Diet analyses of Antarctic fur seals to inform ecosystem-based management of South Georgia fisheries

This project will take an interdisciplinary approach to assess temporal and spatial differences in the diet of Antarctic fur seals to evaluate the impact of this predator on prey populations around South Georgia.
Project background
Top predators play an important role in marine environments and studies of their diet are of great value to inform ecosystem management, particularly in areas exploited by fisheries. South Georgia waters harbour commercially valuable toothfish, icefish and krill fisheries as well as 95% of the global population of the Antarctic fur seal (Arctocephalus gazella). After a period of decline due to hunting in the 18th and 19th centuries and subsequent recovery, Antarctic fur seals now numbering over 4 million individuals are assumed to increasingly compete with fisheries for the same resources. Current monitoring data indicate that some populations of Antarctic fur seals are under stress potentially due to a persistent absence of krill resources to support their diet. Therefore, integrated predator diet studies employing morphological and molecular methods are urgently needed to investigate the diet of Antarctic fur seals to devise conservation strategies for this species, as well as to determine which fisheries resources are exploited by its populations. Of paramount importance to such investigations is the assessment of spatial and temporal differences in diet composition of Antarctic fur seals, as well as differences in dietary preferences between sexes and life stages. Available monitoring data and scat sample collections at two separate locations around South Georgia, Maiviken and Bird Island, provide a unique opportunity to address this potential human-wildlife conflict and to provide important data to inform ecosystem-based management strategies that strive to sustain valuable fisheries resources while safeguarding predator populations.
Research questions
1. Can we improve current morphology-based identification protocols for Antarctic fur seal prey species by complementing these with genetic metabarcoding?
2. Does Antarctic fur seal diet differ between the two South Georgia locations, Maiviken and Bird Island, between seasons and between years?
3. Does diet reflect niche partitioning between sexes of Antarctic fur seal?
4. Is the increasing Antarctic fur seal population having a detrimental impact on demersal fish populations?
5. Can we improve quantification of krill biomass from dietary DNA-based data from Antarctic fur seal populations?
6. How can diet studies of Antarctic fur seals inform ecosystem-based management of South Georgia fisheries?