The Buckland Lecture 2004 Science and the Management of United

The Buckland Lecture 2004

Science and the Management of United Kingdom Crab Fisheries

Dr Julian Addison CEFAS, Lowestoft

The Buckland Lecture 2004 Frank Buckland’s conclusions on the Norfolk crab fishery (1875)

z Closed season from 1 September to 1 March

z Ban on berried females

z Minimum size of 4¼ inches carapace width

z Undersized to be returned immediately, and not broken up

z No live boiling in cold water

The Buckland Lecture 2004 Buckland & Walpole’s 1877 report on crab and lobster fisheries of England, Scotland and Ireland

z Regional minimum landing size: south coast, Scotland, (Ireland): 5 inches east coast 4¼ inches

z Ban on berried females z Ban on soft crabs

The Buckland Lecture 2004 The Buckland Lecture 2004 “The edible crab (Cancer pagurus) is the only species of crab regularly fished for human consumption in European waters”

The Buckland Lecture 2004 New dimensions to studies on crabs over the last 25 years

z Wide range of species now landed

z Brown crab fisheries more widespread, both within UK and in Europe

z Technological advances, multi-disciplinary studies

z Ecosystem approach – effects of crab fishing

z Other sea bed uses impact on crabs

The Buckland Lecture 2004 How science can contribute to effective management of crab stocks

z Basic biological information is essential for effective technical conservation measures z Information on stock structure advises on what is the appropriate management unit z Recruitment studies define what is driving the stock and the fishery z Good quality data and appropriate assessment methodologies provide index of of stock status.

The Buckland Lecture 2004 Lecture themes

z Range of crab species landed

z Studies on stock structure and their relevance for regional management initiatives

z Data collection initiatives - in relation to both crab stock management and impact of other seabed uses on crab stocks.

The Buckland Lecture 2004 Lecture themes

z Range of crab species landed

z Studies on stock structure and their relevance for regional management initiatives

z Data collection initiatives - in relation to both crab stock management and impact of other uses on crab stocks

The Buckland Lecture 2004 Brown crab, Cancer pagurus

The Buckland Lecture 2004 Spider crab, Maia squinado

The Buckland Lecture 2004 Velvet crab, Necora puber

The Buckland Lecture 2004 Green / shore / peeler crab, Carcinus maenas

The Buckland Lecture 2004 Deep water red crab, Chaceon affinis

The Buckland Lecture 2004 Stone crab, Lithodes maia

The Buckland Lecture 2004 Swimming crab, Liocarcinus depurator

The Buckland Lecture 2004 Golden / poor crab, Cancer bellianus

The Buckland Lecture 2004 Hermit crab, Pagurus spp.

The Buckland Lecture 2004 Chinese mitten crab, Eriocheir sinensis

The Buckland Lecture 2004 Red king crab, Paralithodes camtschaticus

The Buckland Lecture 2004 Official UK Landings Statistics - all crab species

Tonnes landed Brown Spider Velvet Green Others

1980 8500 800 N/A N/A N/A

1990 13500 500 1800 400 N/A

Current 20000 1200 2200 500 50

The Buckland Lecture 2004 Official Landings Statistics - Ireland

Tonnes landed Brown Spider Velvet Green Others

1980 N/A N/A N/A N/A N/A

1990 3800 150 200 N/A N/A

Current 10000 300 300 N/A 30

The Buckland Lecture 2004 Brown crab, Cancer pagurus

D3 D4 D5 D6 D7D8 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 F4 F5 F6 F7 F8 Faeroe Bank 61 50 49 z Size: up to 260 mm CW 60 48 47 59 46 45 z Gear: pots (trawls, Rockall 44 58 Bank 43 42 dredges, nets) 57 41 40 56 39 38 z 37 Depth: intertidal to 100m55 36 54 35 z Porcupine 34 Biology: Bank 33 53 32 31 Female migration 52

51 30 Variable catchability 29 50 28 27 49 High fecundity 26 La Chapelle 25 48 Bank 24 23 47 -17 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9

The Buckland Lecture 2004 Spider crab, Maia squinado

D3 D4 D5 D6 D7D8 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 F4 F5 F6 F7 F8 Faeroe Bank 50 61 49 z 48 Size: up to 200 mm CL 60 47 46 45 59 Rockall z Gear: pots, nets (trawls) 44 Bank 43 58 42 41 z Depth: up to 70m 57 40 56 3839 z 37 Biology: 55 36 Porcupine 3435 54 Bank 33 Inshore migration 32 53 31 Terminal moult 52

51 30 29 Form “mounds” 50 28 27 49 La Chapelle 26 Bank 25 48 24 23 47 -17 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9

The Buckland Lecture 2004 Velvet crab, Necora puber

D3 D4 D5 D6 D7D8 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 F4 F5 F6 F7 F8 Faeroe Bank 61 50 49 60 48 z Size: 65-90 mm CW 47 59 46 z Gear: pots (trawls) 45 58 Rockall 44 Bank 43 z Depth: sub-littoral to 70m 42 57 41 56 40 z Biology: 39 38 Swims with ‘paddles’ 55 37 36 54 35 Fast growing species Porcupine 34 Bank 33 53 32 Size at maturity well 31 52 below minimum size 51 30 29 High mortality rates 50 28 27 49 26 La Chapelle 25 48 24 Bank 23 47 -17-15-13-11-9-7-5-3-113579

The Buckland Lecture 2004 Green crab, Carcinus maenas

D3 D4 D5 D6 D7D8 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 F4 F5 F6 F7 F8 61 Faeroe Bank 50 49 z 60 48 Size: up to 90-100 mm CW 47 59 46 45 z Gear: pots, trawls, tiles 58 Rockall 44 Bank 43 57 42 z Depth: shore to 60m 41 56 40 39 38 z Biology: 55 37 36 54 35 Porcupine 34 53 Bank 33 Widely distributed 32 31 52

Extreme tolerance 51 30 29 50 Widely studied 28 49 27 26 25 La Chapelle 48 24 Bank 23 47 -17-15-13-11-9-7-5-3-113579

The Buckland Lecture 2004 Deepwater red crab, Chaceon affinis

D3 D4 D5 D6 D7D8 D9 E0 E1 E2 E3 E4 E5 E6 E7 E8 E9 F0 F1 F2 F3 F4 F5 F6 F7 F8 Faeroe Bank 61 50 49 60 48 z Size: up to 180 mm CW 47 59 46 45 z Gear: pots,gill nets 58 Rockall 44 Bank 43 57 42 (trawls) 41 56 40 39 38 z Depth: 75 to 2000 m 55 37 36 54 35 Porcupine 34 z Biology: Bank 33 53 32 31 Slow growing, long- 52

51 30 29 lived, 50 28 27 49 26 Sporadic recruitment La Chapelle 25 48 24 Bank 23 47 Depth-related migration-17 -15 -13 -11 -9 -7 -5 -3 -1 1 3 5 7 9

The Buckland Lecture 2004 Management regulations for crab species

z Management measures may be at EU, national or regional/local (e.g. SFC, Regulating Order) level

z Technical measures only, no quotas, so biological information is essential

z Permit schemes in many local areas for many years, now national.

The Buckland Lecture 2004 Management regulations for crab species

z Cancer pagurus: regional min. size (EU, national and SFC) parts (SFCs), 75 kg limit on crab claws (EU) ban on berried and soft (national) ban on use as bait (local) potting/trawling zones (local)

z Velvets: 65mm CW min. size (national) (70mm min. size + closed season in Shetland)

z Spider crabs: min. size 120 mm CL (EU), but 130 mm CL for males (national) The Buckland Lecture 2004 Lecture themes

z Range of crab species landed

z Studies on stock structure and their relevance for regional management initiatives

z Data collection initiatives - in relation to both crab stock management and impact of other uses on crab stocks

The Buckland Lecture 2004 Stock structure / regional variation

z Knowledge of stock structure is essential to ascertain the management unit. What are we managing? The stock, only part of it, or multiple stocks

z Spatial scale of variation in population parameters in relation to scale of management area

z Implications for any regional management initiative.

The Buckland Lecture 2004 Movement of tagged crabs in eastern channel

o 35 Released at Long 0.66 E

30 Movement W 25

10 Recapture Proportion Recapture

0 0.615 0.630 0.645 0.660 Decimal Longitude

The Buckland Lecture 2004 Background to east coast larvae studies Crab fishery was essentially inshore until the 1980’s

Tagging studies since the early 1900’s showed that males and immature females were relatively sedentary

Some adult females migrated north along the east coast of England and Scotland

However, tag returns are determined by the distribution of fishing effort.

The Buckland Lecture 2004 The Modern Fishery

z Offshore fishery has developed since the late 1980’s

z Now the largest in the North Sea

z The majority of the landings are of mature female crabs.

The Buckland Lecture 2004 July 1999 survey

55.50 Discrete area of production

of stage I larvae 55.00 44

36 54.50 Larvae from stages I - IV were 32 found but not later stages 28 24

54.00 20

16 Low levels other than stage I. 12 8 53.50 4

53.00 Nos / sqr m / day

Cirolana 4/99 Both grids

52.50 -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00

The Buckland Lecture 2004 July 1999 larvae distributions

Minimal easterly drift, otherwise no movement

55.50 55.50 55.50

Stage II Stage III Stage IV 55.00 55.00 55.00

54.50 54.50 54.50

54.00 54.00 54.00

53.50 53.50 53.50

53.00 53.00 53.00

Cirolana 4/99 Cirolana 4/99 Cirolana 4/99 Both grids Both grids Both grids

52.50 52.50 52.50 -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 -1.50 -1.00 -0.50 0.00 0.50 1.00 1.50 2.00 2.50 3.00 -1.50-1.00-0.500.000.501.001.502.002.503.00

The Buckland Lecture 2004 1976 July Survey 1993 July survey

55.5

55.0

54.5

54.0

53.5

53.0

Cirolana 7a/93 Nos/m²

52.5 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 . The Buckland Lecture 2004 Hydrography

Two distinct regimes during the time larvae are in the water column North of the Dogger Bank; Deep water (>50m) Strongly thermally stratified Permanent pool of cold bottom water, generally <8oC South of the Dogger Bank Shallow & along the NE coastline; Vertically mixed Warm (generally >10oC by June)

Strong horizontal density gradients between the zones gives rise to a seasonal jet-like circulation.

The Buckland Lecture 2004 Water column stratification, July 1999

55.5 Strongly stratified to 55.0 the north 10 Dogger 9 Bank 8 54.5 7

5 54.0 4

53.5 1 Well mixed to the 0 south. -1 ∆Τ 53.0 (°C)

Cirolana 4/99 Delta T

52.5 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 The Buckland Lecture 2004 Mean bottom temperature in June

56 18

55 15

54 12

53 9

52 6

51 3 -202468 Cold water pool to north of Dogger Bank - crab eggs and larvae do not develop at temps < 8oC.

The Buckland Lecture 2004 Drifter Deployments in the Survey Area Filtered Drifter trajectories June - August 1999

56 g RV survey deployments in the main spawning area -

8 cms-1 slow drift to east or southeast

Flamborough front 55 Start Deployments 3.8 cms-1 Start g Northerly deployments - rapid drift passing to north of Dogger

Start ude (N) ude t 54 i t 2.8 cms-1 La Start g Front established in 16/6/99 to 25/07/99 16/6/99 to 25/07/99 transition zone across which 16/6/99 to 25/07/99 Start 11/7/99 to 23/8/99 2 cms-1 little or no exchange occurs. 53 12/7/99 to 7/8/99 30/6/99 to 25/07/99 19/6/99 to 25/07/99 18/6/99 to 22/06/99 16/6/99 to 30/07/99 17/6/99 to 25/07/99 17/6/99 to 25/07/99 16/6/99 to 24/07/99 16/6/99 to 30/07/99 17/6/99 to 24/07/99 52 The Buckland-1 Lecture 0 2004 1 2 3 Longitude (W/E) Drifter Deploymentsgjy in the Southern North Sea

z Movement is

54.5 away from the English coast

54 -1 1.5 cms -1 Start 7 cms ) Start

N Start ( e d 53.5 z No indications u t i t -1 La 8.8 cms of recruitment 53 from the -1 4.5 cms 6 cms English 52.5 Start Start -1 24 hr position 18/5 - 10/6 Channel. 18/5 - 21/6 52 18/5 - 19/7 18/5 - 8/7 19/5 - 29/5

51.5 The00.511.522.533.544.555.56 Buckland Lecture 2004 Longitude (E ) Aggregated stage I larvae distributions (1976 - 1999) and residual drift patterns

COLD g Cold Pool all year in 56 POOL the north. Flamborough Front g Front established Dogger Bank May to October

54 Flamborough g Crab larvae mainly Head to the south of the front

Latitude Norfolk g Slow residual drift east from natal area 52 g No recruitment from the south.

50The Buckland Lecture 2004 -20246 Longitude Conclusions from east coast surveys z Pattern of larvae distribution consistent over a 23 year period z Temperature regime restricts spawning to shallow waters south of the Dogger Bank and coastal areas z The existence of the Flamborough front effectively isolates the main spawning area from the rest of the North Sea z The crab population south of the Dogger Bank may be a separate, self-sustaining stock, which could have implications for the management of both the traditional inshore and recently developed offshore fisheries.

The Buckland Lecture 2004 Movements of edible crabs from French and English tagging experiments in the Channel (from Cuillandre et al, 1984).

The Buckland Lecture 2004 Crab larvae distribution in the Channel in 1989

The Buckland Lecture 2004 The distribution of crab larvae in the Western Channel in 2002

Nos m-2 The Buckland Lecture 2004 The distribution of crab larvae in the Channel in 2003

Only 7 of 35 stations were positive between 0o and 2oW, all < 10 Z1 m-2. East of 0o, 19 of 53 stations had Z1. Nos m-2 The Buckland Lecture 2004 Residual tidal patterns in the Channel

Salomon and Breton. Oceanologica Acta, 1993. 16, 5-6, 439-448 The Buckland Lecture 2004 Crab larvae dispersal models, NE coast spawning grounds: where might settlement occur?

Larvae at 5m depth over 35 days Larvae at 20m depth over 70 days

The Buckland Lecture 2004 Crab larvae dispersal models – where might settlement occur?

Larvae at 5m depth over 70 days Larvae at 10m depth over 35 days

The Buckland Lecture 2004 Spatial analysis of crab distributions by size

International Beam 1995 Trawl Survey data, 110+ 1990 - 2001 mm 54 <60 mm

53 Significant clumping of the smallest crabs around the Norfolk 52 coast. Largest have a much wider distribution

51 0123 The Buckland Lecture 2004 Genetic screening of crab populations © Paul Shaw, Royal Holloway College, University of London

The Buckland Lecture 2004 Lecture themes

z Range of crab species landed

z Studies on stock structure and their relevance for regional management initiatives

z Data collection initiatives - in relation to both crab stock management and impact of other uses on crab stocks

The Buckland Lecture 2004 Collection of data on crabs for management

z Good data is required for scientific advice on management of crab stocks and impact studies

z Data is needed at the right spatial and temporal scales

z Landings and effort data provide index of abundance

z Size distribution data provide index of exploitation (fishing mortality).

The Buckland Lecture 2004 Current data on catch rates of crabs

z Official statistics are poor, under-reported and no reliable effort data

z Catch rate data from Shellfish Licensing scheme essential to provide data at the right spatial and temporal scale for stock management, and will give total effort census

z Currently only such data are EU log books, CEFAS log books and SFC permit schemes.

The Buckland Lecture 2004 Landings and catch rates of crabs in South Wales

Landings of Edible crab Landings of Spider crab Landings of Velvet crab

800 400 25 600 20 300 s in tonnes s in tonness in

g 15 g 400 200 10 200 100 Landin

Landin 5 Landings in tonnes in Landings

0 0 0

0 2 4 6 8 0 2 4 6 8 0 2 0 2 4 6 8 90 2 4 6 8 0 2 0 2 4 86 8 0 92 4 6 8 0 02 9 98 98 9 99 99 9 9 0 0 98 98 00 198 198 1 198 1 1 1 1 199 199 200 200 198 198 198 1 1 199 19 199 199 199 2 2 1 198 198 1 198 199 199 19 199 199 200 2

Year Year Year

Edible crab LPUE Spider crab LPUE Velvet crab LPUE

80 50 70 3 60 40 50 2 30 LPUE 40 LPUE 2 LPUE 30 20 1 20 6 2002 9 2000 9 1998 10 10 1 1 1994 0 1992 0 4 1990 0 8 1988 9 1986 1 0 2 4 6 8 0 2 4 6 8 0 2 1982 0 2 84 6 8 90 2 94 6 8 0 2 1980 198 198 198 198 198 199 199 199 199 199 200 200 198 198 19 198 198 19 199 19 199 199 20 200 Year Year Year Courtesy of Phil Coates, South Wales SFC The Buckland Lecture 2004 Evaluation of impact on crab stocks of other seabed uses

z Provide catch and effort data and GPS reading for each string of pots z Either PC-based electronic log book or can be used on small vessel with no PC, e.g Thistle Marine system

The Buckland Lecture 2004 Fishermen's log books and impact evaluation

z Monitoring programmes in relation to impact evaluation do not always answer the question z Not due to poor design, or poor science z Innate natural variability makes it difficult to identify whether there has been an impact z Monitoring programmes only short term z So need long term monitoring, i.e. fishermen's log books at fine spatial scale

The Buckland Lecture 2004 Geographical information systems (GIS) help to present and interpret fisheries data

0°0'0"E 0°30'0"E 1°0'0"E 1°30'0"E 2°0'0"E

51°30'0"N

Sediment type Gravel Sand

Edible Crab 51°0'0"N

51°0'0"N

50°30'0"N

0°0'0"E 0°30'0"E 1°0'0"E 1°30'0"E 2°0'0"E

z Courtesy of Paul Eastwood, CEFAS The Buckland Lecture 2004 MANAGEMENT

NATIONAL

REGIONAL

The Buckland Lecture 2004 ADVICE MANAGEMENT

SCIENTIFIC NATIONAL

STAKEHOLDER REGIONAL

The Buckland Lecture 2004 SCIENCE ADVICE MANAGEMENT

BIOLOGICAL SCIENTIFIC NATIONAL STUDIES

UNDERSTANDING STOCK STAKEHOLDER REGIONAL STRUCTURE

The Buckland Lecture 2004 SCIENCE ADVICE MANAGEMENT

BIOLOGICAL SCIENTIFIC NATIONAL STUDIES

UNDERSTANDING STOCK STAKEHOLDER REGIONAL STRUCTURE

INDUSTRY

LANDINGS DECLARATIONS FISHERMEN'S & LOGBOOKS EU/SHELLFISH LOGBOOKS

The Buckland Lecture 2004 SCIENCE ADVICE MANAGEMENT

BIOLOGICAL Management of SCIENTIFIC NATIONAL STUDIES crab stocks

UNDERSTANDING Impacts of other uses STOCK STAKEHOLDER REGIONAL STRUCTURE on crab stocks

INDUSTRY

LANDINGS DECLARATIONS FISHERMEN'S & LOGBOOKS EU/SHELLFISH LOGBOOKS

The Buckland Lecture 2004 Acknowledgements

z Dr Eric Edwards, Dr Colin Bannister, Dr David Bennett z CEFAS colleagues, particularly Derek Eaton, Steve Lovewell, Liam Fernand, Emma Young z Colleagues in Wales, Scotland and Ireland – Phil Coates, Ian Tuck, Oliver Tully, Jason Combes z Paul Shaw, Royal Holloway College, University of London z Defra Sea Fisheries Conservation Division who have supported much of this work over many years.

The Buckland Lecture 2004