Biometric study of Common Guitarfish Rhinobatus rhinobatus in Dernah coast, Libya (June – December 2016)

Abstract

Eighty two specimens of Common Guitarfish Rhinobatus rhinobatus were collected from long-lined boats in Dernah
coasts, in duration of June to December 2016, to establish their morphometric characters. Specimens ranged in size
from 45.2 to 93.0 cm and from 150.44 to 700.80 gm. of total weights. Results showed constant value B of the
length-weight relationship was 1.467, meaning so negative allometric growth. The condition factors Kf and Kc
decreased significantly from 2.35 and 1.37 respectively, in the youngest fish size group (49.4 cm), to Kf = 0.22 and
Kc = 0.16 as a nadir values in the largest group (93.0 cm.). Length frequency distribution illustrated that the mid-size
group (65.7 cm) peaked above the quarter of the studied specimens. Morphometric characters of the guitarfishes
were related to total length in percentages. Female bodies were deeper than in males’ bodies, and wider head and
pectoral fins as well.