Freshwater dolphins living in the Amazon river basin are being attacked and killed by local fishermen.

Conservationists have found a number of boto and tucuxi dolphins that have been struck with machetes and harpoons and left to die.

The fishermen attack the dolphins fearing they are stealing their fish and ruining their fishing gear.

Some of the killings may also be driven by strong cultural taboos that suggest the animals bring bad luck.

The discovery of the dolphins came during a survey designed to monitor the mortality rate of both Amazonian dolphins and manatees conducted by researchers at the Mamirauá Institute for Sustainable Development in Tefe, Brazil.

http://news.bbc.co.uk/earth/hi/earth_news/newsid_8184000/8184157.stm