Correction: Gauging the Threat: The First Population Estimate for White Sharks in South Africa Using Photo Identification and Automated Software

Abstract

South Africa is reputed to host the world's largest remaining population of white sharks, yet no studies have accurately determined a population estimate based on mark-recapture of live individuals. We used dorsal fin photographs (fin IDs) to identify white sharks in Gansbaai, South Africa, from January 2007 -December 2011. We used the computer programme DARWIN to catalogue and match fin IDs of individuals; this is the first study to successfully use the software for white shark identification. The programme performed well despite a number of individual fins showing drastic changes in dorsal fin shape over time. Of 1682 fin IDs used, 532 unique individuals were identified. We estimated population size using the openpopulation POPAN parameterisation in Program MARK, which estimated the superpopulation size at 908 (95% confidence interval 808-1008). This estimated population size is considerably larger than those described at other aggregation areas of the species and is comparable to a previous South African population estimate conducted 16 years prior. Our assessment suggests the species has not made a marked recovery since being nationally protected in 1991. As such, additional international protection may prove vital for the long-term conservation of this threatened species.

Sex and Size Influence the Spatiotemporal Distribution of White Sharks, With Implications for Interactions With Fisheries and Spatial Management in the Southwest Indian Ocean

“…Although there is scientific debate on the South African white shark population's size, all population estimates are consistently low, ranging from 500 to 2000 individuals (Towner et al, 2013;Andreotti et al, 2016;Andreotti et al, 2017;Irion et al, 2017). In South Africa, white sharks are captured in shark nets and on drumlines along the KwaZulu-Natal (KZN) coast as part of a bather protection program (Dudley and Simpfendorfer, 2006;Rigby et al, 2019).…”

Estimating apparent survival of sub-adult and adult white sharks (Carcharodon carcharias) in central California using mark-recapture methods

“…This migratory behavior supports the use of a mark-recapture framework for estimation of population parameters at coastal sites . Several studies have demonstrated that the pattern on the trailing edge of the white shark first dorsal fin is stable over many years and can be used as a means of identifying individuals, i.e., serves as a natural "mark" (Gubili et al, 2009;Anderson et al, 2011;Towner et al, 2013). The population trend remains unknown in central California although interpretations of catch per unit effort data of young of the year white sharks in Southern California have been taken to suggest an increasing trend in the smaller length classes (<2 m) (Lowe et al, 2012).…”