Definition: Generate an appropriate title for the given text. The generated title must be short and include the main topic of the text. The preferred titles are under fifteen words.
Input: White-clawed crayfish are being killed off by American signal crayfish which were introduced to the UK in the 1970s. Last July, 600 white-clawed crayfish were moved from the River Witham to more remote chalk streams in the Lincolnshire Wolds. The Environment Agency (EA) said the crustaceans had started to breed in their new home. The signal crayfish was brought to Britain as a food source, but escaped into local waters. It outcompetes the smaller, native species for food and habitat and carries a disease fatal to the UK species. The government's Non-Native Species Secretariat said the signal crayfish also "undermines riverbanks through burrowing and can predate on native fish eggs and aquatic invertebrates". The EA is working with the Lincolnshire Chalk Streams Project and the Lincolnshire Wildlife Trust on an initiative called the "ark project". Richard Chadd, from the EA, said the programme had doubled the area inhabited by the native animal. "Having personally worked on this project - physically picking up these crayfish, measuring them, checking their health and relocating them to their new homes - I'm thrilled that our efforts at protecting them have been so successful," he said.

Lincolnshire conservationists help native crayfish comeback