Distribution of migratory fish in the stream (depth, velocity, body size, predators)
Distribution of migratory fish in the stream (depth, velocity, body size, predators)

Summary/Abstract: In order to supplement the available information for the eco-hydraulic approach to designing fish passages, taking into account the taxonomic, dimensional structure, as well as taking into account the presence of predatory fish in the stream, the distribution of migratory fish of the boreal plain faunistic complex (Russian Federation) was studied. Three depth-velocity sections from the shore to the midstream were investigated: 5 m and 27.8 cm/s, 8 m and 44.4 cm/s, 11 m and 55.6 cm/s. Analysis of the migration distribution of fish showed that in the direction from the shore to the midstream, the proportion of representatives of Cyprinidae decreases from 41.8–24.3% and that of Percidae decreases from 25.0–18.4%. For individuals of two groups: the Acipenseridae and Lotidae, Coregonidae and Esocidae, patterns of distribution in the structure of migratory fish are opposite – their share increases with increasing speed and depth characteristics: 23.0–40.2% and 10.2–17.1%, respectively. An assessment of the dimensional structure revealed a feature of increase in the size range of fish from the shore to the midstream: the dominance of small individuals (<10 cm) in the shore area is replaced by the dominance of large fish (> 30 cm) in the area of higher speeds and depths. A significant difference in the distribution for all studied taxonomic fish groups between the shore and the midstream was shown.

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