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The brightly coloured form of the mackerel is familiar to most people through its frequent appearance on the fishmonger's slab. With its azure back, silver belly and distinctive black stripes it is one of the most striking British species.

I remember, back when I were a lad, so to speak, going for a walk along Preston Beach in Paignton. It was a baking hot day in early June and the sea was absolutely flat with not a breath of wind to disturb its mirror-like surface. As I strolled along I suddenly saw, not one, but a myriad flashes of silver where the concrete steps came to an end and the sand was curved in the shape of a miniature cove. Curious, I quickened my step, especially, now that I came closer, since there were large numbers of people peering excitedly in the water. Pretty soon I could see the reason why; a large shoal of mackerel had trapped a swarm of herring fry between the steps and the shore, leaving them no means of escape. I would not have liked to have been in that shoal of tiny fry. The mackerel had gone into an absolute feeding frenzy, even beaching themselves in their efforts to get to the panic-stricken herring. The edge of the water was littered with their corpses and, ultimately, it was only when the tide finally started to recede that they had a chance to escape. The mackerel moved away but, several hours later, came back to do it all over again. Unfortunately, this time, there were quite a few humans waiting for them! At the beginning of Spring, when the waters of the Atlantic first start to warm and there is an explosion of phytoplankton (microscopic plants), mackerel move closer to the shore, swimming through the dense growth, straining the plankton from the water as they travel from one patch to another. After the lean pickings of the Winter, it must seem almost like manna from Heaven! Enough food to feed thousands upon thousands of fish in one large, extended, super shoal. The mackerel gorge, pack on weight and devote themselves to getting ready to spawn. Then, when this has taken place, the super shoal splits into smaller, more mobile units and the true, predatory nature of this savage little species begins to show its true colours.

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Which is just as well, considering how quickly that first bloom of plankton is eaten. Add in the effects of the water warming - the mackerel's food is digested that much faster - and you can see the need for the species to get onto solid food as quickly as possible. Then, as the weather turns warmer still, the mackerel becomes a very active hunter, mercilessly tearing into smaller species such as herring or sandeels.

Several species of small fish are harried by the mackerel but it seems likely that sandeels form the bulk of their Summer prey