Cetacean and fur seal sightings at sea from the British Antarctic Survey expedition SD046 survey of South Georgia and the Scotia Arc, February to March 2025
GB/NERC/BAS/PDC/02234
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Summary
Abstract:
Cetacean and fur seal sightings in South Georgia and Scotia Arc waters were made by a team of four marine mammal observers during the British Antarctic Survey SD046 expedition on the RRS Sir David Attenborough. This visual survey was conducted from 7 February to 24 March 2025, covering 1,377 nautical miles and 134 hours of survey effort. The latitude and longitude of each sighting, the identified species, bearing and distance from the vessel, and estimated group size are provided, as well as the weather conditions during the survey. These data have been used to investigate cetacean distribution and relationship to krill swarm features.
Funding was provided by the Foreign, Commonwealth and Development Office, as part of the Overseas Territories Blue Belt programme, South Georgia Heritage Trust and Friends of South Georgia Island.
Keywords:
Scotia Sea, Southern ocean, density, pinniped, species distribution, whale
Citation
Bassoi, M., Cubaynes, H.C., Josso, E.R., McLennan, H., Venables, H.J., & Jackson, J.A. (2026). Cetacean and fur seal sightings at sea from the British Antarctic Survey expedition SD046 survey of South Georgia and the Scotia Arc, February to March 2025 (Version 1.0) [Data set]. NERC EDS UK Polar Data Centre. https://doi.org/10.5285/01395ffd-ed1b-4af8-9a63-deb37755c60b
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Constraints
| Access Constraints: | No restrictions apply |
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| Use Constraints: | Data are supplied under Open Government Licence v.3 http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/. |
Basic Information
| Creation Date: | 2026-06-30 |
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| Dataset Progress: | Complete |
| Dataset Language: | English |
| ISO Topic Categories: |
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| Parameters: |
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| Personnel: | |
| Name | UK Polar Data Centre |
| Role(s) | Metadata Author |
| Organisation | British Antarctic Survey |
| Name | Manuela Bassoi |
| Role(s) | Investigator |
| Organisation | Universidade Federal do Rio Grande |
| Name | Hannah C Cubaynes |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Elena R Josso |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Hayley McLennan |
| Role(s) | Investigator |
| Organisation | University of St Andrews |
| Name | Hugh J Venables |
| Role(s) | Investigator |
| Organisation | British Antarctic Survey |
| Name | Jennifer A Jackson |
| Role(s) | Investigator, Technical Contact |
| Organisation | British Antarctic Survey |
| Parent Dataset: | N/A |
Additional Information
| Quality: | Data collection and QC are detailed in 'SD046 Cruise Report Final' and associated publications. Where species identification was unclear, sightings were described as 'unidentified whale' or similar. Any missing values in the dataset (NA) mean that data were not collected for this parameter or timeperiod. | |
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| Lineage/Methodology: | Sightings data were collated using standard cetacean sighting survey protocols as detailed in the associated document "SD046 Cruise Report Final" and in the publications associated with these data. The surveys followed the transect line and distance sampling methodologies (Buckland et al., 2015) and all sightings were recorded on board of the SDA in the digital Event Logger (an interface on the ship that had been customised to input cetacean survey data and conditions). The visual monitoring took place whilst the vessel was sailing at a speed of 8 to 14 knots, in daylight, with a wind speed of up to 27 knots, a sea state of up to Beaufort 6 and moderate visibility (at least 2 nm). Whilst on effort, there were a minimum of two observers on watch at all times and one data recorder (DR) recording sightings. Watch periods were during daylight hours, from about 05.30 to 18.45 local time, and changed during the cruise with sunrise and sunset. Depending on the number of people available, the rotation of the survey team was different. If the team consisted of three people, the rotation took place every 20 minutes, with the observer on port side replacing the observer on starboard side and the data recorder replacing the observer on port side, and so on. This rotation allowed the observer to watch the sea for no more than 40 minutes. When the team consisted of four people, the rotation was performed every 30 minutes, with the resting position replacing the observer on port side, and the data recorder replacing the observer on starboard side, who went on rest. The observers searched with the naked eye and binoculars, scanning their search area as follows: the observer on port side searched the area from 90 degrees port to about 10 degrees starboard, and the observer on starboard side searched the area from 90 degrees starboard to about 10 degrees port (see the cruise report for details). This ensured that the trackline was covered by both observers. All cetaceans and fur seals were recorded, with the exception of the Western Core Box survey (15-18 Feb 2025). During 15-16 Feb, only cetacean sightings were collected due to the high frequency of fur seal sightings potentially distracting from cetacean sightings. Fur seal sightings were resumed on 17 Feb. Each observer had 7x50 binoculars with reticles, and the angles from the trackline to the sighting were obtained from pointers on the mounted angle boards (0° indicating directly ahead of the vessel, Figure 5 of the cruise report), to estimate the radial distance to the sightings. This ensured that the trackline was covered by both observers. All species of cetacean were recorded. The main responsibility of the observer team was to obtain accurate information on the time, angle, radial distance, species identification and school size of as many cetacean sightings as possible. All watches were set to UTC and paper sightings forms and pencils were used if the Event Logger failed. The DR was responsible for accurately recording the effort and weather data in the Event Logger (and on paper forms, see Annexes 3 and 5 of the cruise report) at the beginning and end of each transect, as well as every time the team changed position (every 20 or 30 minutes). Any change in the type of search effort or environmental conditions that might affect the detection of animals was also recorded (changing conditions). When an observer had a sighting, they reported the angle, reticles, clue and method of sighting to the DR as quickly as possible. The DR immediately opened a new event in the Event logger sighting form, which contained the fields to be filled in. When one observer made a detection, the other observer continued to search in their usual way. Re-sightings of the same animals were not recorded. The following weather-related parameters were recorded in the Event Logger. Items indicated with * were automatically filled with data from the vessel's monitoring system. Parameter details are provided in the files associated with this product. Time (UTC)*; transect_no; latitude*; longitude*; effort; transect_type; weather; Beaufort; swell; visibility; sightability; glare; ice; ice_type; SS_temperature(C)*; depth_EA640* (m); obs_port; obs_stbd; DR_1; DR_2; wind_direction (true)*; wind_speed (true)*; speed over ground(knots)*; course over ground (degrees)*; wave_height (m)*; comment. The following parameters were recorded in the Event Logger during a sighting. Time (UTC)*; sighting_no; angle; reticles; method; cue; est_dist; latitude*; longitude*; sp_code; N_min; N_max; N_best; N_groups; calves; swim_direction; behaviour; behaviour_FS; transect_no; effort; obs; duplicate; dupl_ID; photo; camera; photo_no; course over ground (degrees)*; comment. The full list of parameters and their description are included in the data files. |
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Locality
| Temporal Coverage: | |
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| Start Date | 2025-02-07 |
| End Date | 2025-03-24 |
| Spatial Coverage: | |
| Latitude | |
| Southernmost | -63.3 |
| Northernmost | -52.7 |
| Longitude | |
| Westernmost | -54.8 |
| Easternmost | -25.2 |
| Altitude | |
| Min Altitude | N/A |
| Max Altitude | N/A |
| Depth | |
| Min Depth | N/A |
| Max Depth | N/A |
| Location: | |
| Location | Antarctica |
| Detailed Location | Shag Rocks |
| Location | Antarctica |
| Detailed Location | South Georgia |
| Location | Antarctica |
| Detailed Location | Scotia Arc |
| Location | Antarctica |
| Detailed Location | South Sandwich Islands |
| Location | Antarctica |
| Detailed Location | South Orkney islands |
Instrumentation
| Data Collection: | Sighting data were collated using the RRS Sir David Attenborough onboard Event Logger interface (last updated 14/02/22). Observers used 7x50 reticle binoculars and measured sighting distance using reticles, or the naked eye. The angles from the trackline to the sighting were obtained from pointers on the mounted angle boards (0 degrees indicating directly ahead of the vessel), to estimate the radial distance to the sightings. |
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Storage
| Data Storage: | Files: SD046_Sightings.csv - summarises all sightings reported by species (where identified), distance and bearing from vessel and best estimate of group size. SD046_Effort.csv - summarises survey effort and weather conditions during the survey transects including conditions at start and end of each transect. SD046 Cruise Report Final.pdf - provides details of the cruise plan and a general overview of the dataset SD046_cruise_track.csv - provides vessel location data every minute from 1 Feb 2025 to 27 March 2025. |
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