We almost always let them pass, even though they are trout fry killing machines. One friend of mine makes it his highest priority to kill as many as he can for just that reason.
Spending $3/shell to collect some dog food is not optimal.....unless you have a new to you gun ......and its first light.....and they come screaming into your spread and........well..... then there is a high probability the dogs are getting a fish duck treat at dinner