Tyneside scientists are calling for action to prevent fishermen from catching fish they do not want.
Fishermen in the North Sea are already facing strict quotas
The Newcastle University team want the EU and UK government to limit over-fishing in the North Sea.
They say almost one million tonnes of unwanted fish are thrown back into the North Sea each year.
The so-called "discards", which are worth millions of pounds each year, are
thrown back because they are too young or would exceed catch quotas.
The fish, mainly haddock, cod, whiting and flatfish, are usually dead by the time they are returned to the water.
The scientists are calling for restrictions to be placed on certain areas of the sea where the unwanted fish are likely to gather and for gear such as fishing nets to be adapted so that they may be more selective in what is caught.
Under the proposals, the fishermen who comply with the rules would be allocated more fishing days at sea as an incentive.
Although the full extent of the consequences on the marine environment are not known, discards are considered to have contributed to the growth of several
seabird populations such as the fulmar and the lesser black-backed gull.
Lead researcher Tom Catchpole said: "Millions of pounds of potential fish landings are lost through discarding.
"For the improvement of stocks like whiting, haddock and plaice it is essential that discarding be reduced.
"The main problem is that it would initially be at a cost to fishermen.
"Granting better access to fishing grounds or allowing more fishing time to those who fish more selectively are methods that have proved successful."
Co-author Professor Chris Frid added: "For hundreds of years, people in the fishing industry have been aware of the need to reduce the number of discards, and they are committed to achieving it."