Environment Agency - Home

Biggest ever study in bream behaviour

Our fisheries scientists have been closely monitoring the movements and behaviour of bream in the UK’s largest ever study of freshwater fish migration.

The study, which has been taking place in the lower River Witham near Boston, has made use of the latest acoustic tagging technology to track the fish over three years.

“Small acoustic tags were surgically implanted into 83 adult fish, and fixed acoustic receivers positioned along the reach then logged when the fish were close by, to record their movements,” explains Chris Gardner.

“Traditionally, tracking fish has been carried out manually which is very labour intensive. But this new technology means we can monitor fish movements 24-7, 365 days a year. It’s given us a huge amount of useful information, with more than 1.2 million fish detections recorded in the first two years of the project.”

The results have broken new ground in fisheries science. Much more is now known about how fish use the side channels off the main river – and about the distances they travel. Many bream can travel more than 20 kilometres in two or three days, and one tagged fish travelled an incredible 18 kilometres in just 36 hours.

Tracking much larger numbers of fish means fisheries staff now also have a ’bigger picture’ view of the whole fish population, and how they move around and behave at different times of the year.

Ecological Appraisal Officer, Chris Gardner, 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 stocks, which will in turn benefit anglers.”