Labour MP David Drew will be arguing in Parliament this afternoon that public bodies - including schools, hospitals and social services - should only use fish which is 'demonstrably sustainable'. Whilst this Bill has no chance of being passed at the moment, if it ever came to law then it could be the end of the Cornish fishing industry.
The key here is the use of the phrase 'demonstrably sustainable'. Because that means that the judgement will be very subjective. What is sustainable to one person - even one scientist - is not sustainable to another.
Most people can agree that any commercial fishing of some threatened species could lead to their extinction. Bluefin tuna is one such example.
In other cases there needs to be a limit to the amount caught, but some fishing can continue. Species such as cod and haddock fall into this category. (Note that this is not an argument in favour of the EU quota system which is fatally flawed - but it is an argument in favour of some form of restriction to prevent an all nation free for all).
Farmed fish are generally given the thumbs up. But they tend to taste of little. Only a few species get the unrestricted ok - sea bream, coley and gurnard being examples. Even those on the MSC 'fish to eat' list tend to have caveats (where and how they were caught).
And there are a huge number of species judged somewhere in the middle - and therefore off the list according to Mr Drew (who represents Stroud which is not known for its fishing fleet). If he got his way then Cornish fishermen would be restricted to serving us all a never-ending diet of coley.