Tag: Rivers

Fishing for the answer

 

The aggressive and non-native signal crayfish with its distinctive flash of white at its claw joint. This voracious beast is driving our native species towards extinction. Picture from the Non Native Species Secretariat website.

As I mentioned last week, I came across a reserve for the white-clawed crayfish on a recent walk near Threshfield Quarry in the Yorkshire Dales where information boards explained the threat from its foreign cousin, the signal crayfish. The reserve was a small pond designed with the specific needs of the crayfish in mind such as places to hide from predators, the right food, and of course, no sign of the dastardly enemy.

This problem was mentioned by reader John Aston from Thirsk who listed it among a number of invasive plant and animal species affecting our waterways. He’d read my columns about the troublesome invader, Himalayan Balsam, which prompted him to get in touch.

On that note, you may remember that it was the appearance of Anna on The Great British Sewing Bee TV programme that sparked a whole series of columns on this particular invasive species. Anna had highlighted the issue by featuring the pretty pink bloom on an outfit she had created and I was rooting for her because not only was she exceptionally creative, but she came from our very own York. I watched the final last night and guess what? She won! Go Anna!

The white-clawed crayfish is our only native species of crayfish and populations have been decimated by its bigger and brasher American counterpart. This vicious marauder was brought over from the north-west USA in the 1970s and 80s to become a delicacy on fine dining restaurant menus.

Demand led to commercial farms breeding them, but what they did not take into account was that, unlike salmon and trout which, due to a distinct lack of limbs, obligingly remained confined to their ponds, these crafty crustaceans had legs and therefore were able to climb out of the ponds and amble to freedom. If they couldn’t escape over land then, thanks to their scarily big sharp claws, another option was to burrow into the muddy banks until they were beyond the boundaries of the farm. Failing that, option three was to scuttle into the water pipes feeding the pond (which they did to protect themselves from predators) to find that these pipes led somewhere, and so they kept on scuttling, ultimately finding themselves at the opposite end. With one splash they were frolicking in open water.

Once liberated, these prolific breeders began to make whoopee, kicking the smaller, more passive and less randy native white-clawed crayfish out of their homes, leaving them exposed to hungry otters and that other ‘liberated from breeding farms’ pest, the mink. But that was not all – the poor white-clawed crayfish were left with very slim pickings for food, as the greedy Yanks were always first to the table, and just for good measure they also infected their British counterparts with the delightful ‘crayfish plague’ for which they had no resistance due to the fact they’d never been exposed to it before. It was a crayfish calamity which is still having repercussions today.

Round of applause then for those short-sighted idiots who brought signal crayfish over here without a thought for the potential impact on our one and only native species. The scientific blinkers were on, wilfully ignoring past disasters caused by introducing invasive species into the country in the vain hope that all would be OK; that a crayfish wouldn’t think to use its legs to simply crawl to pastures new. How could that be? The American mink catastrophe was still at the forefront of many people’s minds too (brief summary – American mink were imported and bred for their fur. They also escaped their farms through inadequate security and a few well-meaning but dim anti-fur campaigners who thought setting them free was a good idea. Our now almost extinct native water vole would beg to differ).

There are some very hardworking organisations and volunteers who are desperately trying to help these threatened species survive, but unless the invasive predators are brought under control, it is highly unlikely that our freshwater crayfish or our water vole will ever recover.

So if on your travels you see a white-clawed crayfish reserve, also known as an ‘ark’, then stop a while and take time to read those information boards explaining what the conservationists are trying to do. And hopefully, one day, we will learn from our past mistakes.

One day.

Do you have opinions, memories or ideas to share with me? Get in touch with me using the ‘Contact’ button on the top right.

This column appeared in the Darlington & Stockton Times on Friday 25th and the Ryedale Gazette and Herald on Wednesday 23rd September 2026

Experts sowing the seeds of change

The invasive Himalayan Balsam is colonising the banks of our streams and rivers leading to erosion and the decline of native insects and plants. But experts have told me how it should be tackled

My plea for specialist advice on how to tackle Himalayan Balsam has borne fruit. Reader Janice Brabban owns some woodland near Darlington and was horrified to discover it had been invaded by the troublesome plant. She was having difficulty finding out the best way to deal with and dispose of it, and felt she hadn’t received consistent advice from the places she had tried so got in touch with me.

Thankfully, help has come from a proper expert, in the form of Chloe Lawrence, Invasive Species Project Manager at Tees Rivers Trust, who explained that there isn’t one single body with responsibility making the situation more complicated. “Landowners, under the Wildlife and Countryside Act, are responsible for ensuring they don’t spread onto other land, although they don’t have to eradicate them. Councils and local authorities are responsible for invasive species on public land, but not private land. There are also several government bodies, including the Environment Agency, DEFRA and the Non-Native Species Secretariat, all of which have different roles in areas such as prevention, early detection and management.”

She advises: “Himalayan balsam is relatively easy to manage by pulling it out by the roots, making sure the stem is snapped below the first node. It can also be strimmed or scythed, and there is even a biological control being used.”

Chloe acknowledges that although management is easy in theory, the plant is prolific across the UK. “Unless management starts at the source, ideally at the highest point of a watercourse, seeds will continue to spread downstream from upstream populations. Balsam has explosive seed pods which can spread up to seven metres, with each plant producing up to 800 seeds.”

But there is hope, because the Tees Rivers Trust has been awarded a £3 million National Lottery Heritage Fund grant specifically for an invasive species programme, which aims to establish a more unified approach.

Further advice came from George Winn-Darley, a member of the Yorkshire Derwent Catchment Partnership and the Yorkshire Esk and Coastal Streams Catchment Partnership, who is very familiar with our irksome bloom.

“It’s important that balsam is managed before it goes to seed,” he says, “particularly as the hot weather this year has meant it is seeding earlier than usual…The plants can be left in a pile away from any watercourses and will wilt down within a few weeks…They can also be burned on site, although I’d be particularly mindful of the wildfire risk across the UK.

“Seeds only remain viable for about two growing seasons, so if you can stop it going to seed for two consecutive years then you should be able to eradicate that patch…It is shallow-rooting and very easily pulled up by hand but if you lie it on the ground it is likely to root again so you need to hang it over a branch or something so that it dries out and dies which it will do very quickly. You can just knock the flower heads off before they start to create seed, cut it or strim it or just beat it with a stick to prevent it flowering and seeding…By and large you don’t see it in fields that are cultivated or grazed because those activities stop it from thriving.”

Balsam crowds out other vegetation on river banks, but dies back in frosty wether leaving exposed bare soil which is then washed away by winter rains causing the banks to erode, which also leads to water quality problems.

John Aston, from Thirsk, added, “Bees like it, and my beekeeping friends report that balsam honey is excellent. But most fishermen (and I’ve been one since 1963) loathe the stuff.”

John agrees with the methods on how to get rid of it but warns: “It’ll be back. All it needs is a seed on a walker’s boot or in an angler’s net.”

He lists other invasive species affecting our waterways, such as poisonous giant hogweed, knotweed, signal crayfish, demon shrimps, mitten crabs and American mink, all of which have thrived to the detriment of local flora and fauna.

Coincidentally, I came across a native white-clawed crayfish reserve on a walk near Threshfield Quarry in the Dales where information boards explained the threat from its foreign cousin.

But I’ll save that story for a future column.

Do you have opinions, memories or ideas to share with me? Get in touch with me using the ‘Contact’ button on the top right.

This column appeared in the Darlington & Stockton Times on Friday 18th and the Ryedale Gazette and Herald on Wednesday 16th September 2026