grappling the invisible: a derelict crab pot...
TRANSCRIPT
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Grappling the Invisible: A Derelict Crab Pot Removal Pilot Study in the Delaware Bay-
Lessons Learned
Nicole Rodi
Drexel Siok
Kari St. Laurent, Ph.D
Delaware Department of Natural Resources and Environmental Control
Delaware Coastal Programs
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Project Overview
Location: Delaware Bay
New Jersey
Pennsylvania
Delaware
Maryland
Delaware Bay
Project Location: Delaware Bay
• NOAA Marine Debris Removal Grant
• Connecting the Mid-Atlantic
• Similar goals, different challenges
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Delaware Bay vs. Coastal New Jersey Bays
•Much deeper and dredged regularly
•Very open to the ocean and not extremely protected
•Much stronger currents and greater tidal flux
http://portal.midatlanticocean.org/
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Contracting with Stockton University
• Identification of pots in the target area
• Comparing the efficiency and accuracy of the Klein 3900 to the Humminbird Helix 10
• Testing pot removal methods
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517 targets!
~ 6 miles of coast
2 days of scanning
Stockton Identified Pots 2017
Stockton Identified Pots 2018 Identification
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Density
Density
Bay Depth (m)
• Follows the 0-2 MLW depth line
• Raises further questions
• Why are pots aggregating near the shoal tip?
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Efficiency: Klein vs. Humminbird
• 1 Day of scanning:
• Stockton 1.5 sq miles
• DNREC 0.2 sq miles
• Klein 3900 scanner is 12 times more efficient in covering the same area
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Humminbird Scanner with 80 foot swaths
Klein Scanner with 165 foot swaths Accuracy: Klein vs. Humminbird
Photo Credit: Stockton University
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Accuracy: Klein vs. Humminbird
Stockton 2018 Scanned Pots - 27 DNREC 2018 Scanned Pots - 40
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Accuracy: Klein vs. Humminbird
Stockton 2018 Scanned Pots - 27 DNREC 2018 Scanned Pots - 24
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• Scan 1- Mid-December
• Scan 2- Mid- February
• 20 pots identified in the same location (Klein to Klein)
• 77% of pots moved 3+ meters away
Pot Movement
Stockton Overlap 2017
Stockton Overlap 2018
Reidentified Stockton Pots
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Scouring
Photo Credit: Stockton University
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Photo CreditLeft: John Sparks Right: NASA
ICE!!
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Conclusions
• Pots are aggregating in shallow shoal areas
• The Humminbird side scanner is not ideal for original identification of pot abundance and density
• Low confidence in watermen's ability to find and remove pots
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Recommendations
• Focus on a loss prevention program
• Trial more deep water techniques of removal
• Create a pot recycling program so watermen aren’t ditching their old pots
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Thank you Stockton University Marine Field
Station!