Many anglers are aware that the (North American) Signal crayfish are a non-native, invasive species and pose a significant danger but then warned they could be prosecuted if they trap and remove them without a licence, so why this contradiction?
Surely, if you’re faced with an invader that carries a disease known to be lethal to the White-clawed crayfish and one that in general, is an unremitting aquatic mobster, any means of getting them out of the waterways is a good thing, right?
Well, the answer is an unequivocal ‘no’ and there are good reasons why this is so. The fact is, a Good Samaritan whose genuinely held aim is to try and protect our indigenous population by arbitrarily killing the invaders, might instead, be doing more harm than good.
In the UK, there is only one indigenous species of crayfish; the White-clawed, which is dangerously vulnerable to the transmission of the deadly crayfish plague carried by the Signals. Apart from the disease issue, the Signals burrow into banks causing collapse, predate on invertebrates, fish eggs, fish and vegetation.
They are fast breeders and they rapidly colonise and dominate new waters. They also grow faster, are more tolerant of a wider range of conditions and are more aggressive than the endangered White-clawed crayfish meaning they easily out-compete them.
So why must there be restrictions on trapping and dispatching of Signal crayfish? Let’s look at the reasons why this activity is requires regulation and licencing.
1. Any trapping creates the potential for the inadvertent use of unsuitable equipment which could harm or kill other aquatic species. For example, you’re breaking the law if you recklessly allow water voles to drown in inappropriate traps or if you place traps near to water vole tunnels. Licenced trapping ensures approved traps are used because each of them will have an identity tag.
2. It’s also important to know that White-clawed crayfish are a protected species. You can only trap them for scientific purposes.
3. Signals are so aggressive; the adults eat their own. Larger Signals predate on the smaller individuals in a colony so while their breeding habits are robust, it has been proven that leaving the adults in place helps to control population numbers. Many traps are biased towards capturing big males meaning predation of the young is actively reduced when the adults are removed which leaves more juveniles to accelerate the natural procreation process even further. This obviously makes the situation even worse.
4. The crayfish plague can be easily spread, so taking Signals out of their ‘home’ environment could inadvertently result in the disease being introduced to other non-infected areas. That’s why, for example taking them home as aquatic ‘pets’ is illegal. Another consideration regarding spread is that the disease can be carried on wet clothing or equipment so any interaction with Signals at one location could see it easily transported to another. On its own, it’s a perfect illustration of why the Check, Clean Dry campaign is so important.
The government website pages which cover licensing for crayfish and other species, are constantly being updated and will reflect any changes to this status when appropriate. They will also reflect any updates or additions relating to other species, including, potentially, Chinese Mitten Crabs.
One final piece of important information; licences to trap Signal crayfish are issued by the Environment Agency at the time of writing (July 2022). They are not currently processing applications for personal consumption – however licences for fisheries management purposes are available.
So, when all is said and done, what do you do if you know there’s a burgeoning Signal colony in a water near you? Firstly, if you inadvertently catch one, perhaps while innocently fishing, and are a 100% confident of its identity then you can responsibly remove and dispose of it. However, if you are in any doubt if it is a signal or a white-clawed crayfish you should put it straight back. This is consistent with the non-native guidance on the gov.uk which states ‘If you accidentally catch a listed crayfish or crab and can humanely kill it, you should do so. You must not take it home live. If you cannot kill it humanely, you can release it immediately back where you caught it’
From there, the Trust’s recommendation is simple: Contact the Environment Agency as soon as possible on 0800 80 70 60.
And always follow the information about Check, Clean Dry on this link it also includes more details about Signals and other invasive species.