Cod is in the Details

I sometimes wonder, given the crisis afflicting the fishing industry, and the perilously low fish stocks, particularly cod, why isn't Cod Liver Oil really, really expensive? For example, St John's Wort, beloved of the mildly depressed, can cost nearly £15 for a mere 30 days' supply (unless you shop in Costco). Whereas Cod Liver Oil is a fraction of that.

It's something I worry about, constantly.