"The simple interpretation is that genetic rescue doesn't work," said Vucetich, an assistant professor of wildlife ecology at Michigan Technological University. "But what happened here is that when the immigrant came in 1997, in the decade that followed, the moose population declined radically. It's plausible that we didn't see an effect because the wolves were suffering from some other trouble that disguised the benefit. What if wolf No. 93 had never arrived? Vucetich said that it is impossible to know for sure, but the Isle Royale wolves might have disappeared completely. It may be that the Old Gray Guy arrived just in time."