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The Dance of Water and Fish: What scientific secrets are hidden behind the design of fish ladders?
A fish ladder, whether a fish pass, fish step, or fish cannon, is a structure surrounding a man-made or natural barrier (such as a dam, lock, and waterfall) designed to facilitate the natural migration of migratory fish. The design of these fish ladders is not just a simple structure, but a series of results of scientific research and technological innovation to facilitate the passage of fish. As many scientists have pointed out, a properly designed fish ladder can create a perfect balance between water flow and fish, so that fish no longer encounter difficulties in passage.
The history of fish ladders
The history of fish ladders can be traced back to France in the 17th century, when people used tree branches to make crude fish passages to help fish bypass obstacles. Since then, with the advancement of water conservancy projects, the design of fish ladders has become more and more diverse. For example, in 1830, James Smith of Scotland built the first salmon ladder for ponds and dams, a facility that is still in use today and influenced many salmon ladders subsequently built in Scotland.
“Effective fish ladder design can be adjusted according to the swimming abilities of different fish species to ensure that they can flexibly pass through the dam.”
Types of fish ladders
The designs of fish ladders are various, mainly including:
- Pond and Dam System: Consists of a series of small dams and pools that allow fish to pass through in a gradual manner.
- Baffle fishway: By setting up symmetrical baffles in the waterway to guide the water flow and help fish bypass obstacles.
- Fish Elevator: Suitable for taller obstacles, using an elevator-style design to carry fish upstream.
- Fish tank: This is a flexible pipe that uses air pressure to safely and quickly move fish to their destination waters.
Effectiveness of fish ladders
Although fish ladders are designed to facilitate fish migration, their effectiveness varies. One study showed that only 3% of American herring successfully made it through all fish ladders to their spawning grounds. This shows that differences in swimming ability and behavior of different species of fish when passing fish ladders will have a significant impact on their migration success rates.
“We need to find a balance between ecological, engineering and design skills to improve the success rate of fish passage.”
Interaction between water flow and fish
In the design of a fish ladder, the speed of the water flow is crucial. The current needs to be fast enough to attract fish toward the ladder, but not so fast that it washes them back downstream or tires them out. Designers must balance many factors, including the dynamics of water flow and the swimming performance of fish, to ensure the effectiveness of ecological pathways.
Future challenges
With the increasing severity of hydraulic facilities and environmental problems, the design of fish ladders faces new challenges. The destruction of water bodies and accelerated flow rates caused by urbanization make the migration path of fish more difficult. Therefore, scientists and engineers are currently working on developing more advanced solutions, such as using eco-friendly fish passages and smart water flow control equipment.
Comprehensive considerations for fish passages
Designing an effective fishway is not just a simple structural project, but also an overall plan that takes into account fish ecological behavior, fluid dynamics and environmental impact. This requires interdisciplinary collaboration and extensive experiments and simulations to find the best design solution.
Conclusion
Although existing fish ladder facilities have improved fish migration to a great extent, their effectiveness still needs to be enhanced. When discussing every detail of fish migration, should we rethink the way humans interfere with natural ecology so as not to hinder the free dance of fish in the water?
