Movement pattern and habitat use of giant trevally Caranx ignobilis in offshore reef habitats (#65)
Passive acoustic monitoring was used to track the movements of 20 Caranx ignobilis at offshore reefs in the Great Barrier Reef from 2012 to 2014. Acoustic monitoring allows long-term monitoring of the marine animal behaviour and movement via a network of moored listening stations that record the presence of tagged animals. Fifty-six listening stations were deployed on seventeen offshore reefs. Traditional spatial statistics (e.g. activity space) and network analysis (NA) determined temporal movement patterns and habitat use of this reef predator. NA is an alternative approach that treats listening stations as network nodes and analyses movement based on flows between nodes. NA provides new and useful interpretations of tracking data not provided by traditional approaches. Individual Caranx ignobilis were present in the study region between 9 and 205 days (mean = 76). Caranx ignobilis were only detected at the reef they were caught and preferred the southwest side of that reef. Preliminary results showed tide, time of day and size of fish influenced size and location of activity spaces. In addition, Caranx ignobilis individual pathways within each reef varied with time of day, height of tide and size of fish. By defining space use patterns of this important reef predator, the results of this study may improve understanding of functional connectivity within offshore reef habitats and help provide guidance for their management.