All about crawfish 

Or spiny lobsters if you prefer!

 

Why they are considered important, where they live and why we'd like you to record them!

Image by Sally Sharrock  

Recording crawfish

Crawfish (crayfish/spiny lobster, Palinurus elephas) are one of the largest crustaceans found in British and Irish waters and have suffered a dramatic decrease in populations in recent years. They have now been identified as a priority (formerly Biodiversity Action Plan, BAP) species because of the small numbers that remain.

In the last few years, there seems to be a revival in the population, particularly in the southwest of England.

One of our specialist projects, currently assuming greater importance than ever in light of that population recovery, has been to collect more data on crawfish in SW Britain and beyond. To date there have been a number of reports arising from this work all of which can be downloaded from this website.

An extract of the crawfish data is also available from the National Biodiversity Network Atlas (not including size or habitat data). 

We ask you to estimate the size of the animal (for preference this would be the carapace length, not the length of the whole body including the tail) when recording.

However, the animal SHOULD NOT BE DISTURBED and so we have provided a series of photographs for you to estimate the size compared to surrounding features. Recording this information should tell us whether the population is breeding on a yearly basis or whether the output of one or two good breeding years are now growing up.

"Very large" crawfish (carapace 16-20 cm)

Once animals reach this size, they are well above the minimum landing size (MLS) and are bold enough to emerge from the reef into the open.

Very large crawfish

"Large" crawfish (carapace 11-15 cm)

Once animals reach this size, they are above the minimum landing size (MLS) and may be seen out in the open.

Large crawfish

"Medium" crawfish (carapace 6-10 cm)

At this size, the animals seem to be bold/confident enough to be seen out and about. Only those at the upper end of this size -class are large enough to be legally fished (MLS is 9.5-12cm carapace length depending on area).

Medium crawfish

"Small" crawfish (carapace 3-5 cm)

These animals are too small to be legally fished  (MLS is 9.5-12cm carapace length depending on area) and seem to be generally found hiding rather than out in the open.

Small crawfish

"Tiny" crawfish (carapace 1-2 cm)

These animals are only about thumb-sized (the whole animal, not just the carapace) and seem to be generally found hiding either in a crevice in the reef or boiler tubes (the latter seem to be a favourite hangout!)

Tiny crawfish