Rodent DNA reveals black market fur trade

Rodent DNA reveals black market fur trade

Rodent DNA reveals black market fur trade

This article is from Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this one at hakaimagazine.com.

The two landmasses that make up most of New Zealand – the North Island and the South Island – are less than 25 kilometers apart, but they couldn’t be more different. The North Island is home to the country’s largest city, Auckland, and is known for towering volcanoes, legendary surfing beaches and relatively mild weather. In the colder, quieter South Island, the rugged landscape is punctured by pristine lakes, rolling glaciers and snow-capped mountains – familiar sights for fans of the sport. Lord of the Rings film trilogy. Recent research reveals that the islands’ differences even extend to their rodents. And discoveries can change our understanding of history.

It all started two decades ago, when zoologist Carolyn King and one of her students were unraveling the origins of invasive New Zealand mice through genetic analysis. As expected, the researchers found that house mice on the North Island descended from European mice that hitched a ride on the ships of British colonists two centuries ago.

But when King and his team analyzed the South Island mice, they found that the animals were related to a Southeast Asian mouse, a subspecies that is widespread in China but never found outside Asia. The stray mice baffled King, who works at the University of Waikato in New Zealand. “We couldn’t figure out where they came from,” she says.

The rodent conundrum deepened in 2019 when researchers at the University of Auckland in New Zealand discovered the same trend in Norwegian rats. The South Island animals matched a strain known only in China, while the North Island mice were closer to those in England.

Mounting evidence suggests that rats and mice traveled from China to the South Island in the 1800s, when New Zealand was still part of the British colony of Australia. But there were no historical records – at least in English – of direct contact between China and the South Island that would explain how the rodents had arrived. King began to suspect that the circumstances of the rodents’ journey were not entirely honest.

In 2022, King co-authored a study that offers a tantalizing explanation: The rodents arrived with traders who had sailed to China to illegally sell seal pelts from New Zealand and then returned to the South Island. In the 1800s, abundant seal rookeries dotted the rugged coastline of the South Island, fur being the island’s only profitable commodity. And in Guangzhou (now Guangzhou), a bustling port city in southern China that formed the backbone of international trade, seal skins were gaining in value as the world’s sea otters and their precious fur became scarce. Those daring enough to bend the rules by hunting seals could make a fortune.

At the turn of the 19th century, conditions were right for shady businesses to flourish. The starving British East India Company tightly controlled its own monopoly on maritime trade, forbidding the colony from direct trade with China and India. Most official commercial ships from London, England, called at Sydney, Australia, on their way to supply New Zealand’s main port on the North Island.

King hypothesized that unscrupulous fur traders skirted Sydney on their way to and from Canton to avoid the authorities. “Those who wanted to circumvent regulations did so quietly,” she says. These secret trips would also have avoided official record keeping.

To determine whether the invasive South Island rodents arrived on official voyages or via a secret shipping route directly from China, King and his coauthors compared the rodent’s DNA with genetic material from 19th-century rat and mouse specimens unearthed near the harbor. from Sydney.

The results reinforced King’s suspicions. Sydney house mice had European ancestry and the mice’s genes matched those of Norwegian mice found in Great Britain and the North Island. There were no traces of genes from Southeast Asian house mice or the Chinese strain of rats – evidence that ships carrying rodents from China did not pass through Sydney. Or, most of them don’t.

Philippa Mein Smith, a historian at the University of Canterbury in New Zealand who was not involved in the research, says there is some evidence of nefarious dealings through the port. In 1806, colonial authorities arrested Simeon Lord, an ex-convict and Sydney-based seal businessman, for shipping 87,000 seal skins collected from the Antipodes Islands, south of New Zealand, to Canton via Sydney. But, by some small miracle, Lord’s trip must not have released any rodents.

Rogue traders who escaped detection by avoiding official shipping lanes would never have suspected that the genes of stowaway mice and rats might reveal their movements centuries later. “THE [rodents] gave them,” says King.

Mein Smith says King’s conclusion is plausible, given that many Sydney merchants were at least as dishonest and profit-hungry as Lord. “There were all kinds of underhand deals going on,” she says.

Although historians suspected that there was a clandestine trade in seal skins between Australia and China, the paucity of historical evidence made it difficult to confirm.

Genetic evidence can reveal information about the past that cannot be found in historical records or accounts, says study co-author Andrew Veale, a vertebrate pest ecologist and geneticist at Manaaki Whenua Landcare Research. “DNA has this ability to tell the story of what really happened.”

This article first appeared in Hakai Magazine and is republished here with permission.

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