Oral Presentation Australian Society of Fish Biology and Oceania Chondrichthyan Society Conference 2016

Use of baited remote underwater video systems (BRUVs) to estimate presence and size of juvenile white sharks Carcharodon carcharias (#172)

David Harasti 1 , Kate A Lee 1 , Roger Laird 1 , Russ Bradford 2 , Barry Bruce 2
  1. NSW DPI, Taylors Beach, NSW, Australia
  2. CSIRO, Hobart, Tasmania

Baited remote underwater video systems (BRUVs) are commonly used to assess fish assemblages and, more recently, to record the localised abundance and size of sharks. This study investigated the occurrence and size of white sharks (Carcharodon carcharias) in the near-shore environment off Bennett’s Beach, part of a known nursery area for the species in central New South Wales, Australia. Six stereo-BRUV units were deployed approximately fortnightly between August and December 2015 for periods of five hours in depths of 7 to 14 m. BRUVs successfully recorded 34 separate sightings of 22 individual white sharks. The highest number of individuals detected during a single day survey was eight (1.6 sharks/ per hour of BRUVs sampling). All C. carcharias observed on BRUVs were juveniles ranging in size from 1.50 m to 2.46 m total length (mean size of 1.91 m ± 0.05 S.E, n=22). The time to first appearance ranged from 15 to 299 mins (mean 148 mins ± 15 mins). This study demonstrates that the use of stereo-BRUVs is a viable non-destructive method to obtain estimates of size and presence of white sharks, and may be useful to estimate relative abundance in near-shore environments where they are known to frequent.