Crayfish: introduction

What are crayfish?

Called crawfish in the US, they are freshwater crustaceans related to lobsters, and there are two main species in UK – the native white-clawed crayfish (Austropotamobius pallipes), and the non-native American Signal crayfish (Pacifastacus leniusculus), which was introduced to Britain in the 1970s via dedicated farms, and subsequently escaped. There are a few other introduced species but they are not very widespread.

 

UK-native white-clawed crayfish (top), and the American signal crayfish (bottom). The signal crayfish is bigger and has a small blue or white patch at the joint of the claw, and the claws are red underneath.

Signal crayfish are so called because they have white markings on their knuckles, similar to flags used by signalmen. Signal crayfish are bright red on the underside of their claws which makes them easy to identify and distinguish from the native crayfish. They can be up to 25cm long with claws extended. If you’re not sure whether what you’re looking at is a Signal or a native variety, look for the red claws – a sure sign that you’re looking at the Signal variety.

Trapping for food in the UK only involves the Signal species. The native species is now becoming rare. Both species live on the beds and in the banks of streams and rivers and are omnivorous, eating mainly dead creatures and plant debris.

The Signal crayfish can walk overland to establish itself in new waterways, and is now widespread throughout Britain.

Signal crayfish displaying the tell-tale red claws

What are the benefits of catching crayfish?

First – getting food from the wild is always a good idea from an environmental perspective (unless we deplete the resource – but this isn’t an issue here, as we’ll see later). Wild food requires no pesticides, fertilisers, hormones or genetic modification – in fact, no ecological interference at all.

Not only are they delicious to eat, but they are also nutritionally good for you – containing a good amount of high-quality protein and essential vitamins and minerals.

A significant benefit is in reducing their numbers. The invasive American Signal crayfish is causing problems for both their native cousins and for British waterways. They out-compete their UK native counterparts because they are bigger, their eggs hatch earlier in the year, females lay up to 500 eggs (the native species lays around 200), and they are less fussy about what they eat. Also, the signal species carries a fungal disease (Aphanomyces astaci, commonly called the crayfish plague) that kills the native species (it’s not at all harmful to humans though). The American species burrow into the banks of rivers and streams to build their homes, causing erosion of the river banks.

The best way to make a significant impact on Signal crayfish populations is in a closed body of water like a lake or pond, where in-migration is limited. It is hard, particularly with small harvests, to have a big impact on crayfish populations in rivers, but every little helps!

Boil crayfish, then leave to stand for 10 minutes.

What can I do?

Buying crayfish

If you want to eat crayfish without catching them yourself, then you can buy UK-trapped crayfish. It’s worth noting that most crayfish sold in the UK is imported from China (even if it says ‘produced in the UK’ which they can get away with due to the flavouring process in the UK). So be aware of where you are buying from and try and support local trappers who are trying to keep the invasive species populations down.

Trapping crayfish

There are bylaws covering the trapping of crayfish, and what you can do depends on local circumstances – especially if there are native species in your area. Contact the Environment Agency to ask about your local circumstances. You will need a licence from the Environment Agency and tags on your trap for it to be legal.

You also need the landowner or waterway owner’s permission to trap crayfish.

Make sure you check your crayfish traps regularly.

The Environment Agency’s concerns are that if people are allowed to catch crayfish for food, they might be sold, and because there is money to be made, some people might ‘seed’ rivers and streams that don’t have the signal variety, so that they can be harvested in the future. We share this concern, however, the Signal crayfish is now so widespread and in such large numbers, combined with the fact that it takes so long from ‘seeding’ to actually being able to harvest crayfish, that it is a very unlikely and unnecessary activity.

We encourage responsible trapping – either for your own consumption or for selling. This includes being very careful with what you catch – and not releasing it into other waterways. And also never ‘seeding’ or purposefully introducing Signal crayfish into waterways or lakes.

You can buy crayfish traps – and make sure you get the licence tags from DEFRA.

You need a licence to keep crayfish in this country – see DEFRA’s website – in case they escape into the wild. Signal Crayfish are so prolific now that it isn’t necessary to farm them, so this factsheet assumes that you’re not going to keep them, you’re just going to catch them from the wild.

Don’t put any you’ve caught into ponds or other bodies of water temporarily, as they could escape and colonise an area that doesn’t have them.

You can make your own trap. You can make a cylinder with chicken wire, up to a metre long, and bend the ends over to form a cone that crayfish can climb into but not out of. You can do the same with willow (see photo). Exact dimensions will be on your trapping licence application form from DEFRA.

You can make your own crayfish traps using wicker or wire mesh.

Trapping crayfish is mainly a summer activity. In winter, they will be mostly hibernating in the river banks and may be a little trickier to catch.

The trap shouldn’t have an entrance of more than 95mm, because if there are otters in the area, they could get caught. You can get a hefty fine if you are caught using these illegal traps. If you have some already but the entrance is too big, you can make it smaller by following the guidelines here.

Bait the trap with something tasty (like a fish-head), plus a brick to weigh it down, then put it into a stream or lake you suspect has crayfish.

How to catch a crayfish.

It is very important that your trap is well secured, you may want to tie it to something stable on the bank like a stake or tree. The main damage caused by crayfish trapping is from traps getting washed away and lost, these being a constant threat to wildlife on the riverbed, trapping not just crayfish but eels and other creatures.
Check in a few hours, or up to the next day. Anything other than signal crayfish, let go, and don’t leave a trap in a watercourse for more than 24 hours unchecked, in case something other than a crayfish gets trapped in it.

If you catch any native species, let them go – and report them to your local Environment Agency. In fact you shouldn’t be trapping there if you catch any native species, as they only occur where there isn’t an established Signal crayfish population.
Even if you catch small signal crayfish, don’t put them back (in fact it is illegal to put them back, once caught). The Environment Agency in Scotland have urged fishermen to kill Signal crayfish on sight.

Take them out of the trap (keep fingers away from their pincers – although if they do pinch you, it doesn’t hurt that much apparently!), and keep them in tubs of tap water for a couple of days to purge them of any food in their intestines. Be sure to change the water regularly or put them in a bath with the tap running as they can easily run out of Oxygen and die if left in stagnant water, or simply keep them in a chiller with some ice blocks. You can also just give them a good wash and use them straight away.

A cooked crayfish looking very much like a small lobster

Cooking crayfish

Boil a large pan of water and tip them in – they are killed instantly. Bring back to the boil, then turn off the heat and leave in the hot water for another 10 minutes to cook in the residual heat. They turn pink and float when they are cooked, and look like mini-lobsters (which they are).

The commonly eaten parts are the tail and the claws, but all except the guts is edible and worth eating.

Pull and separate the head and tail. Pull off the legs, then grab the end of the flesh sticking out of the tail casing and pull. Sometimes there will be pink eggs – you can eat those too. But give it a bit of a rinse to get rid of all traces of intestines and food (take the black line out the middle of the body – thats the guts). The most flavourful part is the shell body – great for bisque, stock or ‘crayfish butter’.

For the muscle meat from the claws, gently crack the shell with your teeth or a gentle hit with a hard object. Grab the end of the flesh and pull it out of the claw.

You can serve with rice, toast, mayonnaise and/or any number of sauces. It looks and tastes a bit like prawn. There are plenty of recipes out there. For a meal for one person, you’d probably need the meat of 5 decent sized of them. If crayfish are present in that stretch of water, you can easily catch 10 in a trap at the right time of year.

Traditional Louisiana-style crayfish ‘boil’.

Thanks to Bob Ring of Crayfishbob for information.

 


The specialist(s) below will respond to queries on this topic. Please comment in the box at the bottom of the page.

Bob Ring, or ‘Crayfish Bob‘ is on a mission to remove Signal crayfish from UK waters and put them on people’s plates. He set up Crayaway crayfish removal service and has been trapping crayfish for over 15 years. He founded the National Institute of Crayfish Trappers, who aim to provide an environmentally sound legislative framework, to support research and development and to promote the trapping and consumption of non-native crayfish to assist in the conservation of freshwater habitats and species.


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