Authors

Cesaria R. Jimenez

Author

Jaime U. Jimenez

Co-author

Marcelino I. Tumanda, Jr.

Co-author

Institute of Fisheries Research and Development, Mindanao State University at Naawan, Naawan, Misamis Oriental, Philippines

*Corresponding author: [email protected]

ABSTRACT

Different experiments were carried out to assess the growth and survival of the surf clam, Katylesia hiantina, spats as functions of three stocking densities, presence of substrate, and different salinity levels under laboratory conditions. Experiments on stocking rate manipulation for a culture period of 20 days at ambient seawater resulted in no significant differences in shell length (1.19-2.56mm) and survival rates (68.1-73.5%, ANOVA, p>0.05) of spats. Results of the experiment imply that higher spat densities can be used in commercial scale culture for higher economic returns. Spats reared for 20 days with sand substrate showed higher measurements (SL = 40.5 mm and wet weight = 46.3g) than spats reared without substrate (SL = 31.6 mm and wet weight = 31.3g). Higher survival (89.54%) was also obtained in spats reared with substrate than those reared without substrate (67.54%, t-test p<0.05). Spats of most bottom-dwelling species such as K. hiantina can attain better growth in the presence of sandy substratum. The faster growth and higher survival rate of spats reared in the sand substrate indicate that a much shortened hatchery culture period is attainable. Low mortalities in the nursery translate to an increased spat production of the surf clam. Spats grown in different salinity levels for 30 days resulted in significantly smaller shell length (2.29 mm) and lower survival rate (85.3%) than those grown in higher salinity of 24 ppt and 34 ppt (ANOVA p<0.05). Spats reared at 24 ppt were significantly heavier at 15.72 g than spats grown at 34 ppt (12.2 g) and 14 ppt (1.95 g). Spats of K. hiantina, therefore, can survive over a wide range of salinity change although better growth can be obtained at ambient salinity range of 24-34 ppt.