Residency and movement patterns of yellowfin bream (Acanthopagrus australis) released at natural and artificial reef sites

Abstract

The present study investigated the long-term (>2 years) site fidelity, residency and movement patterns of Acanthopagrus australis (Sparidae) at artificial (AR) and natural reef (NR) sites. Acoustic telemetry was used to assess movement patterns of 39 fish released at NR and AR locations and other habitat types within the study area. Detection periods ranged from 1 day to a maximum of 912 days, with 36% of fish detected by the array for >1 year and a further 7% detected for >2 years. Results indicate that tagged fish tended to remain associated with the release site; however, AR fish were detected for considerably longer periods with greater numbers of fish identified as resident within the AR system. AR-released fish were also identified more frequently across the entire array, with the majority (90%) of detections between receiver stations located within the AR system. Results were affected by short detection periods (<6 days) of a relatively high proportion of fish released at the NR, possibly indicating differential rates of fishing mortality between locations. Longer range movements of >200km were also detected, but there was no obvious trend with release location. The results of the present study indicate interactions between existing and introduced artificial habitat are more complex than a ‘draw-down’ effect and provide further evidence that AR systems provide suitable habitat for a variety of species, as well as further support for the use of AR systems in fisheries enhancement initiatives. The results also have important implications for understanding the effect of AR systems and indicate that the size of the reef system may be an important factor in controlling for levels of fishing-related mortality.