An investigation of annual discards of the trawlers and gillnet in Khuzestan coastal water, northwest Persian Gulf

The main objective of this study was to describe and estimate the seasonal pattern of discarded fish in the waters of the Persian Gulf coast in Khuzestan. Data were collected from the fishing dhow with Khuzestan Fisheries partnership in fishing areas of Lifeh, Boseif, Khure-mussa and Bahrakan from October 2011 to September 2012. Discarded fish samples were included 109 species from 67 families, nearly 40 percent commercial and 60 percent of non-commercial species. Rayfish and catfish have been observed in most fishing nets. Average sizes of most species particularly bony fish were under 15 cm. The amount of discarded fish per unit of fishing effort was not significantly different between seasons. The highest portion of the catch belongs to rayfishes. Total discarded fishes of gillnets were estimated 3162 tones. Total weight of commercial fishes with small size in discarded fish was estimated 225 tones. The rate and ratio of discarded fish in total catch of gillnet was estimated 0.23 and 0.31 respectively. Chondrichthyes with 12 species and 60% of gillnet catch has the highest percentage of discarded fish of gillnet. High number of commercial species with small size could be due to nursery role of Khuzestan coastal waters. Trawl net has more impact on type and amount of discarded fish than moving gill net. According to different aquatic groups, the highest percentage of protein (77.84±2.088) in Perciformes belongs to Eupleurogrammus muticus and the lowest percentage (40.40±0.322) belongs to Liza klunzingeri, the most percentage of lipid was in Liza klunzingeri (33.78±0.277) and the lowest percentage was in Grammoplites suppositus (3.34±0.025), the highest and lowest percentage of ash (minerals) were in Cynoglossus arel and Acanthocephola abbreviate (28.14±.377) and oligo duvauceli (0.7±0.02) respectively. Therefore discarded fish have great potential in fulfilling nutritional requirements as fresh food (minimally processed) and with nutritional additives in forms of fish powder and fish oil and it can play an effective role in aquaculture development in the region