In the serene waters of Spain’s Ebro River, a growing menace lurks beneath the surface – invasive catfish. This article delves into the profound effects of these unwelcome guests and how invasive catfish impact the Ebro river ecosystem.
The Catfish Invasion
The invasion of catfish in the Ebro River is a story that began decades ago. In the early 1970s, these formidable creatures, known scientifically as Silurus glanis, were introduced into the Mequinenza reservoir by fishermen seeking a new catch. Their origin traces back to the Danube and Volga rivers in central Europe. These native habitats provided the catfish with ample space to grow and thrive, reaching staggering sizes. Reports from the 18th and 19th centuries describe specimens weighing up to a colossal 375 kilograms and measuring up to 3 meters in length.
One remarkable incident that highlights the extent of this invasion occurred in 2023 when amateur fisherman Francisco Mendoza Clavería reeled in a catfish that measured a staggering 2.34 meters in length and weighed approximately 80 kilos. This event, which took place close to Prado de Tudela, possibly marked the largest catfish ever taken from the Ebro. Mendoza himself had caught a specimen measuring 2 meters and 10 centimeters in April 2022.
Ecological Disruption
The catfish’s impact on the Ebro River ecosystem is far-reaching. With no natural predators once they reach adulthood, catfish have thrived in the warm Ebro’s waters. Their population explosion has triggered a chain reaction of ecological disruptions. One of the most significant casualties has been the native barbel, which saw a precipitous decline in numbers around 2005. The catfish’s voracious appetite and unchecked growth have nearly wiped out this once-abundant species. This decline, in turn, has led to an overabundance of algae and aquatic vegetation, as the barbel used to play a crucial role in controlling these plants.
Unusual Diet and Longevity
The catfish’s adaptability extends beyond its survival in foreign waters. Recent observations have shown that these invaders are not picky eaters. Pigeons and even rats have fallen victim to the catfish’s insatiable appetite. Reports of catfish hunting pigeons under the Pilar bridge in Zaragoza serve as a chilling testament to their opportunistic feeding habits. As adults, their primary diet comprises fish, but they are known to consume ducks, rodents, frogs, crabs, and more, using their large mouths to suction in prey.
This video shows catfish actively hunting and catching pigeons in very shallow water. Interesting that the dialogue is in Japanese? Showing the international interest in this subject.
Furthermore, catfish are remarkably long-lived, with some individuals exceeding 80 years of age. Historically, there have been accounts from the 18th and 19th centuries describing specimens weighing up to a staggering 375 kilograms and measuring up to 3 meters in length. These colossal catfish from the past hint at the enduring challenge they pose to the Ebro River’s ecosystem.
Management Efforts
The menace posed by invasive catfish has prompted action. In 2015, the Government of Navarra issued an order mandating the immediate sacrifice of catfish caught in the Ebro River, classifying them as an invasive exotic species. Similar regulations apply to other invasive species in the river. Efforts to control the catfish population are ongoing, but the challenges they present continue to test the resilience of the Ebro’s natural balance.
As we reflect on the invasion of catfish in the Ebro River, it becomes evident that the consequences of introducing non-native species can be far-reaching and complex. The Ebro’s delicate ecosystem is facing unprecedented challenges, from the disappearance of native species to ecological imbalances. To preserve this unique environment, it is imperative that we support and engage in conservation efforts.
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