Lowry, M., Folpp, H., Gregson, M. and McKenzie, R., 2011. A comparison of methods for estimating fish assemblages on estuarine artificial reefs. Brazilian Journal of Oceanography, Special Issue 1 (CARAH), 59: 33–48.

Summary

Industry and Investment NSW utilising funding generated from the recreational fishing licence fee has deployed a series of artificial reefs in several NSW estuaries (Lake Macquarie, Botany Bay, St Georges Basin, Lake Conjola and Merimbula Lake) as a part of a strategy to enhance recreational fishing. Reefs in Lake Macquarie, Botany Bay and St Georges Basin have been the subject of a monitoring program to assess the effectiveness of artificial reefs. One of the challenges in understanding how artificial reefs work is developing sampling methodologies which accurately reflect the number and type of species attracted to artificial reefs, how this varies from areas of naturally occurring reef and whether this changes over time.

Artificial reefs deployed in Lake Macquarie were observed by divers conducting underwater visual census (UVC) and compared with the results obtained using baited remote underwater video (BRUV). Fifty-one species of fish belonging to 27 families were observed during the study. Resident species, identified on over 75% of observations included bream, snapper and tarwhine. Results indicate that the differences in rates of detection between UVC and BRUV are primarily related to the biology and behaviour of the species in question. UVC provided a better coverage of the rare or cryptic reef associated species. In comparison, the BRUV sampled a smaller proportion of species overall but identified key recreational species such as bream, tarwhine and snapper with increased frequency.

Results indicate that BRUV is an effective method for recording species associated with artificial reefs with the exception of cryptic species that are located within the reef structure itself. BRUV techniques complement UVC by providing increased sampling of species known to be diver-averse as well as providing important information regarding the behaviour of the species identified. Given the limitation of each method, it is recommended that monitoring plans for artificial structures should adopt a multi-method approach utilising BRUV and UVC where possible.