Do pond snails eat fish/shrimp eggs?

I have a 300L pond with pacific blue eyes which are showing all the signs of wanting to spawn. Ammonia and nitrites zero, nitrates 5ppm. 24 deg C, aeration, plants, spawning mops, lots of secure retreats, but no eggs. It could be that they're not ready, that's cool, but there are LOTS of snails and their eggs. I don't believe I overfeed. Would the snails be eating the eggs?
Same situation in my ghost shrimp tanks.
Any ideas. Cheers,
Greg

Thanks guys. Looks like I'm back to square one with the fish, and the shrimp....sheeesh....I never left square one. Thanks Lupin.
Greg