Rubby dubby, a word coined in Cornwall in the 1950s when shark fishing as a sport began to expand in British waters, is a foulsmelling concoction used as a shark attractor. In America, “chumming’ —throwing chopped up pieces of fish into the waterhad long been used to attract tuna and other species of giant game fish.

The best dubby is made from oily pilchards, herring and mackerel, pounded to a pulp with a blunt instrument. Fish offal and unwanted fish are constantly added and some skippers introduce bran to thicken it up. Blood collected from slaughterhouses is also a popular ingredient but contrary to belief it does not stay in a liquid state, due to it being a coagulant. It then resembles jelly, and is a useful additive to existing rubby dubby. Occasionally it is kept separate and after a good stir ladled directly into the sea with an old saucepan.

A word of warning to those prone to sea sickness. If you are beginning to feel “doubtful’—stay right away from the rubby dubby bin. If there is one certainty in sea fishing it is that your “doubtful” tummy will have its mind made up for it immediately.