Have the Blue Whales left the seas of Mirissa?

It is no secret that the tourism industry is an industry that significantly supports the economy of Sri Lanka. Whale watching is one of the most attractive tourist attractions in Sri Lanka. With the recent incident of pilot whales being dumped on the Kalpitiya beach, there was a discussion about whale watching on the coasts of Sri Lanka.

But after that unfortunate incident, it was terrible news for the tourism industry, marine life diversity, and the Sri Lankan community, including environmentalists and zoologists. What was this news? The blue whales have left the coast around Mirissa by this year. There was discussion about it through popular local newspapers and media.

According to this Facebook post, The Blue Whales ranging in the Mirissa seas have departed due to human activities. This was a statement made by the society for whale watching and conservation in Sri Lanka. Although there was a 90% chance of sighting a whale in the past in Sri Lanka, it has drastically reduced this season. The post also mentions that government experts should find solutions to this problem.

However, during previous years, this problem has been raised from various aspects, mainly regarding the threats posed to the Blue Whales on the Sri Lankan coast.

Find the full news article here, Archived.

Our team at Climate Fact Checks investigated the truth behind these statements.

Blue whales in Sri Lanka

The blue whale, or Balaenoptera musculus, is considered to be the largest animal living on earth. Currently, blue whales are classified as endangered. The primary reason they were threatened was commercial whaling which still prevails worldwide.

In 2008 Sri Lanka was famous for its blue whale sightings, especially in the Mirissa area.  Blue whales are attracted to the seas around Sri Lanka because their primary food source, the creel fish, is abundantly found in the water around Sri Lanka. Additionally, monsoon patterns, climatic conditions, etc., contribute to this.

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Balaenoptera musculus indica is the most common blue whale subspecies in the seas around Sri Lanka. According to a survey conducted in 2018, it has been found that this species is the most common marine mammal seen in the ocean around Sri Lanka during the southwest monsoon season of that year. By the monsoon patterns, blue whales were detected in this survey along the south and northwest coasts of the island.

Mainly blue whales are seen in the seas around Sri Lanka from time to time, and this period is called the Whale watching season. Accordingly, blue whales can be seen from March to July in the East Sea around Trincomalee and from December to March in the South Sea around Mirissa.

We contacted Dr. Upul Liyanage, Senior Scientist of NARA’s Kapparathota Regional Office, to inquire further about this incident. He stated that according to the method used to observe blue whales in the surrounding sea, they conducted the study by photographing and observing them. However, the whales that come to the coast around Sri Lanka only stay here occasionally. Generally, a single sighting of a whale will remain in the associated sea for several consecutive days, and it will be months or sometimes years before the whale is seen again.

He further stated that scientists use whale vocalization to identify whales moving towards another sea boundary. For example, blue whales found in Sri Lanka have a unique vocalization. This is called the Sri Lankan call type. He said that blue whales with this distinct voice are rarely found in Madagascar, yet in many cases, in the Maldives, Diego Garcia, and the Arabian Seas. This means that the blue whale variety of Sri Lanka roams in equatorial areas throughout the year yet does not live in the same sea area.

Threats to Blue Whales on Sri Lankan seas.

Illegal whaling has been a significant challenge to the existence of blue whales since the beginning of time. But whales in the northern Indian Ocean face fewer of these threats than whales in other seas. After the Soviets illegally hunted about 1,300 blue whales in the 1960s, the whales of that coast have never faced such threats again. At present, illegal whaling has been stopped by applying strict laws.

Huge ships plying between Singapore and Dubai, a bustling shipping lane around Sri Lanka, are currently the biggest threat to the blue whales worldwide, especially in Mirissa. The number of ships plying this route is quadrupling every year. As a result, blue whales are further endangered by colliding with these ships, often found overlapping the paths of these gentle giants. However, action has been taken, and several shipping companies have shifted their lane. Click here for more information.

Apart from accidents caused by ships, entanglement in gear such as nets used for ghost fishing, ocean pollution due to plastic and polythene, and sometimes noise pollution caused by artificial sounds around the ocean also pose challenges to the existence of these mammals.

Additionally, a new tourism trend has begun recently, where tourists can dive with whales during a sighting. Although this is illegal to do in Sri Lankan water, it is happening now regardless and may be stressing the blue whales of our oceans.

Impact of climate change on blue whale survival

Although blue whales are not directly affected by climate change, it may indirectly affect them. Due to climate change, the melting of the polar ice is gradually accelerating, and the existence of blue whales is indirectly affected. The cold water from this melting ice hinders the survival of algae and plankton. Algae and plankton are the main prey of krill fish. Due to damage to the food sources of the krill fish, the number of krill fish decreases, which affects the ability of blue whales to obtain food.

In addition, due to climate change, changes in the physical characteristics of ocean water, such as temperature and acidity, directly affect blue whales.

More information on blue whale survival with climate change here

Why are blue whales leaving the Mirissa coast?

As mentioned above, based on the human activities conducted in the blue whale habitats, they may have left these waters. However, according to Dr. Upul Liyanage, considering the threats and other influences on their lives, they have migrated to a more temperate area where meeting their needs and having fewer challenges is easier.

But he said there has yet to be a noticeable lack of food sources for krill and other whales in Mirissa and the surrounding seas to the extent that the blue whales will completely disappear.

Accordingly, the most likely reasons for this are ship collisions, changes in water due to climate change, ocean pollution, and unsustainable tourism. However, it is a critical task as a country to pay more attention to the departure of blue whales from the shores of the country, which have added significant value to the biodiversity and the economic situation of Sri Lanka. Hence, we need to find out the reasons for the disappearance of blue whales and make every possible effort to bring them back.

-With Inputs from Mihiri Saparamadhu–