Neuter/return works for Alaskan wolves

From ANIMAL PEOPLE, May 2004:

FAIRBANKS–Animal advocates who sterilize and release feral
cats and street dogs had the right prescription for wolf predation
control all along, Alaska Department of Fish and Game biologists are
discovering.
Clamoring to shoot and trap wolves to reduce predatory pressure on
the depleted Fortymile caribou herd, the Alaska DFG in 1997
grudgingly agreed to sterilize the alpha pairs in 15 wolf packs under
pressure led by Friends of Animals.
“The idea was that the sterilized pairs would defend their
territories against other packs, which they have done quite
successfully,” wrote Fairbanks Daily News-Miner staff writer Tim
Mowry on March 28.
As with feral cats and street dogs, sterile wolves hunt much
less than animals with young to feed. Therefore the caribou herd
would increase.
DFG biologists performed the sterilizations amid prophecies by
hunters and politicians that the experiment would neither work nor
shut up the opponents of wolf-culling, and therefore should never
have been started.

But the Fortymile herd has more than doubled in size since 1995.
“The fact that these pairs of stood up to the test of time is pretty
impressive,” DFG biologist Jeff Gross told Mowry. “Some of them are
10, 11, or 12 years old, and still holding their territories.”
Normally, DFG spokesperson Rodney Boertje said, “Very
seldom do you see an 8-year-old wolf. They get replaced before that,
because they can’t keep up with all the competition.”
The sterilized wolves will eventually die out, and more
wolves will have to be sterilized to take their places, or newcomers
will breed back up to the carrying capacity of te habitat.
Meanwhile, though, sterilization “kind of proved itself a real
viable management option,” Gross conceded. “It has shown it has
longevity. It really is cost-effective in the long run.”
Shooting and trapping wolves, meanwhile, the option
promoted by the Alaska Board of Game, state legislature, and
Governor Frank Murkowski, effects a reduction in predation for only
one or two years, before the survivors and immigrants from nearby
regions are again hunting to feed large litters.