MEPS 553:219-232 (2016)  -  DOI: https://doi.org/10.3354/meps11777

ABSTRACT: Carangids are important ecological components of coastal and reef habitats, in addition to their economic significance as a target species for some fishers. Despite these important ecological and economic roles, little information is available on the movement ecology of these species. Passive acoustic monitoring was used to track the movements of 16 giant trevally Caranx ignobilis and 20 golden trevally Gnathanodon speciosus in Cleveland Bay off the coast of Queensland, Australia. Long-term observations of behaviour and movement were recorded via a network of acoustic receivers, and a network analysis approach (a novel, alternative approach to conventional movement analysis) was applied to the collected data. Tagged individuals were present in the study region between 30 and 394 d (mean ± SD:166 ± 116 d) with a mean ± SE residency index of 0.7 ± 0.1. Notable inter-annual variation occurred with individuals that were detected on more days and more receivers, moved more frequently, and were more resident in some years than in others. In addition, movement patterns differed between species, with C. ignobilis being detected on fewer days by fewer receivers and moving less than G. speciosus. Network analysis revealed that a combination of factors including ontogeny, foraging niche, and habitat influences may explain differences in space use between the species. These results highlight unique behaviours between co-occurring and closely related species and enhance our understanding of animal interactions in inshore habitats.

KEY WORDS: Acoustic monitoring · Caranx ignobilis · Gnathanodon speciosus · Information theoretic approach · Network analysis · Mixed model effects