Life of a Chalkstream. Simon Cooper

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      AFTER THE FRENETIC activity of summer I miss my riverside companions on a winter dawn morning. No reed-chewing water voles suspiciously eyeing my progress along the riverbank, plopping for safety under the water if I come too close. No dew-laden spider webs strung between the purple loosestrife, glinting in the rising sun, as an eager arachnid crabs with intent across the translucent filament harvesting the victims of the night. Even the rabbits have gone, and as for the lolloping hares, no chance of any of those until spring. But even if it is all quiet along the banks, in the ever-clear water of the chalkstream the game is on to create the next generation of trout and salmon.

      Trout and salmon are often spoken of in the same breath, but they are in many respects as close to each other in genetic terms as a horse is to a zebra. For a fly-fisherman they define what you are on a river. As salmon and trout are two distinct breeds, so are the men that fish for them. Not to announce which you are, even though you might fish for both, is like saying you support the Manchester football team. United or City? Salmon or trout? Both are equally tribal.

      For fish whose subsequent lives will diverge so totally they begin life in the same gravel beds, of the same rivers, at precisely the same time of year. In lives that will span five to seven years some brown trout will travel no more than a few hundred yards from their birthplace, whereas the salmon has a round trip of some 4,000 miles to complete its life cycle. While we may think of a salmon as a river fish, in fact the greatest proportion of its life is spent at sea. These salmon are Atlantic salmon – Salmo salar. Defined as anadromous, their natural habitat is the sea, but they must return to the river of their birth to spawn. The eggs are laid in a river and that first year of life, as they grow from fry to parr and then smolt, is all spent in fresh water. But no chalkstream could ever provide enough food for a salmon to grow to maturity, so at a year old, measuring no more than 6 inches long, they head for the ocean and the food-rich waters off Greenland. It is an epic journey that begins and ends in a stream no more than 15 yards wide and a few feet deep.

      The spawning grounds created by salmon and trout in the gravel riverbed are known as redds, and the sight of the first redds, be it in October or November, is something of a red-letter day for us chalkstream watchers. Indeed, redd-spotting becomes something of an obsession from around October time. I say ‘around’ because rivers don’t obey the Gregorian calendar. Like the snowdrops in your garden that appear in January one year and February the next, the creatures of the river adapt their habits according to what’s happening around them, which is in turn dictated by the climate. And not only the weather of now; the effects of a dry summer or harsh winter for instance, may linger many months or years to come.

      I’ll get excited text messages from river keepers: Seen a redd today. First of the year!!!!!!!!!!! . It is exciting because amid the gloom of late autumn and the winding down of a fishing season, it is a small ray of hope for things to come, however distant. It is also proof that as a river keeper you are doing something right. Your river is so damn perfect that fish want to breed in it. How good is that?

      Walking beside the river, you will find the redds are easy to spot once you know what you are looking for: pale lozenge-shaped indentations on the river bottom, with a mound of gravel at the downstream end. Brushed clean of silt and debris, they shine out like lights compared with the surrounding gravel. Sometimes there is just one, sometimes a cluster, but it is the size that immediately marks out the difference between a trout and a salmon redd: the former about the size of a snowshoe, the latter a good-sized door mat. And there is more latent intent about the salmon redd; it will be dug deeper, down to the hard base beneath the gravel. Random gravel stones from the digging will be scattered far and wide across the riverbed. The mound of stones at the end will be much higher and more pronounced. Redds are, of course, made by the fish themselves to harness the flow of well-oxygenated water through the loose gravel to incubate their eggs, and oftentimes the hen will lay in more than one redd. Laying in a single redd is quite literally putting your eggs in one basket, and that basic instinct to perpetuate the species drives the hen to hedge her bets by laying in a series of redds, maybe with other hens. But we have to track back in time to appreciate how and why we have arrived at this point.

      From my daily walks up and down the river the progress of the trout from an everyday Salmo trutta to a body quivering as if electrocuted whilst he releases his milt over the eggs is far easier to track than that of Salmo salar, the Atlantic salmon. It is in September that I start to see the first signs of spawning in the trout, who start to change in appearance in the weeks before they start the actual process of cutting redds and spawning. Suddenly that headlong pursuit of every item of food to feed on in preparation for the winter ahead slackens off. The fish are just as active, but not for food. Somewhere in their fishy brain the search for food is replaced by the search for a mate. The change sweeps over their body and suddenly that golden-brown complexion is replaced by a fierce red blush along both flanks. The males sprout a vicious-looking hook – a kype – on their jaw. The kype is largely for show, but it does make an otherwise innocuous-looking trout look like someone you would not want to mess with.

      During this time the salmon are absent from this river, still making their way along the English Channel from the Atlantic to pick up the scent of their birth river somewhere on the south coast. How salmon navigate the entire journey to the far side of the Atlantic to the waters off Greenland and back again remains something of a mystery. The position of the sun, the stars and the gravitational pull of the earth are all cited as guides, but it is certain that the final leg of the journey is determined by smell.

      Salmon never look to me like creatures that depend on smell for survival – their incredible ability to leap huge waterfalls or swim unceasingly for months on end seem more important – but smell is the thing. Early on in their lives they imprint the odour of their birth river onto a hormone that is secreted in the thyroid gland; it stays with them for evermore. Their hormonal library of smells is highly selective; only the ones that really matter make it onto the data bank. Likewise they will log the odour of their brothers and sisters in the river, picking up their scent in later years when the shoals are travelling across the ocean.

      By the time our salmon sniffs the first scent of home, he or she has surmounted incredible odds to make it thus far. Of those 5,000 eggs laid three years ago in the River Evitt, our salar is probably the sole survivor, or at best one of two. And the dangers are far from over. Ravenous seals are gathering for an autumn feast and the drift nets in the estuary are laid in wait. It is the misfortune of salmon that they make such good eating, though it should be of no surprise. They are super-fit and have spent the past two to three years in the beautifully clean water of the Greenland Sea eating nothing but squid, shrimp, crustaceans, small cod and mackerel.

      As far back as medieval times salmon has commanded a premium price, so the ever-resourceful coastal communities around Britain developed the highly efficient drift net to capture the salmon returning from the sea. There are all manner of types of drift netting, each of which has evolved for the particular locality, but the principle holds good for them all: wait for the tide to go out and then set your nets in such a way that they intercept the salmon travelling towards the estuary bottleneck on the inbound tide.

      Travelling around the coastline of Britain you will see all sorts of weird and wonderful nets rigged up to capture salmon, though they are becoming fewer. Declining runs of salmon, fierce campaigning by conservation groups to have the nets removed and the harsh demands of a truly hard and difficult job are all contributing to the decline.

      The simplest form of drift netting is a long net, anything from СКАЧАТЬ