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The Prehistoric Permanence of Cá Sấu, Vietnam's Farmed Predator

I’ve always hated cá sấu. Not because they’ve threatened my safety or had any real impact on my life whatsoever, but simply because they survived. When a meteor cratered into Earth 66 million years ago and sent sun-engulfing clouds of sizzling rock into the sky, alongside ferocious tidal waves and incessant firestorms, the planet lost some of my most beloved creatures.

Gone were the eight-ton ankylosaurs with spiked cannon balls at the tip of their tails; the triceratops sprinting like runaway freight trains with spears attached to their faces; pterosaurs swooping across the sky with all the grace and terror of Renaissance depictions of Satan’s winged servants; and the plesiosaurs, those savage amalgamations of snakes, dragons and fish. They all went extinct while crocodiles floated on through the millennia like errant logs. The reptiles then outlasted mastodon and sabertooth tigers, sloth bears and glyptodons. Why did such awe-inducing dinosaurs, marine reptiles and ice-age mammals go extinct, while crocodiles — those comparatively slow, dumb, graceless brutes — survive? Life is not fair.

While their earliest ancestors appeared on the planet over 200 million years ago, around 95 million years ago the modern crocodile, Crocodylidae, arose amidst less-recognizable ancient relatives that included ones that walked on two legs, some that had flippers like seals, and a few that even subsisted on nothing but plants. Scientists have theorized that cá sấu’s reliance on external temperatures (i.e. being cold-blooded) gave them a metabolic advantage during the sustained periods of ecological chaos that decimated food chains and claimed other creatures including the dinosaurs. An incredibly robust immune system and versatile feeding methods further allowed them to outlive other animals that succumbed to starvation or competition.

Around 95 million years ago, the modern crocodile arose.

It’s impossible to ascertain exactly how many types of cá sấu have existed, but there are currently 23 species spread across every continent except for Antarctica. Two types are native to Vietnam: saltwater crocodiles (Crocodylus porosus) and their distant cousins, the Siamese crocodiles (Crocodylus siamensis). Morphologically indistinguishable, in Vietnamese, they are both casually referred to as cá sấu with the Chinese word 兽 (shou) meaning "beast" at the core of their name alluding to the violent dispositions that placed them atop the food chains in their respective ecosystems.

Cá sấu’s scaley head surfaces from the murky pools of myth and history alike. They undoubtedly influenced depictions of dragons including giao long and thuồng luồng with appearances on ancient artifacts including Đông Sơn drums. A 17th-century Chinese scholar wrote a book based on materials obtained during the Ming occupation of Vietnam (1407–1427) that included the observation that: “A crocodile can produce some several tens of eggs. When they hatch, those which descend into the water become crocodiles while those which ascend onto the shore become peculiar snakes and worms.” While cá sấu do indeed lay between 30 and 70 eggs, they of course do not magically transform into other animals. It is interesting to note the parallels between that belief and Vietnam’s origin myth of Lạc Long Quân-Âu Cơ.

Allusions to real-life cá sấu also appear in fables, folktales and proverbs wherein they are often used metaphorically to describe greedy, unscrupulous individuals. Stories of crocodile-filled waters or especially murderous individuals were common in the southwest region and helped provided the names for geographical features and areas throughout the region. Ông Vàm Đầu Sấu Pagoda in Cần Thơ even honors one that was reported to sing to passersby on a nearby river and hints at an underexplored examination of their role in worship practices. And while less prevalent in northern Vietnam, a popular story tells of an instance when a 13th-century ruler ordered a poem be composed and thrown into the Re River to ride the depths of menacing cá sấu.

While mythical accounts make no distinction, Vietnam’s saltwater crocodiles (cá sấu nước mặn) and Siamese crocodiles (cá sấu Xiêm) have different habitats and evolutionary paths.

While the mythical accounts make no distinction, Vietnam’s saltwater crocodiles (cá sấu nước mặn) and Siamese crocodiles (cá sấu Xiêm) have different habitats and evolutionary paths. The former, also known as cá sấu hoa cà, is the largest living crocodile on earth, growing up to 6 meters and weighing in excess of 1,000 kilograms during lifespans that can surpass 70 years. Able to survive varying salt levels in their environments, in Vietnam, they once thrived in the Mekong Delta, mangrove swamps surrounding present-day Saigon, forests extending to Tonlé Sap lake in Cambodia and even on Phú Quốc Island. Historical records indicate that at one point they even made it to the Red River Delta in the north where the Trần Dynasty emperors displayed them as exotic pets.

By the beginning of the 20th century, cá sấu nước mặn numbers within Vietnam were dwindling as towns and cities expanded and agricultural and transportation development changed natural landscapes. Because they posed threats to humans and livestock alike, their hunting seemed inevitable especially because their skin was used for fabrics and the flesh was regularly eaten. Human-cá sấu nước mặn conflict was widespread into the 1920s, but as of the turn of the 21st century, they were certainly extinct in the wilds of Vietnam, though they continue to live in other parts of Southeast Asia as well as South Asia and Northern Australia.

In contrast, cá sấu Xiêm are far rarer in the wild with fewer than 1,000 individuals living outside captivity. Occupying freshwater lakes, rivers and marshes, unlike their saltwater relatives, these medium-sized crocodiles can only be found within Southeast Asia. Hunting for skin and meat and habitat loss led to them being nearly completely extinct by the 1990s. However, rigorous conservation efforts are underway to save what is considered one of the least-studied, most-vulnerable crocodile species.

Notably, if cá sấu are going to survive for centuries to come, conservation efforts will likely need to rely on an unlikely ally: the very farms that decimated their populations.

Notably, if cá sấu are going to survive for centuries to come, conservation efforts will likely need to rely on an unlikely ally: the very farms that decimated their populations. In March 2022, conservationists released 25 cá sấu Xiêm donated from commercial farms into Cambodia’s Southern Cardamom National park. The individuals had descended from the wild populations that laid the foundations for thriving captive populations in Cambodia as well as Vietnam and Thailand. As of 2017, around 600,000 crocodiles were being raised in Vietnam by more than 1,000 households in 25 cities, mostly in southern Vietnam so their skins can be made into valuable belts, wallets, purses and watch bands sold primarily abroad.

After at least seven years without a wild specimen being observed, Vietnam again has wild cá sấu Xiêm thanks to reintroduction programs. In 2000, 60 cá sấu Xiêm were released into Bàu Sấu, the nation’s second-largest wetlands located in Cát Tiên National Park. Saigon’s Hoa Cà crocodile farm donated some of the individuals, but before they could be released they had to be genetically tested to confirm they were 100% cá sấu Xiêm, as farmers typically cross-breed them with saltwater and Cuban crocodiles (cá sấu Cuba) to improve leather quality. Protected by rangers and assisted by education programs, the population has more than quadrupled in size.

I’m pessimistic when it comes to humanity’s ability to preserve the planet, so while these developments might seem heartwarming, I have little faith that these reintroduced cá sấu communities will endure amidst continued human population growth and associated increases in pollution and deforestation. In the coming decades, wild tigers, polar bears, sea turtles and gorillas will likely all go extinct with meagre groups hanging on in zoos and private facilities. But given our species’ propensity for showy fashion, it’s reasonable to assume large numbers of genetically diverse cá sấu will flourish in industrial farms. It’s possible that after humans go extinct, as seems all but inevitable given the levels of responsibility we’ve displayed during our species’ blip of existence, the incarcerated cá sấu could re-populate a moderately empty earth. If you ask me what creature will live longer on planet Earth, humans or crocodiles, the smart bet is certainly on cá sấu. Knowing that makes me hate them a little less.

Graphic by Hannah Hoàng, Phan Nhi and Hương Đỗ.

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