Biodiversity aspects of Common Torpedo (Torpedo torpedo) in by-catch in Sidi Sha'ab Harbour, Tripoli, Libya

Forty-four specimen of common Torpedo (Torpedo torpedo) were collected from discarded catch of long-line boat’s haul from Sidi Sha’ab harbor, Tripoli, in May 2016 and used for establishing morphometric traits of the fish. The specimens ranged in size from 13.3 to 68.2 cm and in total weight from 92.61 to 989.25 gm. The results revealed that the value of the constant b of the length-weight relationship was 1.9064 indicating negative allometric growth (b< 3). The condition factors Kf and Kc decreased progressively from 2.54 and 1.82 in the smallest fish size group (17.2cm) to the largest one (67.5cm.) which recorded a rare values of (Kf= 0.32 and Kc= 0.25), respectively. The length frequency distribution indicated that the youngest size-group (17.2cm) peaked to a quarter of the studied samples. Morphometric traits of the torpedo were related to total length as percentage ratios. Disk length and diameter were larger in female (48.6 and 43.0%) than in male (47.4 and 41.2%).