Bohol is an important feeding area for four ray species.

Oceanic Manta Rays, Bentfin Devil Rays, Spinetail Devil Rays, and Sicklefin Devil Rays aggregate seasonally in this area (November–May) to mainly feed on euphausiid krill (Rohner et al. 2017; Stewart et al. 2017; Masangcay et al. 2018; Bessey et al. 2019). The fishing season for mobulids in this area coincides with the northeast monsoon when increased upwelling leads to higher primary productivity in surface waters (Cabrera et al. 2011; Gordon et al. 2011). Fishers catch mobulid rays using drifting gillnets between 10 and 40 m deep, and whenever krill is present because mobulids spend a considerable amount of time at the surface to feed (Acebes & Tull 2016). All four species of mobulids are caught together, sometimes in the same net (Rohner et al. 2017). Between 2013 and 2014, 25% of 790 recorded fishing trips captured more than one species of mobulid in a single net (J Rambahiniarison unpubl. data 2017).

From November to May 2013–2015, the stomach contents of 89 mobulid rays were evaluated from individuals landed in Jagna, Bohol Island, each of which were caught in this area (Rohner et al. 2017).  The euphausiid Euphausia diomedeae was the major prey item for all mobulid species, recorded in 91% of all total stomachs. A strong dietary overlap was found in all mobulid species which suggests that in the Bohol Sea during November–May euphausiid krill are an abundant resource (Rohner et al. 2017; Bessey et al. 2019). This krill has a large size (10–15 mm) compared to other zooplankton and has a swarming behavior that makes them a high-value prey source for large filter feeders (Rohner et al. 2017).

From January to May 2016, the diet of Spinetail Devil Ray was evaluated using 16 stomach contents and stable isotope analyses (Masangcay et al. 2018). Spinetail Devil Rays fed predominantly on the euphausiid Pseudeuphausia latifrons. Larger females of this euphausiid were the most dominant in the diet of Spinetail Devil Ray, which coincided with the peak of the reproductive cycle of the krill (Masangcay et al. 2018).

From December 2012 through to May 2014, muscle samples were collected from Oceanic Manta Rays (n = 42), Spinetail Devil Rays (n = 42), Sicklefin Devil Rays (n = 35), and Bentfin Devil Rays (n = 73) at a landing site in Jagna, to study their feeding ecology using stable isotope analyses (Stewart et al. 2017). The diets of the four mobulid species largely overlapped with an intake dominated by zooplankton. Trophic niche overlap in mobulid rays increases as resources become scarcer, such as in the Philippines oligotrophic tropical waters (Stewart et al. 2017). This could increase the reliance of large filter feeders on high-biomass prey patches that are sparsely distributed (Rohner et al. 2015; Armstrong et al. 2016). Mobulids appear to require prey densities that exceed a threshold level to make feeding energetically profitable (Armstrong et al. 2016). Consequently, in nutrient-poor regions, there may be fewer prey patches of adequate density, resulting in multiple sympatric species converging on the same high-density prey sources with greater trophic overlap (Stewart et al. 2017). Thus, this highly productive area within an oligotrophic region represents an important feeding area for an assemblage of mobulid species.