Estimatin of growth parameters and mortality rates of Psettodes )erumei in the Persian Gulf and Oman sea)Hormozgan province

Authors

1 Department of Marine Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran

2 Iranian Fisheries Research Organization, P.O.Box: 141556116- Tehran, Iran

Abstract

The growth parameters, mortality rates and exploitation population dynamic parameters and exploitation rate of Psettodes erumei were assessed between July 2010 to June 2011 using length frequency analysis. The data were collected from landing sites of Jask, Bandar Abass, Kong and Qeshm Hormozgan province waters. Using total weight (W) and total length (TL) data, the length- weight relationship of this fish species was described as W=00037/L33652/ pertaining to alometric growth. Asymptotic length (L∞) = 74.55 cm, coefficient growth (k)= 0.23 year-1, t0 = - 0.61, longevity (tmax)= 12.43 years and the growth performance index (Φ’)= 3.10 were estimated through the ELEFAN I routine and other modules from the FISAT program. Total mortality (Z), natural mortality (M), and fishing mortality (F) were then calculated as 1.2 year-1, 0.51 year-1, 0.69 year-1 respectively. Although, the estimated exploitation ratio (E= 0.57) was well fitted with the optimum level, careful examination of exploitation rate (U) revealed that the major part of the stock (> 48% length frequency) is being fished out of the defined optimum length. Consequently, the need to improve fishing methods seems mandatory in the future to ensure that total landings do not exceed 525 tons predicted maximum constant yield (MCY).

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