Counters on Open Rivers

For a range of reasons, the installation of a counter within a fish pass or the construction of a weir may not be practical. An alternative can be provided with a hydroacoustic counter. Even with such a counter, a range of specifics requirements must be met to ensure that the counter is sighted in the best location.

River Soundings
Prior to the sighting of a hydroacoustic counter, soundings of the river bed are taken at a range of locations.

Equipment Housing
Flooding can potentially be a serious risk to equipment. In some locations the huts need to be raised stands to ensure they remain above normal flood levels. Alternatively, earth banks can be built up to raise the floor level of the hut.

Transducer Stand
At the river bank a stand is normally constructed to deploy and support the transducer in the water. The stand has an added advantage of allowing cabling to be easily routed from the river bank to the transducer.

Far Bank View of Counter Site
The installation of a hydroacoustic counter can be installed on a river site with only a limited amount of civil engineering required. An additional advantage of these installations is that the entire unit can easily be relocated to alternative sites.

Transducer Mount
The transducer is mounted on a rotating head which allows adjustments to the beams orientation underwater. The transducer is normally surrounded by an additional steel case to provide better protection from debris.

Transducer Positioned for Operation
The transducer is mounted, underwater, within a steel shroud. The cable to the transducer is ducted through steel tubing.

Sample Run
Data processed from a hydroacoustic counter displays echoes received from the transducer from the far bank. When fish swim through the acoustic beam the returning echoes are processed by the counter, including information on swimming direction, date and time.