The South Georgia marine ecosystem is globally recognised as a biodiversity hotspot, and its waters are one target of a growing krill fishery. This sub-Antarctic island was also once the epicentre of modern whaling in the Southern Hemisphere (1904-1965), with over 176,000 whales killed in its coastal waters. South Georgia’s remote beaches are still littered with whalebones and the remains of whaling paraphernalia.
Whaling off South Georgia was the most intense of anywhere in the Southern Hemisphere, mainly catching fin, blue and humpback whales. Not many right whales were caught during this period, because they had already been decimated as early as the 1850s by whaling along the coast of Brazil and Argentina, and offshore in the lower latitudes of the South Atlantic. Right whales swam slowly, floated when struck, liked calm nearshore waters for calving and yielded high-value oil, making them an early and convenient (‘right’) target for whalers for many centuries. In the Southern Hemisphere, southern right whales suffered >350 years of exploitation and are now slowly recovering. Today, southern right whales are the most commonly seen whale in South Georgia waters, an area which is thought to be one of their primary feeding grounds.
Right whales feeding in South Georgia waters in summer have been linked, through photo-identifications and satellite tagging, to their calving ground at Península Valdés in Argentina, showing a migratory connection between the two areas. However the Península Valdés calving ground has had notably high calf mortalities in the last decade. A growing body of evidence suggests that South Georgia environmental conditions directly influence the low latitude population dynamics of these whales, suggesting foraging success is a primary factor influencing reproductive rates.
In summer 2018 (January/February) we carried out a survey of right whales in South Georgia waters, spanning their period of peak occurrence. During summer 2019 we conducted whale surveys in waters local to Cumberland Bay, staying in King Edward Point research station and working from small boats between Stromness and St Andrews Bay. In summer 2020 we will conduct surveys further offshore along the north coast.
The survey is designed to investigate whale prey sources, habitat use in relation to krill fishing within the sustainable-use South Georgia and South Sandwich Islands Marine Protected Area, and to measure genetic diversity, population connectivity with calving areas, and health status.
Our survey uses a variety of innovative technologies, including a newly developed acoustic localisation technique to locate whales. Through photo-identifications, acoustic monitoring, collection of skin samples, satellite tracking and drone deployment, we will collect a broad range of data characterising the status, distribution and health of whales using South Georgia waters.
During January 2019 we were able to satellite tag two humpback whales during their feeding season in South Georgia waters. One travelled to the South Sandwich Islands before transmission stopped. The second spent the season close to South Georgia, probably feeding on Antarctic krill, and is now migrating back to its wintering grounds in Brazil. Follow its progress here!
Key objectives for this study:
- Satellite tracks, acoustic and oceanographic data will be integrated to identify key areas of whale habitat use and foraging patterns in the South Georgia marine ecosystem. A report summarising these findings will be presented to the Government of South Georgia, assessing how well MPA boundaries and fishery closure timings match the patterns of right whale feeding and habitat use in these locations.
- Whale prey and habitat use in relation to the krill fishery and in relation to key oceanographic features will be investigated. Results will be reported to the annual scientific meeting of the Convention for the Conservation of Antarctic Marine Living Resources Scientific Committee in order that right whales can be considered in spatial krill fishery management plans and ecosystem model development.
- Migratory connections between South Georgia waters and calving grounds off Argentina and Brazil will be investigated using photographs, genetics and satellite tracking, linking individuals between regions to measure long-term sightings records and reproductive histories in Península Valdés. Our recent paper to the IWC Scientific Committee using microsatellites to confirm the genetic association of South Georgia right whales with the southwest Atlantic calving grounds will be available here shortly.
- Collect biological data (skin samples, body images and whale blow samples) on health and body condition to infer habitat quality during the feeding season and improve understanding of the causes of calf mortality associated with this feeding ground.