Do MPAs increase fish density?
Catch-per-unit-effort (CPUE, represented as the number of fish caught per angler hour) is used as a proxy for density. When looking at all species combined, CPUE is higher inside MPAs than outside (with the exception of Año Nuevo, in some years). Initial differences in catch rates are due to varying levels of habitat quality at the time of MPA implementation. Additionally, MPA and REF catch rates fluctuate due to changes in the environment over time.