‘The last 30 years have been bad for the European eel. The population has decreased by more than 90 percent. The precise cause of this decrease is unknown,’ says Dr Christian Tudorache. He is studying the physiological and ecological circumstances this animal has to deal with as it migrates to spawn.
Tudorache’s research at the Institute of Biology Leiden (IBL) has two main objectives: new physiological research into the swimming behaviour of migrating eels and the development of an optimal transmitter that does not present too much of a hindrance to the swimming behaviour and energy use of eels as they swim.
The eel stock has decreased dramatically, possibly due to a combination of reasons, including overfishing, environmental pollution and hindrances to migration such as dams, dykes and pumping stations. More knowledge about eel migration and reproduction is necessary to break the downward spiral, knowledge that could be gained by following these animals on their way to the Sargasso Sea. Previous attempts to use satellite transmitters to follow the eels on their journey to the spawning grounds have been unsuccessful. These transmitters were too big and exerted too much resistance. They were buoyant which mean they pulled permanently to the surface and consequently interfered with the eel’s deep dive and the crucial efficiency of its swimming motion, a motion of the whole body rather than just the tail.