Also, contact the local historical society's in the towns surrounding Great Bay. I would bet that they would have information on duck camps, market gunning, and the like around the Bay. There are a few pages on shooting stands around Great Bay in John C. Phillips book titled "Shooting Stands of Eastern Massachusetts."
A serious reduction in the population of black ducks would mean the end of waterfowl hunting for the majority of the New England sportsmen.
Rachel Carson, 1947