I wonder if other birds can also transport live viable fish eggs. When I was still in Grammar school we use to go back to the woods and play in the stream there. There were small sunfish in the deeper pools of water. I always wondered how they got there. It was a small stream that I could jump across in most places and it was not always filled with water. But the large pools were about 1 or 2 ft deep and about the size of a large bathtub. I used seines to catch crayfish and little sunfish and small minnows. The only pond was way downstream about a mile away and it was above the creek. It was a farm pond and the fenced-in area held hogs and the small pond. The road my parents live on is the high area and the stream is on the south side of the road. On the North Side of the road it drops off and there are a few lakes on that side of the road behind the houses there. There was one very small pond on the south side of the road that I would catch frogs and huge tadpoles. It was not but 2 or 3 ft deep. I remember when it got cold the ice would be about 3" thick and as a little kid, I could walk out on the ice. We chopped holes in the ice and used a net to dip out some big tadpoles. They had hind legs formed already. Now that I think about it that little pond could overflow into the stream that I was talking about earlier. Maybe that is where the fish came from. But how did the fish get into that little pond as there was not stream feeding it? It was just rainwater and runoff from around the edge of the pond.
I guess the birds helped bring the fish eggs to the stream and pond. I wonder if other shorebirds eat fish eggs and the eggs survive? There is more research to do. What about the fish that herons eat whole. Could the eggs inside those fish survive and be excreted alive.