish larvae and older specimens. White bream, common bream, bleak, perch, etc., presented the most frequent migrants. Mass migrations fell in spring and summer months. Downstream fish migration showed diel changes. During spring and summer the migrants exhibited a twilight to nocturnal rhythm with one mode in night hours. In the autumn this pattern is less evident, the night activity being split into two modes, at twilight and at night. The species composition differed in the reservoir and among the migrants. This phenomenon is explained by the horizontal and vertical distribution of fishes in the proximity of outlet currens. ....

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Introduction ...4 // Methods ...7 // Fishing gears ...7 // Fish sampling ... 8 // Laboratory examination 9 // Downstream fish migration from the Mostiště reservoir ... 10 // Region of investigations and material ... 10 // Composition of fish species in the reservoir and among the migrants ... 13 // Fish distribution in the reservoir ... 15 // Larvae ... 15 // Fry and fish of older age groups ... 18 // Migration of sac fry and larvae ... 20 // Perch 20 // Pike-perch and other species ... 23 // Migration of fry and fishes of older age groups... 23 // Perch ... 23 // Migration of eel, ruffe and other species ... 26 // Traumatic changes in migrants ... 28 // Downstream fish migration from the Věstonice reservoir ... 30 // Study area and material ... 30 // Species composition of fishes in the reservoir and of the migrants ... 32 // Migration of sac fry and larvae ... 33 // Perch 35 // Pike-perch and other species ... 35 // Migration of fry and other age groups ... 37 // Silver bream ... 38 // Common bream ... 40 // Bleak 43 // 3 // Perch, roach, rudd and other species ... 44 // Comparative analysis of downstream fish migration from deep and shallow // reservoirs ... 45 // Species composition of migrants ... 45 // Size and age structure of migrants ... 46 // Concentration of migrants ... 47 // 24-hour dynamics of fish migration ... 50 // Seasonal dynamics of intensity of fish migration ... 52 // Ecological conditions of the discharge currents and its importance for downstream fish migration... 54 // Conclusion and summary ... 58 // Резюме ... 59 // Literature ... 60

(OCoLC)35532302

cnb000038592