Remote underwater video and analysis with AI show differences between fish communities at chain moorings and at Environmentally Friendly Moorings

Context Block-and-chain moorings are widely used in urban estuaries and are known to damage habitat-forming species. Environmentally Friendly Moorings (EFMs) are emerging as an alternative mooring design to promote habitat conservation. The effects of either type of mooring on demersal fish remains poorly understood. Aims We compared fish abundance and community composition between block and chain moorings, EFMs and nearby reference sites within unvegetated soft sediment habitats. Methods We deployed baited and unbaited remote underwater cameras in south-eastern Tasmania, Australia, to compare the composition and abundance of fish at sites with block- and chain-moorings with those with EFMs and natural reference sites. Fish data were extracted from videos using human observations, alongside novel Artificial Intelligence object detection, allowing a detailed assessment of temporal responses within each video. Key results We found lower variation in the composition of fish communities among baited chain-mooring sites than at EFM or reference sites. The flathead Platycephalus bassensis was more abundant at chain-mooring sites than at EFMs or reference sites, but only under baited conditions. Conclusions Mooring types affect demersal fish communities, but effects vary across taxa and are strongly influenced by baiting. Implications These findings suggest that mooring impacts extend beyond disturbance of benthic habitats, showing shifts in fish community composition and notable effects on the flathead Platycephalus bassensis.