I think you have to be careful there. Recognize that the target for a sustainable fishery is to reduce the stock size down to a level such that you're maintaining sustainable take through time. You can do that by removing over 50% of that stock and still achieve a sustainable take, but you're doing that across the entire stock, not at particular locations. By doing that, what the consequence is for the ecological role of that species in the system is very different. You can imagine that removing 50% of a local population will impair the ecological role of that species in that ecosystem—there's no question.
In fact, there's an outstanding example. I don't want to get into too much detail. The lobster fishery off the coast of Tasmania was a sustainable fishery. With climate change, there was an invasion of a sea urchin into the kelp forests along the coast of Tasmania. In no-take reserves, the lobsters were of sufficient size and number that they could control those sea urchins. Outside of those reserves, where you were conducting a sustainable lobster fishery, you had nonetheless reduced the number and size of the lobsters to where they could not control those sea urchins. As a consequence, the urchins would remove the kelp forests, upon which a multi-million dollar abalone fishery was reliant.
It's induced by climate change, but it's an example of where even a sustainable fishery for one stock can potentially jeopardize the sustainable fishery of another. We learned of that only because we protected the functional role of lobster within those reserves to resist the consequences of that urchin invasion.