Near the coast of California in the United States you can see a very big kind of fishing boat, which is more than sixty metres long. It sends a helicopter out to look for In the 1960s about 350,000 dolphins died this way every year. Then there were new laws about tins of tuna. The tins had to show if the tuna came from a ‘dolphin – friendly’ fishing boat – a boat that does not kill dolphins. In 1986, the number of dolphins that died was 133,000, and in 2001 about 2,027. But is this the real number? We don’t really know. Perhaps it is much more than this. The big fishing boats now have to carry somebody who watches and counts the number of dead dolphins - but they can also tell the fishermen to ‘lose’ the dead dolphins before anyone sees them. Some dolphins die while the helicopter is following them, and baby dolphins may die if their mothers are killed.