Crawfish

Biology

Crawfish, also known as European spiny lobster, are a warm water species that are at the northern limit of their distribution in Cornish waters. Crawfish make rasping noises (creaks) which they are thought to use to communicate and warn other crawfish of danger (Buscaino et all 2011). Young crawfish are called ‘miracle fish’ by north Cornish fishermen. Unlike lobsters Crawfish are far more mobile and are known to migrate for large distances over the seabed. They are thus very vulnerable to being caught in monofilament gill nets (tangle nets) set on the seabed for Monk and turbot.  They are long lived animals living for at least 15 years. More research is needed on their reproductive patterns in our waters. ‘Berried’ females carrying eggs are found here occasionally but it is also thought that their larvae are carried here with warm water currents so stock recruitment may depend on the health of stocks in Brittanny, the Bay of Biscay and the coast of Spain. In the Atlantic Crawfish undertake migration inshore in spring to breed and offshore again in late autumn (R. Goni and D. Latrouite 2005). 

Stock Info

This stock is poorly studied. Catches and catch per unit effort declined massively between 1977 and 1996 after the introduction of monofilament trammel nets and tangle nets to catch crawfish off Cornwall. MMO landings data to Cornwall shows an increase in landings since the mid 90’s. Since 2016 CIFCA have been recording detailed landings infomation on crawfish. It appears that recent increases in crawfish reported in Cornish waters is due to a successful recruitment event. It is not known if more than one year of good recruitment took place. More research is needed. When this large cohort of juveniles reach the minimum landing size there is a danger that they could be over-fished before they have had a chance to reproduce.  

Management

There is a minimum landing size for crawfish inside the Cornwall Inshore Fisheries and Conservation Authority (CIFCA) district of 110mm carapace length. This is larger than the eu minimum size which is 95mm. Additionally any berried crawfish or lobster caught inside the CIFCA district (out to 6 nautical miles limit) must be immediately returned to the sea as close as possible to the area in which it was caught. CIFCA byelaw.

There is no catch limit or quota for this species, or limit on fishing effort in terms of number of nets or pots being used. 

CIFCA Lobster Crawfish and Crab fishing bylaw 2016 requires all shellfishermen (and divers) to hold a commercial fishing licence and a CIFCA shellfishing permit if landing crustaceans caught within CIFCA district. It also ensures that all fishermen submit monthly returns details on catch and fishing effort / gear used. This will enable CIFCA to have an accurate picture of shellfisheries in our district. There are also provisos that enable the authority to bring in additional bylaws to restrict fishing if it is necessary.

Crawfish (spiny lobsters) are a 'designated feature of conservation importance' in the Manacles Marine Conservation Zone (MCZ) and Padstow Bay and Surrounds MCZ. For both sites, spiny lobsters have a general management approach of ‘recover’ to favourable condition.  For each species of marine fauna, favourable condition means that the population within a zone is supported in numbers which enable it to thrive, by maintaining:

Capture Info

Currently most crawfish caught in Cornish waters are caught using monofilament nets (tangle nets or trammel nets) set on the seabed. They can also be collected by divers, a method that can extremely rapidly deplete stocks on key sites such as wrecks or reefs. Both methods combined led to a crash in crawfish populations during the late 1960's and early 1970’s. 

References