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Evaluating Local Lobster Population Dynamics with Geo-referenced Trap Arrays,

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

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Evaluating Local Lobster Population Dynamics with Geo-referenced Trap Arrays,

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  1. Evaluating Local Lobster Population Dynamics with Geo-referenced Trap Arrays, Mark-recapture Methods & Seabed Mapping Richard A. Wahle1 Michael J. Dunnington 1 Kerrie O’Donnell2, Nate Geraldi2 Allen Gontz3, Michael C. Bell 4 1 Bigelow Laboratory for Ocean Sciences 2 The Island Institute, Rockland, ME 3 University of Maine, Orono 4CEFAS, 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. Water column (Pre-settlement) Processes - larval drift & death POSTLARVAE transport LARVAE CRYPTIC JUVENILE emerge ADOLESCENTS hatch disperse / migrate ADULT Seabed (Post-settlement) Processes - movements & mortality (SPAWNERS) Long-term Vision Linking Life Stage-specific Abundance Estimates

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

  5. Validating Trap-based Mark-Recapture Methods 2001 3 Hauls in 10 d 3 Hauls in 10 d 2-4 Weeks – No Research Trapping Etc. ….. 3d 3d Trap Trap Trap Trap Trap Trap Dive Surveys Dive Surveys Sampling Schedule

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

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

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

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

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

  11. N N Rockland Harbor Rockland Harbor 2002 Vinalhaven Vinalhaven 2002 2001 2001 Validating Trap-based Mark-Recapture Methods 2002

  12. Validating Trap-based Mark-Recapture Methods 2002 Carvers Harbor Sheep Ledges Browns Head 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. A. Maine Maine Penobscot Bay Penobscot Bay North Haven North Haven B. B. - - Vinal Vinal haven haven Rockland Rockland C. C. T T Harbor Harbor C1 C1 C2 C2 “ DG ” Buoy APPLICATION: Impact of Dredge Disposal on Lobster & Crab A. A. B. B. Disposal Area “DG” Buoy

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

  17. T T C2 C2 C1 C1 AFTER

  18. Before After T C2 C1

  19. 11/1/02 11/1/02 11/5/02 11/5/02 11/8/02 11/8/02 T T T T T T T T T C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 DISPOSAL BEGINS DISPOSAL BEGINS DISPOSAL BEGINS 11/12/02 11/12/02 11/22/02 11/22/02 11/15/02 11/15/02 T T T T T T T T T C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 11/26/02 11/26/02 12/4/02 12/4/02 12/11/02 12/11/02 T T T T T T T T T C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 12/16/02 12/16/02 12/19/02 12/19/02 T T T T T T C1 C1 C1 C2 C2 C2 C1 C1 C1 C2 C2 C2 Lobster Response

  20. 11/5/02 11/5/02 11/8/02 11/8/02 T T T T T T C1 C2 C1 C2 C1 C1 C2 C2 C1 C1 C2 C2 DISPOSAL BEGINS DISPOSAL BEGINS DISPOSAL BEGINS 11/12/02 11/22/02 11/12/02 11/22/02 11/15/02 11/15/02 T T T T T T T T T C1 C1 C2 C2 C1 C1 C2 C2 C1 C1 C2 C2 C1 C2 C1 C2 C1 C2 11/26/02 12/4/02 12/11/02 11/26/02 12/4/02 12/11/02 T T T T T T T T T C1 C1 C2 C2 C1 C1 C2 C2 C1 C1 C2 C2 C1 C2 C1 C2 C1 C2 12/16/02 12/19/02 12/19/02 12/16/02 T T T T T T C1 C1 C2 C2 C1 C1 C2 C2 C1 C2 C1 C2 Crab Response

  21. Central Traps All Traps p = 0.00008 Crab Lobster Crab Lobster p < 0.00001 p = 0.16 p = 0.18 Response Summary

  22. Validating Trap-based Mark-Recapture Abundance Estimates with Dive Surveys Summary: • 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.

  23. Acknowledgements • 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

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

  25. Different Trap Same Trap Movements Within Array 2001 2002

  26. Why Use Traps? • Efficient • Relatively inexpensive • Sample where divers & trawls can’t • Catch data – reflect basic patterns • 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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