I can't hold myself out as a fisheries lawyer, but I do have some experience with analyzing rights when parties hold a proportional interest to a shared resource. I believe it's reasonable to think that each treaty tribe, on the one hand, and the U.S. of A., on the other, is entitled to 50% exploitation of harvestable surplus.

However, that doesn't mean the average joe has any "right" to fish. Rather, the U.S. of A. as an entity has the right under the treaty, and can decide to do what it wants with that treaty right, including deciding not to press the matter when a treaty counterpart takes more than its share.

Now, I'd need to do a little more digging to understand how management of the nation's interest is delegated to the state.