Did Philip II bring invasive fish to Spain?

By Chris BaraniukFeatures correspondent

A 16th Century king brought several fish species to Spain. But is he responsible for their current environmental impacts?

One dead carp. The king was displeased. For months he had waited in tender anticipation. But all that made it to Madrid was one deceased fish and three dozen live, but small, pike – out of more than 200 fish originally dispatched to him.

Philip II wasn't asking for much. It was 1565 and the Spanish king who would later launch the Spanish Armada had other preoccupations – he merely dreamt of having his garden ponds stocked full of charming fish to dote on. He wanted fish like those in the water gardens he had seen on his travels in Central Europe. That's why he had recruited two "fish maestros" to help. Both from the Netherlands, they had signed up as the king's trusted emissaries. They knew all about fish. And swans, too.

In the harsh winter of 1564-5, the king had sent them on a mission. They were to go, separately, to France in order to collect carp and pike, then transport them to Madrid.

But things did not go well. After arriving in the French city of Bayonne, one was caught apparently sketching an entrance to the city's port. He was promptly accused of being a spy, imprisoned and earmarked for the death penalty. The king's frantically written letters may have saved his life. He was back in Madrid by March. As far as we know, without any fish.

The other fixer fared better. But even he was waylaid by snowstorms and had to temporarily leave 28 pike and eight carp in a monastery pond in the Spanish city of Burgos. He travelled on, purchasing more fish on the king's orders, and eventually arrived triumphantly back in Madrid in February 1565. With one dead carp. And 39 small pike.

Philip II wasn't the first gardener who sought species from afar for his own private Eden. And he was certainly not the last. One might argue that the history of gardening is really a history of transferring one plant or animal, or a whole aesthetic, from one place to another. This rearranging of nature has moulded our own ideas about what gardens "should" look like. But some gardeners have caused havoc by introducing invasive species that go on to spread like wildfire and wreck native ecosystems.

Carp and pike are currently considered invasive in Spain and have been blamed for causing significant damage to ecosystems in the country. But is Philip II ultimately responsible for this? And can scientists use these historic introductions to help anticipate the environmental impacts of other newly introduced species around the world today?

"It is amazing the amount of time and effort, and interest, that the king put into these things," says Miguel Clavero of La Estación Biológica de Doñana, a scientific institute in Spain. In a paper published in 2022, he detailed the escapades of Philip II's fish maestros and described how, through them, the monarch eventually succeeded in bringing many dozens of fish and crayfish to his gardens from abroad. These included the voracious northern pike, Esox Lucius, which is originally from North America and Eurasia, the common carp Cyprinus carpio, which is native to much of Europe, as well as the tench Tinca tinca, which is found throughout Eurasia, and the Italian crayfish Austropotamobius italicus, whose origins are currently hotly disputed.  

Documents and letters in the Spanish royal archives revealed how the king acquired an extraordinary level of knowledge about aquaculture. He had books on the subject in his library and when the 39 pike arrived, Philip II knew, for example, that fish transported in the same containers (to provide food for the pike) were actually too large for the diminutive pike to eat.

The king's obsessions did not stop with fish, either. According to Clavero’s paper, Philip II also sourced various plants for his gardens and some unusual hens – he would often ask his aides about how many eggs the birds were laying.

Transporting the fish was a particular challenge. Clavero isn't sure what kind of containers were used but he suspects a sort of wooden tank on a horse-drawn cart. Winter was chosen for the expeditions, he says, because the maestros knew that the fish were less likely to overheat and run out of oxygen than in the summer.

"I found that really, really astonishing that he should take that level of detailed interest," says Ambra Edwards, a writer and garden historian based in the UK. But that said, the practice of rulers demonstrating their wealth and power via impressive gardens was, even in the 1500s, nothing new.

Thousands of years ago, the Sumerians stocked their estates with plants and animals gathered on their conquests, Edwards explains. And between 141 and 87 BC, one Chinese emperor is said to have filled Shanglin park, a large hunting ground outside the imperial capital Chang'an ( now known as Xi'an) with plants and animals from across the Empire, and further afield. Although it has become the stuff of legend, Shanglin park likely existed for real, says Edwards.

How much scientific information can we really glean from dusty old stories and documents, though? Crucially, it wasn't until roughly the time of Philip II's botanical and zoological acquisitions that reliable descriptions and detailed illustrations of plants and animals emerged in Europe, says John David, head of horticultural taxonomy at the Royal Horticultural Society in the UK.

He mentions the 1613 Hortus Eystettensis as an example, a compendium of flowers that contains elaborate prints of many different plants. "It's a beautifully illustrated book, it's arranged according to the four seasons," says David. But paintings can also be useful, such as the works of the Flemish artist Clara Peeters. One of her paintings, "Still life with fish", also from the early 1600s, depicts carp, pike and crayfish among other aquatic creatures.

Because certain people documented the plants and animals in their midst with reasonable care 400 years ago, researchers today can use that information to make ecological analyses, which is exactly what Clavero has attempted. Historical records also capture mistakes of the past. Take the Nile perch, which in the 1950s was introduced into Lake Victoria, a gigantic expanse of water that straddles parts of Kenya, Uganda and Tanzania. The idea of introducing the perch was to improve the local fishing industry but, from a biodiversity point of view, the project was a disaster because the perch drove hundreds of native fish species nearly to extinction.

As for Philip II's efforts, was he a visionary or a vandal? In his enthusiasm for bringing fish to Spain, he might have introduced non-native species that then colonised the country, perhaps to the detriment of native flora and fauna. But it is not clear whether the populations of carp established by Philip II survived and multiplied.

At the very least, however, he contributed to a trend of bringing carp to the country, which could have influenced the distribution of the species more broadly. It's not clear why, but the pike he introduced eventually seem to have dwindled, says Clavero, as did those transported to Spain in the 18th Century by Philip V, a descendant of Philip II. The invasive pike present in Spain today were introduced in 1949.

Then there are the crayfish. At the moment, the ecological status of the "Italian" or white-clawed crayfish is a matter of some controversy. Though it's found throughout Europe, it's not clear if the species is native to Spain. Establishing this is particularly important, because while this crayfish was previously in decline, its population has begun to recover.  

Clavero argues that the species was likely first introduced by Philip II in the 1580s and the white-clawed crayfish later became widely distributed in Spain as a result. "Crayfish were the original interest of the king," says Clavero. "At some point, people started eating crayfish and spreading it all over. We are aware of several introduction events during the 18th, 19th and 20th centuries."

Other researchers say there is genetic evidence to suggest that this species of crayfish has actually been in Spain for thousands of years.

One line of argument is that 16th Century letters are not reliable or complete enough sources to establish the true natural history of the species. However, Clavero says that while written sources can be flawed or incomplete, so can genetic analyses.

Rafael Miranda at the University of Navarra in Spain, argues that historical documents can provide useful information for ecologists. But he says that whether the white-clawed crayfish should be considered native or not remains an open question. "We have to research more," he says.

Even if the species were present in Spain before Philip II's attempts to import it from afar, the king undoubtedly drew attention to it. And there are reports that Spanish royals continued their appreciation of crayfish, feasting on specimens from the Douro basin just a few decades later, in the mid-17th Century.

All of this historical information could be useful in the coming centuries. Researchers combing through archived papers or plumbing piscine genomes often uncover vital information about how introduced species have spread across countries and even entire regions. That ought to help scientists today to forecast how a newly introduced organism might establish itself in the future.

"We can use the information you get from the past to develop models," says David. "Just as you do for things like pandemics."

But more fundamentally, understanding how gardeners have moved species around so fervently for centuries expands our view of just how much they must have shaped our ideas about what belongs where. Edwards points to the cedar trees in front of Highclere Castle in England – the stately home familiar to many as Downton Abbey. An icon of Englishness. The cedars are not originally native to England, though. "This tree that comes from Lebanon in the mid-1600s," she says.

Philip II may be considered just one of many gardeners who sought, and introduced, species from afar, but he certainly did it with gusto. The archives suggest that his efforts to acquire fish and crayfish spanned at least 25 years. As Clavero puts it, these aquatic sensations perhaps appealed to that most royal of impulses – "the need to be unique".

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