Population dynamics of the oyster Crassostrea virginia from the offshore island of ST. Marin in the coast of Bangladesh

The population structure, growth, age, mortality and exploitation status of oyster Crassostrea virginica were examined in St. Martin Island, Bangladesh between June 2003 and May 2004. Monthly length frequency data of C. virginica were analyzed by FiSAT software for estimation of population parameters which include asymptotic length (Lµ), growth co-efficient (K) and recruitment pattern to evaluate the status of the stock. Asymptotic length (Lµ) was 13.65 cm and growth co efficient (K) was 0.63 yr-1 respectively while the growth performance index (j/) was 2.07. The growth pattern showed negative allometric growth with an asymptotic weight (Wµ) of 224.72 g obtained. This oyster attained a length of 6.38 cm at the end of one year. Total mortality (Z) by length-converted catch curve was estimated at 1.87 yr-1, fishing mortality (F) 0.21yr-1, and natural mortality (M) 1.66 yr-1. The exploitation level (E) of C. virginica was 0.11 that of the maximum allowable limit of exploitation (Emax) which was 0.40. The recruitment pattern was continuous with two major peaks event per year. Habitat temperature and salinity range of the oyster recorded were 25.50c-30.50c and 15.1 ppt-36 ppt respectively. The exploitation level (E 0.50) indicates that the fishing pressure on C. virginica is very low. Thus the status of the stock in St. Martin Island of Bangladesh. Might be under-exploited