STFA/SCCFA/CFMCSpiny Lobster Project

David Olsen, STFAJosh Nowlis, Bridge Environment

Daryl Bryan, STFA

Funded by Caribbean Fishery Management Council

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

)

Landings by Method

19741977

19801983

19861989

19921995

19982001

20042007

2010

-

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

St. Thomas Spiny Lobster Landings

Other

Traps

Diving

Lbs.

19751978

19811984

19871990

19931996

19992002

20052008

2011

0

20,000

40,000

60,000

80,000

100,000

120,000

140,000

160,000

St. Croix Spiny Lobster Landings

Diving

Traps

Other

Lbs.

# Lobster Trips by Island (1974-2006)

19741976

19781980

19821984

19861988

19901992

19941996

19982000

20022004

2006

0

2,000

4,000

6,000

8,000

10,000

12,000

14,000

16,000

18,000Virgin Islands Lobster Trips

St. Thomas Lobster Trips

St. Croix Lobster Trips

Tags and Recaptures

# Trips

# Tagged

# Project Recaptures

# Non-Project Recaptures # Kept

St. Croix 92 1,507 46 9 12St. Thomas 210 4,709 319 43 155

% of Lobster by CL (Complete Trips)

0%

5%

10%

15%

20%

25%

30%

35%

ST. CroixSt. Thomas

Minimum Legal CL

Average VI Lobster CL (1974-2012 from DFW Port Sampling)

19711981

19831985

19871989

19911993

19951997

19992001

20032005

20072009

20112012

90

95

100

105

110

115

St. Thomas/St. JohnSt. Croix

Cara

pace

Leng

th (m

m)

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

St. Croix Recruitment Pulse?

80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 1750

20

40

60

80

100

120

140

2002

2007

Carapace Length (mm)

# Lo

bste

rs

Recruitment Pulse?

80 85 90 95 100 105 110 115 120 125 130 135 140 145 150 155 160 165 170 1750

20

40

60

80

100

120

140

2002

2007

2012

Carapace Length (mm)

# Lo

bste

rs

Recruitment Pulse?St. Croix Size Class Frequencies

19811982

19831984

19851986

19871988

19891990

19911992

19931994

19951996

19971998

19992000

20012002

20032004

20052006

20072008

20092010

20112012

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%<105 mm CL

105-115 mm CL

116-125 mm CL

>125 mm CL

Recruitment Pulse?St. Thomas/St. John Size Class Frequencies

19711980

19811983

19841985

19861987

19881991

19921993

19942004

20052006

20072008

20092010

20112012

20122013

0%

10%

20%

30%

40%

50%

60%

<105 mm CL

105-115 mm CL

116-125 mm CL

>125 mm CL

Monthly St. Thomas Lobster Landings

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec0.0%

2.0%

4.0%

6.0%

8.0%

10.0%

12.0%

14.0%

2000 2001 2002 2003

2004 2005 2006 2007

2008 2009 2010 2011

Average

Monthly CPUE/# Trips

Sep 2012

Oct 2012

Nov 2012

Dec 2012

Jan 2013

Feb 2013

Mar 2013

Apr 2013

May 2013

Jun 2013

Jul 2013

Aug 2013

Sep 2013

Oct 2013

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

20

22

24

26

28

30

32

LT CPUE

Lobster Trips/Month

Pro

ject

Lobs

ter C

PUE

(lbs/

trap

hau

l)

Lobs

ter T

rips/

Mon

th

Peak Wind Period

Short/Berried SeasonalitySe

p-12

Oct

-12

Nov

-12

Dec-

12

Jan-

13

Feb-

13

Mar

-13

Apr-

13

May

-13

Jun-

13

Jul-1

3

Aug-

13

Sep-

13

Oct

-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 CPUE

Berried CPUE

Shor

t Lob

ster

s/Tr

ap H

aul

Berr

ied

Lobs

terT

rap

Haul

Summary of Coral World Tag Retention Study

• 45 lobsters were installed at Coral World between July and October 2013. To date there have been 9 molts with no tag loss.

• In the mean-time we have tagged an additional 10 (<45 mm) small Coral World lobsters. 6 of these molted and 4 lost their tags.

• The smallest lobster tagged in the field was 51 mm CL.

• We do not think tag loss is much of an issue.

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)

0 15 30 45 60 75 90105

120135

150165

180195

210225

240255

270285

300315

330345

3600

5

10

15

20

25

30

35

40

45

Days at Large

Freq

uenc

yDays at Large

Summer Recaptures

Winter Recaptures

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

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

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)

Estimated Spiny Lobster Growth

0 5 10 15 20 25 30 350

50

100

150

200

250

300

Age

Cara

pace

leng

th (m

m)

L∞ =244.9 mmK=0.361W∞ =15.6 lbs

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

Comparison Between Annual Fish Trap Hauls(St. Thomas 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

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

1965 1970 1975 1980 1985 1990 1995 2000 2005 2010 20150

20

40

60

80

100

120f(x) = NaN x + NaNR² = 0

SEFSC Data Adjusted CCR

TIP VIERS

MRAG MARFIN

Trap

Hau

ls/D

ay

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

)

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.

STX Stock Health Indicators

1975 1980 1985 1990 1995 2000 2005 20100

0.5

1

1.5

2Trap CPUE

Divers 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. 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 to 2011

• 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 Carapace Length 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.