Pike and red swamp crayfish: a new case on predator‐prey relationship between aliens in central Spain

Pike in the Ruidera Lakes (central Spain) chiefly ate the recently introduced crayfish Procambarus clarkii . It was the dominant prey in occurrence, number and biomass for every size class and season. Likewise, number (up to 27) and total weight of ingested crayfish were directly related with pike size. The principal prey fish were all introduced species (except the endangered Blennius fluviatilis ), most native species having disappeared since pike were introduced in 1953.