Animals are often automatically associated with habitats and ecosystems that are typical or expected. In all fairness, it makes sense that dolphins should be found in the salty oceans, kangaroos in the plains, or seals in the sea. However, what if I told you there are dolphins in freshwater rivers, kangaroos in the trees in Australia, and freshwater seals in Russia?
All of the above is true, but for now, let’s focus on the secretive and overlooked lives of the world’s freshwater river dolphins.
There are a few species, and they are all very few in numbers. In other words, the five species of the world’s river dolphins are in a general state of peril. Each one of these ultra-intelligent mammals is either listed as endangered or critically endangered - the closest label a living thing can have before it goes extinct.
From the depths of the Amazon jungle to the arid deserts of Pakistan, let’s reveal what river dolphins are all about and what they reveal about us.
Firstly, river dolphins are of the order Cetacea, a grouping of organisms also including whales and porpoises. Curiously, they are found in South America and Asia, but not Africa, Australia or North America.
Considering there are similar climates and ecosystems in these regions to ours, one might ask why river dolphins don’t populate the Great Lakes or the Niagara River. It’s because river dolphins evolved in separate warmer regions of the world and have no blubber to protect them from the cold.
For the tiny portion of people who have even heard of river dolphins, the most common and quietly famous species is the Amazon River Dolphin. To add to the mystery and magic of these creatures, this species is notably pink in colour. It lives in both the Amazon and Orinoco River basins and can be found 3000 km inland from the nearest saltwater environment. It is an endangered species, with an estimated dozens of thousands remaining in the wild. In the world of population biology, that is indeed a low number.
But the numbers that follow here may truly shock you.
A close relative but separate species, the Tucuxi (this is simply what this dolphin is called) shares an overlapping range with the Amazon River Dolphin, yet is smaller. It can also leap up and out of the water, unlike its larger cohabitant. That ability along with its compact body build allow this dolphin to scale tricky rapids and go further upstream, making them a sign of good luck to the indigenous peoples in the area, who also consider them guardians of the river. Given the remote nature of the vast yet shrinking Amazon rainforest, the endangered Tucuxi’s population is unknown - an uncommon comment to make for any intelligent living mammal known to science.
Swimming over to the opposite side of the planet are river dolphins in an impressive and surprising variety of habitats. The endangered Ganges River Dolphin lives in the Ganges and other associated river systems that flow through one of the most densely populated regions on earth. Facing threats of industrial and commercial pollution, this species’ population is said to be less than 3,000 in total.
One major system over, we have the Indus River Dolphin facing the same threats as its friends over in the Ganges. For an unconventional image in your head, the Indus River Dolphin can be found in the desert-like environments through which the mighty Indus River meanders. That is, if you can actually find them - their endangered population is said to be only 2,000 individuals remaining in the wild.
Looking further into the very bleak situation for these remarkable animals, there are only about 250 critically endangered Irrawaddy River Dolphins living in a certain region of southeast Asia.
Crawling up the coast a few thousand kilometres away from the desperation of the Irrawaddy River Dolphins is a the Yangtze Finless Porpoise. The Yangtze River system is one of the busiest and most populated in the world, and up until recently, it was also home to the Yangtze River Dolphin. In 2006, that dolphin species was declared functionally extinct. That's only 19 years ago.
When freshwater river dolphin populations are thriving, they are an indicator that the entire river system is thriving. This is a positive state of flow, quite literally, for both biodiversity and human communities living in these watersheds. Like amphibians, river dolphins (and a porpoise) are representatives of overall ecosystem health.
Their dwindling numbers give us a pulse check on how we are treating the natural world and our greatest rivers. And rivers are the givers of life.
