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

A A Chemagin

doi:10.15421/011930

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. Thus, it has been established that for Cyprinidae during the migration period, the choice shifts in favour of minimizing energy costs, and the choice to avoid the risk of predation from individuals of the groups: Coregonidae and Esocidae, and also Percidae, shifts in favour of the former. The distribution of perch is influenced by the reduction of energy costs and the simultaneous avoidance of predation and cannibalism. For the fish group Acipenseridae and Lotidae, their predominance in the deeper area is due to their less developed visual orientation mechanism in the stream because they are bottom-living fish species.

Highlights

The movement and migration of fish is important for maintaining populations of various fish species, including river fish
For Cyprinidae and Percidae fishes, it was shown that their share in the structure of migratory fish decreases with increasing depth and speed characteristics of the flow in the direction from the shore to the midstream section, for two groups: Coregonidae and Esocidae, Acipenseridae and Lotidae fishes, on the contrary, it increases
The change in the size range of migratory fish in the direction from the shore to the midstream of the studied depth-velocity sections occurs as follows: the dominance of small-sized groups of fish < 10 cm is replaced by the dominance of larger individuals > 30 cm

Summary

Introduction

The movement and migration of fish is important for maintaining populations of various fish species, including river fish. The development of hydro-construction changes the natural flow regimes and can fragment habitats, creating insurmountable barriers (Santos et al, 2016; Mao, 2018; Beesley et al, 2019) for anadromous and potamodromous, and for resident fish species (Enders et al, 2017), as a result of which the number of fish may decrease (Radinger & Wolter, 2014; Santos et al, 2016). For the design and construction of these technically complex structures, ichthyologists carry out a large number of studies in order to assess the physiological capabilities of fish depending on their age, species, gender, and phenotype. The obtained data allow one to correctly calculate the technical characteristics of the bottom substrate, the flow rate, the availability of resting places, etc., which in turn ensures the accessibility of the habitat with certain physical parameters for the realization of life potential by the fish community (Beachum et al, 2016, Booker, 2016; Bravo-Córdoba et al, 2018; Stuart & Marsden, 2019)

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