Ah, I see. I knew that the OP has all muscovies. I didn’t want to create confusion by saying that they wanted to get rid of all the ducks, since “ducks” can also be used just to refer to females. Though I’ve had ducks before I’m not too knowledgeable about them.
It might be better to catch the female ducks first. With only one drake, many ducks could still lay and hatch eggs, but with few ducks and many drakes, there would be less eggs and thus less of a chance of more ducklings being hatched.