Fisheries Research Services is an agency of the Scottish Executive

FRS Marine Laboratory PO Box 101 375 Victoria Road Aberdeen AB11 9DB UK

tel +44 (0)1224 876544 fax +44 (0)1224 295511

enquiries@marlab.ac.uk http://www.frs-scotland.gov.uk

IntroductionFisheries around Scotland exploit the European lobster

(Homarus gammarus), and the edible or brown crab

(Cancer pagurus) and velvet crab (Necora puber). The

green or shore crab (Carcinus maenas) is also exploited

in some areas. The earliest records of edible crab and

lobster fishing date back to the 12th century. Initial

harvesting was at a subsistence level through hand

gathering, using ‘crooks’ and hoop nets, but the

development of baited traps (pots or creels) led to

exploitation on a more commercial basis. The Scottish

velvet swimming crab fishery is a more recent develop-

ment, but has expanded rapidly since the early 1980s to

supply southern European markets. Over the period

1997 – 2002, reported landings have been about 9,000

tonnes for edible crab (£9M value), 400 – 500 tonnes for

lobster (£4M value) and 2,000 tonnes for velvet crab

(£3.5M value). The fishery for shore crabs is far smaller

than the other crab fisheries.

BiologyLobsters and crabs are crustaceans. To a large extent, they

share a similar habitat, and are widespread around

Scotland, although velvet crabs are less common on the

east coast. Lobsters and velvet crabs are mostly found in

Lobsters and Crabs

rocky areas with reefs, boulders and large stones, while

edible crabs are found in these areas as well as on sand,

gravel and even mud. As with all crustaceans, crabs and

lobsters have a hard shell (carapace), and grow by casting

(moulting) this shell, and then hardening a new shell at a

slightly larger size. While immature, animals may moult a

number of times a year, and grow quickly, but once mature,

moulting is often only every one or two years, and growth

is slower. The size at maturity varies around the coast, but

is typically 120 – 130 mm carapace width for edible crab,

40 – 50 mm carapace width for velvet crab, and 80 – 90 mm

carapace length for lobster. Mating occurs while the female

carapace is soft (prior to the new shell hardening). After

spawning (in late summer or autumn) the eggs are carried

by the female under the abdomen until they are ready to

hatch. Female edible crabs produce up to three million

eggs, velvet crabs up to half a million, while lobsters

produce ten to fifteen thousand. Hatching normally takes

place in early summer, and the larvae are distributed by

water movements before settling to the seabed as miniature

adults in summer or autumn. Lobsters and velvet crabs are

rarely thought to undertake any movements over a few

hundred metres, but tagging studies have shown that

edible crabs may move up to a few kms a day, and over

100 kms in the long term (months).

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The FisheriesTraditionally, creeling for lobsters and crabs has been

regarded as an inshore fishery, and since the turn of the

last century the important Scottish centres have been the

south east, Orkney, Hebrides and Shetland. Fishermen

varied the ground they fished depending on the species

they targeted, but catches were generally mixed to some

extent. Recently there has been a significant addition to

fishing effort, with the arrival of large vivier vessels. These

vessels, which have holds containing water for live storage,

target the offshore edible crab grounds around the north

and west coast of Scotland, landing regularly into ports

such as Scrabster and Ullapool. Although few in number,

these vessels contribute to the majority of edible crab

landings into the north of Scotland. Their catches are

mainly shipped live to the continent.

The type of creel used varies around Scotland. The Cornish

Inkwell pot fitted with a single top entrance is favoured

by the larger vessels working offshore grounds for edible

crab, while the traditional Scottish D creel is more common

on inshore grounds. Creels are normally shot (fished) in

fleets of 20 or more and are usually hauled once every

24 hours. Parlour creels (containing an inner compartment)

catch more animals over longer periods, and are used in

some areas (particularly for lobsters) where creels cannot

be hauled daily. Some larger vessels work up to 2,000

creels, although they are not all hauled every day. Inshore

vessels land their catch daily (it may be stored in keep

creels, while waiting for collection), but in the offshore

fishery the catch is stored in water tanks on board the

vessel, and usually landed once a week.

Monitoring and Assessment MethodsRegular sampling of crab and lobster landings takes place

at all the main ports and live storage facilities around

Scotland. A voluntary logbook scheme is also in operation,

enabling catch and effort data to be collected. The

variability of exploitation levels around the coast and the

discrete nature of the stocks makes it necessary for

Fisheries Research Services to carry out separate

assessments for each of the main areas. Exploitation

rates and trends in the fishing mortality and recruitment

are monitored using a variety of assessment methods

using the data.

RegulationsThe main regulatory mechanism for crab and lobster

fisheries in Scotland is a minimum landing size, which is

140 mm and 65 mm carapace width for edible crab and

velvet crab respectively, and 87 mm carapace length for

lobster. A maximum landing size of 156 mm for female

lobsters is also enforced. It is illegal to land edible crabs

carrying eggs, or v-notched lobsters. Daily landing

restrictions also apply to vessels not holding a licence

for crab and lobster fishing.

In addition to national legislation, recent changes to the

Sea Fisheries (Shellfish) Act 1967 allow the management

of crab and lobster stocks at the local level (with a range

of regulatory powers) within Regulating Orders. As of

January 2004, only Shetland has such an Order in place,

though more are proposed for other areas.

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Fisheries Research Services is an agency of the Scottish Executive

FRS Marine Laboratory PO Box 101 375 Victoria Road Aberdeen AB11 9DB UK

tel +44 (0)1224 876544 fax +44 (0)1224 295511

enquiries@marlab.ac.uk http://www.frs-scotland.gov.uk © Crown copyright

Photo © Witek Mojsiewicz, not to be used without permission