Discards are wasteful, damaging and need to be stopped. And measures to bring them to an end are long overdue. Good money is spent catching fish that you then have to throw away with little prospect of them reviving. It's a crazy waste of marine resources and of the effort put in by fishermen. Discards are a big problem for most of the seas around the UK. They cause unwanted mortality in fish stocks and they undermine fishery management. They are no good to us as consumers, they are no good to the health of fish stocks and they are no good to the fishermen.

One of the worst practices is known as "high grading". People do it all the time. It's when fish already caught are discarded to make room for other, more profitable catches. It might be that a skipper has a good catch at the end of a trip so gets rid of some of the older catch because they're not as fresh and he doesn't want to go over his quota. Or it might be because the species in the net is more valuable than the species in the hold.

I have been calling for a ban on discards for several years and to do that we need to reform the Common Fisheries Policy and the system of quotas. Our quota system in Europe talks of Total Allowable Catch, TACs, but what it really means is Total Allowable Landings. Fish landed are recorded but discards don't find their way into the statistics.

We need a system where fishermen land what they catch, backed up by monitoring to make sure it works. Then we would know exactly how many fish have been taken and can adjust fishing properly to levels the stocks can sustain.

Professor Callum Roberts, of the University of York and author of 'The Unnatural History of the Sea', which charts the decline of fish stocks over the last millennium, is one of the world's leading fisheries researchers