Comparison of the species composition and the diversity of retained aquatics in the Bushehr port's Gargoors in the winter season

The present study was carried out with a purpose to compare the species composition and diversity of the Gargoor's trapped aquatics in different depths and soak times in the winter season. This study was done in the port of Bushehr from February to March 2017. The using Gargoors had mesh size of 3.5-4 cm, cross section 150 cm, height 87-92 cm, outer span size 70-79 cm and internal span size 35-36 cm. Comparisons of species composition and diversity were based on weight furthermore number and the Shannon index, respectively. The species composition of the Gargoor's trapped aquatics included 12 species of bony fishes belonging to 7 families, one species of crustaceans, and one species of mollusks (Pharaoh Cuttlefish); While there was a significant difference in different depths as well as soak times (p <0.05). Gargoor's Shannon index for depths of 25-40 meters and 10-25 meters was 1.421 (±0.362 S.D.) and 1.229 (±0.345 S.D.), respectively. This index for soak times of 8-14 days and 2-8 days was 1.441 (±0.302 S.D.) and 1.228 (±0.393 S.D.), respectively. The Shannon index represented the more biodiversity of Gargoors between depths of 25-40 meters compared to 10-25 meters, as well as the soak times of 8-14 days compared to 2-8 days (p ˃0.05). In winter, with the arrival of Pharaoh Cuttlefish in the Gargoor's fishing grounds in Bushehr port is evident, this has high effect on the species composition of Gargoors and it was responsible for the most dissimilarity in the species composition of different depths and soak times as well. Also, if the interaction between depth and soak time taking into account, the highest values of the Shannon index observed in the depths between 10-25 meters, with 8-14 days of soak time.