Little is known about the behaviour, spatial distribution and microhabitat utilization of deep sea fishes. The increasing coverage by photographic surveys and video recordings taken from submersibles and remotely operated vehicles (ROV) have clearly suggested the existence of species-specific habitat associations (Lorance et al. 2002; Milligan et al. 2016; Soffker et al. 2011; Uiblein et al. 2003). Demonstration of these associations is not easy, because many environmental variables, in addition to fish behavioural selectivity and plasticity may be involved (Baker et al. 2012; Demestre et al. 2000). The existence of strong fish-benthos associations may change our perception of the deep ocean, but it also raises some conservation concerns with regard to deep-sea fisheries because certain fishing practices may affect both the targeted species and the benthic fauna to which they are typically associated (Huvenne et al. 2016).
The present work investigates the distribution of deep-sea fishes using a multi-factor approach. The micro-distribution of fishes was tentatively associated to geological, hydrographic and benthic variables in a semi-quantitative method.
Observations along four transects on the continental slope of the Bay of Biscay (Figure 1) were used to assess if latitudinal or depth gradients affected these small-scale associations (Latrouite et al. 1999).
Figure 1. Map showing the four dive stations in the Bay of Biscay, NE Atlantic (Dives 22, 34, 35 and 37). Transects were performed approximately perpendicular to the continental slope.