Ecosystems in recovery – Whales | Polarjournal

On September 1, the government of South Georgia and the South Sandwich Islands, announced the release of a new stamp set to draw attention to the recovery of the territory’s ecosystem and in particular the whales.

The waters around South Georgia and the South Sandwich Islands are protected by a 1.24 million square kilometre Marine Protected Area. However, this was not always the case. During the 20th century, more than 170,000 whales were killed in South Georgia, with untold effects on the ecosystem. Whaling ended in South Georgia in the 1960s. Despite this, whales were rarely seen in this important feeding area over the following 40 years.

A right whale in the waters of South Georgia. (Photo: Dave Rootes)

More recently, anecdotal reports showed that whale populations were increasing and the ecosystem was recovering. During 2017-2021, a project was conducted to estimate the recovery status, abundance, diversity, health, and habitat use of cetaceans on their feeding grounds in South Georgia.

The South Georgia Wild Water Whales project was led by the British Antarctic Survey in collaboration with research experts from around the world.

The project used a range of scientific approaches, including conducting visual and acoustic surveys of cetaceans, collecting photo-identification and skin samples for genetic identification, using transmitters on cetaceans to track their movements, collecting cetacean breath samples with drones, and surveying whale body condition with overhead imagery.

This new stamp series celebrates the recovery of whale populations in South Georgia and features some of the fantastic scientific research that is helping us to better understand and further protect them.

55p – Southern right whale

South Georgia is considered an important summer feeding ground for the Southern right whale. To study how they use this foraging habitat, two southern right whales were tagged with transmitters in the southern summer of 2020 and their movements were tracked by satellite for the following months. While one female whale swam to the ice edge of Antarctica during the summer and fall, the second male whale remained in the coastal waters of South Georgia for six months, mostly on the western edge of the island, and migrated north from South Georgia toward warmer waters in July. These patterns help to highlight which areas are particularly important for feeding right whales, and show individual contrasts between whales and their use of high latitude habitat in summer and autumn.

70p – Humpback whale

Over 600 humpback whales were spotted during a whale watch around South Georgia in 2020. These sightings are shown on the right stamp as red dots, with the size of the dot indicating the size of the group. This information was used to predict areas of high humpback whale density around the island. A high intensity of purple shading indicates a high density of whales. It is important to understand the density and distribution of cetaceans so that we can manage human activities such as shipping that may pose a risk to cetaceans.

80p – Antarctic blue whale

The underwater vocalizations of blue whales were recorded using sonar buoys: acoustic devices that allow whale calls to be detected and the direction from which they come to be measured. These data were collected during expeditions to South Georgia in 2017, 2018 and 2020. The calls and their bearings were analyzed to determine the likely locations of the whales, and these were plotted on a map. In 2017, all calling blue whales were recorded in deep water in both the southwest of the island and the north of the island (shown in yellow). In 2018, blue whales were mapped on the continental shelf off the north coast (shown in green) and in 2020 sonar buoys were deployed throughout the island of South Georgia. This year, blue whales were collected west of South Georgia near Shag Rocks (shown in red) along the northern shelf and southeast of the island. These acoustic data show that blue whale detections are increasing around the island. This pattern is also reflected in the number of visual sightings of blue whales, which have increased in recent years as populations recover from industrial whaling.

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