Migrating Eels caught on camera
The deployment of a high-tech acoustic camera has allowed the Environment Agency to track the movement of migrating adult eels as they pass through the River Huntspill in Somerset. The eels will make a 3,000 mile journey across the Atlantic to get to spawning grounds in the Sargasso Sea.
The cutting-edge acoustic camera was originally designed to carry out safety checks and detect hairline cracks near oil rigs. It uses sound waves (sonar) instead of visible light to provide near video quality images in areas where conventional visibility is poor or nonexistent.
It is hoped that the information gained from use of the acoustic camera will provide scientists with vital information on the eels' life cycle and their numbers. The adult eels were tracked heading out to sea after achieving maturity within UK rivers. Some are up to a metre long and 20 years old. Prior to migration, the eels stop feeding and undergo complex physical changes that include the absorption of their digestive systems in favour of replacement with reproductive organs. The timing of the migration is affected by a number of factors, including rainfall, water temperature and phases of the moon.
The eel population has declined by 95% over the past thirty years as a result of disease, loss of habitat, over fishing and pollution. The data collected over this winter will be compared with a similar study carried out when this equipment was first trialled two years ago.
Commenting, Pete Sibley of the Environment Agency said ‘The introduction of the acoustic camera is our first real chance to record and capture eel numbers by direct observation and increase our understanding of the creature’s mysterious life cycle.’
