It is the "selling" of the fish that is illegal without the permit. If they just put the fish in the freezer and ate it, perfectly legal. We used to get all kinds of inspectors at the aquarium. To top it off, we used a drug to tranquilize the fish and it had to be stored in a locked refrigerator.
Link to the expensive tuna...
http://articles.sun-sentinel.com/201...rcial-purposes

