A designed artificial reef is among the most productive marine fish habitats: new metrics to address ‘production versus attraction’

Abstract

It was recently demonstrated that oil platforms are among the most productive marine fish habitats (Claisse et al. in Proc Natl Acad Sci USA 111:15462–15467, 2014). Designed artificial reef systems are similar, albeit smaller, modified habitats designed to accommodate fish assemblages. We compared fish production at a large designed reef to reported production at oil platforms. Given the focus in artificial reef research on distinguishing between new and aggregated fish production, we used a different approach to that of Claisse et al. (Proc Natl Acad Sci USA 111:15462–15467, 2014) to calculate production, based on a steady-state assumption. This assumption simplifies the analysis and distinguishes ‘local production’, ‘new production’, and ‘biomass flux’. Comparing biomass flux with standing stock biomass enables a new approach to address the production versus attraction debate, by revealing how much biomass is exposed to fishing compared to how much has local production. The local fish production at this artificial reef was 384 g m−2 year−1, which is within the 105–887 g m−2 year−1 range reported by Claisse et al., although our study included visitor species not included by Claisse et al. We estimate that the fish production new to the ecosystem may only be 4–5 % of the local production, due to the large abundance of visitor species on this reef. The annual flux of biomass across this reef was very large, ~380 times greater than the standing stock biomass, meaning that this reef is vulnerable to overexploitation from fishing. Our results show that like oil platforms, designed artificial reefs can be very productive marine habitats, but may not greatly increase the net fish production in a system. The method detailed here will allow similar studies to be done relatively simply at other marine habitats, including fish aggregation devices.