Small-scale patterns of deep-sea fish distributions and assemblages of the Grand Banks, Newfoundland continental slope

Deep-sea fishes are the target of directed fisheries and are considered a conservation concern. Yet, we still know little about the factors that affect deep-sea fish distributions and assemblage patterns on relatively small spatial scales. We used results from remotely operated vehicle surveys that observed 105 km (∼346 960 m2) of seafloor over a depth range of 351–2245 m in three canyons off Newfoundland to examine the occurrence, behavior, habitat specificity, and regional assemblage patterns of deep-sea fishes in this region. We found distinct assemblages based on both depth and habitat classifications. The most obvious unique assemblage was that associated with outcrops, which served as habitat for relatively rare species such as Neocyttus helgae, Hoplostethus atlanticus, and Lepidion eques. Several coral habitats hosted distinct assemblages when compared to other habitats with low or medium structural complexity. Our results illustrate that any program targeted at protecting deep-sea ecosystems must protect a wide-range of habitats and depths to conserve a variety of fish species and assemblages.

► We examined deep-sea fish occurrence, habitat specificity and assemblage patterns.
► Synaphobranchus kaupii, Sebastes spp., and Myctophidae were the most abundant fishes.
► Distinct fish assemblages based on depth and habitat exist off Newfoundland.
► Outcrops had an obviously unique fish assemblage.
► No overall trend of fish assemblages could be related to corals.