Methodology:

Between 31 October and 10 November 2015, British Antarctic Survey flew three lines of aerial survey over sea ice adjacent to the Antarctic Peninsula to survey pack ice seals. Image coverage of Maguerite Bay was taken twice; once on 31 October, and once on 10 November, to assess the variability of seal presence. A separate line was flown over Crystal Sound on 8 November. A Twin Otter aircraft was mounted with a vertical facing high resolution Z/I Imaging Digital Mapping Camera (DMC) and, flying at a height of 1200m, around 1600km of imagery was acquired of the pack ice with an on-the-ground resolution of 12cm per pixel. Images were taken approximately every 700m and had a 40% overlap. Each image was post processed using the IMU (inertial measurement unit) data from the aircraft that gives position and orientation to enable georectification of each photograph.

In the resulting imagery seals can be clearly seen, often with pups and recent tracks. These seals were manually digitised with a single point placed on each seal in ArcGIS (version 10.4 ESRI 2025). Searching was done systematically at 1:800 scale, where images overlapped, only the seals from the first image viewed was recorded. The resulting point shapefiles record all seals in the three flightlines.

Data collection:

Imagery was acquired using Intergraph's Z/I Imaging Digital Mapping Camera (DMC).

Points were digitised in ArcGIS version 10.4

Trimble Applanix software was used to create the camera centre points from the onboard IMU data.

SOCET GXP was used to undertake the areo-triangularization and georectification of the images.

Data quality:

Spatial resolution of the imagery is 12cm per pixel Ground Sample Distance (GSD).

Seal locations have been marked, but species cannot be differentiated.

No accuracy metrics are included.

Horizontal datum: EPSG:3031 - WGS84 Antarctic Polar Stereographic

Vertical datum: MSL (mean sea level)