2023-04-24 18:12:57
The aquariums of the 21st century are important research centers. Many of them are home to large marine mammals, such as bottlenose dolphins and belugas. In aquariums it is possible to carry out investigations with them that are impossible when they live in freedom and that allow us to know in depth even their emotions.
The conclusions of the studies help to ensure that the giants of the sea do not disappear.
Discover a new species of whale
In the year 2021, scientists identified a new species of whale in the Gulf of Mexico. Small animals are regularly discovered, but discovering a new species of large mammal in the 21st century is something extraordinary. For this reason, the discovery of Rice’s whale – that is the name of the new species of whale – shows us how much we still have to learn about life in the oceans. Unfortunately, it also reminds us that it is highly threatened: Shortly after it was discovered, Rice’s whale was listed as “critically endangered”, not least because there are only about 50 remaining.
The relationship between humans and cetaceans –dolphins, orcas, whales, etc.– has been full of contradictions. On the one hand, industrial whaling dramatically decimated many of their populations and even today several species of cetaceans are threatened with extinction.
On the other hand, large marine mammals have always aroused the curiosity and admiration of people, partly because of their intelligence and sophisticated social behaviour.
Probably due to the admiration they arouse, some species of cetaceans –especially the bottlenose dolphin– have been kept in aquariums around the world for a long time. One of the priorities of modern aquariums must be to carry out research that allows us to get to know the animals better, and the study of animal welfare is one of its most active areas.
Some of the studies carried out on the well-being of cetaceans living in aquariums will allow us to better preserve their congeners in the wild.
Dolphin optimism
Animals’ emotions are an essential part of their well-being, but studying them is difficult, especially in animals in the wild. However, the work carried out by a team of scientists at the Parc Astérix aquarium in France has made it possible to identify a behavior that is more frequent in bottlenose dolphins when they are “optimistic”. This behavior – which is easy to observe even in free-living dolphins – is “synchronous swimming”, which consists of two dolphins swimming next to each other, synchronizing their movements.
To reach this conclusion, the researchers previously adapted to dolphins a test that had already been carried out in other species and which measures the optimistic or pessimistic character of the animals. This test is called the interpretation cognitive bias test and its objective is to find out if an animal behaves when faced with an ambiguous stimulus as if it were pleasant. If so, it is concluded that the animal is “optimistic”, while otherwise it is considered that the animal is dominated by negative emotions and is “pessimistic”.
In a way, the test finds out if the animals see the glass as half full or half empty. Well, dolphins that spend more time swimming in sync with another dolphin tend to be more optimistic than dolphins that barely perform this behavior.
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Measure long-term stress
In addition to emotions, another aspect that is of great interest to scientists who study animal welfare is stress. The best known way to study whether or not an animal is stressed is to measure the amount of a hormone – known as cortisol – in its blood. This measurement, however, has two problems. First of all, drawing blood from an animal is not always easy, especially if it is a free-living animal. Second, the amount of cortisol in the blood mainly reflects whether the animal has suffered short-term stress, while it is of little use in identifying long-term stress. This is important because long-term stress has the most negative consequences for animal welfare.
The work carried out by researchers from the Oceanogràfic València and the UAB Faculty of Veterinary Medicine has made it possible to verify the usefulness of a technique that allows cortisol to be measured in the most superficial layer of the skin of dolphins.
Cortisol from this layer can be obtained very easily and without disturbing the animal, and it accurately reflects long-term stress.
The researchers are working to fine-tune the test in other species of cetaceans –such as belugas– and in the future they intend to apply it to free-living animals.
The final objective of this project is to have a tool that allows us to know if certain human activities, such as the sighting of marine mammals or the noise of boats, are stressful in the long term for cetaceans.
The conservation of marine mammals is closely related to their well-being, since animals that suffer from stress or negative emotions tend to live less and are at greater risk of becoming ill. On the contrary, positive emotions are associated with a better state of health.
These are just some of the reasons why research on marine mammals carried out in aquariums is important, not only to improve their well-being, but also to better conserve free-living cetaceans.
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