MADRID — Along the banks of Spanish rivers, a story circulates among fishermen. As they dredge the riverbed in search of prey, they recall a time when the rivers teemed with native crayfish. But, the arrival of an invasive species wiped them out, making them now almost impossible to find.
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After years of meetings and debates, Spain’s Official State Gazette recently published the “Strategy for the conservation of the Iberian crayfish in Spain” with the intention of changing the fishermen’s story and saving the crustacean. Yet not all points of the story are accurate.
There is no concrete evidence that the so-called Iberian crayfish is native. In fact, evidence suggests it was an invasive species introduced by a royal couple’s whim. Overtime, the species spread across the peninsula’s rivers, altering ecosystems, only to be later displaced (once again) by the whim of a dictator.
Its story reveals the interplay of politics, biodiversity, human preferences and how biased decisions can endanger some of the world’s most fragile ecosystems.
Native with an Italian accent
Just as small acts can change human history, they also have the power to alter the course of life on our planet. In the case of this crayfish, one of those small acts took place in 1588 — potentially the year in which the first crayfish arrived in Spain.
They were part of the cargo of a ship that sailed from Livorno, Italy to Alicante, Spain to fulfill the wishes King Philip II and Queen Isabel de Valois (his third wife, daughter of the king of France and Catherine de Medici, of the influential Republic of Florence). The couple had embarked on a mission to landscape the royal estates in Madrid, filling them with ponds and new species — as was the fashion in Europe.
Having pike, carp and crayfish became a symbol of exclusivity.
The first species to arrive were carp and pike, in 1565. And in 1588, it was the turn of the Italian crayfish (Austropotamobius fulcisianus).
“Landscaping was a novelty in Spain, where there were only vegetable gardens and crops up to the doorstep of the house. The royals faced many difficulties in bringing the new species, but they succeeded eventually. From then on, having pike, carp and crayfish became a symbol of exclusivity,” explains Miguel Clavero, a scientist at the Doñana Biological Station (EBD-CSIC) and a crayfish expert.
“From that moment on, no one knows exactly how, but crayfish slowly expanded and became a very popular fishing catch.”
According to Clavero’s research, it is very likely that this was when the crayfish arrived, as there is no evidence in historical records (which were already quite exhaustive) indicating the presence of another species of river crayfish in the territory before 1588.
And the story continues, with the next reference, a century later, placing the new species in the rivers of Valladolid, in northwestern Spain. The first records of its culinary use can be traced back to the 18th century. During the 19th century, references to the expansion of the species through the rivers of the entire peninsula multiplied.
An American invader
The next major chapter in this crayfish’s conquest happened during Francisco Franco’s dictatorship. It started with the approval, in 1942, of the law regulating the promotion and conservation of river fishing. But the real boom in sport fishing began in the 1950s.
“The promotion of sport fishing focused on salmonids, large introduced predators, such as pike and black sea bass, carp and crayfish. While salmon and pike were for the lords, crayfish were for the common people,” Clavero says. “That is when the population of these crustaceans began to decline due to overfishing.”
Faced with the scarcity of catches, people began to call for the introduction of a new, more resistant species, as was already done in other European countries. And this is when the invaders mentioned at the beginning of the story came into play: American crayfish.
Their expansion was explosive.
First imported in Badajoz, Spain in 1973, adaptation to their new environment was successful prompting new releases in Doñana, on the southwest coast of Spain. “The interest and demand were so high, many people began to introduce crayfish from America in their rivers. Their expansion was explosive,” the researcher says.
The new invasive species, the red crayfish and the signal crayfish, carried with them a disease that, in just a few years, decimated the Italian crayfish. Their populations drastically decreased and collapsed in almost all rivers. Today, there are only about a thousand of them left, isolated in the headwaters of rivers. This situation led to the Italian crayfish to be labeled as vulnerable in the Spanish Catalog of Endangered Species. As a result, a strategy for its conservation was drawn up.
In the catalog and in the strategy, the species appears under the name Austropotamobius pallipes and not Austropotamobius fulcisianus, despite the fact that there is no evidence of the presence of the former in the Iberian peninsula’s rivers.
“The taxonomy of European crayfish is very poorly developed, so the generic name A. pallipes has been used for all of them for some time, although many other subspecies exist. This is also the name used by the International Union for the Conservation of Nature and the EU Habitats Directive,” Clavero explains.
Protecting an invasive species
The conservation strategy for Iberian crayfish in Spain includes measures to conserve the existing populations and expand their habitats through captive breeding and reintroduction programs (actions that have been carried out for years). They will be released in small and high rivers where other crayfish and the American species are not present.
“The problem is that these habitats are scarce and delicate, and many other species need them. And crayfish are animals with a great impact on their environment,” the expert says.
These crustaceans prey on many other river species, especially less mobile animals, such as small invertebrates that live among riverbed stones, or the eggs and larvae of amphibians and fish. Many of them are also endangered species or even endemic species that do not benefit from the same interest or support as the crayfish.
“Beyond whether it makes sense or not to protect it, what does not make sense is that the Italian crayfish is a conservation priority,” Clavero concludes. “Throughout the territory, there are a lot of freshwater species on the verge of extinction, many unique species in the world that are being lost forever with almost nothing being done to prevent it.”
