Why are stranded whales so difficult to rescue?

At around 8 am on April 19, a sperm whale ran aground in the waters outside Ningbo Xiangshan Shipu Industrial Park. Fortunately, after a day of intense rescue, at around 6 am on the 20th, the tugboat took advantage of the high tide to bring the whale back to the deep sea, completing a rescue without any danger! Whale stranding incidents happen from time to time, but this time we successfully helped the whale return home in a rare way.

But on April 28, worrying news came again. Fishermen in Taizhou found the body of a whale, which was suspected to be the sperm whale that had been rescued earlier.

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Why do whales often get stranded? How are stranded whales rescued and brought back home? Let's find out.

01

Why do sperm whales get stranded and what are the risks?

To understand why whales get stranded, we must first understand what kind of creatures whales are. Although whales have the word "fish" in their name, they are often called "whales", but this name is actually very inaccurate because they are not actually fish, but a type of aquatic mammals that look like fish but have exposed skin.

Whale species are diverse and abundant, including the blue whale, the largest animal on earth, as well as smart and cute dolphins and finless porpoises. Most whales live in the ocean, but unfortunately, due to human hunting and pollution of the marine environment, a quarter of whale species are on the verge of extinction.

Whale stranding is a phenomenon that occurs on coastlines around the world. It can be observed all over the world and at different times. It was first recorded in Aristotle's book "Historical Zoology" in ancient Greece, and there are also scenes of whale stranding in 17th-century oil paintings. Most of these strandings are single individuals, and in rare cases, collective strandings occur.

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The consequences of a whale stranding are very serious, because once stranded, it is difficult for a whale to return to the water on its own. The whale on the shore loses the support of the water, and its chest and abdominal cavities will be under great pressure. Its internal organs will be damaged due to its own weight. In addition, stranded whales often have some diseases, so it is even more dangerous.

Why would a whale run into a beach so obviously and get stranded? There are many reasons, which can be roughly divided into natural and man-made reasons.

Natural causes include geomagnetic storms, climate or ocean events, disease, unique ocean currents and winds, etc., which cause individual whales to lose their way and eventually become stranded on the beach. Or they may enter shallow bays on the shore during high tide and be unable to leave after low tide. They may also be washed ashore by waves after becoming ill or dying of natural causes.

Human factors include: chemical pollution toxins, plastic ingestion, fishing, ship collisions, sonar activities and human noise. Whales are guided by sonar when sailing at sea. The sounds emitted by human military sonar or shipping are likely to disrupt the direction of whales. Pollutants consumed by whales may cause them unbearable pain and eventually stranding.

In addition, if the leading whale in a group of whales loses its way, the entire group of whales will follow the leader astray, and finally cause the serious consequence of group stranding. According to domestic data from 1950 to 2018, a total of 1,763 stranding incidents were recorded in these 68 years, involving 36 species of cetaceans from 8 families. Importantly, 30.5% of the recorded species are currently classified as threatened in the IUCN Red List. From 1950 to 2018, the number of whale strandings gradually increased, and from 1990 to 2018, the number of strandings increased faster.

02

What to do if a whale gets stranded?

Every year, there are many cases of whale strandings on coastlines around the world. Only a small number of them are discovered by humans in time, while the rest are either dying or dead, or die alone because they are stranded on coasts far away from humans. For those whales that are discovered by people in time, how can we get them back to the sea safely?

Small dolphins can be released directly back into the sea. However, for larger killer whales and sperm whales that cannot be released back into the sea immediately by human power, it usually takes several hours or even longer to rescue them. Therefore, the whales must first be able to breathe, and their bodies must be straightened with their blowholes facing upwards to ensure normal breathing. At the same time, the blowholes must be cleaned to prevent mud and water from entering the whale's respiratory tract, which may cause lung infections and lead to death.

As mentioned before, since whales have no limbs to support their bodies, their chest and abdominal cavities will be under great pressure when stranded. Therefore, they should be kept in shallow water as much as possible to support their bodies with the help of buoyancy; the skin of whales cannot withstand long-term dryness, so their skin must be kept moist and not exposed to direct sunlight.

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After rescue arrives, depending on the whale's physical condition, it can be released directly back into the ocean. If it is too large, such as the sperm whale this time, it cannot be released directly into the ocean, so we can only wait for high tide and keep it hydrated before that. If the health of the whale is relatively poor, it can be transferred to an artificial environment and released back into the ocean after it recovers. If it is really impossible to rescue it, it can only be euthanized.

How can we better help whales? We need to start with timely rescue and reducing the number of stranded whales. First, based on the domestic data of whale strandings in 1968, we have determined the concentrated seasons and locations of whale strandings. We can arrange patrols during these periods to rescue stranded whales as soon as possible.

Secondly, we should improve the marine environment, reduce the amount of pollutants and garbage dumped into the sea, and provide whales with a better living environment. Finally, we should develop citizen science to make the public pay more attention to marine life represented by whales, so that more people will spontaneously protect the ocean, which will not only treat the symptoms but also the root cause.

Everyone says "When a whale lands, all things come to life", but this whale shouldn't have landed on land.

Author | Xu Jiaxian

Review | Huang Chengming, Researcher, Institute of Zoology, Chinese Academy of Sciences

Editor | Jiang Fan

Editor | Ding Zong

References:

1. Mingming Liu, Mingli Lin, Songhai Li, Species diversity and spatiotemporal patterns based on cetacean stranding records in China, 1950–2018, Science of The Total Environment, Volume 822, 2022, 153651, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2022.153651.

2. Why do whales always get stranded? What can humans do for them? Xiaoxiang Morning News

3. Zhao, L., Zhu, Q., Miao, https://doi.org/10.1007/s13131-017-1100-5

4. Alvarado-Rybak, M., Toro, F., Escobar-Dodero, J. et al. 50 Years of Cetacean Strandings Reveal a Concerning Rise in Chilean Patagonia. Sci Rep 10, 9511 (2020). https://doi.org/10.1038/s41598-020-66484-x