There are more than 87 MPAs worldwide. These were 87 MPAs that were studied in the same ways using the same methodologies, and so on. There were measures of biomass, the number of species, species diversity, and different things like that. Some of these things you expect. If you close an area, then you're going to have an accumulation in that area. If you don't have removals, there will be an accumulation. If you see increases in certain large sharks within a 10-year period, it's not likely those were due to local production of sharks. It's because sharks moved in there and they haven't moved out yet, depending on the size of the MPA.
The particular study looked at having one criteria, two criteria, three criteria. It wasn't until you had all five criteria in place did you actually see a large effect in these metrics in biomass and standing stock, and so on.