Ray Collier Country Diary - Mackerel

11th February 2008 - Mackerel

The silver underside and iridescent blue green stripes over its upper parts may make the mackerel conspicuous to our eyes but it camouflages the fish well in the open sea. Sometimes the usual striped marking are absent and the fish has a scribbled pattern although this is unusual. Apart from the normal dorsal and ventral fins the fish has a number of smaller fins called finlets that act like aerofoils. Everything about the fish is streamlined so that it can swim faster either for chasing prey such as sand eels and whitebait or avoiding predators such as seals. The fins are slender and crescent shaped and can be pulled into depressions and flattened against the smooth scaled body to reduce drag through the water. It even has a jelly like surround to the eyes, again to reduce drag. The whole body is designed for long periods of high speed swimming with minimum energy. The fish normally grow to 16 ins long although larger ones up to 26 inches have been taken.
Spawning takes place in the summer months peaking around May and June when large shoals can be seen anywhere around the coast. A female mackerel will lay around 500,000 eggs with each one having a large drop of oil to make it buoyant. The eggs float among the plankton for a couple of days before sinking to the mid water level where the baby fish hatch, The tiny fish absorb the yolk and then start feeding on animal plankton. Even when they are only half an inch long they start to resemble adult fish. The young fish do not leave the coast until the autumn when they join the adult fish to deeper water for the winter when feeding virtually stops.
It is difficult to over-estimate the importance of mackerel as for centuries they have been an important source of food. It must be one of the easiest of sea fish to catch and many a sea angler has started off with catching them. If you put white or coloured feathers on hooks and drag them through the water when a shoal is around then you may catch a fish on every hook in every cast. Fortunately even at this time of the year here are plenty of mackerel in the shops. In the past huge commercial catches have been made and there are stories of trawlers losing all their gear when their nets were choked with enormous numbers of mackerel. There are fewer mackerel now but unlike those two other great food sources, the cod and herring, they have not suffered the same catastrophic decline in numbers through over fishing. There is one small but very important problem with mackerel and that is although when fresh they can be as delicious as any other fish they rapidly lose their taste and freshness. The fish do not travel well and cannot be frozen and even after a relatively short time they are almost inedible because of a build up in toxins from bacterial decay. At times it has even been illegal to sell the fish on Sundays as that was the day fishermen did not go out so the fish could not be fresh. In some places round the Scottish coast mackerel were shunned because it was thought they fed of the bodies of people who drowned at sea. The fish has a place in weather lore as there is a cloud formation known as a mackerel sky as the small ridged clouds resembles the back of the fish. Hence the lines ‘Mackerel sky, mackerel sky / Never long wet and never long dry. Mackerel clouds in sky / Expect more wet than dry.