Population structure of the krill prey of the spinetail devil ray Mobula japanica (Chondrichthyes, Mobulidae) from Southeastern Bohol Sea, Philippines

Krill samples were obtained from the stomachs of bycatch M. japanica individuals (n = 16; for ray body lengths, see Masangcay et al. 2018) caught monthly from January to May 2016 in Butuan Bay, Southeastern Bohol Sea, Philippines (Figure 1). Krill were carefully identified following the descriptions of Weigmann (1971) and Brinton (1975). In order to determine krill size-structure, a sub-sample was randomly collected from the entire M. japanica stomach content samples. We identified the krill as Pseudeuphausia latifrons (G.O. Sars, 1883) (Figure 2). The population structure of ingested P. latifrons from each of the 16 ray individuals are shown in Figure 3. Krill total lengths ranged between 4.0 mm and 10.9 mm for both sexes.