Oostvaardersplassen there are too many adult carp. The carp can be predated on by the Eurasian otter, the white tailed eagle and the wels catfish. The wels catfish can be found in the canals surrounding the Oostvaardersplassen and they represent the easiest way of improving the aquatic ecological pyramid. The problem is that it is not possible for carp to leave and for welsh catfish to get into this nature reserve.
I found a great Youtube movie showing adult welsh catfish; with a length that can be over two meters, they are fear inspiring fish... Enjoy !!