Way too many ducks for .62 acre pond. Apart from the nitrogen buildup in the pond, that many will seriously mess up the edges via their dabbling as well as crapping all over. You could very easily wind up with a lifeless pit in a short period of time without taking some action. The Coyotes will get the odd duck but may not be as successful as you would like from my experience. Racoons will take ducks as well as hawks and Great Horned Owls. Ducks will eat small animals when they catch them but it is not a staple of their diet. Sorry to be pessimistic because I like and have ducks, but in this case it really is too much of a good thing.
Jim