Frequently Asked Questions

No, especially not in a vertical slot fishway. The fishway ensures that most/all fish will go through the Riverwatcher.

Approx. 500

Yes, in fact it works very well in places where you can gather all the fish.

It can, there is no physical limitation to the height of the scanner, only the width between the scanner plates need to be adjusted to water turbidity.

The scanner plates distance width can be adjusted. The generic setup is 40 cm wide but could be wider if the water is very clear.

The Riverwatcher is 98% accurate counting fish. If the fish has a PIT tag it is detected with 100% accuracy.

Algae and/or debris buildup can affect the performance of the counter. For best results, keep the counter as clean as possible. Some sites have a lifting mechanism to access the equipment. The frequency of such maintenance depends on water characteristics but vary from every week to once per month.

The turbidity limit of the IR scanner is 90 NTU. You will not see anything on a video long before that limit is reached but the Riverwatcher will count and measure each fish and provide a silhouette image.

These are two different optical systems. The IR system creates a curtain of beams in the water. When the fish breaks the beams, he is measured and counted. Speed and direction is also logged. The video system uses AI to detect, recognize and measure the fish.

We have seen fish getting startled if they are e.g. migrating at night in the dark and suddenly they enter the photo chamber with bright lights. To deal with this we recommend using infra-red lights during the night. It creates a black and white video but the fish will not be startled and can carry on his journey without interference.