Population parameters of siluroid catfish (Eutropiichthys vacha) from indus river, Pakistan

Abstract

Population dynamics parameters and exploitation status of Eutropiichthys vacha (Hamilton, 1822) in the Indus River were evaluated (February 2011 to January 2012) collecting (n= 821) specimen with 459 males and 362 females. The total length was 10 to 34 cm with an average of 21±4.329 cm and weight ranged 15 to 210 g with an average of 71±39.911 g for both sexes. The pooled, male and female length weight relationship was estimated as W= 0.016 L2.692 (R2= 0.913), W= 0.014 L2.750 (R2= 0.909) and W= 0.017 L2.674 (R2= 0.885) respectively. Length frequency distribution data was analyzed by using ELEFAN-I method in FiSAT-II software to estimate von Bertalanffy growth parameters. The L∞, K, t0, and Rn were estimated at 35.7 cm, 0.30/year, -0.358 year and 0.295 for pooled sex, 33.6 cm, 0.64/year, -0.610 year and 0.206 for males and 35.7 cm, 0.58/year, -0.573 year and 0.267 for females respectively. The annual total mortality (Z), natural mortality (M) and fishing mortality (F) were estimated at 1.09/year, 0.762/year and 0.33/year for pooled sexes, 1.85/year, 1.129/year and 0.721/year for males and 1.51/years, 1.041/year and 0.469/year for females. For the pooled data the exploitation ratio was estimated 0.302, for male and female 0.389 and 0.31 respectively. Because the present fishing mortality 0.330/year was smaller than the limit biological reference points (Fopt= 0.762/year, Fmax= 1.2/year and F0.1= 1/year), indicating that the stock of E. vacha is not being over-fished.