The study is from 2001. Since then, those reserves were established. 98% of the captures for fish for the aquarium trade in Hawaii are done in one island, the Big Island, where all those reserves are present. The yellow tang is completely protected in 70% of it's range, and is only fished in a small portion of the remaining 30% of its range (the Big Island).
No, the study is not evidence of an irresponsible fishery. It is evidence that a sustainable fishery is possible with the presence and enforcement of marine reserves, which is exactly what happens there.