The benthic and pelagic phases of Muraenolepis marmorata (Muraenolepididae) off the Kerguelen Plateau (Indian sector of the Southern Ocean)
Muraenolepis marmorata life cycle is poorly investigated. This benthic species occurs mainly on the shelf slope and deep-sea as juvenile and adult stages but its early life is strictly pelagic off the Kerguelen Plateau. The upper layers (0-500 m) of the pelagic waters off the shelf are used by fingerlings both day and night during summertime. Dense aggregations (swarms) are sometimes observed by echo sounder (gas swim bladder detection) then have been confirmed by midwater trawl sampling. Fingerlings reach the size of about 55 mm before disappearing (ontogenic migration to the bottom) from the pelagic catches in autumn. M. marmorata and the myctophid Krefftichthys anderssoni are the only species to be present during the day in the upper layers of the water column off the Kerguelen Plateau. M. marmorata becomes a prey for top predators such as king penguins (Aptenodytes patagonicus) in their known depth diving range of their foraging area. Strong interannual variations in density of fingerlings are noted. The biomass of M. marmorata, evaluated in the bathymetric range 100-1000 m, was about 300 tonnes, which places the species at the 17th rank of the 19 demersal species occurring on the shelf and slope of the Kerguelen Islands.