A genetic assessment was done on the greenblotch parrotfish (Scarus quoyi Valenciennes, 1840) in three bays within southern Mindanao, Philippines. Mitochondrial 16S rRNA recovered 12 haplotypes, one of which was dominant in all sites. Despite the reported phenotypic variation from previous assessments, there was neither evidence of genetic structure (global Φst = 0.012, p = 0.13) nor isolation by distance (r = 0.05, p = 0.50). Genetic diversity was also low (Hglobal = 0.472; πglobal = 0.13%), with ~ 77% of haplotype diversity accounted for with just 69 samples. While connectivity suggests continuous larval exchange within southern Mindanao owing to the species’ high dispersal potential, low genetic diversity implies reduced effective population size, probably due to recent bottlenecks (e.g. overfishing, habitat destruction). Although this study provides baseline genetic information on the local population, inferences are considerably limited by the genetic marker used and the spatial scale under investigation. A thorough understanding of the population will be possible if the entire habitat range of the species is assessed using markers with high resolving power, such as the hypervariable mitochondrial control region, microsatellites, or genome-wide single nucleotide polymorphisms (SNPs).

Octocorals are relatively understudied than other coral reef organisms despite their ecological and economic values. The Philippines is known to have high marine biodiversity, but information on octocorals is lacking. This study investigated spatial and temporal variations in the assemblage of octocorals in selected reef sites in the West Philippine Sea (WPS)- the Kalayaan Island Group (i.e., Pag-asa, Sabina, Lawak, and Northeast Investigator) and Ulugan in 2017 and 2019. Results showed high octocoral taxonomic richness (at least 10 families) in the study sites. Mean percent octocoral cover in WPS was 5.35% SE ± 0.55, with Sabina having the highest octocoral cover in both years. Significant differences in octocoral cover were observed among sites in both years, but among-station differences were only observed in 2017. Octocoral assemblage also differed among sites in both years (ANOSIM: R > 0.5, p < 0.05), wherein different octocoral taxa dominated in different sites. In particular, variations were driven by high cover of holaxonians, nephtheids, and coelogorgiids in Sabina, and clavulariids, tubiporiids, and xeniids in Northeast Investigator in 2017. In 2019, significant variations were driven by high cover of helioporiids in Pag-asa, while Sabina had higher abundance of holaxonians, nephtheids, alcyoniids, and xeniids. Short-term temporal variation on octocoral cover in monitoring stations in Pag-asa was not observed (Kruskal-Wallis, p > 0.05), although the overall mean octocoral cover increased from 1.23% ± SE 0.47 in 2017 to 2.09% SE ± 0.37 in 2019. Further, there was no significant change in the octocoral assemblage in Pag-asa between years (ANOSIM, R = 0.11, p = 0.07). This study highlights high octocoral taxonomic richness in the WPS relative to other sites in the Indo-Pacific Region and provides baseline information on the octocoral assemblages, which can be useful for future ecological studies and marine biodiversity conservation efforts.

Evaluating reef fisheries potential is crucial in understanding the benefits derived from coral reefs. In this study, fisheries production of three offshore reefs in the West Philippine Sea was characterized using both fishery-dependent and fishery-independent approaches. Experimental fishing was done using speargun and multiple hook-and-line in Pagasa Island and Sabina Shoal, Kalayaan Island Group (KIG) while interviews to assess fisheries production for the Scarborough Shoal were conducted in Masinloc, Zambales. Catch composition, total catch, and catch rates were obtained. Catch composition differed among gears although it was commonly dominated by Acanthuridae, Balistidae, Lethrinidae, and Scombridae. The catch rate was lowest for hook-and-line across all sites. Using varying levels of fishing days per year, mean catch rates ranged from 0.25–1.53 mt/fisher/yr for hook-and-line and 1.26–3.80 mt/fisher/yr for spearfishing. Estimated yields ranged from 2–31 mt/km2/yr. The potential annual yield for the three reefs was 1,053–2,733 mt/yr. When extrapolated, the KIG reefs can potentially produce around 61,557–90,850 mt/yr, or 3–5% of the total marine capture fisheries output. Interview results further revealed that the dominant gear type in Scarborough changed from speargun in the past to gillnets at present. This could be attributed to an observed shift in fishing grounds when access to the reefs became more restricted. The study shows that fisheries production in the three offshore reefs is still high compared with other areas in the country. However, these reefs have remained exposed to various anthropogenic threats, which could lead to significant fisheries losses if they remain unmanaged. Especially in offshore reefs where benchmarks are lacking, information on fisheries productivity should be compiled if it were to be sustained.