Department of Planning and Natural Resources Division of Fish and Wildlife

  • Published on
    06-Jan-2016

  • View
    24

  • Download
    0

Embed Size (px)

DESCRIPTION

Spatial and temporal variation in stock abundance of queen conch, Strombus gigas , in the US Virgin Islands. Research conducted by Gordon & Tobias. Department of Planning and Natural Resources Division of Fish and Wildlife. Biology of Queen Conch. About 3-3.5 years to reach sexual maturity - PowerPoint PPT Presentation

Transcript

  • Spatial and temporal variation in stock abundance of queen conch, Strombus gigas, in the US Virgin IslandsDepartment of Planning and Natural ResourcesDivision of Fish and WildlifeResearch conducted by Gordon & Tobias

  • About 3-3.5 years to reach sexual maturity Reaches 12 inches in lengthMature conch has flared lipLifespan as long as 20 years (Berg, 1987)

    Biology of Queen Conch

  • Mate during the warm summer months

    Require at least 50 conch/hectare for reproduction (Stoner & Ray 1996)

    Produce about 400,000 eggs per spawn

    Spawn about 6 times a summer

    Conch Reproduction

  • Conch ReproductionPlanktonic larvae stage (veligers) drift in water column for 2-3 weeks

    Settle to the bottom and change into regular conch form

  • Habitat & Feeding HabitsCommonly found in seagrass and algae habitat Can be found in all habitatsGraze on various species of algae and seagrassReported to depths of 400 feet Burying behavior (juveniles)

  • Harvest size limits-minimum length 9 inches (23 cm) OR-minimum lip thickness 3/8 inch (9.5 mm)

    Closed season extension* June 1 October 31 each year*In 2008 VI government extended seasonal closure by 2 months for the territory because of overfishing concerns on STX Territorial Regulations in the USVI

  • Recreational quota-6 conch per day per recreational fisher-maximum of 24 per boat per day

    Commercial quota-maximum of 200 conch per day per registered commercial fishing vessel

    No sale of undersized conch shell permittedTerritorial Harvest Quota

  • Landing quota developed in June 2008:-50,000 lbs. annually per district-Thereafter, the season will be closed until November 1 of that year.

    All conch must be landed and reported in the district from which they were harvested.

    Must be landed whole in the shellTerritorial Landing Restrictions

  • Total queen conch by fishing year. MSY is a range of 30,000 (CFMC) - 60,000 lbs (Olsen 2007). USVI MSY set at 50,000 lbs.

    Chart1

    289925773

    152740404.75

    130068897.5

    142255015.5

    94157294

    1669101720

    2654.25127366.5

    3037105326.5

    2150126096

    444136264.5

    3325244225.5

    1869196628

    88883032.5

    119597848.5

    Esitimated range of MSY

    STT/STJ

    STX

    Total Pounds

    Reported queen conch commercial landings by fishing year, USVI (1995-2009)

    Sheet1

    ISLANDFISHING_YEARSumOfCONCHISLANDFISHING_YEARSumOfCONCHTOTAL USVI

    STX1986-8715592STT/STJ1986-87273818330

    STX1987-8821446STT/STJ1987-88547426920

    STX1988-89889STT/STJ1988-890889

    STX1989-905330STT/STJ1989-901005430

    STX1990-9147157STT/STJ1990-91047157

    STX1991-9221751STT/STJ1991-922521776

    STX1992-9312484STT/STJ1992-9337512859

    STX1993-9442205STT/STJ1993-94691949124

    STX1994-9537783STT/STJ1994-9558638369

    STX1995-9625773STT/STJ1995-96289928672

    STX1996-9740404.75STT/STJ1996-97152741931.75

    STX1997-9868897.5STT/STJ1997-98130070197.5

    STX1998-9955015.5STT/STJ1998-99142256437.5

    STX1999-0057294STT/STJ1999-0094158235

    STX2000-01101720STT/STJ2000-011669103389

    STX2001-02127366.5STT/STJ2001-022654.25130020.75

    STX2002-03105326.5STT/STJ2002-033037108363.5

    STX2003-04126096STT/STJ2003-042150128246

    STX2004-05136264.5STT/STJ2004-05444136708.5

    STX2005-06244225.5STT/STJ2005-063325247550.5

    STX2006-07196628STT/STJ2006-071869198497

    STX2007-0883032.5STT/STJ2007-0888883920.5

    STX2008-0997848.5STT/STJ2008-09119599043.5

    Fishing YearSTT/STJSTXUSVI

    1995-9628992577328672

    1996-9715274040541932

    1997-9813006889870198

    1998-9914225501656438

    1999-009415729458235

    2000-011669101720103389

    2001-022654127367130021

    2002-033037105327108364

    2003-042150126096128246

    2004-05444136265136709

    2005-063325244226247551

    2006-071869196628198497

    2007-088888303383921

    2008-0911959784999044

    Sheet1

    Esitimated range of MSY

    STT/STJ

    STX

    Total Pounds

    Reported queen conch commercial landings by fishing year, USVI (1995-2009)

    Sheet2

    Sheet3

  • Harvest size limits (9 length or 3/8 lip thickness) Recreational limit= 3 conch per person or 12 per boatCommercial limit= 150 conch per dayNo hookah Conch must be landed with meat and shell intactNo harvest in EEZ except Lang Bank, STX from October 1 June 30

    Federal Regulations

  • USVI = total of 52 sites/114 transects (STT=12 sites/28T; STJ= 12/24T; STX=30 sites/62T)Underwater Scooter Transects

  • Conch transect sites around St. Thomas/St. John, 2008-2009. Note: Two new sites were added to the original 22 based on fisher input.

  • Conch transect sites around St. Croix, 2009-2010. Note: Eight new sites were added to the original 22 based on fisher input and areas of concern such as Lang Bank.

  • 28 scooter transects around St. Thomas. *New sites based on commercial fisher input .

    Chart2

    15.565781360527.2401173809

    38.06971621441408.5794999316

    013.8586586624

    170.9155084652139.8399614715

    2.8830.21

    00

    4.25049001470

    015.6021357328

    89.69746414544.9831924525

    3706.52277.989110172

    43.480284814624.8458770369

    882.1654254192103.7841676964

    Adults

    Juveniles

    Density (conch/ha)

    Density of adult and juvenile queen conch for 2008-09 observed on scooter transects around St. Thomas, USVI

    Density

    STTSTTSDCRRBSGPVALSt. ThomasSt. JohnSt. Croix

    AdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdt. DensityJuv. DensityAdtJuvAdtJuv

    SiteDensityAdt. DensityJuv. DensityBolog0.000.000.000.000.000.000.000.000.000.000.000.0052.370.00

    Bolongo Bay42.815.5727.24Fortuna0.000.000.000.000.000.000.0010.7049.43247.13

    *Brewers Bay1446.738.071408.58

    Fortuna Bay13.90.0013.86

    Inner Water Is.310.8170.92139.84

    Lindqvist Bay33.12.8830.21

    Magens Bay0.00.000.00

    Outer Water Is.4.34.250.00Inner Water0.000.0010.540.000.000.00105.370.00115.910.000.000.000.009.59

    Perseverance Bay15.60.0015.60Linquist0.000.0048.8814.0651.5718.750.000.0086.31138.10

    Pillsbury Sound94.789.704.98Magens0.000.000.000.000.000.000.000.000.0052.077.010.00

    *Saba3984.53706.52277.99Outer water0.000.000.000.000.000.000.000.000.000.00

    Secret Harbor68.343.4824.85Perserv.0.000.000.000.000.000.000.000.000.000.000.000.00

    West End986.0882.17103.78Pills.0.000.000.000.000.000.000.000.000.000.0036.170.00

    ACD0.000.001.510.000.000.000.000.000.000.0025.712.3420.942.340.0062.7715.71487.00

    Avg Density (*new sites included)583.37412.80170.58SD0.000.003.980.000.000.000.000.000.000.0043.655.7439.676.630.007.850.002.67

    StDev1166.621066.54398.320.0018.260.000.00

    SD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *57.49137.98

    Avg Density (10 sites)156.93120.9036.04ACD0.001.561.510.0014.480.009.9891.070.000.0023.192.01304.501022.46

    SD0.004.133.890.0028.950.0011.05157.740.000.0040.405.3125.3785.21

    29.88150.55

    STJ

    SiteDensityAdt. DensityJuv. Density

    Fish Bay397.486.39310.99

    Francis Bay0.00.000.00

    Haulover Bay32.132.10.00STJSDCRRBSGPVALcoefficient of variation for VINP transects compared to other STJ transects

    Johnson/Cinn. Bay0.00.000.00AdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuvVINPOTHER

    Lameshur36.517.0319.46Fish0.000.000.000.000.000.00Johnson/Cinnamon Bay0.00Fish Bay0.00

    Leinster Bay64.564.520.00Francis0.000.000.0010.70Francis Bay10.70Two Brothers73.30

    Mingo/Lovango0.00.000.00Haulover0.000.000.000.000.000.00Haulover Bay0.00Turner Bay40.30

    Reef Bay6.42.134.25johnson Reef0.000.000.000.000.000.00Lameshur52.07Rendezvous Bay0.00

    Rendezvous Bay8.98.930.00lameshur0.000.000.0052.070.000.00Leinster Bay0.00Round Bay0.00

    Round Bay0.00.000.00Leinster0.000.000.000.00Reef Bay0.00Mingo/Lavango0.00

    Turner Bay303.4182.03121.35Mingo0.000.000.000.00total62.77total113.60

    Two Brothers34.930.983.87Reef0.000.000.000.000.000.00ACD10.46ACD18.93

    Rendezvous0.000.000.000.000.000.00SD20.83SD31.1324696525

    Avg Conch Density73.6735.3438.33Round0.000.000.000.000.000.00COV(SD/mean)1.99COV1.64

    StDev132.3554.0592.55Turner0.000.0013.4326.87

    2 Bro.12.220.0061.080.00

    TOTAL12.220.000.000.000.000.0013.4378.940.000.0061.0810.70

    STXACD1.110.000.000.000.000.002.6915.790.000.005.550.97

    SiteTotal DensityAdt. DensityJuv. DensitySD3.680.000.000.000.000.006.0123.380.000.0018.423.23

    1117.633.5983.97

    2702.2149.54552.66SD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *

    3329.9293.8436.09ACD1.110.000.000.000.000.002.6915.790.000.005.550.97

    4956.678.63878.00SD3.680.000.000.000.000.006.0123.380.000.0018.423.23

    543.330.8912.36

    60.00.000.00

    70.00.000.00STXSDCRRBSGPVAL* max scale 120 (was 25);units by 20 (was 5)

    81.61.630.00AdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuv

    911.611.580.00site 122.440.0015.000.0015.000.00

    103.10.003.1120.0079.0849.43168.05

    1115.012.522.5030.009.590.000.000.000.00

    12338.384.58253.75486.31138.10

    1377.043.3033.6857.010.000.000.000.000.000.00

    140.00.000.0060.000.00

    1547.817.7030.1070.000.00

    16536.6313.04223.6080.000.000.000.0036.170.00

    1715.613.372.239127.7185.14

    183.90.003.92100.000.00

    19A27.09.0018.00110.000.00

    19B0.00.000.00120.000.005.4348.88

    20A2.01.960.001315.71487.00

    20B0.00.000.00140.000.000.002.670.000.00

    2124.010.6813.35150.000.000.000.00

    220.00.000.001657.49137.98

    *CC11176.7619.94556.36TOTAL29.459.590.000.000.002.6786.31217.18142.7185.14179.23841.91

    *CC226.716.999.71ACD7.362.400.000.000.001.3421.5872.3915.869.4619.9193.55

    *CC3127.149.9277.14SD10.584.800.000.000.001.8943.1669.2942.2428.3822.33161.28

    *CC4155.381.3373.94

    *LB179.179.140.00SD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *

    *LB216.316.330.00ACD7.362.400.000.000.001.3421.5872.3915.869.4619.9193.55

    *LB337.437.350.00SD10.584.800.000.000.001.8943.1669.2942.2428.3822.33161.28

    *LB4201.1201.130.00

    AvgCD (w/ new sites, 30 sites)158.5369.0089.51

    StDev290.45128.86202.12

    Avg Density (22 sites)135.546.0889.47

    StDev86.984209.520

    Density

    Density (conch/ha)

    Figure 2. Density of queen conch for 2008-09 observed on 28 scooter transects around St. Thomas, USVI

    Density by Habitat

    Density (conch/ha)

    Figure . Density of queen conch for 2008-09 observed on 24 scooter transects around St. John, USVI

    Length

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    00

    956.6

    117.6

    702.2

    329.9

    43.3

    0.0

    0.0

    1.6

    11.6

    3.1

    15.0

    338.3

    77.0

    47.8

    536.6

    15.6

    3.9

    27.0

    0.0

    2.0

    0.0

    24.0

    0.0

    1176.7

    26.7

    127.1

    153.3

    79.1

    16.3

    37.4

    201.1

    0.0

    Adults

    Juveniles

    Density (conch/ha)

    Density of adult and juvenile queen conch for 2009-10 oberved on scooter transects around St. Croix, USVI.

    insert depth from KD

    397.4

    0.0

    32.1

    0.0

    36.5

    64.5

    0.0

    6.4

    8.9

    0.0

    303.4

    34.9

    Adults

    Juveniles

    Density (conch/ha)

    Density of adult and juvenile queen conch for 2008-09 observed on scooter transects around St. John, USVI

    Thickness

    Adults

    Juveniles

    Density (conch/ha)

    Density of adult and juvenile queen conch for 2008-09 observed on scooter transects around St. Thomas, USVI

    004.130

    0003.89

    00028.95

    00157.7411.05

    0000

    005.3140.4

    Adult

    Juvenile

    Habitat type

    Mean conch/ha

    Figure 13. Mean density for adult and juvenile queen conch by habitat type around St. Thomas, USVI in 2001

    003.680

    0000

    0000

    006.0123.38

    0000

    0018.423.23

    Adult

    Juvenile

    Habitat type

    Mean density (conch/ha)

    Figure 14. Mean density for adult and juvenile queen conch by habitat type around St. John, USVI in 2001

    004.810.58

    0000

    001.890

    0069.2943.16

    0028.3842.24

    00161.2822.33

    Adult

    Juvenile

    Habitat type

    Density (conch/ha)

    Figure 16. Mean density of adult and juvenile queen conch by habitat type around St. Croix, USVI in 2001

    0039.66799591616.6291260736

    00018.2571543218

    0029.8763925974150.5524248625

    Adult

    Juvenile

    Island

    Mean density (conch/ha)

    Figure 5. Mean density for adult and juvenile queen conch observed on scooter transects around the United States, Virgin Islands in 2001

    Density (conch/ha)

    Figure x. Density of queen conch for 2008-09 observed on scooter transects around St. Thomas, USVI

    Adults

    Juveniles

    Density (conch/ha)

    Figure x. Density of adult and juvenile queen conch for 2008-09 observed on scooter transects around St. Thomas, USVI

    Density (conch/ha)

    Figure X. Density of queen conch for 2009-10 observed on scooter transects around St. Croix, USVI

    Percent habitat distribution encountered during 114 conch transects, 2008-2010STTSDCRRBSGPVALSt. ThomasSt. JohnSt. Croix

    AdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdt. DensityJuv. DensityAdtJuvAdtJuv

    Habitatcount%Bolog0.000.000.000.000.000.000.000.000.000.000.000.0052.370.00

    Rubble796.49Fortuna0.000.000.000.000.000.000.0010.7049.43247.13

    Algae15612.81

    Pavement17013.96

    Seagrass54644.83

    Sand22418.39

    Coral Reef433.53

    Inner Water0.000.0010.540.000.000.00105.370.00115.910.000.000.000.009.59

    1218100.00Linquist0.000.0048.8814.0651.5718.750.000.0086.31138.10

    Magens0.000.000.000.000.000.000.000.000.0052.077.010.00

    Outer water0.000.000.000.000.000.000.000.000.000.00

    Perserv.0.000.000.000.000.000.000.000.000.000.000.000.00

    Pills.0.000.000.000.000.000.000.000.000.000.0036.170.00

    ACD0.000.001.510.000.000.000.000.000.000.0025.712.3420.942.340.0062.7715.71487.00

    SD0.000.003.980.000.000.000.000.000.000.0043.655.7439.676.630.007.850.002.67

    0.0018.260.000.00

    SD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *57.49137.98

    ACD0.001.561.510.0014.480.009.9891.070.000.0023.192.01304.501022.46

    SD0.004.133.890.0028.950.0011.05157.740.000.0040.405.3125.3785.21

    29.88150.55

    STJSDCRRBSGPVALcoefficient of variation for VINP transects compared to other STJ transects

    AdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuvVINPOTHER

    Fish0.000.000.000.000.000.00Johnson/Cinnamon Bay0.00Fish Bay0.00

    Francis0.000.000.0010.70Francis Bay10.70Two Brothers73.30

    Percent habitat distribution for 28 transects around St. ThomasHaulover0.000.000.000.000.000.00Haulover Bay0.00Turner Bay40.30

    countjohnson Reef0.000.000.000.000.000.00Lameshur52.07Rendezvous Bay0.00

    Rubble3lameshur0.000.000.0052.070.000.00Leinster Bay0.00Round Bay0.00

    Algae60Leinster0.000.000.000.00Reef Bay0.00Mingo/Lavango0.00

    Pavement16Mingo0.000.000.000.00total62.77total113.60

    Seagrass218Reef0.000.000.000.000.000.00ACD10.46ACD18.93

    Sand18Rendezvous0.000.000.000.000.000.00SD20.83SD31.1324696525

    Coral Reef12Round0.000.000.000.000.000.00COV(SD/mean)1.99COV1.64

    327Turner0.000.0013.4326.87

    2 Bro.12.220.0061.080.00

    TOTAL12.220.000.000.000.000.0013.4378.940.000.0061.0810.70

    ACD1.110.000.000.000.000.002.6915.790.000.005.550.97

    SD3.680.000.000.000.000.006.0123.380.000.0018.423.23

    SD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *

    ACD1.110.000.000.000.000.002.6915.790.000.005.550.97

    SD3.680.000.000.000.000.006.0123.380.000.0018.423.23

    STXSDCRRBSGPVAL* max scale 120 (was 25);units by 20 (was 5)

    Percent habitat distribution for 24 transects around St. JohnAdtJuvAdtJuvAdtJuvAdtJuvAdtJuvAdtJuv

    countsite 122.440.0015.000.0015.000.00

    Rubble320.0079.0849.43168.05

    Algae2030.009.590.000.000.000.00

    Pavement20486.31138.10

    Seagrass10757.010.000.000.000.000.000.00

    Sand4860.000.00

    Coral Reef1470.000.00

    80.000.000.000.0036.170.00

    2129127.7185.14

    100.000.00

    110.000.00

    120.000.005.4348.88

    1315.71487.00

    140.000.000.002.670.000.00

    150.000.000.000.00

    1657.49137.98

    TOTAL29.459.590.000.000.002.6786.31217.18142.7185.14179.23841.91

    ACD7.362.400.000.000.001.3421.5872.3915.869.4619.9193.55

    SD10.584.800.000.000.001.8943.1669.2942.2428.3822.33161.28

    Percent habitat distribution for 30 transects around St. Croix

    countSD *SD *CR *CR *RB *RB *SG *SG *PV *PV *AL *AL *

    Rubble73ACD7.362.400.000.000.001.3421.5872.3915.869.4619.9193.55

    Algae76SD10.584.800.000.000.001.8943.1669.2942.2428.3822.33161.28

    Pavement134

    Seagrass221

    Sand164

    Coral Reef17

    685

    01.564.130

    1.51003.89

    14.480028.95

    9.9891.07157.7411.05

    0000

    23.192.015.3140.4

    Adult

    Juvenile

    Habitat type

    Mean conch/ha

    Figu...

Recommended

View more >