Distribution of the juveniles of common roach Rutilus rutilus, common bream Abramis brama, vimba bream Vimba vimba, and zander Sander lucioperca in the Lower Don in low-water year of 2017
When the Tsimlyansk Hydrounit had been put into operation, it introduced changes in the distribution of the intra-annual runoff of the Lower Don River, which meant partial or full accumulation of spring floods and an increase in expenses during the summer-autumn and winter low-water period (baseflow). The major bulk of the accumulated water was utilized for shipping and agriculture. With this mode of operation of the Tsimlyansk Hydrounit, spring flooding of the floodplain did not occur in the low-water year of 2017. The studies on the distribution of juveniles of common roach, common bream, vimba bream, and zander were carried out in May–September, 2017 at the Lower Don area, from the Kochetovsky Lock to the mouth. As a fishing gear, a 32-meter fry dragnet was used for catching the juveniles in the coastal zone. The location of the stations was selected taking into account availability of suitable sites for dragnet hauls. In the dragnet catches, 35 species belonging to nine families were recorded. In the low-water year of 2017, juveniles of low-value fish species prevailed in the ichthyocenosis composition (86.86 %), whereas juveniles of valuable fish species accounted for only 13.14 %. Among valuable fish species in the ichthyocenosis composition, roach juveniles were more abundant than those of the bream and vimba bream. The share of zander juveniles was insignificant. The juveniles of roach, bream, vimba bream and zander confined themselves to sparse macrophyte beds, covering a significant area of coastal shallow waters, and to the river estuaries flowing into the Lower Don River In the low-water year of 2017, the downstream migration of juvenile roach, bream and zander began in June, while for the vimba bream yearlings it began in late May. During their downstream migration, juveniles stick to coastal shallow waters overgrown with macrophytes and to the estuarine parts of the rivers flowing into the Don River. From June to September, migrating juveniles of roach, bream, vimba bream and zander accumulated in the middle part, where they were feeding and fattening for some time, and then migrated further downstream. An analysis of the data collected during the field studies allowed to assess the generation of roach, bream, vimba bream, and zander born in 2017. It has been evaluated as low-yield.
| Main Authors: | , , |
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| Other Authors: | |
| Format: | Journal Contribution biblioteca |
| Language: | Russian |
| Published: |
2020
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| Subjects: | Vimba bream, Roach, Bream, Zander, Intra-annual runoff, Coastal zone, Ichthyocenosis, Juveniles, Abramis brama, Vimba vimba, Sander lucioperca, Rutilus rutilus, Судак, Тарань, Гидроузел, Лещ, Рыбец, |
| Online Access: | http://hdl.handle.net/1834/17252 |
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