Zoological Studies

Zooplanktivory in the Endemic Freshwater Sardine, Sardinella tawilis (Herre 1927) of Taal Lake, the Philippines

Rey Donne S. Papa, Roberto C. Pagulayan, and Alicia Ely J. Pagulayan (2008) In this study, we compared the composition and relative abundance of zooplankton found in the vicinity of Napayun I., Taal Lake, the Philippines, with the zooplankton found in stomachs of the freshwater sardine Sardinella tawilis (Herre 1927) caught from the same location.  Samplings were conducted monthly from July 2003 to June 2004.  Ninety percent of the stomach contents were composed of relatively large-bodied adult copepods; the remaining 10% contained cladocerans and rotifers.  Selectivity coefficients computed from comparing the fish diet with the available prey from the environment showed a high preference for copepods and a low to no preference for cladocerans and rotifers for all 10 mo sampled of the 12 mo study.  A high preference for calanoid copepods noted in Apr.-June coincided with the peak spawning of S. tawilis according to previous studies.  The preference for large prey such as calanoids, despite the dominance of small-bodied zooplankton present during that time may have been related to increased food intake during spawning.  These results indicate a preference for larger zooplankton due to size-selective particulate feeding exhibited by clupeids such as S. tawilis.