Growth and mortality of brushtooth lizardfish,saurida undosquamis,from PakistaniLaters

Growth and mortality parameters of brushtooth lizardfish saurida undosquamis (richardson,1848) were investigated using the length frequency data from five research trawl surveys from pakistani waters during 2009 - 2010. the analysis was based on fisat computer software package. the pooled data of s. undosquamis consist of n = 870 pair of length weight data and n = 3607 length frequency data of both sexes combined with maximum length and weight of 38 cm (fl) and 492 g respectively. the length-weight relationship parameters from pooled data were a = 0.008,b = 3.000 and r2 = 0.965. the von bertalanffy growth function parameters were l∞ = 39.90 cm,k = 0.270 year-1 (using elefan method) and age at zero length t0 = - 0.572. based on those growth parameters,the total mortality rate was calculated using length-converted catch curve analysis as 1.15 year-1. the natural mortality (m) was 0.687 using pauly's equation (the annual average sea surface temperature was 27°c) hence the fishing mortality (f) was estimated by f = z - m = 0.463 year-1. the yield per recruitment analysis indicated when tc was assumed to be 2,fmax was estimated at 1.1 and f10 at 1; when tc was assumed to be 1,fmax was estimated at 0.85 and f10 at 0.7. currently age at first capture is about 1 year and fcurrent was 0.463,therefore fcurrent was smaller than f10 and fmax. this indicates that the current fishery is in a safe condition. using gulland (1971) biological reference point fopt was equal 0.687. the current fishing mortality rate of 0.463 year-1 was lower than biological reference point. © copyright 2014 zoological society of pakistan.