Why are guillemots washing up dead on Scottish beaches? Are "atfish in the North Sea so diseased that they shouldn't be eaten? Will farmers of the future be breeding halibut and plaice?
Fergus Keeling and Lionel Kelleway look at the problems faced by fish and the animals associated with them and find out whether the crop we harvest but do not sow, can last for ever.
Producer GEORGE MONBIOT BBCBristol
(Re-broadcast next Sunday)