I think it's going to be a lot less interesting than people think.

They're domesticated animals, bred for docility for a couple centuries. They never learned to hunt as pups. They've never seen anything but a cage. They've never eaten live prey. They're small animals with no experience dealing with predators. They're all starting in a small area that can't support even a fraction of them. It's almost winter. They're incredibly high metabolism animals that must eat constantly to survive.

Also... one thing to note. Mink farms are continually leaking mink into the surrounding ecosystem. Always and forever. It probably actually hurts the local mink population (these are native to the area) in the long run by introducing subpar domesticate traits into the wild population.

There will be a brief and localized surge in predation, then the overwhelming majority will starve to death and the mink population will rapidly return to where it was before, with worse genetics. In a couple years there may actually be fewer mink than there were before.