A new remote-controlled ‘boat’ being developed at Cranfield University for the Environment Agency could assist in the recovery of fish populations in UK rivers, by improving migration routes and access to vital food and breeding grounds.
The surveying device, or boat, will gather detailed information about the hydrodynamics – the movement of the water – in rivers to identify why some man-made passages are more attractive to fish than others.
Connected rivers provide fish with access to essential resources, but large structures such as dams and flood barriers can block routes and cause habitats to become fragmented. A large number of fish passages have been created over the last decade to tackle the problem, however evidence suggests that many of these only work well for some fish species or life stages.
Thomas Kriechbaumer, PhD researcher on the project at Cranfield University said: “The problem is that fish often can’t find and enter the passages we create. They don’t feel like a natural river to the fish because the hydraulic properties of the water are different, and so they won’t pass through.
“This new boat will help us gather detailed information about the hydrodynamics of rivers. Once we can measure what the fish experience, we can assess how attractive a certain passage is to them and give recommendations for minimising the ‘blocking’ effect that large structures have on freshwater ecosystems, and improve existing passages for the fish.”
The new remote-controlled devices will send out sonar signals and listen to the sound that is returned using acoustic technology. This indicates how fast the water is moving, the depth of the water, and flow complexity.
Whilst similar techniques are already in use, the new device will be sleeker and easier to manoeuvre, allowing measurement of all the nooks and crannies of each river.
Dr Monica Rivas-Casado, the Principal Investigator and specialist in applied environmental statistics at Cranfield said: “These precise measurements could make all the difference. The better we can understand the natural habitats and preferences of the fish, the easier it is to encourage them to use artificial passages. This will ultimately improve habitats and ecosystems, leaving us with healthier rivers.”