Ya,,, like a fish egg or fish fry will be able to survive out of water long enough on a birds foot to be transported across 7,000 acres. Anyone ever tried to hatch a fish egg that has been out of water over 30 seconds?
Secondly almost all fish lay very adhesive eggs. What ever the egg hits after it is laid it adheres strongly to. If the egg by remote chance gets laid on a bird foot how will the bird get it off its foot/leg at the next pond? I don't see many birds flying around with stuff dangling off their feet such as algae or weeds with possible eggs attached. Again dehydration is a huge hurdle to over come.
Fishermen are the most NORTORIOUS fish stockers on this planet. Anywhere anyplace they will find a way to create their own secret fishin hole.
