Enjoy cod’s revival, but the extent of our ruination of the sea remains unknown | Mark Kurlansky

I received the exciting news with a sense of dread. According to the Marine Stewardship Council (MSC), which rates the sustainability of fish all over the world, North Sea cod is “back”. It says that the current stocks are such that it can now be fished without fear and purchased without guilt by eco-friendly consumers.

Since North Sea cod has been teetering on the verge of extinction since the 1970s, longer than the MSC has been rating fisheries, this seems startling and welcome news. After decades of reduced fishing quotas, fewer vessels, limited time at sea, wider-mesh nets, the periodic closing of some areas, cod has rebounded in the North Sea. Fishermen were promised that if they submitted to this draconian regime, in time stocks would be restored and they could return to a full-scale prosperous industry.

Related: Sustainable British cod on the menu after stocks recover

Related: It’s fish and chips night – but can we eat cod with a clear conscience? | Callum Roberts

Climate change is altering ocean ecology and changing habitats. The seas are getting warmer and fish are moving north