STFASpiny Lobster Project

Third Progress Report 8/12/2013

Virgin Islands Spiny Lobster Landings

19741976

19781980

19821984

19861988

19901992

19941996

19982000

20022004

20062008

20100

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

St. Croix ACL= 107,307 lbs

St. Thomas/St. John ACL= 104,199 lbs

Year

Land

ings

(lbs

)

• On both islands periods of high lobster landings (St. Thomas/St. John from 2003-2006, 136,000 lbs and St. Croix 2006-2009, 156,000 lbs) were followed by decreased landings which have not returned to prior levels.• Did these levels represent overfishing?• If so, what levels can be sustained?

Island Differences in Methods2010 CCR Data

Island Diving Traps

St. Thomas/St. John 1.7% 98.3%

St. Croix 92.4% 7.6%

Average sizes are significantly different betweenIslands (F= 102.7, p<0.001)

Difference between size of Trap and SCUBA caught lobsters on St. Croix not significant (F=0.76, p=0.38)

Distribution of 2006 Lobster Landings

1.004.00

7.0010.00

13.0016.00

19.0022.00

25.0028.00

31.0034.00

37.0040.00

43.0046.00

49.0052.00

55.0058.00

61.0064.00

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

St. CroixSt. Thomas

# Fishermen

% o

f Tot

al La

ndin

gs

# Lobster Trips by Island (1974-2006)

9741976

19781980

19821984

19861988

19901992

19941996

19982000

20022004

20060

500

1000

1500

2000

2500

3000

3500

4000

St. Croix

St. Thomas/St. John

% of Lobster by CL (Complete Trips)

0%

5%

10%

15%

20%

25%

30%

35%

ST. CroixSt. Thomas

Minimum Legal CL

Island Differences in SizesCFMC Project Complete Trips

Island Average CL

St. Thomas/St. John 101.9 mm

St. Croix 91.9 mm

Difference significant at 0.001 level

St. Croix Size of LobsterTraps vs Diving

Anova: Single Factor

SUMMARY

Groups Count Sum Average Variance

Traps 990 105,236 106.30 220

Diving 2,451 262,190 106.97 250

ANOVASource of Variation SS df MS F

P-value F crit

Between Groups 319 1 319 1.32 0.251 3.844

Within Groups 833,276 3,439 242

Total 833,596 3,440

Monthly Landings: St. Thomas

January

February

March AprilMay

JuneJuly

August

September

October

N ovember

December

0%

2%

4%

6%

8%

10%

12%

14%

16% 1989

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2006

2005

Average

Monthly Landings: St. Croix

0%

2%

4%

6%

8%

10%

12%

14%

16%

18%

20%1991199219931994199519961997199819992000200120022003200420052006Average

Short/Berried Seasonality

September-1

2

October-1

2

November-1

2

December-1

2

January

-13

February

-13

March-13

April-13

May-13

June-13

July-13

0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Shorts CPUEBerried CPUE

Shor

t Lob

ster

s/Tr

ap H

aul

Berr

ied

Lobs

ters

/Tra

p Ha

ul

St. Thomas Tags and RecapturesMonth

Cumulative # Tagged

Adjusted for

MortalityProject

RecapturesNon-Project Recaptures # Kept

September-12 492 492 6 1 2October-12 1267 1255 15 1 1

November-12 1586 1545 16 2 4December-12 1884 1814 29 2 12

January-13 2151 2042 26 2 9February-13 2419 2264 20 3 8

March-13 2675 2465 24 1 4April-13 3269 3000 32 4 7May-13 3593 3272 28 3 27June-13 3843 3446 26 3 10July-13 3957 3478 16 11 9

August-13 3957 3478 238 33 (12%) 93

Summary of Coral World Tag Retention Study

• 22 lobsters were installed at Coral World on 8 May 2013.

• To date there have been 4 molts with no tag loss.• On about 15 July some UVI students who were doing a

lionfish study removed the grate separating the lobsters from the pump intake, resulting in total mortality.

• We are waiting to restock until catches of small lobsters increase.

• In the mean-time we have tagged an additional 10 (very) small Coral World Lobsters.

0 20 40 60 80100

120140

160180

200220

240260

280300

320340

0

10

20

30

40

50

60

# Recaptures/ Days at Large

# Days at Large

STFA Lobster Landings (% of Total Lobster Landings)

2,003.00 2,004.00 2,005.00 2,006.0080,000

90,000

100,000

110,000

120,000

130,000

140,000

150,000

75%

80%

85%

90%

95%

100%Total Lobster LandingsSTFA Lobster LandingsSTFA % of Total

Lobs

ter L

andi

ngs (

lbs)

Average Monthly

Percentage

Projected Monthly Landings

# LobstersProject Lbs

Caught% of Projected

Landings

September 7.3% 6,165 3,447 1015 13.0%

October 8.2% 6,934 2,997 2125 31.3%

November 8.6% 7,249 3,152 2292 32.1%

December 10.7% 8,985 3,005 3184 46.8%

January 10.6% 8,908 3,380 1426 18.7%

February 9.2% 7,722 2,989 2014 29.8%

March 9.4% 7,938 3,253 2480 33.7%

April 8.7% 7,336 2,921 3606 54.6%

May 7.3% 6,156 2,732 2292 37.1%

June 6.3% 5,271 2,286 1731 33.5%

July 6.9% 5,813 3,416 1146 14.8%

Mortality Adjusted Population Estimate

September

October

November

December

January

February

March

AprilMay

JuneJuly

August

200,000

250,000

300,000

350,000

400,000

450,000

St. Thomas Average CL

1970 1975 1980 1985 1990 1995 2000 2005 2010 201590

95

100

105

110

115

120

St. Croix Average CL

1980 1985 1990 1995 2000 2005 2010 201590.0

95.0

100.0

105.0

110.0

115.0

120.0CL

(mm

)

Mortality Calculation• Von Bertalanffy growth equation . • Solve for (t) for carapace length. • This provides the age for each size class in the size frequency

distribution so that total mortality (Z) Where: is the number of fish at time (t) and (t-1)andZ is the rate of total mortality.

can be calculated as the difference in numbers from the size class bin at full recruitment and the size class bin containing L

Total Mortality (Z) Calculated from TIP Data

19711981

19831985

19871989

19911993

19951997

19992001

20032005

20072009

2011

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

St. Thomas Moving average (St. Thomas)

St. Croix Moving average (St. Croix)

Tota

l Ann

ual M

orta

lity

(Z)

01224364860728496108120132144156168180

0 1224 3648 6072 8496 108120 132144 156168 180

Fishing mortality rate

Size

at fi

rst c

aptu

re (m

m ca

rapa

ce le

ngth

)

St. Thomas St. Croix

Yield Per Recruit

• On both islands periods of high lobster landings (St. Thomas/St. John from 2003-2006, 136,000 lbs and St. Croix 2006-2009, 156,000 lbs) were followed by decreased landings which have not returned to prior levels.• Did these levels represent overfishing?• If so, what levels can be sustained?

Comparison Between Annual Fish Trap Hauls(CCR Reports and Fishermen Interviews)

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 20070

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

450,000

500,000

CCR Reports Fishermen Interviews

Year

Tota

l Ann

ual T

rap

Hau

ls

Comparison Between Annual Lobster Trap Hauls(CCR Reports and Fishermen Interviews)

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 20070

50,000

100,000

150,000

200,000

250,000

300,000

350,000

400,000

CCR Trap Hauls/Day

Adjusted Trap Hauls /Day

FISHER CODE YEARFISH_POTS_IN_WATE

RLOBSTER_POTS_

IN_WATERCOMBINED_TRAPS_IN_

WATERFISH_TRAPS_

HAULEDLOBSTER_TRAP

S_HAULEDGEAR_TYPE_HAULED

COMBINED_TRAPS_HAULED TRIPS

B/C 2011 (blank) (blank) 82 (blank) (blank)Traps 0 1B/C 2011 (blank) (blank) 110 (blank) (blank)Traps 0 1B/C 2012 (blank) (blank) 82 (blank) (blank)Traps 0 1B/C 2012 (blank) (blank) 85 (blank) (blank)Traps 0 2B/C 2012 (blank) (blank) 90 (blank) (blank)Traps 0 3B/C 2012 (blank) (blank) 110 (blank) (blank)Traps 0 1J 2011 (blank) (blank) 110 (blank) (blank)Traps 0 1J 2011 (blank) (blank) (blank) (blank) (blank)Traps 0 1J 2012 (blank) (blank) 110 (blank) (blank)Traps 0 1J 2012 (blank) (blank) 120 (blank) (blank)Traps 0 2J 2012 (blank) (blank) (blank) (blank) (blank)Traps 0 1S 2012 (blank) (blank) 194 (blank) (blank)Traps 0 1U 2011 (blank) (blank) 5 (blank) (blank)Traps 0 1U 2012 (blank) (blank) 5 (blank) (blank)Traps 0 3U 2012 (blank) (blank) (blank) (blank) (blank)Traps 0 2U 2013 (blank) (blank) 5 (blank) (blank)Traps 0 2U 2013 (blank) (blank) (blank) (blank) (blank)Traps 0 1V 2011 (blank) (blank) 20 1 (blank)Traps, Fish 1 8V 2011 (blank) (blank) (blank) 1 (blank)Traps, Fish 1 1V 2012 (blank) (blank) 20 1 (blank)Traps, Fish 1 23W 2012 (blank) (blank) 700 (blank) (blank)Traps 0 1Y 2012 (blank) (blank) 10 (blank) (blank)Traps 0 1Z 2012 (blank) (blank) 68 (blank) (blank)Traps 0 8Z 2012 (blank) (blank) 76 (blank) (blank)Traps 0 1AB 2012 (blank) (blank) 530 (blank) (blank)Traps 0 1AG 2011 (blank) (blank) 4 (blank) 1Traps, Lobster 1 1AG 2011 (blank) (blank) 30 (blank) 1Traps, Lobster 1 1AG 2012 (blank) (blank) 5 (blank) 1Traps, Lobster 1 2AJ 2012 (blank) (blank) 182 (blank) (blank)Traps 0 1AT 2011 (blank) (blank) 610 (blank) (blank)Traps 0 1AY 2012 (blank) (blank) 97 (blank) (blank)Traps 0 1AY 2012 (blank) (blank) 102 (blank) (blank)Traps 0 1

Traps/Day Hauled in St. Thomas (TIP, Historic and Adjusted CCR Data)

1965 1970 1975 1980 1985 1990 1995 2000 2005 20100.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

f(x) = 1.79170982869248 x − 3525.0792390348R² = 0.939675637834702

TIPMARFINMRAGVIERSAdjusted CCR

Year

Trap

Hau

ls/D

ay

Total STT/STJ Lobster Landings(lbs x 1000)

19751977

19791981

19831985

19871989

19911993

19951997

19992001

20032005

20072009

20110

20000

40000

60000

80000

100000

120000

140000

160000

Divers Trap

Year

Land

ings

(lbs

x 1

000)

1970 1975 1980 1985 1990 1995 2000 2005 20100

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

STT Trap LandingsObserved LandingsPredicted Landings

Year

Land

ings

(kg)

1970 1975 1980 1985 1990 1995 2000 2005 20100

1000

2000

3000

4000

5000

6000

STT Diver LandingsObserved LandingsPredicted Landings

Year

Land

ings

(kg)

1970 1975 1980 1985 1990 1995 2000 2005 20100

0.20.40.60.8

11.21.41.61.8

2

STT Trap IndexObserved IndicesPredicted Indices

Year

Stan

dard

ized

CPUE

1970 1975 1980 1985 1990 1995 2000 2005 20100

0.5

1

1.5

2

2.5

STT Diver IndexObserved IndicesPredicted Indices

Year

Stan

dard

ized

CPUE

STT Stock Health Indicators

1975 1980 1985 1990 1995 2000 2005 20100

0.5

1

1.5

2

2.5

Trap CPUE Divers CPUE

Year

Rela

tive

CPU

E va

lue

1975 1980 1985 1990 1995 2000 2005 2010707580859095

100105110115120

Avg Length Minimum size Size at 50% Maturity

Year

Cara

pace

Len

gth

(mm

)

1970 1975 1980 1985 1990 1995 2000 2005 20100

2000

4000

6000

8000

10000

12000

14000

STX Trap LandingsObserved LandingsPredicted Landings

Year

Land

ings

(kg)

1970 1975 1980 1985 1990 1995 2000 2005 20100

10000

20000

30000

40000

50000

60000

70000

80000

STX Diver LandingsObserved LandingsPredicted Landings

Year

Land

ings

(kg)

1970 1975 1980 1985 1990 1995 2000 2005 20100

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2 STX Trap IndexObserved IndicesPredicted Indices

Year

Stan

dard

ized

CPUE

1970 1975 1980 1985 1990 1995 2000 2005 20100

0.5

1

1.5

2

2.5

3

STX Diver IndexObserved IndicesPredicted Indices

Year

Stan

dard

ized

CPUE

Total STX Lobster Landings

19751977

19791981

19831985

19871989

19911993

19951997

19992001

20032005

20072009

20110

20000

40000

60000

80000

100000

120000

140000

160000

180000

Divers Trap

Year

Land

ings

(lbs

x 1

000)

STX Stock Health Indicators

1975 1980 1985 1990 1995 2000 2005 20100

0.5

1

1.5

2Trap CPUEDivers CPUE

Year

Rela

tive

CPUE

val

ue

1975 1980 1985 1990 1995 2000 2005 2010707580859095

100105110115120

Avg Length Minimum size Size at 50% Maturity

Year

Cara

pace

Leng

th (m

m)

Summary of Status: St. Thomas• On St. Thomas, landings increased gradually from the mid-1980s to peaks of

just over 136,000 lbs in 2003 through 2006, followed by decreased landings following this period.

• During this time of historically high catches, the stock showed no consistent signs of decline in catch per unit effort or in the average size of catch.

• The average size of catch itself remained well above the minimum size limit and the size at first maturity.

• As such, catches of 130,000 lbs a year appear to be sustainable. Current OFL is 115,776 lbs.

• Ongoing catch reporting and port sampling allow us to watch for future signs of overfishing, and would allow for the opportunity to adjust catches downward if necessary.

Summary of Status: St. Croix• On St. Croix, landings grew dramatically starting in the mid-1990s to a

peak of over 155,000 lbs in 2008. Catches have exceeded 135,000 lbs most years since 2005.

• Indicators of health provide conflicting information. Whereas catch per unit effort has consistently increased since 2003, the average size of catch has mostly declined since 2007, with particularly dramatic drops in 2011 and 2012. The value in 2012 was close to the minimum size limit and size at first maturity, indicating lobster were being caught just as they grew to legal size and were capable of contributing new lobsters to the population.

• Given the data sources (port sampling versus self-reporting) and problems with assessing diving effort, the size information should probably receive greater consideration than catch per unit effort.

• While the size information is no guarantee that the stock is in poor condition, it does raise concerns about the current catch levels.

• Catches of 100,000 to 120,000 lbs were sustained in the early 2000s and may be a suitable quota, pending ongoing monitoring of this stock. Current OFL is 119,230 lbs.