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Urbantrout Diaries 6: Taking the Fight to Invasive Non-native Species

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A Hippo bag full of Himalayan balsam... A Hippo bag full of Himalayan balsam...

This month our intrepid urban angler has taken the gloves off (or rather put them on...) and is fighting back against the aliens...







In the course of exploring many urban rivers – often with the business end of a fly rod – I’ve found it a constant source of wonder that these once-lifeless waterways could have recovered so swiftly, and so successfully. Catching trophy-sized trout and grayling in post-industrial rivers flowing through the middle of Sheffield, south London or Sowerby Bridge is something that still hasn’t got old for me, and I suspect it never will.

But even whilst relishing the totally counterintuitive wonder of urban fly-fishing, a sense of deep disquiet has been creeping up on me. So many of these rivers, so recently brought back from the dead, are now at real risk of slipping away from us again. And this time it’s not the threat of pollution that’s putting them in danger, it’s the immediate prospect of strangulation by invasive non-native species (often abbreviated to INNS).

Although I’d heard of the so-called ‘Big Three’ – Himalayan balsam, Japanese knotweed, and giant hogweed – and even seen the first of these smothering the banks of the Wear in Durham during my college rowing days, I got my first real sense of the danger of INNS whilst researching Trout in Dirty Places on the Ballinderry River in Northern Ireland. Thanks to years of understandable neglect during the Troubles, when most people had other things to worry about, ten-foot battalions of giant hogweed marched down this lovely little river’s banks. Eventually the stands of massive, toxic plants became so thick that local anglers could hardly fish the river at all between May and September if they wanted to avoid third-degree burns inflicted by the plant’s sun-activated sap.

Later, in the parks and school playgrounds along the Afon Lwyd, I learned from the Wye & Usk Foundation’s Tom Richards that the best way of dealing with both giant hogweed and Japanese knotweed is spraying or injecting their stems with glyphosate - a process requiring intensive training and certification, which I’ve now taken myself as part of the Wandle Trust’s efforts to get on top of INNS in our own catchment.

But in the meantime, I’d started seeing those INNS everywhere. Literally everywhere.

Pulling HB on the WandleFrom Devon to the Dolomites, the Big Three seemed spookily focused on destroying riverbanks from above, while signal crayfish and mitten crabs tunnelled into them from below – all of them dumping silt straight into the local fish populations’ spawning beds. (Alarming recent research confirms that a kilometre-long infestation of Himalayan balsam could deposit as much as 10 tonnes of silt into your river every year). Meanwhile, across every media platform, headlines suggested that at least two species of so-called ‘killer shrimp’ might have arrived on these shores via rowing boats, kayaks or other water sports equipment – a reminder that biosecurity awareness really needs to cut across almost all sports and outdoor activities.

That’s why, when my publishers floated the idea of a tightly-focused handbook, containing all the information an ordinary member of the public might need to start getting organised and fighting back against this all-angled invasion, I didn’t take much persuading. With advice from key people in Defra, the Environment Agency and Ireland’s Central Fisheries Board, I put together a hit-list of 40-plus species and started to write…

About a year later, The Pocket Guide to Balsam Bashing – and how to tackle other Invasive Non-Native Species is the result. It covers all the worst and most actionable threats to the British and Irish environment, from Japanese knotweed, signal crayfish and floating pennywort to mink, invasive deer, grey squirrels, Asian longhorn beetles and a variety of pathogens like chalara (ash dieback) and chytrid fungus. It provides practical advice on what to do about all of them, including legal aspects and useful links to many organisations which may be able to assist your efforts. It’s the book I wish I’d had when I started out in river restoration.

And if it helps to stop the Wandle, Irwell, Tame, Torridge, or any of my other favourite rivers and landscapes (or yours) being strangled by INNS, I’ll consider it a job well done.

The Pocket Guide to Balsam Bashingand how to tackle other Invasive Non-Native Species is published by Merlin Unwin Books on 08 May 2014, priced at £7.99 and you can read a full review here on Flyfishing.co.uk shortly!




Theo PikeTheo is a freelance marketing, fly-fishing and environmental writer. He’s also Chairman of Trustees of the Wandle Trust, and founding editor of Urbantrout.net a website and eco-brand dedicated to urban fly-fishing and river restoration improvements.


Theo’s trailblazing book Trout in Dirty Places: 50 rivers to fly-fish for trout and grayling in the UK’s town and city centres was published by Merlin Unwin Books in 2012.

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