Effectiveness of Philippine Nationally Managed Marine Reserves in Improving Biomass and Trophic Structure of Coral Reef Fish Communities

Abstract Many studies have examined the performance of locally managed marine reserves in the Philippines but the effectiveness of nationally managed marine reserves under the National Integrated Protected Areas System (NIPAS) Act is poorly understood. This study assessed the biomass and trophic structure of reef fishes inside and outside marine reserves from seven NIPAS seascapes. These were compared to other protected seascapes being proposed for inclusion under the NIPAS. Total fish biomass was higher inside marine reserves than outside; however, the effect of protection was not evident when total biomass of commercially valued families was compared. Furthermore, the total biomass of commercially important fishes was lower in NIPAS reefs and fell below threshold values for sustaining fisheries. No difference in trophic structure was found between inside and outside marine reserves in both NIPAS and non-NIPAS reefs. In addition, the relative biomass of predatory fishes (trophic levels ≥ 4) was smaller in reefs with low fish biomass (<25 mt km−2; which describes many NIPAS reefs), than those with higher total fish biomass. The overfished state and depauperate predator biomass of NIPAS reefs may be attributed to poor enforcement of no-take regulations and lack of stakeholder engagement, suggesting the need for improved management.