1. Nephrops assessment:
“the hole story”
Dr Ewen Bell
Senior Inshore Advisor
Cefas, Lowestoft

2. Commercial importance
-
5,000
10,000
15,000
20,000
25,000
30,000
35,000
Landings in 2011 (tonnes)
Celtic Sea
Irish Sea
West of Scotland
North Sea
ICES Landings &
MMO annual statistics

3. Commercial importance
-
5,000
10,000
15,000
20,000
25,000
30,000
35,000
Landings in 2011 (tonnes)
Celtic Sea
Irish Sea
West of Scotland
North Sea
>£100 million to UK
ICES Landings &
MMO annual statistics

4. Commercial importance
-
5,000
10,000
15,000
20,000
25,000
30,000
35,000
Landings in 2011 (tonnes)
Celtic Sea
Irish Sea
West of Scotland
North Sea
>£100 million to UK
1 Nephrops £111
2 Mackerel £107
3 Scallops £63
4 Monks or Anglers £40
5 Crabs £38
6 Haddock £35
7 Lobsters £32
8 Cod £28
9 Sole £16
10 Herring £15
ICES Landings &
MMO annual statistics

5. Fisheries
34

6. Fisheries
Fladen ~12kt
Irish Sea
West ~8kt
34

7. Fisheries
Fladen ~12kt
Irish Sea
West ~8kt
34

8. Fisheries
Fladen ~12kt
Irish Sea
West ~8kt
34

9. Management

10. Management
Male only.
Quota

11. Management
Male only.
Quota
Creeling only

12. Management
Male only.
Quota
Creeling only
No restrictions but low effort

13. Management
Male only.
Quota
Creeling only
No restrictions but low effort
•Quota
•Skagerrak/Kattegat (IIIa)
•North Sea (IV)
•West of Scotland (VI)
•Irish & Celtic Seas (VII)
•Biscay
•Northern Spain
•Portuguese

14. Management
Male only.
Quota
Creeling only
No restrictions but low effort
•Quota
•Skagerrak/Kattegat (IIIa)
•North Sea (IV)
•West of Scotland (VI)
•Irish & Celtic Seas (VII)
•Biscay
•Northern Spain
•Portuguese
?!

15. Biology
Burrows
Muddy sediment
Photos by Mars et al, UMBSM

16. Biology
Burrows
Muddy sediment
0 5 10
50
52
54
56
58
60
62
longitude
latitude
Fladen
MorayFirth
Noup
Firthof Forth
Devil's Hole
Farn Deeps
Norwegian Deep
Botney Gut
Off Horn's Reef
Skagerrak
Kattegat
Redistribution
Photos by Mars et al, UMBSM

17. Biology
Burrows
Muddy sediment
0 5 10
50
52
54
56
58
60
62
longitude
latitude
Fladen
MorayFirth
Noup
Firthof Forth
Devil's Hole
Farn Deeps
Norwegian Deep
Botney Gut
Off Horn's Reef
Skagerrak
Kattegat
Redistribution
Feeding
Eat anything!
Photos by Mars et al, UMBSM

18. Biology
Burrows
Muddy sediment
0 5 10
50
52
54
56
58
60
62
longitude
latitude
Fladen
MorayFirth
Noup
Firthof Forth
Devil's Hole
Farn Deeps
Norwegian Deep
Botney Gut
Off Horn's Reef
Skagerrak
Kattegat
Redistribution
Feeding
Eat anything!
Photos by Mars et al, UMBSM

19. Biology
Burrows
Muddy sediment
0 5 10
50
52
54
56
58
60
62
longitude
latitude
Fladen
MorayFirth
Noup
Firthof Forth
Devil's Hole
Farn Deeps
Norwegian Deep
Botney Gut
Off Horn's Reef
Skagerrak
Kattegat
Redistribution
Feeding
Eat anything!
Growth by moult
Photos by Mars et al, UMBSM

20. Assessment objectives
Stock Size

21. Assessment objectives
Stock Size Fishing rate

22. Sledge deployment
Aberdeen 1999
Cefas 2010

23. Sledge deployment
Aberdeen 1999
Cefas 2010
Celtic Voyager Scotia Corystes Endeavour

24. Sledge deployment
Aberdeen 1999
Cefas 2010
Celtic Voyager Scotia Corystes Endeavour

25. Sledge deployment
Aberdeen 1999
Cefas 2010
Celtic Voyager Scotia Corystes Endeavour
Wheel  GPS
Incandescent bulbs  LED
Ruler  laser
DV  HDTV

26. 1. Crescent shaped entrance
2. Scrape markings and
spoil
3. Entrances pointing to
centre.
4. Nephrops
1.
2.
3.
4.
What to look for
Burrows NOT holes

27. Interpreting the pictures

28. Interpreting the pictures
Sometimes it’s easy

29. Interpreting the pictures
Sometimes it’s easy
Sometimes it’s not

30. Interpreting the pictures
Sometimes it’s easy
Sometimes it’s not

31. Turning TV pictures to advice
2 4 6 8
2468
Station= 4
CCC= 0.715 : Pearson= 0.744
199:KRB00
1:PWJ00
2 4 6 8 10
2468
Block
t[,1]
1.0 1.5 2.0 2.5 3.0 3.5 4.0
1.02.03.04.0
Station= 5
CCC= 0.041 : Pearson= 0.046
249:JME00
4:KRB00
2 4 6 8 10
1.02.03.04.0
Block
t[,1]
Training &
validation

32. Turning TV pictures to advice
2 4 6 8
2468
Station= 4
CCC= 0.715 : Pearson= 0.744
199:KRB00
1:PWJ00
2 4 6 8 10
2468
Block
t[,1]
1.0 1.5 2.0 2.5 3.0 3.5 4.0
1.02.03.04.0
Station= 5
CCC= 0.041 : Pearson= 0.046
249:JME00
4:KRB00
2 4 6 8 10
1.02.03.04.0
Block
t[,1]
Training &
validation
Raise
observations
to total area
Assumptions:
1 per burrow
>17mm
Burrows collapse quickly

33. Turning TV pictures to advice
2 4 6 8
2468
Station= 4
CCC= 0.715 : Pearson= 0.744
199:KRB00
1:PWJ00
2 4 6 8 10
2468
Block
t[,1]
1.0 1.5 2.0 2.5 3.0 3.5 4.0
1.02.03.04.0
Station= 5
CCC= 0.041 : Pearson= 0.046
249:JME00
4:KRB00
2 4 6 8 10
1.02.03.04.0
Block
t[,1]
Training &
validation
Raise
observations
to total area
Assumptions:
1 per burrow
>17mm
Burrows collapse quickly
Harvest rate
Numbers caught / population

34. Turning TV pictures to advice
2 4 6 8
2468
Station= 4
CCC= 0.715 : Pearson= 0.744
199:KRB00
1:PWJ00
2 4 6 8 10
2468
Block
t[,1]
1.0 1.5 2.0 2.5 3.0 3.5 4.0
1.02.03.04.0
Station= 5
CCC= 0.041 : Pearson= 0.046
249:JME00
4:KRB00
2 4 6 8 10
1.02.03.04.0
Block
t[,1]
Training &
validation
Harvest rate for MSY
Raise
observations
to total area
Assumptions:
1 per burrow
>17mm
Burrows collapse quickly
Harvest rate
Numbers caught / population

35. The future
Age determination
Automated video recognition
Further research into
burrow occupancy & size
Credit: (Left, Top and
Bottom) Raouf
Kilada/University of New
Brunswick; (Top Right)
NOAA; (Bottom Right)
iStockphoto