In 1974, Spain imported two tons of American red crayfish for aquaculture; 50 years later, the species cannot be removed

• Fifty years ago, American red crayfish were introduced to Spain's Guadalquivir River basin, and they have since established a permanent presence.
• These aggressive invaders have wreaked havoc on local wildlife and disrupted aquatic ecosystems.
• Yet, local communities have successfully built an economy around their harvesting and processing.