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Profile updated on 8 December 2021
Blue swimming crab, Flower crab
Blue manna crab, sand crab, blue crab, horse crab. Local names include “kasag”, “alimasag”, “lambay”, or “masag.
The Blue swimming crab, Portunus pelagicus, is widely distributed throughout the waters of the Philippines, particularly in nearshore shelf areas. The stock structure for blue swimming crab in the Philippines is not well understood. There had been contention over the taxonomy of Portunus species as well as evidence of several ‘cryptic’ species across the Indo-Pacific region and identification of localized zones of hybridization or high genetic differentiation ((Stephenson et al. 1968); (Bryars and Adams 1999); (Lai et al. 2010); (Klinbunga et al. 2010)). A recent taxonomic revision based on the morphological and genetic divergence between populations across the species’ vast range has revealed that the species is actually a four-member species complex: as P. pelagicus sensu stricto, P. reticulatus (Herbst 1799), P. armatus (A. Milne-Edwards 1861), and P. segnis (Forskål 1775), with juxtaposed ranges and some peripheral regions of overlap (Lai et al. 2010). The presence of only one species, P. pelagicus, in the Philippines has been suggested, being centrally positioned within the species range of P. pelagicus sensu stricto. However, a more recent analysis using genetic data identified the presence of two Portunus species, the P. pelagicus sensu stricto and a previously identified but un-described Portunus species from Japan (Sienes et al. 2014).
This profile is for the Blue swimming crab in the Philippines Fishery Management Area 11 (FMA - 11), covering the waters in the Visayan Sea, Guimaras Strait, and Tañon Strait. FMAs were established in January 2019 (Fisheries Administrative Order 263) to focus on the ecosystem approach to fisheries management. The Visayan Sea and Guimaras Strait (i.e., the Western Visayan Seas), are the most important crabbing areas in the Philippines, containing about half of the country's crab picking stations (Mesa et al. 2018). The official production volume is reported as “Blue crab (alimasag”) in the Philippine Statistics Authority or PSA (see OpenSTAT).