Environmental Biology of Fishes

, Volume 72, Issue 2, pp 213-221

Use of natural marks on population estimates of the nurse shark,Ginglymostoma cirratum, at Atol das Rocas Biological Reserve, Brazil

  • Andrey L. F. CastroAffiliated withDepartment of Biology, University of South Florida
  • , Ricardo S. RosaAffiliated withDepartamento de Sistemática e Ecologia, CCNE, Universidade Federal da Paraíba Email author 

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We assessed information on the population structure of the nurse shark, Ginglymostoma cirratum, at Atol das Rocas, northeastern Brazil, through underwater observations. Based on photographic records of natural distinctive marks for individual recognition, we used probabilistic estimators (Petersen–Bailey and Jolly–Seber) to assess population size. We found that 46% of the sharks (194 individuals) had distinctive marks. The population size was estimated in 368 individuals, using the Petersen–Bailey estimator, and 339 individuals using the Jolly–Seber estimator.


underwater visual censuses photo-identification sighting–resighting population size population structure