SGF,
Keep in mind that these parasites, birds, fish etc have been involved in this relationship for thousands and thousands of years and the fish are still here. I see parasites all the time in the trophy fish I take in as a taxidermist and it doesn't seem to keep them from becoming trophies. There are are nonlethal ways of keeping the birds out of the water and the use of shellcrakers is a good idea. But don't fall prey to declaring war on the birds as I did at one time (with federal permits). They are only doing what is natural.
