I can't say for sure that the RCA's themselves are solely responsible for better fishing. I do know that when the larger size restriction was introduced in the inside strait it was very difficult to even catch a legal size ling in the gulf islands. At that time I personally believe the populations there were on the verge of collapse. I have fished the Gulf islands for 45 years, so I have a pretty good view of the populations ups and downs for a long time. Once the size restrictions were introduced the populations very slowly began to rebuild. The greatest increase in size and numbers has occurred since the introduction of the RCA's. That is not scientific proof that the RCA's are working. It is merely anectdotal evidence that they have helped the stocks rebound. I would not like to see any more RCA's over there as much of the better areas are already closed. I was initially very resentful that almost all of my favorite locations were closed. Now I realize the closures were necessary and I don't gripe about them anymore.
I am no fisheries biologist, but I think the idea could be improved upon by rotating closed areas occasionally over time. Maintain the same number of closures but open an area for fishing that has been closed for many years for one season, and close a different area to give stock there a chance to rebuild. Only a thought, but it might give great opportunities for fishing while helping another area in decline.
Just my opinion