Differences in fish communities on natural versus artificial temperate reefs, groundfish conservation applications in British Columbia

Abstract

Human-made marine habitats such as artificial reefs are used to mitigate marine habitat degradation and aid conservation of species at risk. We used ROV and sonar to survey threatened rockfish (Sebastes spp.) and other groundfish species associated with 18 artificial and natural reefs along the south coast of BC, Canada. Using an information-theoretic approach, we found that community composition significantly differed between natural and artificial reefs. Artificial reefs had high variability in rockfish abundance, some supporting very high or low relative abundance. Natural reefs consistently supported intermediate rockfish abundances. Groundfish diversity was significantly greater on natural reefs than artificial reefs. Depth and relief were significant predictors for both abundance and species richness. Interestingly, rockfish abundance was negatively associated with proximity to nearest rockfish conservation area. This research is a first step in understanding causal mechanisms leading to differences between fish communities on artificial reefs in our study system, and which reef attributes may facilitate successful contributions to conservation. Though artificial reefs show promise in the conservation of some threatened species, the maintenance of diverse fish communities depends on protection of heterogenous natural reef communities.