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- Freshwater ecosystems are some of the most threatened in the world
- Large freshwater animal populations declined by 88% worldwide between 1970 and 2012, largely because of overfishing and river damming
- Megafish just aren’t cute enough for the general public or scientists to care about as much as, say, polar bears
- There are freshwater conservation success stories that prove these animals can be saved from extinction
Freshwater ecosystems are some of the most threatened on the planet
Have you ever dreamed of seeing a baiji river dolphin? Ever wanted to swim with one just to get a closer look at its odd snout or teeny-tiny eyes? Too bad, because they’re probably extinct. But the bad news doesn’t stop there: Large freshwater animals, like massive stingrays, giant river otters, and 600-pound catfish, are in trouble all over the world. A recent study has illuminated just how much their populations have suffered at human hands.
While rivers and lakes only cover about 1% of Earth’s surface, they’re home to one-third of all vertebrates. However, many of these animals are overlooked in popular culture, science, and conservation. They’re paying dearly for it.
For example, look at the largest of all freshwater animals: the freshwater megafauna. They all weigh at least 66 pounds (as adults) and spend some part of their lives in rivers and lakes. This includes everything from river dolphins to crocodiles to giant salamanders. Between 1970 and 2012, their numbers around the world decreased by 88%. That’s twice as much as land-based and marine ecosystems lost in the same time frame.
Between all the different kinds of freshwater megafauna, megafish are having it the worst. Their numbers declined by 94%. People generally see them as a source of food and not much else, despite the fact that some of these species have been swimming in rivers and lakes for millions of years.
While you couldn’t count all the threats to freshwater megafauna on just your hand, two particular threats have done the most damage: overfishing and river damming.
Relentless overfishing has driven megafish to near-extinction, making them more valuable
Megafish are often killed for their meat, skin, and eggs. Take the sturgeon, for example. They are long fish with pointy snouts and have spent 200 million years looking just about the same. They’re also the most threatened group of animal species on our planet. For decades, they’ve been exploited and overfished, especially for their highly coveted eggs.
Caviar — practically a synonym for luxury and wealth — is made of beluga sturgeon eggs. Its popularity has been ushering in the species’ decline, because to harvest it, fishermen carve the sturgeon open for her unfertilized eggs.
Since beluga sturgeon are critically endangered, the United States Fish and Wildlife Service banned imports of wild-sourced beluga products in 2005. In fact, many sturgeon species are now legally protected from commercial fishing. However, plenty of them are still illegally caught and the new protection doesn’t reverse the havoc that’s been wreaked on them in the past.
In some parts of the world, the rarity of particular megafish makes them all that much more enticing to eat. In Vietnam, some restaurants advertise critically endangered Mekong giant catfish and giant barbs on their menus, despite the fact that they’re illegal to sell.
The problem is that people can make a lot of money from selling rare, huge fish and the government isn’t enforcing the laws. But it’s not just Vietnam’s problem; most of these fish are coming from Cambodia, where even their cultural significance as godlike entities can’t save them from being sold to support a struggling family.
“Freshwater fish aren’t a priority in wildlife conservation circles,” Zeb Hogan, a co-author on the recent study and expert on the Mekong River’s giant fish, told National Geographic. “They’re hard to study, not much is known about them, and there’s not as much public empathy and support.”
River damming is harming freshwater habitats
There are thousands of dams in rivers all across the world. They’re reducing flooding, generating power, and completely interrupting the ecosystems around them.
In fact, dams produce nearly one-fifth of the world’s electricity in the form of renewable hydropower. However, they also cut off migration routes for fish (including sturgeon and salmon) and interfere with their access to reproductive and feeding grounds. They change water flow and river temperatures, which can lead to invasive species flourishing in the new environment.
Around 3,700 new dams are in progress or planned for the world’s rivers. These will certainly interfere with freshwater ecosystems even further. About 800 of them will be built in “biodiversity hot spots,” like the Amazon, Mekong, Ganges, and Congo river basins. These hot spots are locations that are home to a lot of different species compared to the average freshwater ecosystem.
As if these threats weren’t damning enough for freshwater animals, they’re also facing pollution, climate change, and other forms of habitat degradation.
The giant catfish’s uncharismatic appearance isn’t enough to save it from extinction
Many conservation programs are fueled by the public’s support for saving adorable animals like the giant panda. Unfortunately for the gaping-mouthed, dead-eyed megafish, they simply aren’t cute by society’s standards. They also don’t make somber, beautiful songs like whales. As a result, freshwater megafish have largely been forgotten by the public. The nearly extinct sturgeons are practically begging, “When will we get the freshwater version of Finding Nemo?” (Although that movie created its own conservation issues.)
For many of these species, it’s unclear what role they play in their respective ecosystems. Freshwater species simply aren’t studied as much as those living in terrestrial or marine environments. So if knowing an animal’s exact ecological function isn’t enough to make you care about its demise, consider this: It’s an economic problem as well.
People make a living off of these threatened species. A fisherman in Cambodia can (illegally) sell a Mekong giant catfish and make more off that one fish than he’d normally make in a year. But at some point, these animals are going to be gone and that income will be too. The people who depend on these species for their livelihood are going to need alternate means of providing for themselves.
Not everything is doom and gloom; there are success stories
Overall, freshwater megafauna are losing their numbers, but there are a few success stories. For instance, in the same river that Mekong giant catfish are being fished into oblivion, the Irrawaddy river dolphins are making a come back.
The endangered freshwater dolphins live throughout Southeast Asia, in several different rivers, where they’re facing habitat loss and inescapable fishing nets meant for other animals. In Cambodia, they once numbered in the thousands until people hunted them to just 100 individuals or fewer.
So to save their local dolphins, the Cambodian government teamed up with the World Wildlife Fund. Fishermen had been using poisons and dynamite to catch their prey — like they were Wile E. Coyote after the Road Runner — so the government and WWF put a stop to that. They declared a section of the Mekong protected dolphin habitat, banned fishing there, and enforced it with 32 guards.
Plus, since the Irrawaddy dolphin is blessed with a cuter face than the giant catfish, the government and WWF marketed the animal as a tourist attraction.
In the last two years, the Cambodian Irrawaddy dolphin population has increased — by 20 or so dolphins. But they aren’t out of the woods yet; a new dam is planned to go in their habitat that could still kill them all. On the bright side, that section of protected river benefits other endangered species that live there.
So far, conservation actions have positively impacted 13 freshwater megafauna species. Along with the Irrawaddy dolphin, the American beaver and green sturgeon populations are increasing. Plus, people reintroduced the Eurasian beaver into regions it used to live in.
But of course, those conservation efforts will only happen for our dear river monsters if people start to care about them as more than just a meal.