Duck eggs smaller then normal

[Newxxxduck]

I have been getting a few smaller size eggs this passed week. I was wondering if it is because I have younger, newer ducks in with the older ducks or is my older ducks coming to an end with laying? I added a photo of a normal size egg I get with the small one.

 

[AquaDuck]

Looks like "fart eggs", eggs containing only white and no yolk. Is it the younger ducks' first eggs ever? The first eggs they lay can be all kinds of weird, double yolked, without shell etc.