A minimally invasive technique to assess several life-history characteristics of the endangered great hammerhead shark Sphyrna mokarran

A dorsal-fin photo-identification technique paired with a non-invasive parallel laser photogrammetry technique was used to non-invasively identify individual Sphyrna mokarran over time. Based on the data collected over a duration of 59 days, 16 different S. mokarran (mean +/- s.d. pre-caudal length: 22082 +/- 1366 cm; mean +/- s.d. cephalofoil width: 7138 +/- 794 cm) were identified using dorsal-fin photo-identification, with a mean +/- s.d. shark re-sighting frequency of 405 +/- 306 at-sea days. The results illustrate a high S. mokarran sighting rate and therefore, the utilization of parallel laser photogrammetry and dorsal-fin photo-identification may be a plausible multi-year approach to aid in non-invasively determining the growth rate and inter-annual site fidelity of these animals.