Winter Krill at South Georgia

The Winter Krill project is a Darwin Plus project, funded by Defra, and its activities are focussed on South Georgia (SG), which is part of the UK Overseas Territory (OT) of South Georgia & the South Sandwich Islands. The project is led by BAS, along with key project partners, the Government of South Georgia and the South Sandwich Islands (GSGSSI) and the Antarctic Research Trust who are providing logistical and financial support to the project. 

The overarching objective of the project is to obtain information on i) the distribution and abundance of Euphausia superba (Antarctic krill) during the winter; and ii) overlap between the distribution of krill-dependent predators and krill in the fishery area. The motivation behind this is that the commercial krill fishery around SG operates exclusively during the winter period, yet information on the stock dynamics and distribution of krill during this period are sparse. Although MPA restrictions include a 30 km no-take zone around the SG coast, there is evidence to suggest that the foraging habits of krill-dependent predators such as penguins and seals vary depending on the abundance of krill, and that this may result in overlap between them and the krill fishery, particularly during low krill years. There is also evidence of baleen whales returning to SG in large numbers during the summer and of some remaining during the winter, with the increased prey demand potentially further increasing competition for krill resources.  

Fig 1: Infographic showing the key elements of the winter krill project.

The information gathered throughout this project will directly inform fisheries management by feeding into the CCAMLR initiative to develop a more dynamic management approach for the krill fishery. This requires data on krill biomass and predator distribution so that a spatial allocation of catches, based on the krill demand of predators, can be developed. The project will run for 2.5 years, from 1st December 2021 to 31st May 2024. Core activities include acoustic surveys of krill distribution and biomass, gentoo penguin tracking, and cetacean observation, detailed further below. We will also work closely, and share outputs, with all our interested stakeholders. 

To gather data on krill, acoustic surveys that extend within and outside the MPA no-take zone will be undertaken during the austral winter period in two consecutive years (2022 and 2023). Surveys will take place in May, July and September of each year corresponding to the start, middle and end of the fishing season. The survey transects (shown in the map in Fig. 1) are based on those surveyed historically as part of the Eastern Core Box (ECB) surveys and approximately 4 transects will be selected to correspond to the areas of greatest coincidence with the krill fishery. Comparative summer surveys will also be carried out by BAS. Surveys will be carried out on the SG Fisheries Patrol vessel, the Pharos SG, which will have 38 kHz and 120 kHz transducers installed by the GSGSSI for the purposes of the project. In addition, the Western Core Box (WCB) has been operated by BAS from 1996 to present and will continue to run throughout the course of this project, giving us useful contextual and comparative data.  

To gather data on predator distribution and potential overlap with the krill fishery, gentoo penguins will be tracked from April in each of the two survey years, from two locations on SG (Bird Island and Maiviken) that have differing proximities to the krill fishing grounds. This will provide high resolution data on habitat use of the penguins during the fishing season, and will be complemented with data on subsequent reproductive performance that is gathered as part of the regular penguin monitoring work carried out by BAS. Seabird and marine mammal observations will be conducted using JNCC observation methods during all of the surveys to gather data on distribution and abundance in relation to krill. Detailed cetacean surveys will also be conducted by specialist marine mammal observers during the July surveys of each of the two survey years.  Cetaceans will also be detected and identifed acoustically during the expedition, with funding support for this work provided by South Georgia Heritage Trust and Friends of South Georgia Island.

Core staff involved in the project are Prof Martin Collins (PI), Dr Sophie Fielding, Dr Jen Jackson, Dr Cecilia Liszka, Prof Eugene Murphy, Dr Norman Ratcliffe, Prof Geraint Tarling and Prof Phil Trathan (all BAS), Susannah Calderan and Russell Leaper (specialist cetacean observers) and Dr Klemens Pütz (Antarctic Research Trust).  For further details on project team members, please see our People page.

Fig.2: Map of part of the South Georgia and South Sandwich Islands Marine Protected Area (SGSSI MPA) showing the Eastern Core Box survey transects that will be occupied during the project, and the Western Core Box survey (WCB) regularly occupied by BAS. Also indicated on the map are the no-take zones where fishing is prohibited, including a 30 km distance from the SG coastline and a 12 nm (22.2 km) distance from the coastline of Clerke and Shag Rocks. Credit: Cecilia Liszka

Introductory Stakeholder Meeting

On Monday 24^th January 2022 we held an introductory Stakeholder Meeting where we shared details of the project.

The event was recorded and can be watched here. Passcode: 0B=JG#J@

Gentoo Penguin Tracking

In early May 2023, we equipped four gentoo penguins with Wildlife Computers SPOT 367A satellite transmitters at winter roosts at Bird Island and a further eight at Maiviken, in Cumberland Bay. The tags relay positions via the ARGOS system for around 300 days so there is no need to recapture the birds to obtain data; an important requirement since gentoo penguins do not always return to the same roost site each night and may range considerable distances along the coast. The locations are shown on the following map.

Click on a track to find out how far the bird has gone from the release location.

In mid May 2022, we equipped eight gentoo penguins with Wildlife Computers SPOT 367A satellite transmitters at winter roosts at Bird Island and Maiviken, in Cumberland Bay. Two more will be deployed at each location in July. The tags relay positions via the ARGOS system for around 300 days so there is no need to recapture the birds to obtain data; an important requirement since gentoo penguins do not always return to the same roost site each night and may range considerable distances along the coast. The locations are shown on the following map. The names of the tags were given by sponsors of the Antarctic Research Trust, we thank them for their contribution to the project.

Click on a track to find out how far the bird has gone from the release location.

Relevant papers

1. Baines, M., et al., Population abundance of recovering humpback whales Megaptera novaeangliae and other baleen whales in the Scotia Arc, South Atlantic. Marine Ecology Progress Series, 2021. 676: p. 77-94. https://doi.org/10.3354/meps13849
2. Monier, S.A., R.R. Veit, and L.L. Manne. Changes in positive associations among vertebrate predators at South Georgia during winter. Polar Biology, 2020. 43(10): p. 1439-1451. https://doi.org/10.1007/s00300-020-02720-4
3. Savoca, M.S., et al., Baleen whale prey consumption based on high-resolution foraging measurements. Nature, 2021. 599(7883): p. 85-90. https://doi.org/10.1038/s41586-021-03991-5
4. Reid, K., A. S. Brierley, and G. A. Nevitt. An initial examination of relationships between the distribution of whales and Antarctic krill Euphausia superba at South Georgia. Journal of Cetacean Research and Management 2000 2(2): p. 143-149. https://archive.iwc.int/?r=230&k=250d7df0b3