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¹ Persian Gulf and Oman Sea Ecology Research Center, Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Bandar Abbas, Iran
² Iranian Fisheries Science Research Institute, Agricultural Research Education and Extension Organization (AREEO), Tehran, Iran DOI : 10.4194/1303-2712-v17_6_08 Viewed : 4119 - Downloaded : 7967 In this study, size selectivity of Scomberomorus guttatus sampled from commercial surface and mid-water drift gill nets off the northern part of Persian Gulf were studied using model inferring retention from girth measurements. For the net marks at five positions on fish’s body, the girth at the second dorsal fin was considered as a maximum girth (ANCOVA, P<0.05). Fish were captured at the most efficiency when the ratio of girth at capture to mesh perimeter ranges from 1 to 1.2. In all meshes, fish enmeshed vertically between opercular and maximum section body accounted for the most frequency of catches. Optimum selection length was estimated as 33, 37, 42, 44, 50 and 59 cm FL for the nominal stretched mesh size of 70, 76, 79, 90, 101 and 114 mm respectively. For the mesh size at 76 mm, however, there was also a second mode with low level which was resulted from snagging processes, leading to inconsistency to the selectivity curve. It seems that the nets with 90 mm mesh size to be more suitable for the exploitation of S. guttatus taking into consideration both the catch efficiency and protection of juvenile fish. Keywords : S. guttatus, Persian Gulf, girth measurements, drift gillnets, selectivity