Caribou populations fluctuate - established fact.  This herd's size had dropped significantly from peak, and still appears to be dropping, even if at what the present rate of decline is somewhat in dispute.
The State of Alaska attempts to manage game for a persistently steady, maximum population, even though this is a farming adapted concept not suitable to most wildlife populations.  They justify slaughtering all predators except human in an attempt to achieve this unnatural steady state - but not to merely Limiting human predation [no slaughter of excess human predators required] and disruptions until the population has varifiably stabilized??  As I understand it, the problem perceived by those 'on the ground' with a strong past hx of 1st hand observation over lengthy time is that aircraft over-flight and other such human disturbance may be a strong contributing factor in the decline, or may contribute to slowing the recovery of this herd.  Seems reasonable to test this out.