Then if you could fence out part of the lake so it is inside their enclosure and leave them in for a couple of weeks that might work. What I do is give them enough feed in the morning to last until about noon. My ducks run in and out of the pen to get food along with foraging on my pond and...
How big is the lake? Can you include part of the lake in their fenced area? That's what I do so they have access to the pond when cooped up. Even on my small pond I sometimes have to wade it to herd them inside for feeding time. You may want to consider a longer break-in period. They won't...