Winter krill study underway off South Georgia | Polarjournal
The fisheries patrol vessel MV Pharos SG was specially equipped with an echo sounder for the winter krill project to detect the krill swarms. Photo: Martin Collins, BAS

In December 2021, the British Antarctic Survey-led Winter Krill Project launched in South Georgia to learn more about Antarctic krill in the winter months, on which many penguins, other seabirds and marine mammals depend. After successfully completing the first survey in May, the second has now begun.

The marine protected area around South Georgia and the South Sandwich Islands is the largest in the world. In the 30-kilometer-wide no-take zone along the coast of South Georgia, commercial krill fishing is completely prohibited, and in the outer zone of the protected area, it is only allowed in winter. However, little information is available on krill stock dynamics and distribution in winter. But there is evidence that krill predators such as penguins and seals may leave the 30-kilometer prohibited zone depending on krill abundance and that there may be overlap with the krill fishery, especially in years when krill are scarce. In addition, there is evidence that some of the baleen whales that spend the summer around South Georgia remain there during the winter, further increasing competition for krill as prey.

Therefore, the winter krill project – a Darwin Plus project – was launched with the aim of collecting information on

  • the distribution and abundance of Antarctic krill (Euphausia superba) during winter, and
  • Overlap between the distribution of krill-dependent predators and krill in the fishing area. 
Overview of the winter krill project with the key components: Plankton nets to catch krill; echo sounder to estimate krill biomass; temperature and salinity measurements; satellite tracking of penguins; observation of seabirds and marine mammals; and Passive Acoustic Monitoring to detect whales. Infographic: Tracey Dornan, BAS (screenshot BAS website)

To collect the required data on krill, the fisheries patrol vessel MV Pharos SG has been equipped with an echo sounder to detect krill swarms. Surveys will take place in May, July and September this year and next – at the beginning, middle and end of the fishing season – and will be conducted in transects inside and outside the no-fishing zone. In the southern summer, the British Antarctic Survey conducts comparative surveys.

The map shows South Georgia with the 30-km no-take zone (green) and the boundary of the protected area (black line). The orange and green stripes mark the transects along which the surveys were conducted. Map: Cecilia Liszka, BAS 

The surveys will focus on an area northeast of South Georgia, with the ship covering 800 nautical miles of transects in May, repeated day and night, to study how krill distribution is changing. The acoustic surveys will be combined with krill catches to monitor their status, at-sea observations of seabirds and marine mammals, and satellite tracking of gentoo penguins to learn more about potential competition between the fishery and marine predators that rely on krill for food.

The lines show the routes of eight gentoo penguins that were fitted with satellite tags by the research team in mid-May. Last update of the map: July 27, 2022. Map: Screenshot BAS website

During the May survey, the research team recorded numerous swarms of small krill, as well as 66 humpback whales and 53 fin whales feeding on the krill swarms. These were primarily detected over the South Georgia shelf, a marine area with a depth of less than 1000 meters.

“This is the first scientific data collected on krill distribution during the winter months for many years and will provide critical information to support the management of the krill fishery which is restricted to the winter months to avoid competition with breeding wildlife that feed on the small crustaceans. It’s been brilliant working in partnership with the Government of the South Georgia and South Sandwich Islands on this great project,” says Tracey Dornan, biological oceanographer at the British Antarctic Survey.

The information gained will contribute directly to the CCAMLR initiative to develop a more dynamic management approach for the krill fishery.

The project is being carried out by the British Antarctic Survey in collaboration with the Government of South Georgia and the South Sandwich Islands and the Antarctic Research Trust.

Julia Hager, PolarJournal

Featured image: Uwe Kils via Wikipedia

Link to the project website: https://www.bas.ac.uk/project/winter-krill-at-south-georgia/#about 

More on the topic:

„Pathway to Protection“ – extensive protected area for South Georgia.
New protected area: South Georgia and South Sandwich Islands
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