You take a crate, with about 2 inches clearance between slants, you put in a head of a slaughtered animal if large or some road kill, put a lid on the crate, fix it on with nails, tie a rope to it and toss it into lake for the night. Hungry eels get in, gorge themselves and can't get out. In the morning you pull out the crate and take them out.
Well that's what I've heard...