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Evaluating Local Lobster Population Dynamics with Geo- referenced Trap Arrays, Mark-recapture Methods & Seabed Mapping Richard A. Wahle 1 Michael J. Dunnington.

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Presentation on theme: "Evaluating Local Lobster Population Dynamics with Geo- referenced Trap Arrays, Mark-recapture Methods & Seabed Mapping Richard A. Wahle 1 Michael J. Dunnington."— Presentation transcript:

1 Evaluating Local Lobster Population Dynamics with Geo- referenced Trap Arrays, Mark-recapture Methods & Seabed Mapping Richard A. Wahle 1 Michael J. Dunnington 1 Kerrie O’Donnell 2, Nate Geraldi 2 Allen Gontz 3, Michael C. Bell 4 1 Bigelow Laboratory for Ocean Sciences 2 The Island Institute, Rockland, ME 3 University of Maine, Orono 4 CEFAS, Lowestoft, Suffolk, UK

2 Overview Background Proof of Concept Study: Integrating mapping, trapping, mark-recapture –Dunnington et al. (NZJMFR 2005) –Geraldi et al. (CJFAS 2009) Application: Disposal Impact Study –O’Donnell et al. (MEPS 2007)

3 Seabed (Post-settlement) Processes - movements & mortality JUVENILE CRYPTIC disperse / migrate emerge ADOLESCENTS ADULT (SPAWNERS) LARVAE hatch POSTLARVAE transport Water column (Pre-settlement) Processes - larval drift & death Long-term Vision Linking Life Stage-specific Abundance Estimates

4 Seabed Mapping Geo-Referenced Trap Arrays Jolly-Seber Multiple Mark- Recapture Method  Abundance, Gains & Losses  Movement & Growth Proof-of-Concept Project Make Traps a Better Tool by Integrating Methodologies

5 Validating Trap-based Mark-Recapture Methods Weeks – No Research Trapping 3 Hauls in 10 d 3d Trap 3 Hauls in 10 d Trap Dive Surveys Sampling Schedule Etc. …..

6 N Validating Trap-based Mark-Recapture Methods 2001 Rockland Harbor Vinalhaven Penobscot Bay

7 Analysis Mark-recapture based vs Diver-based estimates of abundance Diver Surveys by Substrate Substrate Mapping Population Estimate Research Trap Catch Mark- Recapture Analysis Validating Trap-based Mark-Recapture Methods 2001

8 Analysis Mark-recapture based vs Diver-based estimates of abundance Diver Surveys by Substrate Substrate Mapping Population Estimate Research Trap Catch Mark- Recapture Analysis Validating Trap-based Mark-Recapture Methods 2001 Catch per Trap (+/- 1SE)

9 Geo-referenced Catch Patterns 2001 All Lobsters Catch Per Trap June 20, 2001June 21, 2001June 22, 2001July 6, 2001July 9, 2001July 12, 2001July 27, 2001July 30, 2001August 2, 2001August 24, 2001August 27, 2001August 30, 2001September 21, 2001September 24, 2001September 27, 2001October 29, 2001November 1, 2001November 5, 2001December 20, 2001

10 Analysis Mark-recapture based vs Diver-based estimates of abundance Diver Surveys by Substrate Substrate Mapping Population Estimate Research Trap Catch Mark- Recapture Analysis Validating Trap-based Mark-Recapture Methods 2001 Diver-based & Mark-recapture-based Abundance (+/- 95% C.I.) Diver-based Pop Density Estimates Mark-recapture –based Gain & Loss Estimates Mark-recapture-based Abundance Estimates (+/- 95% C.I.) Tagged 10,000 Lobsters

11 Validating Trap-based Mark-Recapture Methods Rockland Harbor Vinalhaven N Rockland Harbor Vinalhaven N

12 Validating Trap-based Mark-Recapture Methods 2002 Browns Head Sheep Ledges Carvers Harbor Dogfish Island

13 Sediment Cobble Ledge Movements Within Array Tagged & Recaptured in Research Traps Lobster first tagged on

14 Movements Beyond Array Tagged in Research Traps. Recaptured in Commercial Traps

15 A. B. A. B. APPLICATION: Impact of Dredge Disposal on Lobster & Crab “DG”Buoy C1 T C2 Maine Penobscot Bay Rockland Harbor North Haven Vinal - haven A. B. C. C1 T C2 Maine Penobscot Bay Rockland Harbor North Haven Vinal - haven A. B. C. Disposal Area “DG” Buoy

16 C1 T C2 C1 T C2 (b) C1 T C2 BEFORE

17 C1 T C2 C1 T C2 AFTER

18 C1 T C2 Before After

19 DISPOSAL BEGINS 11/1/0211/5/0211/8/02 11/12/02 11/15/02 11/22/02 11/26/0212/4/0212/11/02 12/16/0212/19/02 C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T DISPOSAL BEGINS 11/1/0211/5/0211/8/02 11/12/02 11/15/02 11/22/02 11/26/0212/4/0212/11/02 12/16/0212/19/02 C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T Lobster Response

20 11/5/02 11/8/02 11/12/02 11/15/02 11/22/02 11/26/0212/4/0212/11/02 12/16/0212/19/02 DISPOSAL BEGINS C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T 12/19/02 DISPOSAL BEGINS C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T 11/5/02 11/8/02 11/12/02 11/15/02 11/22/02 11/26/0212/4/0212/11/02 12/16/02 C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T C1C2 T Crab Response

21 All Traps Crab Lobster p < p = 0.16 Central Traps p = Crab Lobster p = 0.18 Response Summary

22 Seabed mapping a critical tool for habitat-specific abundance estimates & impact assessment Trap-based catch rates highly correlated with abundance. M-R analysis a powerful tool in translating catch into abundance, gains, loss estimates. Longer time series more robust. Approach can be tailored for different spatial scales and time-frames. Potential use in MPA assessment and environmental impact studies. Validating Trap-based Mark-Recapture Abundance Estimates with Dive Surveys Summary:

23 Funding: Sea Grant US Army Corps of Engineers Island Institute Industry: Walter Day, Vinalhaven Fishermen Interns of 2001, 2002: Selena Kirby, Nick Sosin, Curt Brown, Shelly Tallack Acknowledgements

24 Analysis Mark-recapture based vs Diver-based estimates of abundance Diver Surveys by Substrate Substrate Mapping Population Estimate Research Trap Catch Mark- Recapture Analysis Validating Trap-based Mark-Recapture Methods 2002 Carvers Harbor Sheep Ledges Browns Head Dogfish Island Carvers Harbor Sheep Ledges Browns Head Dogfish Island Carvers Harbor Sheep Ledges Browns Head Dogfish Island Carvers Harbor Sheep Ledges Browns Head Dogfish Island Carvers Harbor Sheep Ledges Browns Head Dogfish Island Estimated Population Size (+/- 95% C.I.) Carvers Harbor Sheep Ledges Browns Head Dogfish Island Estimated Population Size (+/- 95% C.I.) Carvers Harbor Sheep Ledges Browns Head Dogfish Island Browns Head Sheep Ledges Carvers Harbor Dogfish Island

25 Movements Within Array Different Trap Same Trap

26 Efficient Relatively inexpensive Sample where divers & trawls can’t Catch data – reflect basic patterns Why Use Traps? The Problem With Catch Data: Don’t know how catch rates relate to abundance or dynamics. Not all traps are created equal. Lobstermen fish traps to catch lobsters.


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