Spring doesn’t start properly for me until I’ve caught a trout on my local River Usk in South Wales. That only becomes possible when thousands of insects collectively decide to crawl out from under the stones they have called home for several years and swim to the surface to begin their brief adult life. As they do this, they provide a vital food source for trout and young salmon, either en route to
the surface or during their rapid transformation from larvae to elegant mayflies in the surface film.
Trout anglers, as well as trout and baby salmon, wait eagerly for this large dark olive (Baetis rhodani) hatch in late March or early April. The first hatches of the year start at lunchtime on warm sunny days and can last no more than 15 minutes, stopping as suddenly as they began.
When they really get going, there can be hundreds of olives floating down each pool in the river like miniature yachts, their wings held aloft as a mainsail, as they prepare for take off. The river comes alive with splashes and sucking noises as the fish feast on this bounty. It is a carefully timed relationship that has developed over millennia in our streams and rivers.
Because thousands of olives hatch at the same time, most of them evade the trout and gather for dances in the air alongside the river, choosing a mate and then laying their eggs on the water. Sand martins and swallows gorge on them after their recent return from Africa – another vital confluence of lifecycles.
The appearance of stomping wagtails along the water’s edge is often a sign that a hatch of olives is about to begin. They ambush the mayflies in a hectic flutter just as they are in the first few feet of their maiden flight. It’s worth keeping an eye out for the white-throated dipper, too, which will bob up and down on a boulder before plunging underwater to catch the insects as they emerge from among the stones.
Kingfishers will be about as well, their iridescent dart-straight flight taking them from nest to fishing perch, on the hunt for minnows and trout fry. Earlier in the morning, otters will have slipped through the pools to snatch a fish for breakfast.
All of this life relies on the emergence of these insects. Watching this spectacle each spring reassuringly confirms to me that winter is over and the river’s natural cycles are still functioning normally, supporting the lives of millions of creatures.
But in all too many rivers, these early hatching Baetis no longer emerge and no longer provide food for fish and birds, and so these complex webs of life collapse. It could be that the flows are too low in the summer because water is being sucked out of them to irrigate fields, flush toilets and wash cars. The spaces between the stones where the insects live might be filled with tonnes of soil that has been washed in from a potato field, or from riverbanks eroded by cattle. The water quality may have declined due to sewage overflows or farmyard manure, or if oil and chemicals were tipped into storm drains.
Many of our rivers have quietly died a death of a thousand cuts from a combination of all these things and others. All of our rivers suffer to some extent from a number of these ailments. More than 75 percent of rivers in England and Wales have not yet achieved Good Ecological Status, which is required for all watercourses by the EU’s Water Framework Directive by 2015.
Rivers suffer because they have so many uses: they provide water for homes, industry and agriculture; they power mills and turbines; they flush sewage and rubbish away; they drain the land and they provide a place to play, to swim, to catch fish, to mess about in boats.
We have, over many generations, taken advantage of rivers’ vast generosity. We have strangled them with dams, encased them in concrete, overwhelmed them with storm drains, poisoned them with cocktails of chemicals and faeces and sucked them dry in summer.
Although they will still sparkle and burble – it takes a lot to stop rivers doing that – many of these vital arteries in our landscape have lost their vim and vigour. It’s hard to tell this from a casual look at a river – unless of course it has dried up completely or is obviously full of raw sewage – and this can make people complacent because the water looks so attractive it is impossible to imagine that there is much wrong with it.
River health check
To find out how it is really doing, we have to inspect it a little more closely. The best way is to look under submerged rocks. Does the water flow through the gravel, or is it choked with silt? The abundance and diversity of insects hiding under stones is an excellent indicator of the overall health of the river. You can see for yourself: have a rummage under a few stones, ideally with a small net positioned downstream to catch dislodged insects.
Thousands of people volunteer each year to monitor their rivers in this way, through the Riverfly Partnership’s Anglers’ Monitoring Initiative. By sampling a number of points along the river, these amateur scientists can pinpoint polluting farms or sewer overflows. A water quality chemical sample only tells us what was flowing past on that day; an invertebrate sample provides a comprehensive check-up on the health of the river.
In recent years, some rivers have received special care from a rapidly growing network of river trusts that nearly covers the whole of the UK. Set up mainly by anglers, but run as charities for the public benefit, these organisations are taking action to reverse decades of mismanagement and complacency. They are fencing tributaries to keep out cattle, removing dams and weirs, advising farmers about better soil management and restoring natural riverbank habitats.
For example, the Wild Trout Trust provides advice and technical assistance to groups of volunteers and anglers who want to restore their river habitat to good health. This work is bearing fruit and many rivers are improving, but these organisations need more funding and volunteers.
Your local river needs your support. Get to know it and find out how it’s doing. Visit it regularly throughout the year to see how it changes with the seasons. Take a note of the birds and flying insects you see. Go for a paddle and look under the stones. Get a group together and volunteer with the Riverfly Partnership. Find out if there’s a river trust in your area and if there isn’t, set one up. You and your family can also help to protect rivers by cutting down on water use and avoiding the use of damaging chemicals.
Getting to know more about your river and its ways will enrich your life immeasurably. Fishing has taught me most of what I know about rivers and has given me many treasured glimpses of their unique rhythms and processes.
It’s hard to put this into words, but Roderick Haig-Brown has a good try in his wonderful essay To Know a River: “A river is never quite silent; it can never, of its very nature, be quite still; it is never quite the same from one day to the next. It has its own life and its own beauty, and the creatures it nourishes are alive and beautiful also. Perhaps fishing is, for me, only an excuse to be near rivers. If so, I’m glad I thought of it”.