Everyone including the ecologists agree the quota system is wrong. The root problem in France and probably in the UK is that the public only eat very few species of fish and these species are under much stress. Fish that don't sell well are thrown overboard.Agreed.. technology, particularly the large factory ships , and in Ireland's case, the generous quotas to Spain. But there was also some silly loopholes in the fishing regulations, wherein small fish caught and killed in the nets could be dumped back at sea, retaining ones quota rather than been harvested for fishmeal or fish fingers...
Global warming will in future affect stocks, .. warm water retains less oxygen.
On the other hand the Spanish eat just about anything and species with low market value are transformed into paste or other byproducts.