Ifremer participated - together with the University of La Rochelle, in the biological sampling of mesopelagic fauna by pelagic trawling on the Bay of Biscay slope during the EVHOE scientific cruises in fall between 2002 and 2022 (https://doi.org/10.18142/8). Analyses of the species densities collected during the cruises suggested that depth was the most important variable structuring the community, defining four depth-related species assemblages. A vertical gradient of structuring environmental variables was identified with dynamic variables explaining individual species distribution in the epipelagic layers and topographic and bathymetric variables explaining more variance in the deeper layers.

Ten opportunistic pelagic trawls deployed at nighttime in sound scattering layers detected above 200 m depth provided first abundance and biomass estimates. Only species known to undertake diel vertical migration (i.e. mesopelagic species) were included in order to provide a proxy of migrant biomass. These opportunistic data show high geographic and annual variability with Myctophidae (lanternfish), Sternoptychiidae (hatchetfish), and Alepocephalidae (slickheads) account for most of the fish migrant biomass.

Cheret Isabelle (2004). Viperfish (Chauliodus sloani). Ifremer. https://image.ifremer.fr/data/00676/78846/