Experts from the Environment Agency are making use of CCTV technology in a bid to monitor migrating fish numbers in a Cambridgeshire river.
At Dog in a Doublet Fish pass on the River Nene near Peterborough, fisheries staff have mounted a small digital camera underwater, which monitors all the fish travelling through the pass. The data is then recorded and hours of footage can be downloaded from the computer on site. Environment Agency staff then have the laborious task of watching the footage and noting down each fish that goes past.
The fish pass was built by the Environment Agency in 1994 to help fish in the river get past Dog in a Doublet sluice. By slowing the flow of water through a carefully designed channel it enables fish to pass the structure and complete their natural migration upstream. Previously they would have had to negotiate an alternative, more difficult, route under the sluice, and many would fail or be picked off by predators such as cormorants and otters.
Since the pass was built, many thousands of fish have made their way past the lock. Before the digital camera was installed, Environment Agency staff set traps in the pass in order to get an idea of how many and which species of fish were using it. Staff had to empty the traps and record the contents as often as six times a week. Today, information is downloaded from the site once a month and staff can record the numbers and species of fish from the comfort of their desks. Some of the fish that have already been caught on candid camera include roach, eel and some large specimens of pike.
Technical Specialist Chris Randall explains: ‘This new technology helps us to get a picture of the species and number of fish using the pass, an indicator of the quality of the health of the river. It also makes monitoring more efficient, as our staff no longer have to spend time going to and from Dog in a Doublet to empty the fish traps. This means that we can use our limited resources to improve fisheries elsewhere in the region.
‘This is the first time the Environment Agency in Anglian Region has made use of this CCTV technology to monitor fish numbers and if successful we will consider using it where other more traditional techniques are not available. It’s important that we know how effective we are at protecting and improving our fisheries. Monitoring those populations tells us if we have been successful.’