Start by demanding withdrawal from the EU which oversees the dumping back dead into the sea of up to NINETY PER CENT of many catches! ( 1 million tonnes of dead fish in the N. Sea alone annually!)Secondly - ask your local chippy if they are prepared to offer white fish other than cod and haddock and
Thirdly - if they do -then buy it!
Coley, hake, pollock et al are all the equals of the more popular white fish.
