This article covers UK law and advice on catching and eating Signal Crayfish.
First lets cover the law as that is what I'm sure is on the minds of everyone who is thinking of having a go.
It is illegal to trap crayfish without two things...
a) Landowners permission .
b) Consent from your governing body ie the environment agency
(this is not a rod licence) and is free to people who are using for personal consumption and is relatively easy to get with a small amount of info, the most important being your desired area to fish.
The environment agency take three main things into account when processing your application:
1) Is the same area populated by native crayfish species (if it is there is no chance of permission).
2) Previous permissions (unusually over fishing is not there consideration as they would be quite happy for you to eradicate the population but they are looking to be fair to avoid confrontation).
3) Your trap, advice on acceptable trap-sizes for trapping these are available on the environment agency's website these are set so getting permission to trap with home made traps is difficult as the native crayfish are generally three inches in length and the signal can be double that.
This is the hard bit so be sensible who wants them gone? The environment agency, so ask the question in my experience they are extremely helpful and will be quite happy to point you in the right direction.
Don't however just except some grid references and apply, get out there be logical about suitability of the spot for you ,a three mile hike across fields is not ok for all of us and don't be afraid to go back to them if its not right for you also take some time to take notice of the wildlife surrounding your permission otters have been killed by being trapped trying to raid traps while the agency will try and point you in the right direction they can't be expected to know everything about every stretch of water.
And lastly you will be asked how many traps you would like to use, be sensible think about your factors
Time: Aprox 30 mins to set a trap correctly taking into account traveling to and from
Need: How many of you are eating them with most shellfish there best fresh so catching more than you need is pointless.
Cost: a good shop bought trap can cost up to £ 25 if your going to the trouble of getting permission then the cheep folding net ones at not ideal for continous setts ,and if you are making your own the cost in time alone will be large in itself so getting permission for 50 traps is just not feasible. My recommendation is two traps per adult eating and one per child.
Once you have been issued permission tags for your traps these need to be secured to any trap you set. If you loose one or one is taken report it don't just ignore it, make sure you have a note of your tag-numbers (these are registered to you and marked clearly on your tag)
There are two other things to be aware of
1) Once you trap any invasive species it is illegal to release it again
2) Transportation of crayfish in water is not allowed you have to transport them dry (the crayfish can carry a disease which is harmful to our native crayfish species so the environment agency do not want potentially contaminated water to be transported).
The target species Is the signal crayfish this is a non native species and has for different reasons been responsible for the decline of our native white clawed species the biggest of these being that the signal crayfish carries the crayfish plague which themselves are immune but our native species are not and the spores can last for 20-30 days in damp conditions without a host. Taking this into account we ourselves have to be responsible; good practices include thorough cleaning of any traps between use and trying to set traps in the same area over again by this I mean try not to take one trap two miles up stream and reset when first finding your hotspots on your permission start upstream and work down as you find your best trapping spots .
When setting traps look for places which may provide cover for the crayfish such as rocks, roots, etc. these areas provide cover for the crayfish and the algae which grows in these areas is also a food base for the crayfish. These areas also give the crayfish a good place to hide while hunting for fish fry and anything else they can catch and eat alive. Use your common sense setting a trap in the middle of a river won't give you good catches I try for overhanging banks with a depth of three feet I then tie ribbon to a tree to indicate where I've set traps to usually in a direct line but ten feet or so away from the bank as not to draw direct attention to the trap also be aware that you are likely to be getting wet .
Baiting Your Trap
Baiting your traps is a topic that in my experience comes down to personal experience I've read about people using cat food, hotdogs and all sorts of weird and wonderful things to tempt them into the trap one thing I will say is that they are picky eaters and in my personal experience fresh fish heads or guts are by far the best and fresh is important if its not don't bother wasting your time. Bait cages are far superior to bait jars just the fish feeding through the cage spreads the scent nicely, freezing bait blocks works well and makes good use of your fishing waste. Once you find a good spot in honesty over 48hrs a standard hall will likely to be 2-3 lbs but I have heard of 15lbs coming out of a single trap. I tend to leave set for 48 hrs but until you are knowledgable about your permission 24hr checking is needed
Unfortunately or fortunately depending on how your looking at it trapping is no quick cure for over populating crayfish and in fact you will find that at the start of trapping a new permission you will in fact increase the population as the fish caught will be the big males who are the bully boys who have been keeping the population down by eating the young. Spear fishing is much more effective for the decline of the population as you will generally spear in the shallows where the smaller females are hiding beneath the stones wilst the larger males stay in deep water and hunt fish, this is great fun and can be done without trapping consent from the environment agency as can netting, permission from the land owner is still required.
If you intend to revisit the same area for netting or spearing piling rocks will attract them into your desired area nicely and improve your catch.
One of the very important things to learn is how to tell the difference between the signal and the white clawed as you will be heavily fined if found removing the white clawed from the water. The easiest way is the claws on the signal are large and heavy, red underside with a turquoise or white patch on the upper side.
And are much thinner and longer on the white claw and of course the size is the main way the signal are generally double in size of our native species.
White-Clawed Crayfish (UK Native)
May grow to 12 cm (5 inches) long, although sizes below 10 cm are more common.
Signal Crayfish (Invading Species)
Are typically 6–9 centimetres (2.4–3.5 in) long, although sizes up to 16–18 cm (6.3–7.1 in) are possible.
Preparing to eat your catch
My personal favourite is strait out of the water over the fire on the tail of the fish there are scales on the very rear of the tail there is one shaped like a fan pull that back towards the head until you feel it snap and then pull strait back this will remove the nastys. If your taking your catch home leave them in a sack they will last longer than in water as they need the air you can keep them alive for a day or so without any problem but the longer you keep them the more you deteriorate the taste at this point you will need to purge.
How to Purge
My method is put them into a bucket pour salt on them and then pour water on them this will make them spew all of the toxins out leave them for only five minutes or so you don't want to kill them then pour out the salt Water and wash with fresh water several times discarding any which float to the top.
My ending comments are if you are lucky enough to be given a permission which I'm sure many of you will be and you come across our native white claw crayfish please report it yes this will probably end up with you losing your permission but the environment agency will undoubtedly find you another and I would happily give up any permission to give them a chance of repopulating.