QUESTION: Is it OK to eat cod again? Martin from Brighton, UK
ANSWER: Martin, being from Brighton you are probably talking about Atlantic cod, which lives in the cold, deep regions of the North Atlantic. It is a very important fish, and in the UK it is best known as the most common (traditionally) ingredient in fish and chips (the famous “fish supper”). Cod is by far the most popular whitefish in the UK, with 14,100 t landed in 2011, and a retail consumption of approximately 36,000 t of whole fish (about 9% of the world’s catch). 
Wikipedia does a pretty good job of describing the historical context of cod as a British culinary tradition:
Fish and chips became a stock meal among the working classes in the United Kingdom as a consequence of the rapid development of trawl fishing in the North Sea, and the development of railways which connected the ports to major industrial cities during the second half of the 19th century, which meant that fresh fish could be rapidly transported to the heavily populated areas. 
This doesn’t quite capture the true position cod holds in the hearts and minds of British diners – it isn’t quite as culturally revered as the cup of tea, but it is close.
Today cod stocks everywhere are viewed with a wary eye to the Northwest Atlantic Cod fishery (off the US and Canada), as in the early 1990’s the stock experienced an abrupt, almost unprecedented collapse. Suddenly there were just no cod at all. Charts and graphs and predictions showed a gradual decline over the preceding years but the severity and suddenness of the following collapse has made for much discussion about fisheries management and the value of the precautionary principle. There is a very scientific definition for this principle, but what it really means is exercising extra prudence and reserve, even in the face of data showing little imminent danger.
The collapse resulted in a complete moratorium on fishing from 1993 -97, and while recovery plans are in force or are being developed for most stocks, many have shown no signs of recovery or remain outside safe biological limits. What it graphically showed was that with some species, perceived health may hide a looming disaster.
But what about stocks in the seas around Great Britain? Your reticence on the consumption of cod probably comes from information you have received about how your local stocks are in danger. On this there has been some some good news as of late; things seem to be getting better. The EU has adopted a long-term plan for cod (the Cod Recovery Plan) in most of the areas around Britain and fishing industry groups have been working on techniques to limit over fishing. The results are that spawning stock biomass (the actual amount of fish able to reproduce) has increased from the historical low in 2006, and fishing mortality (the removal of fish from the stock due to fishing activities) has declined since 2000. Recruitment (new fish of breeding age), however has been poor and the stock remains outside safe biological limits.  The Marine Conservation Society (a UK charity for the protection of the seas around the United Kingdom) still rates poorly cod caught in most British waters. 
We would recommend adjusting your views on cod consumption, expanding your seafood choices; there are many other species out there ready to be tasted, and which are not under the same sort of pressures as cod. As we have suggested before, mussels are just about nature’s perfect marine protein source. Sardines are very good grilled, and anchovies can add an extremely nice robustness to any sauce. Think “Mediterranean Diet” where proteins are used to add richness, heft and mouth-feel, but with less actual ingredient. Gumbos, soups and chowders are also great ways to enjoy seafood without requiring a huge white fillet.
We can still eat seafood, but by just expanding our culinary repertoires, we can relieve pressure from heavily harvested stocks. If you are still craving a fish supper fix, try limiting it as a choice, interspersing with other seafood-based meals.
Deep Blue Public Relations
 Seafish, UK – Responsible Sourcing Guide: Cod
 Wikipedia: Fish and Chips
 Marine Conservation Society