Does HSUS need hunting to continue?

Do HSUS and other anti-hunting groups need hunting?  From an excellent 5-part series on "The Vanishing Hunter," which appeared in 2008 in Delta Waterfowl's magazine:

"Perhaps Jim Posewitz of Orion—The Hunter's Institute summed it up best when he wrote in Pheasants Forever magazine, 'The animal rights and anti-hunting campaigns occupy more of our time and attention than they deserve. While they raise a lot of money and live well, they have not done much serious damage. They are a parasite and we are their host. They are an irritation, but are not likely to kill us—they and their business model require us.'"

Have anti-hunting organizations done any lasting damage or are they, as Jim Posewitz suggests, merely an irritation?