In 2013, Arizona Game and Fish began its on-going program to reintroduce bighorn sheep to the Santa Catalina Mountains. At the time, 31 of them were relocated to the area from Yuma.

More than half of that herd were killed by mountain lions a few months later - causing the department to eliminate three of them for preying on the sheep. They've been largely criticized for that move, and for the reintroduction as a whole by groups like Friends of Wild Animals.

Another 30 bighorns were reintroduced this past November and Game and Fish plans to release another 30 at the end of this year, too.

The department is now saying that the reintroduction is helping both bighorns and mountain lions. 

Reportedly, the number of mountain lions killed by hunters in the Catalinas declined by 40 percent last year.

Hunting without dogs is allowed within the 22,500-acre protected area, according to a press release by the Center for Biological Diversity, but that technique is harder and thus less common - so that could have caused the decline.

To be clear, hunting with dogs in the area is banned.

The release gives some background, saying lion killings in the Catalinas were up to a couple of dozen by 2012, then when the bighorns were introduced, this leveled off, and last year the deaths dropped to 12 by hunters, 1 by bighorn program and 1 by a rancher as of December 2014.

From a press release sent by the Center for Biological Diversity:

The dramatic decline followed the establishment of a 22,500-acre bighorn
sheep protected area in the Pusch Ridge Wilderness in July, 2013. Hound
hunting of lions is prohibited within the protected area.

Those seeking to prevent the return of bighorn sheep to the Pusch Ridge
Wilderness assert that depredation kills conducted by the program are
devastating the lion population. The decline in hunter kills, however,
greatly outnumbered the single lion killed by the program in 2014 and the
two killed in 2013. With these included, 2014 and 2013-2014 remain the
largest single and two-year declines in lion killings since 1982.

From Kierán Suckling, executive director of the center:

Restoring sheep to the Pusch Ridge Wilderness is good for the sheep, good for lions, and good for the mountain.The cautious, innovative ecosystem approach taken here should serve as a model for bighorn restoration everywhere.

I checked out the Friends of Wild Animals Facebook to see what they had to say:

Hunting lions with dogs is prohibited, but hunting lions is allowed. Also, the bighorn sheep advisory committee and the AZG&F Department sanction a houndsman hunting any lions that may have killed a sheep. The hunting of lions with hounds is bad for both lions and sheep because the lion dies for doing what lions do - eating sheep - and the hounds used by the houndsman are very bad for the ewes and their newly born lambs.