Skip to main content
Article thumbnail
Location of Repository

Accuracy of Using Visual Identification of White Sharks to Estimate Residency Patterns

By David G. Delaney, Ryan Johnson, Marthán N. Bester and Enrico Gennari

Abstract

Determining the residency of an aquatic species is important but challenging and it remains unclear what is the best sampling methodology. Photo-identification has been used extensively to estimate patterns of animals' residency and is arguably the most common approach, but it may not be the most effective approach in marine environments. To examine this, in 2005, we deployed acoustic transmitters on 22 white sharks (Carcharodon carcharias) in Mossel Bay, South Africa to quantify the probability of detecting these tagged sharks by photo-identification and different deployment strategies of acoustic telemetry equipment. Using the data collected by the different sampling approaches (detections from an acoustic listening station deployed under a chumming vessel versus those from visual sightings and photo-identification), we quantified the methodologies' probability of detection and determined if the sampling approaches, also including an acoustic telemetry array, produce comparable results for patterns of residency. Photo-identification had the lowest probability of detection and underestimated residency. The underestimation is driven by various factors primarily that acoustic telemetry monitors a large area and this reduces the occurrence of false negatives. Therefore, we propose that researchers need to use acoustic telemetry and also continue to develop new sampling approaches as photo-identification techniques are inadequate to determine residency. Using the methods presented in this paper will allow researchers to further refine sampling approaches that enable them to collect more accurate data that will result in better research and more informed management efforts and policy decisions

Topics: Research Article
Publisher: Public Library of Science
OAI identifier: oai:pubmedcentral.nih.gov:3326037
Provided by: PubMed Central
Download PDF:
Sorry, we are unable to provide the full text but you may find it at the following location(s):
  • http://www.pubmedcentral.nih.g... (external link)
  • Suggested articles

    Citations

    1. (2007). A computer-aided program for pattern-matching of natural marks on the spotted raggedtooth shark Carcharias taurus.
    2. (2011). A first estimate of white shark, Carcharodon carcharias, abundance off Central California.
    3. (1989). A simple population estimate based on simulation for capture-recapture a capture-resight data.
    4. (2007). Aggregations of juvenile whale sharks
    5. (2005). An astronomical pattern matching algorithm for computer-aided identification of whale sharks Rhinocodon typus.
    6. (2010). An empirical probability model of detecting species at low densities.
    7. (2007). Annual re-sightings of photographically identified white sharks (Carcharodon carcharias) at an eastern Pacific aggregation site (Guadalupe Island,
    8. (2005). Carcharodon carcharias. In:
    9. (2009). Coastal swimming patterns of white sharks (Carcharodon carcharias) at Mossel Bay, South Africa.
    10. (2003). Computer-assisted photo-identification of individual marine vertebrates: a multi-species system.
    11. (2009). Concordance of genetic and fin photo identification in the great white shark, Carcharodon carcharias, of Mossel Bay,
    12. (2004). Distribution and abundance of humpback whales (Megaptera novaeangliae)a n d other marine mammals off the northern Washington coast.
    13. (2007). Effects of provisioning ecotourism activity on the behaviour of white sharks Carcharodon carcharias.
    14. (2010). Environmentally sensitive life-cycle traits have low elasticity: implications for theory and practice.
    15. (1999). Estimating size and assessing trends in a coastal bottlenose dolphin population.
    16. (1996). Estimating tag-shedding rates 548 for experiments with multiple tag types.
    17. (2004). Estimating the adult survival rate of central north Pacific humpback whales (Megaptera novaeangliae).
    18. (2002). Genetic tagging to determine passive integrated transponder tag loss in lemon sharks.
    19. (2002). Incorporating uncertainty into demographic modelling: application to shark populations and their conservation.
    20. (2001). Individual recognition of amphibians: effects of toe clipping and fluorescent tagging on the salamander Plethodon vehiculum.
    21. (2000). Life histories and elasticity patterns: perturbation analysis for species with minimal demographic data.
    22. (2011). List of Threatened Species.
    23. (2011). Longterm individual identification and site fidelity of white sharks, Carcharodon carcharias, off California using dorsal fins.
    24. (1998). Matrix photo-identification technique applied in studies of free-ranging bottlenose and humpback dolphins.
    25. (2007). Migration and habitat of white sharks (Carcharodon carcharias) in the eastern Pacific Ocean.
    26. (2008). Multi-scale features for identifying individuals in large biological databases: an application of pattern recognition technology to the marbled salamander Ambystoma opacum.
    27. (2008). Multi-year validation of photographic identification of grey nurse sharks, Carcharias taurus, and applications for noninvasive conservation research.
    28. (2007). Photo-Identification of sea otters using nose scars.
    29. (2005). Photographic identification of fin whales (Balaenoptera physalus) off the Atlantic coast of Nova Scotia,
    30. (1996). Population dynamics of white sharks in South Africa.
    31. (1996). Population dynamics of white sharks in Spencer Gulf,
    32. (2006). Preliminary observations of tag shedding, tag reporting, tag wounds, and tag biofouling for raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa.
    33. (2009). Reproduction of the blue-spotted maskray, Neotrygon kuhlii (Myliobatoidei: Dasyatidae) in south-east Queensland,
    34. (1996). Residency patterns of white sharks at the South Farallon Islands,
    35. (2001). Shark tagging: a review of conventional methods and studies.
    36. (2005). Site fidelity, residence times and home range patterns of white sharks around pinniped colonies.
    37. (2011). Size and structure of a photographically identified population of manta rays Manta alfredi in southern Mozambique.
    38. (2012). The use and abuse of photographic identification in sharks and rays.
    39. (2005). Transoceanic migration, long-distance return migration and local movement patterns in the great white shark.
    40. (2005). Use of natural marks on population estimates of the nurse shark Ginglymostoma cirratum, at the Atol das Rocas Biological Reserve,
    41. (2006). White shark abundance: Not a causative factor in numbers of shark bite incidences. Pages 1–19 in Finding a balance: White shark conservation and recreational safety in inshore waters of Cape Town, South Africa:

    To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.