User blog comment:Kaido King of the Beasts/Chapter 829: Take Me Down to the Sweet City Where the Puffs are Pristine and the Sons are Yummy/@comment-26803131-20160616162521

I am going to go ahead and speculate that Pedro was once a part of Big Mom's crew. Or every so often Minks explore the world and since Totland seems pretty inviting (minus the whole rampaging withdrawls from Big Mom) they end up living on the islands.