Mallard ducks

Hi....we have a pond adjoining our property and when we moved in a couple of years ago there were about 25 mallard ducks in and around.Now we have about 200 and this will increase greatly again this spring.Whilst they look lovely they do create problems with both mess and destruction of plants.Another problem is that we cannot let our dogs out without an inevitable chase.What can I do to drastically reduce numbers.Is there anyone or organisation that can rehome them somewhere else?