Spain imported US crayfish in 1974; 50 years later, they cannot be removed

Fifty years after two tons of American red crayfish were legally shipped into southern Spain to boost the rural economy, scientists have confirmed that the aggressive invasive species is in the Guadalquivir River basin to stay.In the spring of 1974, aristocrat and cattle rancher Andrés Bores Saavedra imported roughly 4,400 pounds (2,000 kilograms) of Procambarus clarkii, commonly known as the red swamp crayfish, from Louisiana. Bores intended to cultivate a fast-growing species in controlled aquaculture ponds near La Puebla del Río, hoping to stimulate Andalusia’s local economy and introduce a new regional culinary delicacy.Instead, the operation triggered the most destructive biological invasion in Spanish history.Breach of containment and rapid spreadThe species quickly breached its containment. Equipped with the ability to walk across dry land, dig tunnels over three feet deep, and survive severe droughts in low-oxygen conditions, the crayfish spread rapidly.