ELFI is a collaborative product of Waardenburg Ecology and Visserij Service Nederland. ELFI is used for monitoring eels migrating upstream, in the life-stages from glass eel to yellow eel. ELFI is often combined with VIE tagging
(Visible Implant Elastomer), a method of colour-coding animals. These two techniques answer questions such as:
- Where, when and how many glass eels migrate?
- How long do glass eels spend trying to pass a certain barrier?
- How quickly, and in what quantities do glass eels use a fish passage?
- What are the migration routes of glass eel?