Grupo de Oceanografia de Altas Latitudes
One of our project members, Dr. Elisa Seyboth, has recently returned from the International Antarctic Coastal Circumnavigation Expedition, a research trip that occurred between 23 November 2024 and 30 January 2025 (Figure 1). Together with another four members of the GOAL (Grupo de Oceanografia de Altas Latitudes, High Latitude Oceanography Group), from the Universidade Federal do Rio Grande (FURG), Brazil, one of the institutions engaged in the Whales and Climate program. There were 67 researchers in total, onboard the R/V Akademik Tryoshnikov.
Figure 1. Map indicating track of the International Antarctic Coastal Circumnavigation Expedition 2024-2025 (red line).
One of the objectives of the GOAL team during the ICCE was to monitor the occurrence of marine mammals along the circumnavigation route. For that, whenever the vessel was sailing at a minimum speed of 6 knots and the conditions were favorable (sea state Beaufort ≤ 5, visibility ≥ 3 nautical miles, and daylight), the method of linear transect sampling with distance sampling, known as Distance Sampling, was used for marine mammal observation, with a higher focus on cetaceans. This methodology aims to estimate encounter rate, relative density, and abundance of marine mammals. Considering the set up during the voyage and the reduced team onboard, with only one observer available for this task, the methodology was slightly adapted. The observer scanned the whole area forward of the vessel, covering 180 degrees, working from the bridge of vessel. The perpendicular distance between the observed cetacean group and the transect line at the time of the sighting was obtained through trigonometry, based on the direct distance between the group and the observer, and the horizontal angle of the sighting in relation to the transect. For this, reticulated binoculars and angle boards were used (Figure 2a). All information, including the sightings and oceanographic and meteorological information, was recorded on a laptop connected to a GPS, using the LOGGER software.
For each sighting, the following data were recorded: species identification, number of groups, number of individuals per group, date, time, location (geographical coordinates), sea state, environmental conditions, number of reticles, and angle in relation to the vessel’s bow. Environmental conditions were also recorded at the beginning of each observer shift and whenever they changed.
Figure 2. Observer during marine mammal monitoring from the bridge of the R/V Akademik Tryoshnikov (a) and a group of humpback whales spotted during the expedition (b) – this was the most common species observed during the ICCE.
In total, 101 sightings were recorded during the observation effort. The species observed included groups of humpback whales (Megaptera novaeangliae) (n=60; 102 individuals), fin whales (Balaenoptera physalus) (n=9; 19 individuals), minke whales (Balaenoptera spp) (n=7; 8 individuals), orcas (Orcinus orca) (n=3; 29 individuals), ), sperm whales (Physeter macrocephalus) (n = 2; 2 individuals), and blue whales (Balaenoptera musculus) (n = 1 ; 2 individuals. Other sightings could not be identified to the species level (n=20). These were grouped and are indicated as sightings of unidentified species in Figure 3. In addition, four species of seals were observed: crabeater (Lobodon carcinophaga), Ross (Ommatophoca rossi), Weddell (Leptonychotes wedelli) and leopard (Hydrurga leptonyx), which positions were also recorded. Please note these numbers refer to sightings during line transect observation effort, not including opportunistic sightings.
Figure 3. Map with the location of the cetacean sightings during line transect monitoring as part of the ICCE activities.
II – GOAL TEAM COMPONENTS
Ana Paula Tavares Costa (Universidade Federal do Rio Grande – FURG)
Andres Eloy Piñango Jauregui (Universidade Federal do Rio Grande – FURG)
Elisa Seyboth (University of Pretoria – UP)
Fabiane Serra (Universidade Federal do Rio Grande – FURG)
Luísa de Moraes Garcia (Universidade Federal do Rio Grande – FURG)
Figure 4. GOAL team members who joined ICCE 2024-2025: Andres, Fabiane, Elisa, Luísa and Ana Paula.
