Читать книгу Life of a Chalkstream - Simon Cooper - Страница 7

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DISCOVERY

FROM A DISTANCE water meadows look unkempt and uninviting, but once you get into them they have a beauty all of their own, with a myriad grasses, flowers and stunted shrubbery growing in an apparently irregular pattern. The pattern is dictated by the cattle that graze the wet pasture of the river valley.

Cattle, sheep and other livestock are the cloven-hoofed landscape gardeners that create the meadows. Without their relentless chewing, battering down the growth, fertilizing the ground and churning up the turf, the fields would soon become a dense, overgrown bramble thicket. Where they graze tight to the sod the sun and light let the buttercups thrive; cowslips spring from the nitrogen-rich manure patches and where their hoofs punch holes in the soil, the rhizomes of the yellow flag iris are split and separated to create fresh growth for the following season.

And sure enough, as I picked my way across the meadows I spied a diverse collection of cattle grazing in the distance, only their upper bodies visible above the pasture. Livestock are also great path-makers. Their sense of direction may be slightly off-kilter, and they may fail to realize that the shortest route between two points is a straight line, but they are canny and I know that if you deviate from the path they’ve trodden you will soon become stuck in boggy ground. So I followed their zigzag path across the field.

Reaching the cattle, a motley collection of brown and white Hereford crosses, black Aberdeen Angus and the pale, long-limbed, lean continental types, I paused to consult the map. The cattle paid me little interest, raising their heads now and then to check me out, but never pausing as they masticated their way through their daily mass of roughage. I’m told that meadow-grazed beef is the sweetest, most tender meat of all but it seemed unfair to share this news with them.

To my right the summer brown of the grassland gave way to a vivid green ribbon, the best indication yet that the river was close by. The dry cattle path petered out, giving way to wet ground poached by a thousand hoofs where the cattle had grazed right up to, and under, a barbed-wire fence. In fact the grass immediately under and just the other side of the fence had been grazed as tightly as a bowling green; proof that – for cattle at least – the grass is greener on the other side of the fence.

Picking the stoutest fence post, I climbed onto the top strand and from this vantage point caught my first view of a sparkling river. I was still separated from the river itself by 30 yards of rushes and as I leapt to the ground the other side I sent up two silent prayers of thanks. First, that I had had the foresight to put on waders – those 30 yards were likely to be slimy, smelly and difficult to negotiate. Second, that the river was fenced, because cattle and rivers simply do not mix. Give cattle a chance to graze right up to the edge of the river and that is what they will do. However, cattle are big, clumsy beasts that don’t mind getting their feet wet in search of that extra special, tasty mouthful. So they yomp up, down and along the edge of the river, gradually destroying the banks and vegetation.

Imagine you have a fenced river corridor that is 50 yards wide. In the middle you have 20 yards of river, a width that the river has arrived at more or less of its own accord to accommodate the variable winter and summer flows. Either side of the river lie 10 yards of semi-aquatic vegetation: plants like rushes, watercress and wild mints that like to live half in and half out of the water. This wet area is the perfect home for the insect life that will ultimately sustain a fly-fishing river. The final outer five yards on either side will be hard bank that contains the river in all but the heaviest of flood conditions and is home for the sedge grasses and tussocks that like their feet dry for most of the year. So far so good. Now take away the fencing. Within a matter of hours the cattle will discover this new Elysium and within a few days the wetland greenery will have been grazed to water level. Not content to leave it alone, the cattle will persistently graze the new shoots. Their strong legs and sharp hoofs will destroy the root structure, slowly killing the plants from below. The first winter flood will wash away the soil, exposing the gravel bed below, and the plants will be unable to re-establish themselves in the faster water. Within a short time the river that was once 20 yards wide is now 40 yards wide, shortly to become 50 as the cattle destroy the hard bank as they lumber in and out of the water. Having a river that’s two and a half times wider might not seem such a bad thing, but assuming the volume of water stays the same, which it will on a chalkstream, the depth will be two and a half times less, and for a trout at least, this is bad news on every level – food, survival and breeding. If you are a trout hanging out in your favourite spot close to the bottom, looking upstream into the column of water above you for stuff to swallow, then the greater the depth, the greater the choice of food, which is why trout tend to gravitate to the deepest pools unless they are in search of particular food or get chased out by bigger trout.

Always on the lookout for food, trout are wary creatures that have plenty of predators. When they are small the greatest danger is other trout or maybe kingfishers, but as they grow larger pike, cormorants, herons and ospreys, otters and mink are ever-present dangers. In every case, except for the smallest of fry, the deeper the water the less likely these threats are to attack the trout, and if they are attacked the depth gives more options for escape. Trout fry on the other hand like to hide out in the reed beds either side of the main channel. More practically, for the survival of the species trout need to lay their eggs in loose gravel that is constantly washed with rapidly flowing, well-oxygenated water that percolates down to the eggs. Take away that speed of flow by spreading it across two and a half times the width and suddenly too little good water will flow over the eggs and they will slowly die due to lack of oxygen.

However, standing just past the fence contemplating striding out across 30 yards of swampy reeds to reach the river I was more concerned for my safety than with any ecological niceties. I have learnt from bitter experience that the worst thing to do is to adopt a bold Neil Armstrong-like moon stride – all that will happen is that your leading leg will disappear into the mud, upending your face into the slime. Far better to shuffle forward, letting the weight of your feet break through the surface and allowing you to sink slowly until you reach firm bottom;^* then it is a question of somehow walking/shuffling/pushing your way through the mire with reed roots grabbing at your feet. Each movement that disturbs the mud releases a noxious smell: part methane, part rotting vegetation, part musty odour. Sometimes your passage will bring an oily slick to the surface. And unpleasant though that might be, it does demonstrate what a huge natural filter the river’s edges provide, the excessive nutrients and run-off degrading in the mud rather than being washed directly into the river.

Hindsight suggests that I had not picked the easiest place to get into the river. As it turned out, a few hundred yards upstream the reed margin narrowed to a few feet, but as I stepped out of the reeds I was in the most perfect river, and at that moment it was worth the effort. A fast, clear stream with huge rafts of waving green crowfoot, which is essentially water buttercup with a white rather than yellow flower, filled the river, the gaps interspersed with bright gravel patches. Donning polarized sunglasses to cut out the surface glare I began to scout the depths of the water, picking out the occasional brown trout in the open water and disturbing shoals of grayling as I waded upstream.

Seeing the trout made me happy, but seeing the grayling happier still – not so much from an angling viewpoint but because grayling are an indicator species that confirm the good health of a river. They are far more sensitive than trout to declining water quality, and if they disappear you know you are in for problems. They are not so much the canary in the cage that drops dead when the danger has arrived, but rather the bird that flies away at the first sniff of trouble. As for salmon, my suspicion was that I would see them in the autumn; the Evitt has a reputation for a run – an influx of fish from the sea – that comes in late autumn to spawn, but for now that was simply conjecture.

As I pushed on up the river the morning began to warm up and after a while a hatch of olives appeared above the water. ‘Olives’ is one of those words fishermen bandy about. It is a catch-all name that describes a whole range of insects that are to be found flying on the river, going about their daily business of survival and procreation. They are important to anglers because olives are one of the staple foods in the trout’s diet.

I say ‘appeared’ because it always seems to be that way – one minute there are no insects, the next there is a cloud gathered above the water or alongside the water. For the chalkstream fisherman the sight of a hatch is a promise of things to come, because eventually when those insects alight on the surface of the river, either to lay their eggs or to die, hungry trout will eye them up, rise to the surface and swallow them down along with a gulp of water.

The very essence of dry fly-fishing, dating all the way back to the Macedonians around the time of Christ, is to imitate this process. Take a hook, decorate it with fur and feather to create a fake that looks like the real fly. Tie the hook to the end of your line and then use a rod or cane to cast the fly onto the water so that it lands like thistledown on the surface, thereby imitating the natural landing and fooling the trout into mistaking it for food and making a lunge for it. If all goes according to plan you raise the tip of the rod, tighten the line and set the hook into one very surprised, and soon to be furious and fighting, trout.

In fishing jargon, this is referred to as ‘matching the hatch’ – observing the insects on which the trout are feeding and fishing the artificial imitation. Spend time in the company of anglers reporting back from a day on the river or read the comments in the catch record book and you’ll get a sense of how knowledge of entomology, rudimentary, encyclopedic, or just plain guesswork, dictates the pace of a fishing day. You’ll come across phrases like ‘a great hatch of olives’, ‘plenty of blue-wings about’ or more honestly, ‘couldn’t really make them out – maybe some sort of small olives?’ You will nod your head wisely but will most likely be none the wiser at all and put it down to some riverine double-speak. In an idle moment you might even pause to wonder what this much spoken about ‘olive’ is, but move on quickly – you probably have a life to live.

Actually the truth is you have probably seen olives on thousands of occasions without even registering their existence, for Baetis, to give them one of their more common Latin names, inhabit just about every lake, pond and river in the British Isles. Next time, look out for a small cloud of insects, hovering just above or beside the water – they are certainly some kind of olive that hatch through spring, summer and autumn. An individual olive will look like a round bundle of fur fluttering on the air, keeping in time and close proximity to the hundreds of others, all identical. In fact olives are not round at all, they just look that way, as their wings are a blur to the human eye, beating thousands of times a minute to keep them aloft.

If you can ever get one to alight on your hand they are creatures of the most extraordinary beauty: big black eyes, impressive mandible, large translucent, veined wings and long triple tails shaped like a cat’s whisker that double the length of their tapering, segmented body. In angling parlance they exist as large, medium and small. Large is the size of a blueberry, medium a pea and small an unsplit lentil. As the name suggests, they are olive-coloured or a drab green of varying hues. Sometimes the wings differ in colour from the body, which gives rise to types such as the blue-winged olive, but anglers like to keep their nomenclature simple and to the point, if a little dull. But that said, the blue-winged olive has a hint of the exotic about it, and the claret dun a gravity that suggests it must succeed.

‘Dun’ – there’s another word that creeps out of the angling lexicon, but what on earth does it mean?

Essentially the insects you see in the cloud by the water are at one of the latter four stages of life – egg, nymph, dun and spinner. The first two stages take place in the water, mostly out of sight, while the third and fourth are played out in the air for all to see.

The dun is the olive you can see hovering above the water, flapping his or her wings for all he is worth as he keeps up with the pack. He is, in human terms, a maturing adolescent, just a few hours or at most days old. The pack instinct is part mating ritual, part holding pattern while the body matures and morphs into the next stage: the spinner. Even in the world of drab olives, becoming a spinner equates to a new level of attractiveness – your tails get longer (truly!) and you’ll be a much brighter colour than your previous dun camouflage. This heralds a brief flurry of sexual activity.

Spinners. I have no idea how they got their name. Maybe it describes the mating dance when the pair flies up in unison and then hovers for a moment at the top of the climb before relaxing their wings to spin down on the air. Maybe it is because in olden times people thought the long trail of eggs was something akin to spinning yarn. Or maybe it is the dead insect circling on the current. Whatever the reason the female spinner, ready to lay her eggs, is brighter than in her maiden form. Clearly the consummation brings colour to her wings and body. The egg-laying is a bittersweet moment to watch. On the one hand it is the proof that a new generation is on the way, but on the other that the insect will be dead in a matter of minutes or a few hours at most.

Some days on the river I will see one type of insect to the exclusion of all others, but today was one of those days when the diverse population was out in force; good news for the ever-hungry trout. There is not a lot of nutrition in a tiny insect, even for a trout, so it’s all about the effort/reward equation. A huge fat mayfly – the size of a dandelion head – is worth that extra effort, but the tiny corpse of an olive a gentle slurp. Somewhere in between is the impregnated female, stuffed with energy-rich eggs. The latter is so attractive to fish that fly tiers will add a tiny wrap of yellow thread to the underside of a fly – no more than an eighth of an inch long – to represent the egg sac.

There are dozens of species of fly to be seen. They make their lives on the river, but ultimately the eggs will be laid in one of two ways: on the surface or beneath it. For the angler and casual observer it is the surface layers that are the most interesting, especially the sedges. Sedges, or caddis, are big flies in the general run of a chalkstream. Not as big as the mayfly, but four or five times the size of your average olive. They are very much summer creatures, present beneath the current all year but hatching only in June, July and August. If they look like anything else, it is the common household moth with its wings folded in to create a tent over the body. If that sounds clumsy you would be right. Sedges are clumsy; the worst fliers and worse still at landing. Their approach to the river surface will look fine, but come the final few inches, instead of swooping gently down to clip the water to allow the surface tension to draw the eggs from her body, the female caddis will crash onto the water. Alerted by the commotion, trout from many feet away, even facing in the opposite direction, will turn and make a grab for the egg-laden wreckage. The smaller olives are, by comparison, incredibly delicate, getting within a fraction of an inch of the water before depositing their eggs.

For the angler tying on a sedge imitation this is a moment sent from heaven. There’s no delicate cast required here. No, a splashy cast will do as well, if not better, and the eager trout will do all the work to grab the fly. The olives are a different matter. You will need your thinnest line, your tiniest fly, your most accurate and delicate presentation. And even when you get it perfect, the languid trout, with time to weigh up all the options, will as often as not reject your offering.

It is relatively easy for the sub-surface egg-layers to go about their business unobserved, but the big problem is getting through the surface tension of the water. An insect with wings is quite bulky; it has a large surface area that is gripped by the water. Just sitting on the top and hoping to paddle their way underwater will not work. They need purchase and they find this from the reeds, stones and tree roots emerging from the water. As I pushed upstream on that July morning it was the perfect time of year for the blue-winged olive. And sure enough there they were with their drab olive bodies and translucent blue wings, arrayed along the length of the upright dark green reeds that gently swayed in the margin. Unfortunately there is an unusual predator that lies in wait.

As I watched the olive closest to the water edge down towards the film, and as she forced her body into the water, I could see the six tiny legs straining on the reed, the little suction caps on the feet giving her the leverage required. But in this moment of supreme effort it is the misfortune of the olive that the European eel chooses this very time of year to begin its downward migration to the sea. After ten or fifteen years in a muddy pond Anguilla anguilla heads for the Sargasso Sea, but before the ocean the river provides a welcome source of food. In the shade of the reed it is hard to see the eel going about his business, but in the early morning or late evening you will surely hear them. It is a slurping sound, a bit like a child sucking up the last of a milkshake with a straw, as the eel quite literally sucks the insect into his mouth at the very moment it is caught by the surface tension.

Fortunately there are many more olives than eels to consume them, so very soon the sunken spinners are laying their eggs beneath the surface. These then drift slowly down on the current to lodge in the stones, silt and general debris of the riverbed where they will remain for week or months until they become nymphs and embark on the next stage of life. I am not sure if the spinners themselves are able to hold their breath or even breathe underwater, but it probably does not matter. The time is short between submersion and being spent, namely eggs laid and becoming a semi-lifeless body, tumbling downstream on the current. The spinners that lay on the surface fare no better, collapsing exhausted on the surface, the job done. At first they lie on their sides, with one wing up, but as the life seeps away the other wing collapses and the end finally comes with convulsions that cause the water to ripple outwards around the insect until it stills.

Trout are no respecters of death, and sure enough, just off the main current, in a back eddy I came across a confident trout cruising in the slack water. With his back out of the water and his body submerged to eye level he languidly circled around, his mouth open, the flow of water carrying the spent spinners down his throat. This is the ultimate effort/reward equation and he keeps at it until the surface is cleared. Above him the duns, newly hatched, buzz in the air but he pays them no attention and the insect mortuary empty, he fins down to the deep to await the next funeral cortege.

A chalkstream in summer – June and July – is when it is most alive. It seemed that every step I took that morning, in the river or on the meadows, brought a new discovery. Above the shallows, on a dead branch, a kingfisher waited impatiently for the fry to move into the shallow water as it was gradually warmed by the morning sun. I am not sure kingfishers are really impatient, but the way they cock their head back and forth makes it look that way. I am certain the head-cocking is just to change their angle of vision so that they can see through the surface glare to catch sight of the fish, but for whatever reason, once locked in on the fry a rapid blue streak flashes from branch to water and back again in an instant. Holding the fish crossways in his beak the kingfisher raises his head, straightens his neck, turns the fry head-first and swallows it whole.

With a shake of his feathers, the watch will resume. This is likely to be an all-day affair, because the more the sun shines, the warmer the shallows will become and the more fry will appear in darting shoals. And the kingfisher is on a mission to feed. Somewhere along the bank, in a spot I was yet to locate, was a nest burrowed into the soft soil. In that nest would be maybe up to half a dozen chicks, each of which needs a dozen or more fish a day. That is getting on for a hundred fish. I watched our impatient friend catch four more and then left him to it, making a wide circle around the shallows to leave his hunting ground undisturbed.

By now the geography of the river and the meadows was starting to make some sense, and as I waded upstream the structure of the place began to arrange itself before me. The main river was the spine. Coming in from the left was a bourne, a small stream that only flowed in any significant sense during the winter and early spring, so by now was near to dry. It would remain so until the autumn rains. Cutting off at a sharp angle to the right, heading due north for most of its run, was a carrier, a channel dug by hand many centuries ago whose sole purpose was to flood the meadows from February to May. Now abandoned and choked with overgrowth, the carrier was clearly once pivotal to the water-meadow system. As the channel that moved the water out of the main river across the meadows it had leats or ditches that ran off at regular intervals on both sides as conduits for carrying off the water to flood the fields. But in an arid July the leats were dry and hidden by the summer meadow grasses. Come the winter they would reveal themselves.

As I pushed on up the river the sun burnt off the cloud; it was getting warm but I still had two more things to find: the Drowners House and the brook. Wading in gin-clear water under an azure blue sky is hardly the toughest job in the world, especially in a chalkstream like the Evitt that has no great incline to it. It doesn’t race like a tidal river or rush in torrents like a mountain stream; rather it glided across the face of my waders at a gentle walking pace. Looking upstream from where I was standing I could see a full 300 yards of river ahead, and I’d be hard pushed to swear that I could see a difference in height. In fact I knew that the source, 30 miles from the sea, is only 85 feet above sea level, so that is no more than two inches’ drop in every hundred yards. For potomologists – those who study rivers – this is just about as benign a flow as a river can have.

This is a floodplain that is almost as flat as the river that flows through it, and it was only in the far distance, at least 3 or 4 miles way, that I could see the sheep-grazed downs that gradually rose to a few hundred feet. Long, long ago, in the ice age, the river valley was carved as a shallow ravine, but gradually, over millennia, the water flowing to the sea had left soil, silt, gravel and sand behind after the floods of winter, creating the flat plain on which the water meadows sit today. But nature did not do this all alone; man played his part. It is the conjunction of water with meadows that makes this such a very special landscape. There are meadows the world over, but in very few places has man harnessed the seasonal floods to irrigate and protect the grassland for the sole purpose of making the sward grow faster, lusher and more nutritious for cattle to graze. This ancient agricultural practice has, by chance and unintended consequence, created a home for a unique collection of creatures that are my constant companions.

Through a gap in the reeds I thought I spied what looked like the Drowners House some way across the meadows, with a bedraggled thatched roof covered as much by wild grass and weeds as by darkened straw. Heading for the gap to haul myself out of the river I crossed the path of a water vole swimming fast along the edge of the reeds, hugging the margin for protection. For such small creatures, seemingly so ill-adapted to water, they really can swim fast. In the water there was no way I could keep up in my waders, and on the bank I’d need to maintain a brisk walk as they stretch out their brown furry bodies, nose poked up in the air while their legs paddle like fury.

But this one, in common with all water voles, can only keep up the furious burst of speed for a short while. Quite suddenly he stopped, gave me a look with those little black eyes and with a plop disappeared beneath the surface. Under the surface things are a mad scramble for the water vole. With all that waterproof fur they are naturally buoyant, and their tiny lungs are not suited to holding their breath for long. But he had chosen to dive at this spot for a purpose. Beneath the water he wove between the roots of the reeds, heading for the bank. I could track his progress by the muddy trail he was leaving in the water until he reached the entrance to the burrow. At the tiny hole – no bigger than the size of an egg, just above water level and shiny from constant use, he stretched out the hand-like claws of his front legs, pushed them into the soft soil and using the purchase, squeezed himself inside the burrow.

Like the kingfisher, these are the breeding months for our water vole (Arvicola amphibius), which is now probably into its third or possibly fourth litter of the year, having started back in March. In the burrow, lined with dried grass torn and gathered from the bank above, anywhere between five and eight tiny voles, no bigger than your thumb, will be mewling for food. Back and forward go the adults, for anything up to eighteen hours a day. Fortunately they are pretty promiscuous in their diet on the herbivore scale. Little tooth marks on the reeds and sedges are easy to spot. Wild mint and watercress are chewed with relish, but of all the things it is wild strawberries that they fall on like mammals possessed. But really they will eat anything; the family demands it.

Doing the maths, you’d think that we’d be overrun by water voles by June – after all they are not great travellers and this one nest will have produced fifteen offspring by now. The truth is that being born a water vole is a high-risk incarnation. First, the weather might get you: lengthy bouts of bad weather, or worse still an ill-advised burrow that gets flooded. Inside the burrow you might be generally safe, but the common brown rat or worse still a stoat or mink will make short work of you and your family if you’re discovered. Once outside you are assailed from above and below: owls, buzzards, otters and pike are just four of the predators who see you as a tasty morsel. If you make it to the semi-hibernation of winter you have done well.

By now it was getting a bit hot for trudging across rough meadows in waders, so I took a direct line to the Drowners House, stumbling on the way into what were most likely carrier ditches, still soggy at the bottom beneath the tangled grasses. Ducking down under the oak lintel of the doorless entrance I entered the cool of the house. With no windows it took a few moments for my eyes to adjust to the dark, while some streaks of light came through the holes in the dilapidated thatch, illuminating the river that ran beneath the ragged floorboards. A house with a river running through it for no apparent purpose? It could only be for the drowners.

The drowners are long gone, the purpose for their livelihood disappearing when modern agricultural methods consigned the water meadows to history. But for four centuries these were the men who regulated the flow of water from the river, through the drains and carriers dug across the meadows, to quite literally ‘drown’ the late winter and spring grasses in water. Warming the soil and air of the meadows – grass grows at 5°C, chalkstream water is 10°C – plus all the nutrients the water carried with it, was the perfect way to get cattle grazing earlier and thus create heavier crops of hay. Of course all this came at a price in terms of working conditions. Obviously the times when the water levels needed most adjustment, hourly and daily, came when the weather was most foul, so the drowners built these houses. They built them over the water for the same reason they drowned the grass – warmth.

I didn’t need to take out a thermometer to check the temperature inside the house today; I knew it would be exactly the same as the water – 10°C. The thick triple-skinned red-brick walls, damp from the foundations in the wet land, helped keep the place the same temperature all year round. Today I was grateful to find it a full 10° cooler than in the sun outside, but I doubt nearly as grateful as the drowners were when the mercury fell below freezing in winter. Today, other than the house itself, there is not much evidence of the drowners’ tenure. There are soot-blackened nooks hollowed out in the brickwork as candle-holders and some initials carved in the oak beams, but the current residents are mostly house martins that have coated the walls with white guano from their nests in the rafters above.

I found myself a handy log, placed it up against the hut wall and sat down to contemplate my options. To say the river and meadows were in crisis would pitch it too strong. Severe neglect was closer to the truth; a river caught in a spiral of decline. For all the beauty of the river and the wildness of the meadows the creatures were in retreat. With every year that passed the spawning grounds were growing fewer as the streams and carriers progressively became blocked. Along the banks the scrubland was encroaching, eliminating the wide open spaces that natives like the water voles require. In the meadows, without proper grazing, the meadow plants were being crowded out. Untended, the clear, fast chalkstream waters of the floodplain would revert to a swampy morass, with insects like the olives and mayflies disappearing.

It could be saved, but was it worth saving? The answer had to be yes. The question now was how.

^* I have no hard or fast rule about what to do if you don’t reach hard bottom. Generally if I am still sinking when the gloop reaches my waist I rapidly turn tail to heave myself back onto the firm bank with a fair imitation of an arthritic walrus.