Money and power. AK and BC keep on keeping on. BC won't consider getting off of the fish until AK cuts back. Since nobody else takes AK's fish, where's the pressure point.

One possible option may be through ESA and the International CITES treaty/rules. That bans trade in endangered species. IF AK or BC can't show that the fish in question came from non-endangered sources (i.e. marked hatchery fish) then they couldn't be imported. So, one could not go to BC, catch fish, and bring them home without documentation proving they were listed. Long shot, I know, but if you can't stop the fishery maybe you can stop the trade.