Assessment of the commercial stock of Distant Scallop (Bractechlamys vexillum, Reeve 1853) in Asid Gulf, Philippines

The study investigated the growth, mortalities, recruitment, yield-per-recruit and exploitation rates of the commercially important Distant scallop (Bractechlamys vexillum) in Asid Gulf, Philippines as basis for interim management. The fishery is economically valuable because it produces the highest yield of scallop in the country on a per unit area basis. Optimum total monthly length frequency data (n=3,987) were collected from April 2018 to March 2019. Using an objective fishery software to analyze the data, the growth (K) was revealed to be 0.65/year attaining an asymptotic shell height (SH∞) of 7.98 cm. Recruitment pattern was continuous and bimodal with minor and major peaks in April and August, respectively. The total instantaneous mortality (Z) is 3.18/year with fishing (F) and natural mortality (M) of 2.637 and 0.543, respectively. Current exploitation ratio (Ecurr) of 0.83 is higher than the biological reference point (BRP) E10 (0.816) and E50 (0.428). However, Ecurr is lower than the estimated exploitation at maximum sustainable yield (Emax = 0.907). Relative to the estimated Emax, the present result is a good indicator that the stock has the potential for recovery from an overexploited state. This may be due to the reduced fishing effort, increase in length at first capture (L50), size restriction by traders and the existing close season ordinance in the Municipality of Cawayan. Nevertheless, strict management measures must be put in place to prevent future collapse of the stock. The fast growth and the availability of recruits encourage prospects for mariculture.