Theres a couple of otters at Blueplanet, I remember cos my little boy and I were looking at the pictures of when we went a few months back! I think they were Canadian Otters...they had their babies in another close by enclosure who didn't stop crying (it was real close to dinnertime) and kept running around looking out for the keeper...i have a picture somewhere:
They were much bigger than I expected!
Just found the Blueplanet website: Theres a page about their otters as well. They have 2 different breeds apparently.
Hope thats of some help anyway.
oh my deepest apologies, you specifically asked about wild otters, sorry...only spotted that as i was about to leave the page