Freshwater fish play an important role in the aquatic system of the many waters within a country. In order to come to sustainable, long lasting fish-populations it is important that fishes can freely roam and migrate between different habitats and living areas in order to complete their lifecycle. These forms of fish migration take place between salt- and freshwater systems (and the other way around) but also internally between different freshwater systems / polders. Examples of migratory (diadromous) species are the ide (Leuciscus idus), three-spined stickleback (Gasterosteus aculeatus), and European smelt (Osmerus eperlanus). Some migratory species cross entire oceans during the migratory process, examples of these are the European eel (Anguilla anguilla), and salmon (Salmo salar). During these migratory movements, fish endure a lot of obstacles in the water systems, due to human influences. The most common obstacles for fish are dykes, dams, weirs, pumping stations and hydro-electric power plants.

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For water managers fish migration has become an important subject in the recent years. Solving fish migration obstacles is beneficial to the health and diversity of the fish stocks, which results in a better ecological rating for the WFD (Water Framework Directive).

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The process of solving an obstacle location requires a solid preparation and precise execution. Research has to be done on the urgency of free migration at that location. Also, the current situation has to be researched. After this research, we are able to answer questions such as: which fish species currently populate the backland or polder at a location; or: does any fish get damaged or killed when traveling through the pumping station/power plant; and so on. This information also enables us to monitor the effectiveness of a solution once it has been realized at the location.

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We can coordinate this process from A to Z, but you can also hire us for individual tasks within the subject of fish migration. We can give advice on a preferred solution or solutions for a location, we can perform baseline research as preparation, perform research on damage and mortality of fish at a pumping station or power plant, or monitor the effectiveness of existing fish migration solutions.

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Due to the fact that every location differs from the other, fish migration research requires a custom approach every time. For most location a custom research setup will have to be worked out. For this research we generally make use of fish traps, and portable lift nets.

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