Hungry Humpbacks

Whales are the largest krill predators in the UK Overseas territory of South Georgia, yet their impacts on krill stocks are poorly understood. Recently, whale surveys revealed high summer abundance and extended use of South Georgia waters into winter, coincident with the winter krill fishery. This project measures how humpback whale foraging intensity varies across the feeding season in South Georgia, using UAV-based (drone) measurements of body condition and satellite-tracking of whale diving rates to measure season-specific krill consumption, and inform krill quota-setting for the Subarea 48.3 CCAMLR krill risk assessment.

The UAV pilots will collect calibrated UAV aerial images from humpback whales near Cumberland Bay, South Georgia. Small-boat surveys will also be conducted near Cumberland Bay, collecting whale sightings, photo-identifications and biopsy samples. Humpback whales will be instrumented with depth-recording satellite tags, to identify spatial habitat-use and how foraging depth and intensity varies across the feeding season.

This project will provide seasonal krill consumption estimates for humpbacks and generate satellite tracking-based winter habitat use models to describe whale distribution. Both datasets will be integrated into the CCAMLR Area 48.3 krill risk assessment and will provide baseline measurements of krill consumption in SG waters by whales across seasons.

Funding: Darwin Plus, South Georgia Heritage Trust and Friends of South Georgia Island. Logistical support from the Government of South Georgia and the South Sandwich Islands.