kalaülekäigud

Kalaülekäigud, also known as fish passages or fishways, are structures designed to help fish migrate past obstacles in rivers and streams, such as dams, weirs, or culverts. These passages are crucial for maintaining the ecological health of aquatic ecosystems by allowing fish to access spawning grounds, feeding areas, and escape predators. Without them, migratory fish populations can become isolated, leading to reduced genetic diversity and potentially severe population declines.

The design of a kalaülekäik varies depending on the type of obstacle, the species of fish it is intended to benefit, and the specific hydrological conditions. Common types include fish ladders, which consist of a series of steps or pools that reduce water velocity, allowing fish to swim upstream, and denil fishways, characterized by a series of baffles that create resting areas. Other designs include nature-like passages that mimic natural stream conditions and fish lifts or elevators that physically transport fish around obstructions.

Effective kalaülekäigud are designed to mimic natural conditions as closely as possible, with appropriate water flow, depth, and substrate. The success of a fish passage is often measured by the number and species of fish that successfully migrate through it. Monitoring is essential to ensure the passage is functioning correctly and to identify any necessary improvements. The implementation of kalaülekäigud is a key component of river restoration and biodiversity conservation efforts worldwide.