Discards characteristics of Bottom trawl fishery in Khuzestan coastal waters (case study: Bosif fishing grounds)

The aim of this study was to estimate the amount and species composition of discards in bottom trawl fisheries in the Bosif fishing ground in the coastal waters of Khuzestan. Furthermore, the biological parameters of discarded species were assessed. Specimens were collected from commercial catch data of trawl vessels in three seasons, autumn and winter 2017 and summer 2018. The results showed that discarded samples included 33 species from 28 families. Orangefin Pony fish and striped piggy species were the most frequent species in this study. The results also showed that the mean length of most of the discards species was below 30 centimeters. The amount of discards per unit of catching effort was 57.33±9.87, 27.50±16.64 and 32.33±7.50 in the autumn, winter and summer seasons, respectively. The catch per surface area in autumn, winter and summer were 2.77 ± 0.064, 0. 73 ±0.39 and 1.73 ± 0.44 kg/nm2, respectively. The results showed that CPUE and CPUA in winter were significantly higher than those in autumn and summer (p<0.05). In general, the results of this study represent high fishing pressure on ecologically important species in Bosif fishing ground especially in their critical life cycle which may affect local ecosystem structure and function in future.