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10th June 2010, 12:15pm
Fish migration study biggest in Europe
Fish migration study biggest in Europe The University of Lincoln is working with the Environment Agency on one of the biggest studies into freshwater fish migration ever to take place in Europe.

The project aims to record fish movements and habitat use on the lower River Witham in Lincolnshire. Information gathered will be used to help develop habitat improvement schemes.

Chris Gardner, of the Environment Agency’s Data Analysis and Reporting (Fisheries) team, is leading the study. He said: “The Witham Bream Project began in 2006 when seven native bream were caught and tagged with acoustic transmitters. Over the last three-and-a-half years, more than 80 large adult bream, weighing between four and seven pounds, have been tagged. The survey is taking place on a 40km stretch of the River Witham between Bardney Lock, near Lincoln, and the Witham’s tidal limit at Boston. The river’s side channels are particularly precious as it is thought these are used by the its fish population. This study aims to gain evidence to be used to maintain and enhance this important habitat.”

Dr Paul Eady, Reader in Behavioural Ecology at the department of Biological Sciences, University of Lincoln, and Dr Charles Deeming, the University’s Senior Lecturer in Conservation Biology, are working with Chris on the project.

Dr Eady said: “This is truly groundbreaking research into the secret lives of lowland river fish. Apart from the practicalities of tagging and monitoring the fish, one of the main challenges has been the analysis and interpretation of more than three million pieces of data. However, from this data, we have uncovered some fascinating insights into the behaviour and ecology of bream in the Witham which can be used to inform the management of this important lowland river habitat.

“Given that it is difficult to see what the bream are doing under water, we have utilised acoustic telemetry to identify where individual fish are 24 hours a day, seven days a week. One of the surprising findings is that a number of bream make substantial journeys of around 20km in around one day, with one fish travelling just short of 120km within a month.”

The tags, which emit ultrasonic ‘pings’, can last up to 20 months. They transmit signals to 27 fixed receivers along the length of the river and in some of the side channels and can monitor fish movements 24 hours a day, seven days a week. Receivers log the date, time and tag number when activated by a passing fish.
The study has also identified that most activity happens in spring and that the fish congregate en-masse in certain areas of the river over winter.

Data will continue to be collected until November 2010.

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