Growth and Mortality of Sillago sihama (Forsskål) from Karachi Coast, Pakistan
Abdul Baset *
Department of Zoology, Bacha Khan University Charsadda, Pakistan and College of Fisheries, Ocean University of China, Qingdao 266003, China.
Qun Liu
College of Fisheries, Ocean University of China, Qingdao 266003, China.
Baochao Liao
College of Fisheries, Ocean University of China, Qingdao 266003, China.
Abdul Waris
Department of Biotechnology, Quaid-i-Azam University, Islamabad, Pakistan.
Han Yanan
College of Fisheries, Ocean University of China, Qingdao 266003, China.
Zhang Qingqing
College of Fisheries, Ocean University of China, Qingdao 266003, China.
Imtiaz Ahmad
Department of Botany, Bacha Khan University Charsadda, Pakistan.
*Author to whom correspondence should be addressed.
Abstract
Length frequency data of silver sillago, Sillago sihama (Forsskål) were collected and measured from the fisherman catches using beach seines and handlines, at random, during 2012 from the Karachi coast of Pakistan. In this study, 1846 fish individuals (male and female combined) were collected ranging from 10 to 24 cm with dominant individuals ranged 12 to 16 cm (total length). Weight ranging was measured from 9 to 110 g. The above length-frequency data were analysed for the estimation of growth and mortality parameters. The power coefficient b of length-weight, the relationship was estimated at 2.9177. The estimated von Bertalanffy growth, function parameters of 25.20 cm (L∞) and 1.00 year-1 (K) were calculated by ELEFAN method equipped on FiSAT computer package. With length-converted catch curve analysis, the total mortality rate (Z) and its 95% confidence interval were 2.42 (2.174-2.669) year-1. The natural mortality rate (M) was 1.84 year-1 calculated with Pauly’s equation (the annual average seawater temperature was 27°C). Therefore, the fishing mortality rate was Z-M= 0.5787year-1. The exploitation ratio (E) estimated as F/Z=0.239 which is less than biological reference point (0.5), therefore it indicates that the stock of S. sihama was exploited at managed.
Keywords: Pakistan, Sillago sihama, growth, mortality, FISAT.