Population Dynamics of Shortfin Scad (Decapterus macrosoma) Bleeker 1851 in Babuyan Channel, Philippines

Abstract

The study was conducted to determine the status of Decapterus macrosoma stocks in the Babuyan Channel. Data were collected from January 2016 to December 2017 following the standard methodology of the National Stock Assessment Program (NSAP). The data were analyzed using the Fisheries Stock Assessment Tool II software and R package. Results showed that the species is available throughout the year and is most productive during summer. Decreased catch landings were affected by environmental, biological, social, economic, and regulatory factors. Beach seine has the largest contribution of catch but has the most number of immature catches. The highest catch per unit effort for all the gears occurs from February to June. Fishing mortality for beach seine (F = 2.98) is higher than the natural mortality (M = 1.76) values, indicating that the species is already experiencing high fishing pressure. D. macrosoma exhibited a bimodal mode or recruitment with unequal strengths. Similarly, the observed exploitation ratio (E = 0.63) is beyond the sustainable exploitation level. In order to sustainably manage the species population, introducing environment-friendly gear, banning beach seine, and establishing Marine Protected Areas should be implemented to support species productivity. These are some of the effective management measures being implemented in different parts of the country and found in the study of Cabigas et al. (2012), Valdemarsen and Suuronen (2001), and Hilborn and Ovando (2014).