Environment Agency fisheries scientists have been closely monitoring bream in one of the largest freshwater fish migration studies that has ever been done.
Over the past two years, the Environment Agency has been monitoring the movements of bream in the lower River Witham between Bardney Lock and Boston. Adult fish weighing between 4-6lbs had small acoustic tags surgically implanted, which send out coded ultrasonic ‘pings’ to receivers that log the fishes movements as they travel up and down the river.
However, one particular fish – fish 251 – or ‘Betty’ as she has been named, has secured the attention of fisheries staff with her very regular patterns of behaviour. Originally tagged at Tattershall Bridge in February 2007, she soon moved up to the Bardney area where she spent the rest of the year. During the spring and early summer she spent every night in the main river, and each day at 7am sharp she would move into the Sincil dyke for the day, returning to the main river at 7pm. Betty kept up this regular pattern of behaviour right through the spring and summer months, only changing her routine during high flow events.
Ecological Appraisal Officer, Chris Gardner, from the Environment Agency said: ‘This project has really opened our eyes to the mobility and dynamic behaviour of fish stocks in the Lower River. Understanding patterns of habitat use by fish will help us target river habitat improvement projects and manage the river better for the benefit of fish stocks, which will in turn benefit anglers.”’
Traditionally, tracking the movements of tagged fish was carried out manually and would be labour intensive, but new technology allows movement to be monitored 24/7, 365 days a year, automatically.
The project has generated a huge dataset with more than 1.2 million fish detections recorded in its first two years. Analysis of the dataset has revealed some significant findings, which will be used to influence the management of the river and target fisheries habitat improvement projects.
