Abstract

Background:
This study presents the first morphometric examination of the pectoral fins of 19 shark species in the Libyan Mediterranean Sea using 88 specimens collected from November 2023 to November 2024.

Aim:
The observed morphometrics successfully differentiate between benthic Squatiniformes, demersal Squalidae, triakis, and pelagic lamnids and carcharhinids.

Methods:
Statistical analysis revealed significant interspecific variation (P< 0.05) in different calculated ratios, with the highest level of discrimination power being shown by PL/PF and PA/PB. Multivariate data analyses also supported unique morphological groupings of ecologically and phylogenetically close members.

Results:
The present study also recorded significant biogeographical information with five shark species being first reported in Libyan waters: Heptranchias perlo (Bonnaterre, 1788), Squalus megalops (Macleay, 1881), Carcharhinus altimus (Springer, 1950), Carcharhinus obscurus (Lesueur, 1818), and Squalus mitsukurii (Jordan & Snyder, 1903). It is noteworthy that S. mitsukurii was first reported in the entire Mediterranean Sea, a considerable expansion of its known range.

Conclusion:
These results are important to emphasize the ecological significance of the area and make further observations to improve our knowledge of shark diversity and distribution in the southern Mediterranean. In addition, the present findings help to underline the high diagnostic significance of pectoral-fin morphometrics and the usefulness of the present methods on species identification and shark biodiversity in the southern Mediterranean Sea.

Key words: Libya; Mediterranean; Morphometric analysis; Pectoral fins; Shark species.