Another charming story, of the nature of so many found in popular natural histories, was once told by Lacépède, who quoted Admiral Pleville-Lepley as his authority. On the coast of Greenland are certain shallow bays which are almost landlocked. The water is clear, and the bottom of mud. There, throughout the winter, thousands of mackerel might be seen with their heads stuck in the mud and their tales pointing skywards. As might be supposed, when they first resumed their vertical position at the advent of summer, their eyesight was affected, and they were netted without difficulty; later on they were caught with hooks and lines.

The man had his hand over my arm and spoke to me closely.

‘There’s the bollocks you hear about mackerel. Did you know they have no air bladder so they have to keeping moving through the water to stop themselves from sinking and drowning? So if that is true, and I am told that it is, then how is the fish to spend the winter with its head in a bed of mud.’

‘All that they do when its cold is slow down and move closer to bottom of the ocean where they can where can move through the slow water. They have spent the summer here filling themselves with sprats and squid and anything that else thats of a size to get caught in their ever opening jaws. Feck I’ve had them out of the water here and they have been thick and heavy with what they have been eating and a fish may still have the tail of another smaller fish hanging out from between its teeth but it has still been greedy enough to take a bite at the hook that’s pulled it up short and out of the water and into my hand.’

‘If they keep away from the hooks for the summer then when it gets cold and dark they move out from here and into deep waters where then slow down and use up slowly that fat they have built up for themselves whilst they’ve been greedy over the summer. And as that fat gets used up they slow down some more until there’s no movement left and they have to keep what is left for the spring.’

‘Then there’s a click in the water that comes from a mixture of the extra light in the day and an extra degree of warmth in the sun and its time for them to rise up from their depths again and they come up in great black billowing clouds to the surface and into the light.’