Nope. Just genetic variation. Like the Kermodi Canadian Spirit bears, they have greater salmon fishing success.
The direct factual result is that as they are successful feeders, they survive to reproduce more of this successful kind.
The Kermodi inland near Terrace and usually a pale sky-blue color, on the outer coast, they are white.
In just the last couple of years, a few grizz/polar hybrid bears have been killed in Nunavut.
I can't imagine the Polar bear range extending so far south and inland with prey that they have no instincts to hunt.
Armed guards took groups of kids out for Hallowe'en in Churchill, Manitoba.