Benefits

Mark-recapture methods

ELFI is often combined with mark-recapture methods (for example Lincoln-Petersen or Chapman), whereby captured animals are provided with a colour-mark. Based on recaptures, estimates can then be made of the absolute numbers of elvers at the research site, migration speed and the potential barrier effects of the installation (the weir, pumping station, waste-water treatment works or lock). Marking techniques most often used for this are Visible Implant Elastomer Tags (VIE tags), but also staining with Bismarck Brown.

 Traditional dip nets

ELFI offers many advantages over traditional dip net monitoring, such as continuous monitoring, less personnel effort and possibilities to investigate migration behaviour (such as the effect of lure currents and migration speed).

Benefits of ELFI at a glance:

• Can be used for many research purposes, including:
• Migration of elvers and glass eels.
• Continuous monitoring.
• Testing parameters of eel gutters (to be realized), such as climbing substrate, location, lure flow and effect of drainage.
• Cost-effective research method.
• Detection at very low numbers is also possible.
• The result is objective and uniform, the execution is the same everywhere.
• The combination with mark-recapture methods.
• ELFI can be placed at any location where a lure current can be generated.