Distribution, abundance and ecological relevance of pelagic fishes in the Lazarev Sea, Southern Ocean

The distribution and abundance of larval and postlarval fishes was investigated in the Lazarev Sea, Southern Ocean, in March and April 2004. The upper 200 m of the water column were sampled with an 8 m² rectangular midwater trawl at 93 stations. The larval species community clustered in a diverse coastal community with high densities of Antarctic silverfishPleuragramma antarcticumlarvae and a less diverse offshore community dominated by Antarctic jonasfishNotolepis coatsiand the lanternfishElectrona antarctica. No postlarval fish were caught in coastal areas. The offshore community of postlarval fishes consisted of the deep-sea smeltBathylagus antarcticus, and the lanternfishesGymnoscopelus braueri,G. nicholsiandE. antarctica. The latter species clearly dominated, occurring at mean individual and wet mass densities of 0.17 individuals m–2and 0.26 g m–2, respectively. A generalized additive model significantly related the density of postlarvalE. antarcticato the abundance of Antarctic krillEuphausia superba, ocean depth and sea surface temperature. The diet ofE. antarcticawas dominated by copepods and euphausiid larvae. Mean energy density ofE. antarcticain the upper 200 m was 2.8 kJ m–2, which is equivalent to 36% of the energy stored in Antarctic krill stocks and probably would be considerably higher if a greater depth range were considered. This suggests thatE. antarcticais a major energy transmitter in the food web of the Lazarev Sea, challenging the classical krill-dominated food web paradigm of the Southern Ocean.