Since purse seining of tuna by targeting dolphins began, it is estimated that over 7 million dolphins have been killed, mostly by entanglement in fishing gear. The collapse of fisheries as a result of over-fishing has in cases meant the targeting of dolphins as scapegoats, and the fishing of them as a new source of food. The increasing phenomenon of diseased and dying dolphins washing up on shorelines has been linked to marine pollution. Measures need to be taken to protect dolphins and conserve their numbers.
The European Cetacean Society promotes and coordinates the scientific study and conservation of cetaceans such the dolphins. It gathers and disseminates information to members of the society and the general public, and organizes international conferences and workshops. It has six working groups concerned with: sightings schemes; stranding schemes; incidental catches of cetaceans in fishing gear; computer data bases compatible between countries; Mediterranean Sea; Baltic and North Seas. Sea Watch Foundation obtains information vital to the well-being of whales, dolphins and porpoises in British waters, and uses this information to achieve greater protection for these animals. Greenpeace has documented, taken photos and recorded film footage of dolphin deaths caused by the use of driftnets by fishing fleets. Such media has been viewed by millions of people worldwide, fuelling political and consumer pressure to end such fishing practices.
In 1998 the USA, plus five South American countries and Vanuatu agreed to measures to protect dolphins from tuna fishing operations.