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 at hakaimagazine.com.

The two continents that make up most of New Zealand – the North Island and the South Island – are less than 25 kilometers apart but couldn’t be more different. The country’s largest city, Auckland, is on the North Island, and is famous for towering volcanoes, great surfing beaches, and a mild balmy climate. On the cooler and quieter South Island, the rugged landscape is punctuated by glassy lakes, rolling glaciers, and snow-capped mountains – backgrounds familiar to country fans. lord of the rings film trilogy. Recent research shows that the islands’ differences extend all the way down to their rodents. And the results could change our understanding of history.

It all started twenty years ago, when zoologist Carolyn King and one of her students were unraveling the origins of New Zealand’s invasive mice through genetic analysis. As expected, the researchers discovered that house mice in the North Island are descended from European mice that were encountered on British colonial ships two centuries ago.

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

The rodent measure increased in 2019, when researchers at the University of Auckland in New Zealand revealed the same trend in rats in Norway. The South Island animals came from a strain known only from China, and the North Island rats were closest to English rats.

Mounting evidence suggested that rats and mice made their way 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 arrived. King began to suspect that the circumstances of the rodents’ travels were not entirely overboard.

In 2022, King coauthored a study that offered a surprising explanation: the rodents arrived with traders who had sent to China to illegally sell New Zealand fur seal balls, and then returned to the South Island. In the 1800s, many fur seal rookies dotted the South Island’s rugged coastline, and it was the island’s only lucrative commodity. And in Canton (now Guangzhou), a bustling port city in southern China that was the backbone of international trade, fur seal pelts were gaining value as the world’s sea otters and their precious fur became scarce. Those daring enough to evade the rules may succeed by hunting fur seals.

At the beginning of the 19th century, conditions were ripe for shady dealings to flourish. The profit-hungry British East India Company tightly controlled its own monopoly on maritime trade by banning the colony from direct business with China and India. Most of the official trading ships from London, England, made pit stops in Sydney, Australia, on the way to supply New Zealand’s main port on the North Island.

King said unscrupulous fur traders were passing Sydney on their way to Canton and back to avoid authorities. “Those who wanted to circumvent the regulations did it very quietly,” she says. Such secret trips would avoid official records.

To determine whether the South Island’s invasive rodents arrived on official expeditions, or via a secret shipping route directly from China, King and her co-authors compared the rodent DNA with genetic material from 19th-century rat and mouse specimens found in near Sydney harbour.

The results added to the King’s suspicions. Sydney house mice had a European ancestor and the rats’ genes matched those of Norway rats found in Britain and the North Island. There was no trace of the genes of Southeast Asian house mice or the Chinese strain of rat – evidence that the ships carrying the rodents from China did not pass through Sydney. Or, most of them weren’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 unfavorable involvement through the port. In 1806, colonial authorities busted Simeon Lord, an ex-convict entrepreneur and sealer based in Sydney, for shipping 87,000 sealskins collected in the Antipodes Islands, south of New Zealand, to Canton via Sydney. But by some small miracle, the Lord’s journey should not have let any rodents loose.

Rogue traders who escaped detection by avoiding official shipping channels would have no doubt that the genes of stowaway mice and rats could reveal their movements centuries later. “The IS [rodents] he gave them away,” says the King.

Mein Smith says that King’s conclusion is plausible, since many traders in Sydney were at least as devout and profit-hungry as Lord. “There were all kinds of unhandled deals going on,” she says.

Although historians have inkled there was a clandestine trade between Australia and China in seal fur seals, it has been difficult to confirm due to a lack of historical evidence.

Genetic evidence can reveal information about the past that cannot be found in records or historical accounts, says study 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 was first published in Hakai Magazine and is republished here with permission.

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