In some countries cormorants are trained by fisherman to catch fish

Humans have historically exploited cormorants' fishing skills, in China, Japan, and Macedonia, where they have been trained by fishermen. A snare is tied near the base of the bird's throat, which allows the bird only to swallow small fish. When the bird captures and tries to swallow a large fish, the fish is caught in the bird's throat. When the bird returns to the fisherman's raft, the fisherman helps the bird to remove the fish from its throat. The method is not as common today, since more efficient methods of catching fish have been developed.

http://en.wikipedia.org/wiki/Cormorant