Life of a Chalkstream. Simon Cooper
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