Determination of relative composition and density of invertebrates in shrimp trawler in Persian Gulf (Hormozgan province)

The aim of this study was to investigate catch composition and catch per unit effort of invertebrates in shrimp trawl in different areas and depths. This research was carried out in Hormozgan coastal waters (Bandar Abbas and Hormuz Island) at depths of less than 10 meters, 10-20 meters and over 20 meters in shrimp fishing season in 2015. 40 hauls that duration of each one was approximately 2 to 2.5 hours with a total catch of 7623 kg were done. The catch composition included 1068 kg of commercial shrimp and 6555 kg of by-catch that included invertebrates and fish which were 2386.8 and 4168.2 kg, respectively. The results showed that the catch composition consisted of 14% shrimp (1068 kg), 31% by-catch invertebrates (6555 kg) and 55% by-catch fish (4168.2 kg). There were significant differences among the CPUE in the different areas and depths as well as the interaction of area and depth on CPUE of the total catch, target species (Shrimp), Oratosquilla oratoria, Portunus pelagicus, Crustacea (Small crab), Sepia pharaonis, Anthozoa, Demospongiae, Rhizostomatidae (Jelly fish), Asteroidea and Octopoda (POratosquilla oratoria, Rhizostomatidae and Sepia pharaonis and the Demospongiae was at the least.