By Eurico Borges
The third biggest in the animal kingdom, river dolphins are considered smart for the complexity of their social structures, communication systems, and morphological and physiological characteristics of their brains, which are, in proportion to their weight and size.
In saying that, they need our help as their numbers are quickly shrinking. There are five species of freshwater dolphins, and they are being threatened by water pollution, hydropower development, and unsustainable fishing practices.
This makes them one of the world’s most endangered groups of mammals. The Amazon river dolphin or pink dolphin is the largest of them, with males reaching up to 2.5 meters, 200 kilograms, and living until 35 years old. Their pink colour is more accentuated in male botos, and it gets more intense as they get older.
They can turn their heads to an angle of 90 degrees and, despite having small eyes, they possess incredible vision, being able to distinguish colour, answer to light, see outside of water and, in cooperation with their astute minds, recognise other dolphins, boats and objects.
Boto’s bodies are flexible, with massive paddle-shaped fins that can move backward, making them extremely agile. Despite their big size, they can move quickly through the water to dodge obstacles and catch prey, using high-frequency sonar clicks to construct a three-dimensional echogram of the riverine world and are able to swim upside down.
They are the only species of dolphin that does not swallow its food unchewed, using its unique molar teeth to munch it before ingestion, and its dentition is non-renewable. Their diverse diet of over 40 animals includes turtles, shrimps, fish, and crabs.
The amazon river dolphin travels alone (adult males) or in small groups of two to four individuals (mother and her offspring). This got them a classification of data deficiency by the International Union for Conservation of Nature (IUCN).
During the mating ritual, male pink dolphins catch floating herbs or pieces of wood with their mouths, spin in circles, and then smack the object on the river’s surface. They can also fight with a rival for a partner’s interest, and the resultant scar tissue has its characteristic pink colour.
They were thought to be a silent species, but recent investigations prove that botos communicate via inaudible bat-like clicks, which, when decelerated by 100%, sound like popcorn popping in a microwave.
Even though the study of population behaviour in the wild did not start until 30 years ago, the people who live on the banks of the Amazon have a prolonged and difficult relationship with the species.
In the Brazilian Amazon, their reputation is contradictory, being known for guiding fishers to areas with fish but also attracting them to dangerous areas by intentionally confusing navigators and sinking their boats.
When approaching vessels, Amazon River dolphins often enjoy stealing fishermen’s paddles with their beaks and swimming off with them, throwing sticks and plants, and pulling algae underwater. They are also known for playing with other animals in the ecosystem, namely fish, turtles, and snakes.
Lots of myths are associated with these dolphins, and most of the tales are about their mischievous nature. In some, the boto is a magical being responsible for mysterious events; in others, it represents compassion, elegance, and sensualism.
However, over time, the stories have acquired a darker side. According to one myth, they morph into beautiful men by evening and come onto dry land dressed in white clothing, being so seductive that women end up pregnant with their babies.
Images of smiling botos are abundant in wall painting and graffiti, but while the legend remains, the animals are dying. In 2018, the pink dolphin was added to the Red List of endangered species, being in dire need of protection.
In the past, people did not catch or kill them because of their mythological nature; most were scared that their spirit would retaliate. While those fears are fading, the species is still generally resented. The stories that once protected these animals have turned them into targets.
As the area’s access to markets expands with local food demand increasing due to migration and high fertility rate, competition for the same fish species is getting out of control. Human fishing activities are the main cause of boto deaths and, considering the rise of international demand for Amazon’s fish, the situation is bound to get worse.
Pink dolphins remove the best exemplars from the nets and lines, causing damage to the equipment and the capture. Most of the Amazon river dolphin deaths occur via entrapment by fishing nets, both accidental and deliberate, because of the increase in intensity and volume of fishing in the Amazon Basin.
According to Associação Amigos do Peixe-Boi, the illegal hunting of botos in the Amazon, whose meat is used as bait to fish the highly valuable carnivore fish “Piracatinga”, kills 2.500 specimens annually just in Brazil, having affected the animal’s communities immensely.
It is almost impossible to estimate the total living boto population, but scientists noticed a rapid decline in the dolphin population around the turn of the millennium. Project Boto counts the pink dolphin population each year, and their numbers are dropping by 50% every decade.
The actual decline may be even harsher, as dolphin killings are less likely to occur near the protected waters of the reserve than in other parts of the Amazon, and more dolphins are attracted to its comparatively peaceful waters.
The challenges in counting them are that their greyish colour is often hard to detect under the river’s muddy waters and the fact that they prefer not to be seen, spending most of their time underwater and only swimming with the tips of their heads out when they come up.
The pink dolphin’s vast habitat is also a problem for tracking them, as well as regulating and enforcing laws to protect them. The baiji, other species of river dolphin affected by the same issues, was considered critically endangered in 2007.
To avoid the Amazon river dolphin’s extinction, it is crucial to train local guides and residents with workshops about conservation initiatives. Other ways to help include the promotion of preservation ideals to tourists and spreading awareness about their endangerment.
We need to act now. Otherwise, the pink dolphin could disappear forever. If we allow them to become extinct, this could result in more sea life disappearing. It does not stop there as we would be next. Therefore, we need to look for ways to protect this species to allow them to thrive free from threats in their waters.
Your Communication Partner with Sustainability at the heart of our organisation
Mount Street Lower