Long-term individual identification and site fidelity of white sharks, Carcharodon carcharias, off California using dorsal fins

Mark-recapture techniques can be used to estimate white shark (Carcharodon carcharias) population abundance. These frameworks are based on assumptions that marks are conserved and animals are present at the sampling location over the entire duration of the study. Though these assumptions have been validated across short-time scales for white sharks, long-term studies of population trends are dependent on these assumptions being valid across longer periods. We use 22 years of photographic data from aggregation sites in central California to support the use of dorsal fin morphology as long-term individual identifiers. We identified five individuals over 16–22 years, which support the use of dorsal fins as long-time individual identifiers, illustrate strong yearly site fidelity to coastal aggregation sites across extended time periods (decades), and provide the first empirical validation of white shark longevity >22 years. These findings support the use of fin morphology in mark-recapture frameworks for white sharks.

[1]  S. Anderson.  CHAPTER 20 – White Shark Reactions to Unbaited Decoys , 1996 .

[2]  G. Cliff.  CHAPTER 36 – First Estimates of Mortality and Population Size of White Sharks on the South African Coast , 1996 .

[3]  David G. Ainley,et al.  Great white sharks : the biology of Carcharodon carcharias , 1996 .

[4]  M. Meÿer,et al.  Transoceanic Migration, Spatial Dynamics, and Population Linkages of White Sharks , 2005, Science.

[5]  D. Sims,et al.  Concordance of genetic and fin photo identification in the great white shark, Carcharodon carcharias, off Mossel Bay, South Africa , 2009 .

[6]  A. Klimley.  CHAPTER 33 – Residency Patterns of White Sharks at the South Farallon Islands, California , 1996 .

[7]  M. Domeier,et al.  Migration patterns of white sharks Carcharodon carcharias tagged at Guadalupe Island, Mexico, and identification of an eastern Pacific shared offshore foraging area , 2008 .

[8]  B. Block,et al.  A first estimate of white shark, Carcharodon carcharias, abundance off Central California , 2011, Biology Letters.

[9]  Michael L. Domeier,et al.  Annual re-sightings of photographically identified white sharks (Carcharodon carcharias) at an eastern Pacific aggregation site (Guadalupe Island, Mexico) , 2007 .

[10]  Adam C. Brown,et al.  Philopatry and migration of Pacific white sharks , 2010, Proceedings of the Royal Society B: Biological Sciences.

[11]  Ioannis Pavlidis,et al.  Human behaviour: Seeing through the face of deception , 2002, Nature.

[12]  W. R. Strong.  CHAPTER 37 – Population Dynamics of White Sharks in Spencer Gulf, South Australia , 1996 .

[13]  Scot D. Anderson,et al.  Migration and habitat of white sharks (Carcharodon carcharias) in the eastern Pacific Ocean , 2007 .