The document summarizes a study on the effects of a no-take zone (NTZ) established in 2008 on crustacean populations in Lamlash Bay, Scotland. Key findings include: 1) Abundance, size, biomass, and reproductive output of lobsters, brown crabs, and velvet crabs were higher inside the NTZ compared to areas open to fishing. 2) Lobster catch per unit effort was 107.14% higher and legal lobster catch was 143.33% higher inside the NTZ versus the nearest fished area. 3) Lobsters inside the NTZ were on average 11.64% larger than those in the nearest fished

1. The Effects of a No-Take-Zone on
Crustacean Population Recovery
in Lamlash Bay, Scotland
©Andrew Testa, New York Times (2015)
Brian Christie
Supervisor: Bryce Stewart

2. © Scottish Fishermen’s Federation (2013)© Paul Kay
© Howard Wood

3. • Severely degraded
marine environment
(Howarth et al., 2013)
• Pelagic & groundfish
stocks collapsed by
early 21st Century
(Thurstan and Roberts, 2010)
• Prawn trawling &
scallop dredging
now dominant
(McIntyre et al., 2012)

4. © Arran COAST
• Established
in 2008
• Scotland’s
first No-
Take-Zone
(NTZ)
• Covers
2.67km2

5. • Common Lobster
(Homarus
gammarus)
• Edible/ Brown Crab
(Cancer pagarus)
• Velvet Swimming
Crab (Necora puber)

6. • Common Lobster
(Homarus
gammarus)
• Edible/ Brown Crab
(Cancer pagarus)
• Velvet Swimming
Crab (Necora puber)
Common Lobster
• Value for 2013:
o £10.6 million
Brown Crab
• Value for 2013:
o £13.8 million
Velvet Crab
• Value for 2013:
o £4.0 million
(Barreto and Bailey, 2015)

7. Aims Lobsters Brown Crabs Velvet Crabs
Abundance
Size
Biomass
Reproductive
Output
Health
Recaptures
• Distance trends from NTZ boundary
• Compare to previous years’ data sets

8. 10 fathoms
Soak time: 24-72 hours

9. © Bryce Stewart© Brian Christie
© Brian Christie
© Jennifer Stark© Bryce Stewart© Bryce Stewart

10. Arran
NTZ
Far Control
Fishing Observations:
• Recorded lobster
abundance, size,
gender & presence of
berries
• Brown crab, velvet crab
& bycatch abundance
• Not capture & release

11. NTZ
Near
Control 1
Near
Control 3
Near
Control
2
Surveys:
• Recorded size and
abundance for lobsters,
brown crab & velvet crab
• Recorded lobster health,
presence of berries &
recaptures
• Recorded bycatch
abundance
• Tagged all lobsters
• Capture & release

12. Area
No. of
Fleets
No. of
Creels
No. of
Lobsters
Gender
Ratio (M:F)
No. of Legal
Lobsters
(CL > 87mm)
NTZ 18 90 87 1 : 0.45 73
Near
Control 18 90 42 1 : 0.69 30
Far
Control 94 811 702 1 : 0.96 204

13. 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
NTZ Near Control Far Control
CatchPerUnitEffort(CPUE)
Mean Lobster CPUE
CPUE 107.14% higher in NTZ versus Near Control (Mann-Whitney-
Wilcoxon Test, U = 243.5, p < 0.01)
CPUE 9.19% higher in NTZ versus Far Control (Mann-Whitney-Wilcoxon
Test, U= 898, p = 0.682)
Catch Per Unit Effort = Number of lobsters caught
Number of creels in the fleet

14. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
NTZ Near Control Far Control
CatchPerUnitEffort(CPUE)
Mean Legal Lobster CPUE
Legal CPUE 143.33% higher in NTZ versus Near Control (Mann-
Whitney-Wilcoxon Test, U = 244, p < 0.01)
Legal CPUE 224.54% higher in the NTZ versus Far Control (Mann-
Whitney-Wilcoxon Test, U = 1358.5, p < 0.001)

15. 0
5
10
15
20
25
30
35
40
45
52-58 59-65 66-72 73-79 80-86 87-93 94-100 101-107 108-114 115-121 121-127 128-134 135-141
Frequency(%)
Carapace Length (mm)
Mean Lobster Size
NTZ Near Control Far Control
• Lobsters inside NTZ 11.64% larger than Near Control & 21.22% larger
compared to Far Control
• Legal lobsters inside NTZ 11.18% larger compared to Near Control &
11.17% larger compared to Far Control
(All one-way ANOVAs p < 0.001)
Minimum Landing
Size (MLS)

16. WPUE 186.90% higher in NTZ versus Near Control (Mann-
Whitney-Wilcoxon Test, U = 260.5, p = 0.002)
WPUE 87.52% higher in NTZ versus Far Control (Mann-
Whitney-Wilcoxon Test, U= 1189, p = 0.006)
Lobster weight:
• Males = 0.0022 * (carapace length (mm) ^ 2.7416))
• Females = 0.0016 * (carapace length (mm) ^ 2.8134))
(Howarth, 2014; Leslie et al. 2006)
WPUE = Total weight of lobsters caught
Number of creels in the fleet
0
100
200
300
400
500
600
700
800
900
NTZ Near Control Far Control
WeightperUnitEffort(g)
Mean Lobster WPUE

17. 0
100
200
300
400
500
600
700
800
NTZ Near Control Far Control
WeightperUnitEffort(g)
Mean Legal Lobster WPUE
Legal WPUE 232% higher in NTZ versus Near Control (Mann-Whitney-
Wilcoxon Test, U = 259, p = 0.002)
Legal WPUE 346.9% higher in the NTZ versus Far Control (Mann-
Whitney-Wilcoxon Test, U = 1450.5, p < 0.001)

18. 0
200
400
600
800
1000
1200
1400
1600
1800
NTZ Near Control Far Control
ReproductiveOutputPerUnitEffort(No.
ofEggs)
Mean Potential Lobster ROPUE CL
> 81mm
• Egg output per individual
= (carapace length (mm) * 155.4) - 10286)
(Howarth, 2014; Lizárraga-Cubedo et al. 2003)
ROPUE = Egg potential for fleet
Number of creels in the fleet
CL > 87 mm ROPUE 76.94% higher in NTZ versus Near Control (Mann-
Whitney-Wilcoxon Test, U = 224, p = 0.04)
CL > 87 mm ROPUE 42.82% higher in the NTZ versus Far Control (Mann-
Whitney-Wilcoxon Test, U = 1043, p < 0.119)

19. R² = 0.2019
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
-2000 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000
LegalCPUE
Distance from NTZ Boundary (m)
Mean Legal Lobster CPUE
R² = 0.2503
0
200
400
600
800
1000
1200
1400
1600
-2000 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 20000
LegalWPUE(g)
Distance from NTZ Boundary (m)
Mean Legal Lobster WPUE

20. 0
0.2
0.4
0.6
0.8
1
1.2
1.4
2012 2013 2014 2015
LegalCatchperuniteffort(CPUE) NTZ
Outside NTZ

21. Carapace
Length =
135mm!!!
Conclusions
• The NTZ is restoring
lobster population size/
age structure
• This is increasing
biomass and may be
significantly increasing
reproductive output
• The benefits of the
recovering population
seem to be spilling over
• However, low abundance
this year so interpret
carefully, but…

22. Thank you to:
• COAST for funding this research
• Bryce for being an excellent supervisor
… & thank you for listening! 
Any questions?