Source: Scottish Natural Heritage

The first ever crayfish barrier' has been installed between two rivers in the south of Scotland.

A landmark in attempts to control the spread of North American signal crayfish, the barrier has been specially designed to stop them moving from one river catchment to another. It is the first time this approach has been tried anywhere in the UK or beyond.

Recent survey work on the River Clyde has shown that signal crayfish have spread into many of its headwaters, after they were first discovered in the river in 1996. There are now fears that they might move into the neighbouring River Annan catchment, near the Beattock summit in south Lanarkshire. The Annan, which runs from Moffat in the north to Annan on the Solway coast, is one of the best salmon and sea trout rivers in the south of Scotland, and is very important to the local economy.

To tackle the problem, a partnership of bodies including Scottish Natural Heritage (SNH), the Annan District Salmon Fisheries Board, the Clyde River Foundation and South Lanarkshire Council have installed the custom-made barrier at a site close to where the headwaters of the rivers Clyde and Annan meet.

It is great to hear of someone doing something. It will be fascinating to hear how successful it is. Do please keep us informed, Editor.

However the spread of crayfish seems to me to be more willfully done by uninformed idiots who transplant crayfish into new rivers and areas for their own dubious benefit. Without a wholsale campaign to inform said idiots and others that it is illegal to do so and how damaging their actions are, the deliberate spreading of Signal crayfish is likely to continue.

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Newbie here:

I'm against invasive alien species in general and on principle (I shoot grey squirrel) but how, if at all, does this affect trout and salmon fishing?

Maybe it doesn't and my first, overarching, point stands but I'm curious to know if this affects fishing or just (!) biodiversity.

Thanks

Here's a taste: Asian Carp are now in several of the mid-western rivers in the US. Bye the bye, there are several utube clips, different rivers with the same thing going on.

Couple of them are a hoot as the guys are actually shooting them out of the air with bow and arrows.

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People put grayling, barbel and signal crayfish into the Clyde. You can legally catch grayling and barbel, but you can't catch crayfish. It's illegal to remove them from the water. If you do, it's then illegal to return it to the water. You must crush it.

The point being, if people are hell bent on taking these things to other waters for their own benefit, then they will. No law is going to stop them. So why not do the sensible thing and grant licenses to responsible applicants who will remove them from the water for food? The people who are illegally harvesting crayfish for the pot, from the Clyde right now, might then learn the importance of bio-security, and might comply. But right now it's being driven 'underground' with no way of regulating who is doing what. It's a bit like making it illegal to shoot grey squirrels and building a giant fence around a populated forest. Would that work?

I've watched elvers in their thousands ascend concrete walls, out the water, so this will have to be some big barrier to hold the crayfish back from doing what is inherent to them, migrating.

I personally dont think it can be stopped perhaps slowed until people give up and it covers all waters.
I can see it now they will end up introducing something that can kill crayfish and then it will become a problem of another sort.
You just have to look at what they did with maxi for rabbits are we any better off well by the looks of things up here it is even worse even if thousands are killed each year.