During the day, myctophids (lanternfish), krill, squid and jellyfish form layer-like aggregations in the mesopelagic zone (200-1000m deep) to reduce exposure to visual predators. These layers can be detected by echosounders and are known as deep scattering layers (DSLs). Myctophids are very abundant in DSLs and offer great potential as a protein source for human consumption, but play a key trophic role as food for predators. In the framework of the Commission for the Conservation of Antarctic Marine Living Resources, pressing management issues arise because myctophids make up to 90% of the diet of deep-diving air-breathing predators such as King Penguins (Aptenodytes patagonicus, dive depth >350m) and Southern Elephant Seals (Mirounga leonina, dive depth >1500m). More data on DSLs are needed to develop a biogeographic zonation and understand likely future responses to climate change before any large-scale exploitation begins.  A unique data set of DSL geographic variability in depth and echo-intensity (proxy for biomass) throughout the Southern Ocean was collected during the Antarctic Circumnavigation Expedition (ACE), along with CTD data and satellite remote sensing. We also collected position, depth and accelerometry data from predators off the coasts of South Georgia and Kerguelen as the ACE vessel approached each island. The tracking data are co-located with the DSL landscape to better understand predator-prey interactions and inform fisheries and conservation management.

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Field work: 

       > ACE expedition: 2 months - acoustic measurements on Deep Scattering Layers

(with the following stops: Germany - South Africa - Crozet - Kerguelen - Heard & McDonald islands - Australia)

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       > British Antarctic Survey : 3 months - field work on king penguins (King Edward Point, South Georgia) (with the following stops: Signy - Rothera - Falkland Islands).