|Longfin spadefish (Platax teira) at Daryl Laut dive site in Batangas.|
The science of marine protected areas is conclusive: marine protected areas lead to more fish, bigger fish, more biomass, and greater diversity. The specific increases vary depending on a number of factors including enforcement, size, and even things like unforeseen cascading interactions within the ecosystem.
One of the benefits is the spillover effect, wherein fish who can't read (like Nemo's dad, Marlin) wander outside the boundaries of a marine protected area and into the nets of local fishermen. I learned recently that the spillover effect has its limits, though, and that on average extend only 600 meters past a park's borders (which suggests to me that optimal marine spatial planning would place a marine protected area every 1200 meters).
|Longfin spadefish (Platax teira) at a fish market in Manila.|