In 1974, a Spainish rancher imported 2,000 kg of American crayfish from Louisiana. 50 years later, it has become an invasion nobody could stop

The red swamp crayfish was supposed to be a tidy farming experiment near Seville. Instead, it walked out of its ponds, took over a national park, and became a European delicacy nobody can get rid of.

Fifty years after a Spanish cattle rancher shipped roughly 4,400 pounds of American red swamp crayfish into southern Spain, scientists say the species has become a permanent fixture of the Guadalquivir River basin. The region never managed to remove it. Instead, it built an industry around it.