I've alway's measured from the most forward part of the fin fully extended.That is how Mark & Kieth did the measuring when we were checked a couple years ago.They are the park rangers.I agree with this hieght thing being to long it should fall some where between 2" &
1 3/4".If they would just make 100% fin clipping mandatory in the native & other hatcheries we wouldn't be having this topic.
Good luck,
STRIKE ZONE