Great Cormorant Phalacrocorax carbo Is Threatening Fish Populations and Sustainable Fishing in Europe
Abstract .—Based on the EU Council Directive 79/409/EEC on the Conservation of Wild Birds (1979), the number of great cormorants Phalacrocorax carbo has increased enormously in many European countries and the distribution of the species has extended considerably. In the middle of the last century, breeding sites were mainly limited to coastal areas; however, today, colonies have become numerous on inland waters. In Germany, for example, breeding pairs expanded from 794 in 1980 to about 23,000 in 2005, and the growth of the population still continues. In the whole of Europe today, there are more than 350,000 breeding pairs constituting more than 2 million cormorants. The increasing expansion of cormorants in Europe causes ecological damage to fish populations and economic and sociocultural damage to fishing. An estimate of the daily food intake of cormorants in Europe is about 1,000 metric tons. Special concern exists for endangered fish species such as grayling Thymallus thymallus , brown trout Salmo trutta , and European eel Anguilla anguilla . Rearing of fish in farms and stocking of juveniles in natural waters are often unsuccessful because of cormorant predation.