Comparative feeding ecology of two fish species bluestripe herring, Herklotsichthys quadrimaculatus Ruppel (Clupeidae) and big eye scad, Selar crumenophthalmus Bloch (Clupeidae) caught in the stilt fishery in southern Sri Lanka

Abstract

The dietary habits and food resources partitioning of H. quadrimaculatus and S. crumenophthalmus caught by stilt fishing in southern Sri Lanka were studied. Food particles found in the gut contents of 112 specimens of H. quadrimaculatus and 166 specimens of S. crumenophthalmus were identified. Different food categories were sorted by taxonomic groups to calculate food electivity, overlap, trophic niche breadth and food preference of each fish species. H. quadrimaculatus fed on both phytoplankton and zooplankton while S. crumenophthalmus solely fed on zooplankton. Gut content of H. quadrimaculatus consisted of 46 food items and it preferred diatoms, dinoflagellates and calanoid copepods. S. crumenophthalmus preferred calanoid copepods, cyclopoid copepods and crustacean larvae (protozoea and nauplii) and it consumed 41 food items. Two fish species had low dietary overlap (16%) and their niche breadth was significantly different (p< 0.05). Therefore, these two fish species can aggregate with minimum competition for food and that may be one of the reasons for their seasonal congregation on shallow reef areas in the Southern coast of Sri Lanka.