The Catch Per Unit of Swept Area (CPUA) and Estimated Biomass of Large Head Hairtail (Trichiurus lepturus) with an Improved Trawl in the Persian Gulf and Gulf of Oman, Iran

The Kish trawler fleet targets large head hairtail (Trichiurus lepturus) in the Persian Gulf and the Gulf of Oman. These vessels are equipped with a new improved trawl. The objectives of this study were (i) to estimate the catch per unit area (CPUA) and biomass of T. lepturus, (ii) to identify the catch composition and percentage of target and bycatch species in the total catch and (iii) to compare the CPUA between two selected strata using a bottom trawl survey. Surveys were conducted during the periods August to October 2007 in the Persian Gulf and Gulf of Oman. The sampling area was divided into two strata and a stratified random sampling design was used to determine sampling sites. Catch per unit of area varied significantly between the two selected strata (P 0.001). Mean CPUA for T. lepturus in the total area was 4,308 kg.nm^-2. The total biomass of T. lepturus was estimated to be 842 tonnes in stratum 1 and 1,430 tonnes in stratum 2. Trichiurus lepturus made up 74.4% of the total weight in stratum 1 and 70.02% in stratum 2. Among the non-target species in the trawl catches, the species with highest catch rate were Pampus argenteus (4.629%), Batoids (2.274%), Carangidae (2.693%) and Ilisha sp. (2.672%) in stratum 1 and Carangidae (5.710%), P. argenteus (5.245%), Batoids (3.256%) and Ilisha sp. (2.995%) in stratum 2.