Nets with a trap door are being trialled off the south-west coast to try to reduce the number of dolphin deaths.
Trawlers are blamed for deaths
Scientists are conducting the experiment because an increasing numbers of dolphins are being caught in nets used by fishermen catching sea bass in British and French waters.
More than 270 dead dolphins have been found in Devon and Cornwall so far this year, compared with 216 for the whole of last year.
The new net, being tested by Scottish scientists for the government, allows the dolphins to escape through a "trap door".
In 82 hauls over a seven-week period, only two dolphins were caught in the nets.
Fisheries minister Elliott Morley said the results were very encouraging, and he would be pressing the industry to adopt the new nets.
But he warned that if dolphin deaths in the South West were not reduced in the short term, he could not rule out closing the bass fishery.
He said "Of course, it is disappointing that any died in the nets but we are confident that the system can be refined to prevent this in future years.
"In addition there appeared to be virtually no loss of the target fish in the nets, which means that, using the nets, fishing for sea bass can be economically
viable as well."
The trials were carried out by scientists at the Sea Mammal Research Unit at St Andrews University.