Blue Whales Return to Seychelles Seas

Blue whales are fascinating creatures. At 24-30 meters long (longer than a basketball court) they are the largest animals on The planet. They are additionally among the most rarest. Estimates suggest that there are something like 5,000 to 15,000 blue whales left on the planet.

Their populations experienced an 89-97% downfall because of commercial whaling activities worldwide that began in the North Atlantic in 1868. Blue whales were valued for their blubber, changed into oil and used in cosmetics and soap, for the lubrication of industrial equipment, and as lamp oil. In 1978, the last deliberate capture of a blue whale was recorded off Spain.

Today, blue whales are found in all seas except the Arctic. They generally move from their summer feeding grounds where they almost feed on krill to their winter breeding grounds. However, their migration pattern is poorly understood, especially in the Indian Ocean, where limited research has been conducted.

Historically, the Seychelles archipelago - off the coast of East Africa - was an opportunistic whaling ground for Soviet whaling fleets on the way to and from the Antarctic. In the waters of the northern Indian Ocean, whalers illegally killed more than 1,200 blue whales, including 500 near the Seychelles, between 1963 and 1966.

Since then, no dedicated exploration has occurred to assess the abundance of blue whales until 2020, according to the records of the University of Seychelles and Oceanic Films (UK).

Two expeditions have been finished in November 2020 and 2021. In the wake of reviewing around 5,500km across the northern Seychelles, a sum of five sightings of up to 10 blue whales have been found.

This was a phenomenal finding. Blue whales are at a high level of hunting which occurred fairly recently and no information was available since the last blue whale was killed in the region in 1964.

Even though blue whales are not generally hunted and are protected by several international conventions, they are still listed as endangered on the IUCN (International Union for the Conservation of Nature) Red List of Threatened Species. They face a range of dangers. For instance, shipping traffic causes noise pollution that can modify communication and lead to collisions. Environmental change is additionally influencing the distribution and abundance of their key food, krill.

Tracking down the whales

The blue whale's oceanic habitat and elusive nature make them incredibly challenging to study. Besides, their deep dives and extensive migrations spanning thousands of kilometers present logistical hurdles for researchers aiming to track their movements and behavior.

Understanding their ecology, population dynamics and conservation requires innovative and resource-intensive methods, for example, systematic studies from huge vessels or planes to assess their abundance or satellite tagging to explore their migrations and movements.

Mostly expedition comprised vessel-based visual surveys that focussed on the deep waters (500−2,000 meters) off the northern portion of the Mahé Plateau.

In addition, for more than a year, we placed a hydrophone (an underwater microphone capable of recording whale vocalizations) in a space where blue whales were likely to occur. This permits us to confirm that blue whales in Seychelles were more common than thought but exceptionally occasional (even though the recorded blue whale calls throughout the year), essentially from December to April.

This method additionally revealed that the expeditions (in November 2020 and 2021) didn't happen when blue whales were the most abundant. It implies that our future survey should occur during the long stretches of March and April when their abundance is at its peak.

Their songs matched those of blue whales recorded close to Sri Lanka (around 3,100km from Seychelles), in the central tropical Indian Ocean. The seasonality in Seychelles is like the presence of blue whales in Sri Lanka, which is additionally highest from December to April.

In the wake of enduring five weeks of scanning the ocean, a sum of 23 types of whales and dolphins were recorded in 30 days of dynamic pursuit exertion, which is momentous.

More than 100 sightings of Bryde's whales (Balaenoptera edeni), a non-moving whale species exclusively living in tropical and subtropical waters, yet additionally numerous sperm whales (Physeter macrocephalus) and beaked whales. The presence of this multitude of species in Seychelles proposes that the climate is sufficiently useful to support enormous amounts of cetaceans.

Blue whales exist in the Indian Sea. The pygmy blue whale is the subspecies visiting Seychelles, based on the physical characteristics of the animals and the nature of their call.

The pygmy blue whale is generally smaller than other subspecies. It commonly reaches lengths of around 21-24 meters. Other blue whale subspecies, like the Antarctic blue whale, can grow up to 30 meters or more. The pygmy blue whale is primarily found in the southern hemisphere and has acoustic attributes that are distinct from others, especially Antarctic blue whales.

As a result of blue whale discoveries, local tourism operators and the government, particularly identify measures to limit the impact of the potential development of whale watching as an activity. These are positive steps towards their conservation. The involvement of local students at the University of Seychelles and young researchers is also critical for the long-term sustainability of research and conservation initiatives.