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 alternative mooring designs 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-east Tasmania, Australia, to compare the composition and abundance of fish across sites with block-and-chain moorings, EFMs or 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 compared to 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, revealing shifts in fish community composition and notable effects on the flathead Platycephalus bassensis.
Langley et al. (Fri,) studied this question.