Some Biological Aspects of Hilsa Shad Tenualosa ilisha in Iraqi Marine Waters, Northwest Arabian Gulf

Abstract

Some biological aspects of hilsa shad,Tenualosa ilisha in Iraqi marinewaters, northwest Arabian Gulf were described during the period from November 2012to October 2013. Fish samples were collected by steel dhow fishing boat (Zainab) usinggill nets of different mesh sizes. Fish lengths ranged from 12 to 47cm in the total length.The large fish sizes (>30cm) were dominant the catch during March-June and themedium sizes (<30cm) during July-February. The length-weight relationship for all fishwas W= 0.0041 xL3.2683. The operculum was used in age determination. Nine age groupswere recognized for T. ilisha and their lengths were 18.0, 28.5, 35.3, 41.3 and 46.3 cm,respectively. The growth parameters were L∞= 61.7cm, K= 0.257 and to =0.349. Theoverall sex ratio was 1:1.62 (male: female). The sizes at first maturity were 20 and22cm for males and females, respectively. GSI for females ranged from 0.45 in Octoberto 8.52 in May and for males from 0.11 in October to 1.14 in March. The resultsrevealed the biological characteristics of the species before starting reproductionactivity in the Shatt al-Arab and its branches.