The Southern Ocean is rapidly changing, with future environmental changes likely to have wide- reaching consequences for the structure and function of marine ecosystems. Along with well-designed sampling and observation programs, ecosystem models are the central means by which we can gain insight into how these changes affect ecosystems. Developing ecosystem models that can provide robust predictions and management advice depends on knowledge of environmental drivers and trophic linkages for constituent species. In the Southern Ocean, this information is largely lacking for the the mid- trophic level fish and squid groups that comprise major energy pathways making primary producers accessible to higher-order predators including whales, seals, penguins, flying seabirds. Knowledge of mid- trophic levels has also been identified as a key uncertainty for understanding top predator trophodynamics globally and this knowledge gap represents a major impediment to the development of conservation and management strategies.
The Kerguelen Axis is the most important area for primary production in the Southern Indian Ocean, and a key area of interest for Australia. However, ecosystem structure and drivers in this region are poorly understood. In January to March 2016, the Antarctic Climate and Ecosystems CRC led an integrated ecosystem survey program along a 8850 km path comprising 9 transects. The voyage track was designed to encompass major environmental transitions in the region including frontal features, the maximum extent of winter sea-ice coverage, and gradients of sea surface temperature and surface primary production, with extensive biological and oceanographic sampling. The goal of this voyage was to characterize pelagic foodweb structure and trophic linkages in this region and to pilot methodologies for future ecosystem observation and monitoring in the region. Here, we present a summary of the fish and squid sampling conducted on this voyage and show how empirical data are being coupled with modelling to better understand ecosystem status and trends in this region.