Biology of the seerfish landed by exploratory trawlers

Abstract

Among the four species of seer fish namely Scomberomorus guttatus, S. commerson, S. koreanus and S, lineolatus landed by fishery trawlers along the mid west coast of India, the dominant species is S. guttatus. The lengthweight relationship of the first three species was studied and it is described by the logarithmic equations for both the sexes. Analysis of covariance showed that the regression lines of both the sexes of these three species did not differ much from each other. Therefore, combined equations are proposed for both the sexes together and it is Log W = -1.9386 + 2.8226 Log L for S. guttatus, Log W = -1.4473 + 2.4987 Log L for S. koreanus and Log W = -20557 + 2.8704 Log L for S. commerson. Sex ratio did not indicate dominance of any one sex among them, von Bertalanffy growth equation for S guttatus is L^ = 843 (1-e •''•'^" (t - 0.0174) for S. commerson L^=1212 (1-e -""s^'Ct - 0.0390) and for S. koreanus L^ = 1060 (1-e •'"""'^ (t - 0.0205). Gut content analysis showed that the empty stomached fishes were dominant (46.1 %), followed by half full (19.2 %), full stomach (16.5 %), quarter full (15.8 %) and finally the three fourth full (2.4 %). The qualitative analysis of the gut content showed that these species are piscivorous in nature. The order of food preference is Stolephorus spp. (86 %), lesser sardines (9 %), silver bellies (2 %) and squids (1 %).