The non-native 'American Signal Crayfish' pose as one of the biggest problems that UK fisheries currently face. The rapid breeding of crayfish means that a small, manageable population, can quickly become huge, and begin to have  negative impacts at various levels;

 

 

•  American 'Signal Crayfish' have been known to prey on our native 'White-Clawed Crayfish', but perhaps more significantly, compete with them for food, territory and spawning grounds. Our native 'White-Clawed Crayfish' is no match for this invasive species, it being far larger and more aggressive. Consequently, they have driven our native crayfish almost to extinction. Only small populations still remain in the North of England and Wales. 

• Another impact 'Signal Crayfish' can have is the increased erosion and eventually the collapsing of lake and river banks. When the water gets below about 10 degrees, Crayfish burrow into the bank, creating tunnels up to 3 feet in length! This, over time, weakens the banks, leading to the gradual destruction of the river/lake banks, and puts any infrastructure bordering the water body in potential danger. Crayfish have even been know to tunnel through dam walls!

• American 'Signal Crayfish' are carriers of the 'Crayfish Plague' (although they're not affected by it). It is however, lethal to our native 'White-Clawed Crayfish'. The Crayfish Plague (Aphanomyces Astaci) is a virulent, fungal disease, that can quickly be spread amongst and between populations.

• American 'Signal Crayfish' are also known to eat the eggs of fish, thus having a negative effect of the recruitment within a fishery. This also reduces the amount of natural food that wold normally be available to fish in the water body.

• The rate in which 'Signal Crayfish' can breed is rapid. A small population can quickly become very large, and without the correct management, can get out of hand. The prolific breeding of crayfish is the key reason for them spreading between water-bodies, with populations quickly 'exhausting' the necessary resources in any particular site, giving the need to move on to the next, highlighting the 'invasive' nature of this species. A single female 'American Signal Crayfish' can produce 250 eggs at any one time.

• One of the most significant impacts that these 'pests' have is the impact on recreational fishing. They are known for eating anglers baits, tangling end tackle, and even removing tiny plastic hair stops from rigs! This occurrence is not a myth, and has even been captured on video footage before. Crayfish are known to take angler's hook-baits several inches into their burrows, rendering them completely useless as fishing baits. Whether the fishery is aware or not that this is happening, it undoubtedly has an impact on the catch rates of anglers, which suffers dramatically when a large population of crayfish is present. 

 

Watercraft Management  offer a removal service for 'American Signal Crayfish', using a combination of 'Fladen' and 'Fyke' nets, to suit any situation. We have a great track record, practically eliminating populations from target waters. We are fully licensed for the trapping of non-native crayfish from the EA (Environmental Agency). Crayfish removal can be carried out on any river, lake, pond or canal with the landowners permission.