Some young people are working at the Greifenstein fish migration aid to carry out fish monitoring.

The transparent
fish 4.0

25 May 2018

"What is already standard in the pet sector is now being used in the scientific investigation of our fish migration aids," explains Walter Reckendorfer, who is supervising the project on behalf of VERBUND. The tiny transmitter chip from Biomark is individualized and implanted in the fish's stomach. For trained personnel, this means just a few simple steps that cause the fish less pain than a hobby fisherman's hook.

The fish are marked on the underside to prevent them from swallowing the chip. The chip is usually removed when the fish are gutted. This means that nobody needs to worry that their movement data will suddenly appear on Walter Reckendorfer's computer. In addition, the fishermen are warned about the transmitter by their fishing associations and asked to return it. This is another way of collecting data on the fish. But the intention is different.

Receiver stations are installed along the fish migration aid, which are addressed by the fish's transmitters. In this way, we know the movement behavior of the fish and can find out the different preferences of the species. How long does a fish stay in the fish migration aid? How often does it use the fish migration aids - and the old question of all power plant operators: how many fish use the navigation locks on the Danube to migrate, and how many whistle on the strenuous journey over the fish ladder?  What is already quite normal in supermarkets - customers log their cell phones into the free WLAN and the company tracks their movement profile - is now also happening in the fish migration aids. 

Walter Reckendorfer, an employee at VERBUND, shows our editor how fish monitoring works. They are sitting in front of a computer and Walter shows a small fish to the camera.

The fish trap in Greifenstein is very busy. Horst Zornig and Benjamin Droop from Profisch have already caught, identified, measured and chipped 500 fish in Greifenstein in the first four weeks since it opened. Today, barbel, aitel, lavel, sooty nase, gudgeon and gudgeon have been caught in the fish trap. They also include immigrant blackmouth gobies and a Volga zander. 

With this hard and transparent data, the functionality of the fish migration aids can be proven watertight. The transmitter standard also makes it possible to identify tagged fish from other renaturation projects on the Danube. This makes the Danube the best-monitored river in the world. What used to be laboriously limited to a few specimens by hand or with an expensive transmitter can now be extended to almost the entire population with little effort. Surprises are not excluded.