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

Abstract

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: 220·82 ± 13·66 cm; mean ± S.D. cephalofoil width: 71·38 ± 7·94 cm) were identified using dorsal-fin photo-identification, with a mean ± S.D. shark re-sighting frequency of 4·05 ± 3·06 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.

Philopatry and Regional Connectivity of the Great Hammerhead Shark, Sphyrna mokarran in the U.S. and Bahamas

“…At both sites, it was possible to capture and equip great hammerhead sharks with acoustic, satellite and conventional tags, however Bimini's excellent underwater conditions enabled our team to use additional methods, such as breath-hold diving to attach tags, photo-identification and laser photogrammetry to supplement tracking data (O'Connell and Leurs, 2016). Methods varied based on study site and available personnel and gear, and these, and the associated monitoring periods, are summarized in Table 1.…”

“…Interestingly, a handful of observations have documented great hammerhead sharks' use of extreme shallow water (< 2 m) habitats in Andros Island and Eleuthera (Roemer et al, 2016), as well as two predation events in Bimini on a southern stingray (Dasyatis americana) and spotted eagle ray (Aetobatus narinari) (Strong et al, 1990;Chapman and Gruber, 2002). However, more recently, great hammerheads have been reliably encountered off the west of Bimini, in shallow sand bottom waters during the winter months (O'Connell and Leurs, 2016).…”

First insights into the population characteristics and seasonal occurrence of the great hammerhead shark, Sphyrna mokarran (Rüppell, 1837) in the Western Tuamotu archipelago, French Polynesia

“…Photographs of great hammerhead sharks were taken to catalog all sharks sighted on the day. Individual great hammerhead sharks were identified using natural markings (e.g., spots, and dark patterns on the body and fintips), fins morphology (e.g., notches, outgrowth, shortened), scars (e.g., wounds, scratches, depigmentation marks), and ventral pigmentation (Domeier and Nasby-Lucas, 2007;O'Connell and Leurs, 2015;Guttridge et al, 2017) (Figure 2; Table 1). Given the fast-healing capacity of elasmobranchs (Chin et al, 2015), we only used scars for intra-annual identification (within a season).…”

“…Most studies on great hammerhead sharks have been conducted in the northwest Atlantic Ocean (Piercy et al, 2010;O'Connell and Leurs, 2015;Guttridge et al, 2017;Doan and Kajiura, 2020;Heim et al, 2021;Macdonald et al, 2021), southwest Pacific Ocean (Stevens and Lyle, 1989;Harry et al, 2011;Raoult et al, 2019), and to a lesser extent in the Western Indian Ocean (Cliff, 1995) and in the Arabian Gulf (Hsu et al, 2020). Extensive industrial fishing in those regions over the past half-century has resulted in an unprecedented increase in the risk of extinction of sharks and in particular of pelagic sharks (Pacoureau et al, 2021;Walls and Dulvy, 2021).…”

Measuring mantled howler monkey (Alouatta palliata) testes via parallel laser photogrammetry: Expanding the use of noninvasive methods

“…Unlike other forms of photogrammetry, PLP does not require an object of known size to be in the frame or other information for scaling. Furthermore, it has been used for a wide variety of taxa, including ungulates (Bergeron, 2007; Kumar et al, 2012; Weisgerber et al, 2015), fishes and marine mammals (Durban & Parsons, 2006; Leurs et al, 2015; O'Connell & Leurs, 2016; Rizzo et al, 2017; Rogers et al, 2017; Rohner et al, 2011; Webster et al, 2010), and both terrestrial and arboreal primates (Anzà et al, 2022; Barrickman et al, 2015; Brown et al, 2022; Chappell et al, 2015; Galbany et al, 2016, 2017; Lu et al, 2016; Richardson et al, 2022; Rothman et al, 2008; Sandel et al, 2022; Schuppli et al, 2016; Wright et al, 2019, 2020).…”