Nibblet was first cataloged in 2007 and reliably shows up every year. Most of our whales with white have large patches, but Nibblet is the only one with these small "eyebrow" patches just inside the trailing edge of its flukes and for this reason is easy to recognize.
This diving sequence (August 31, 2011 in Favorite Channel near Bird Island) and front edge view of Nibblet's flukes shows other markings that can be used to identify this whale. None of my flat ventral fluke shots show a series of small, parallel white lines from the leading edge, but they can be just made out in the last two diving shots. The leading edge shot (left, June 29, 2012 in North Pass) shows white markings, but these do not continue underneath to the ventral side.
Nibblet has the dorsal fin and caudal spine of a juvenile whale: very sharply pointed and obvious vertebrae visible when "humping" for a dive.