NOAA Submerged 

Derelict Trap 

Detection Methods 

Workshop 

June 2-4, 2009 

Silver Spring, MD, USA 

Sarah E. Morison and Peter M. Murphy (eds.) 

National Oceanic and Atmospheric Administration 

Technical Memorandum NOS-OR&R-32 

August 2009 

US Department of Commerce 

National Oceanic and Atmospheric Administration 

National Ocean Service 

Office of Response and Restoration 

Marine Debris Division 

Silver Spring, MD 20910 
Mention of trade names or commercial products does not constitute endorsement or recommendation 

for their use by the National Oceanic and Atmospheric Administration. 
NOAA SUBMERGED DERELICT TRAP DETECTION 

METHODS WORKSHOP 

June 2-4, 2009 

Silver Spring, MD, USA 

Sarah E. Morison1 and Peter M. Murphy 2 (eds.)

1 

 National Oceanic and Atmospheric Administration

 Office of Response & Restoration

 NOAA Marine Debris Division

 Silver Spring, MD 20910, USA

2 Genwest Systems, Inc.

 Edmonds, WA 98020, USA 

National Oceanic and Atmospheric Administration 

Technical Memorandum NOS-OR&R-32 

August 2009 

This document should be cited as follows: 

Morison, S. and P. Murphy (eds.). 2009. Proceedings of the NOAA Submerged Derelict Trap 

Methodology Detection Workshop. June 2-4, 2009. NOAA Technical Memorandum NOSOR&R-32. 

For copies of this document, please contact: 

NOAA Marine Debris Division 

N/ORR, SSMC-4 

1305 East-West Highway 

Silver Spring, MD 20910 

www.MarineDebris.noaa.gov 
                   

                   

                       

                       

                    

                       

                       

                             

                       

                                   

                       

                              

                             

                           

                   

                           

                         

                          

                       

                  

                       

                       

                       

                         

                          

        

PREFACE

Welcome to the proceedings of the NOAA Submerged Derelict Trap Methodology

Detection Workshop, held June 2‐4, 2009, in Silver Spring, Maryland. These

proceedings include a Detection System Selection Guide which was developed based on

the discussion at the workshop and the presenter abstracts and presentations. This

invitation‐only workshop was hosted by the NOAA Marine Debris Program.

The objectives of this workshop were to review existing methods for locating,

surveying, and assessing derelict traps, to share best practices across different projects,

and to prepare a document that would be available to any interested party to assist

them in choosing the best detection system. The workshop focused on presentations

with discussion after each, coupled with a larger discussion at the end of days 1 and 2 to

highlight similarities in activities and results, potential best methods, and identify any

gaps in knowledge. Day 3 was used by those invitees who were writing project plans

associated with derelict traps to incorporate the lessons learned on days 1 and 2 into

their plans. All twelve presentations from days 1 and 2 are included here, with

abstracts and slides as deemed appropriate by the presenters.

Days were organized to focus the first day on derelict pot detection methodology and

the second day on techniques for assessing impacts to habitat, target and/or non‐target

species from derelict pots, which varied by project. A document developed based on

the presentations and discussion from Day 1, a Detection System Selection Guide, is

included in this Proceedings after the Table of Contents.

Appendices include the workshop agenda, and a list of workshop participants and

contact information.

These proceedings are meant to be a compilation of the workshop presentations and

one output (discussed at the workshop, but drafted and finalized afterwards, with

attendee input). Presenters have sole responsibility for the view and data in their

presentations. The content of presentations does not necessarily reflect the view of the

National Oceanic and Atmospheric Administration.

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TABLE OF CONTENTS

PREFACE ................................................................................................................................i
 

TABLE OF CONTENTS .............................................................................................................ii‐iii
 

WORKSHOP OUTPUT: Detection System Selection Guide................................................1‐3
 

ABSTRACT AND PRESENTATIONS ..........................................................................................4‐35
 

Opening Remarks | Dr. Holly Bamford
 

Day 1: Side Scan Sonar and Towed Diver Techniques

Sonar – Points to Consider | Mr. Peter Murphy ................................................14
 

Playing Hide and Seek with Derelict Pots | Mr. Jeff June ................................15
 

Use of Side Scan Sonar Survey Techniques to Answer the Question:
 

Are Derelict Crab Traps a Problem in Chesapeake Bay? | Dr.
 

Steve Giordano ..................................................................................................16
 

Derelict Blue Crab Traps in the Virginia Portion of the Chesapeake
 

Bay | Mr. David Stanhope...............................................................................17‐18
 

North Carolina Derelict Crab Pots: Shallow Water Side‐Scan Sonar
 

Efforts | Mr. Andy Wood ................................................................................19‐21
 

Towed‐Diver Surveys for Assessing Derelict Spiny Lobster Traps
 

and Trap‐Related Debris in FKNMS | Ms. Amy Uhrin ..............................22‐24
 

Day 2: Impact Studies

Derelict Crab Pot Impact Studies: Impact, Mortality and Loss‐Rate |
 

Mr. Jeff June .......................................................................................................25
 

Derelict Crab Trap Assessment and Impacts: Are Derelict Crab
 

Traps a Problem in Chesapeake Bay? | Mr. Ward Slacum.........................26
 

Derelict Blue Crab Traps in the Virginia Portion of the Chesapeake
 

Bay | Mr. Kory Angstadt .................................................................................27
 

ii 
                     

   

   

                   

                 

     

   

   

North Carolina Derelict Crab Pots 101: Shallow Water Efforts | Mr.
 

David Lee ...........................................................................................................28‐34
 

Lobster Trap Loss, Persistence, and Impact on Natural Resources in
 

Florida Keys National Marine Sanctuary | Mr. Tom Matthews................35‐36
 

APPENDICES

A: Workshop Agenda.......................................................................................37‐39
 

B: Workshop Participants ................................................................................40‐41
 

iii 
WORKSHOP OUTPUT: 

Detection System Selection Guide 

1
 

 

 

 

 

 

 

 

 

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DERELICT POT DETECTION SYSTEM SELECTION GUIDE
 
 

When looking to reliably locate derelict pots on the bottom of any body of water, there are many 

variables that must be taken into account when deciding which technology to use. This 

document identifies key environmental and technological factors to consider when selecting a 

detection system to locate items of the appropriate shape and size of pot specifications. (Only 

through trial and error can derelict pots be distinguished from other targets of similar size.) If 

multiple systems are applicable the user should examine the technologies identified and conduct 

further research to determine which will work best in their environment. 

Each of the detection methods carry their own inherent detection error, which will vary by the 

environment and conditions of the survey area. To ensure a successful assessment project, a 

ground truthing component should be incorporated to evaluate the detection error particular to 

the project. Ideally, this evaluation should be done early in the project so as to evaluate the 

efficacy of the method being used prior to completion of the entire survey area. This ground 

truthing is most commonly achieved through manual observation. 

The tables below present different sets of information and variables to consider when selecting 

the detection method for a given survey area. The detection methods listed are side scan sonar, 

side imaging, multibeam sonar, diver tow, video, surface visual, and aerial visual. The 

information is presented in three matrices: by survey environment; survey approach, and 

logistical background. Taken together, this information will aid in the selection of the best 

method to detect derelict pots. 

Table One: DETECTION SYSTEM APPLICABILITY* 

DETECTION METHOD SURVEY ENVIRONMENT 

High SAV > SAV < 

Flat Sandy / Rocky =< Rocky > Relief trap trap High 

Bottom Muddy Pebbles Boulders Seamounts Bottom height height Turbidity 

Side Scan Sonar Yes Yes Yes No No Yes No Yes Yes 

Side Imaging Yes Yes Yes No Yes Yes No Yes Yes 

Multibeam Sonar Yes Yes Yes No Yes Yes No Yes Yes 

Diver Tow Yes Yes Yes Yes Yes Yes Yes Yes No 

Video Yes Yes Yes Yes No No Yes Yes No 

Surface Visual Yes Yes Yes Yes No No No Yes No 

Aerial Visual Yes Yes Yes No Yes No No Yes No 

*Please note, Table One is not meant to be an exhaustive list of all survey environments or habitat types, 

but rather to provide an initial list of environments in which survey techniques have been used in the past, 

and their relative effectiveness. 

Table Two: IMPLEMENTED METHODOLOGIES 

DETECTION METHOD SURVEY PROTOCOLS 

Water Depth Elevation Frequency Swath Speed 

Surface to sea floor Water Above sea floor Coverage Area 

in work area Air Above sea level Width 

Side Scan Sonar 

Side Imaging 

Multibeam Sonar 

Diver Tow 

Video 

2 - 600 m 

1 - 10 m 

> 2m; Frequency 

Dependent 

2 - 15 m 

2 - 6000 m 

10% of water depth 

N/A - Hull Mount 

N/A - Hull Mount 

Topography 

Dependent 

Vis Dependent 

300 - 600 kHz 

455 kHz 

240 - 455 kHz 

N/A 

N/A 

20-50 m 

20-25 m 

3.5 x Elevation 

Vis Depedent 

Vis Dependent 

4 - 5 kts 

4 - 5 kts 

4 - 5 kts 

< 1.6 kts 

< 1 kts 

Surface Visual Location Dependent Surface N/A Vis Dependent < 1 kts 

Aerial Visual 0 m 300 - 1000 ft N/A Vis Dependent 85 - 110 kts 

2
Table Three: LOGISTICAL INFORMATION 

DETECTION METHOD LOGISTICAL NEEDS 

Side Scan Sonar 

Side Imaging 

Multibeam Sonar 

Diver Tow 

Platform Recording Geo Referencing Data Tracking Recommended Special Equipment 

Video 

Surface Visual 

Aerial Visual 

Vessel Portable HD GPS 

Survey/ 

Acquisition/ 

Processing 

Software 

Winch 

Vessel Portable HD / 

RMU 

GPS dB Extension Cable, Pole/Mount 

Vessel Portable HD GPS 

Survey/ 

Acquisition/ 

Processing 

Software 

-

Vessel 

Video/Still 

Camera, 

Underwater 

Writing Tablet 

GPS dB Manta Tow Bar 

Vessel 

Video/Still 

Camera, 

Writable 

Surface 

GPS dB Pole / Mount 

Vessel 

Video/Still 

Camera, 

Writable 

Surface 

GPS dB -

Plane Still/Video 

Camera 

GPS dB Synchronized GPS + Camera 

timestamps 

GLOSSARY: 

SAV Submerged Aquatic Vegetation 

SSS Side Scan Sonar 

Vis Visibility 

HD Hard Drive 

GPS Global Positioning System 

dB Database 

RMU Removable Memory Unit (e.g., flash or USB drive) 

3
ABSTRACTS AND PRESENTATIONS
 

4
NOAA Submerged Derelict Trap Methods

Detection Workshop 

Introduction, Purpose and Expected Outcomes
	

Courtyard by Marriott 

Silver Spring, Maryland
	

June 2-4, 2009
	

Holly Bamford, Ph.D.
 

NOAA Office of Response & Restoration
 

Marine Debris Program, Director
 

5
Previous Allocation of MDP Resources 2005-08
 

6
2009 Program Re-Focusing
 

Regional workshops 

•Hawaii 

•Alaska 

•New England 

• Information Forum 2008 and Regional workshops 

• Assessment of what we know, what we don’t know and what we need to know 

• Regional needs aligned with NOAA’s mandates 

• Development of a strategic plan 

• Base funded 

• Performance measures 

• Focus efforts through research and internal projects 

• Move from proposal request to partnership projects 

7
2009 MDP Priorities 

1. Monitoring - National Marine Debris Quantification Index 

1. Quantify the density of marine debris along coastal shorelines, 

sediment/sand grabs, pelagic, and submerged. 

2. Smart Partnerships 

1. Partnership grants 

2. Engage academia 

3. Investigate popular questions - GGP 

3. Research - Assess impacts of Derelict Traps 

1. Species impacts (targeted and non-targeted species) 

2. Habitat impacts 

3. Economic impacts 

8
 

9

Pot and Trap 

Fisheries 

Dungeness 

Spiny Lobster 

American Lobster 

Blue Crab 

Fin Fish 

Black Sea Bass 

Stone Crab 
Purpose of the Workshop 

1. Compile and summarize derelict trap/pot assessment techniques 

1. Move towards standardization 

2. Sharing of information 

3. Reduce the likelihood of reinventing the wheel 

2. Develop a national understanding of trap/pot impacts 

1. Links across projects 

2. Regional comparisons 

3. National significance 

3. Develop better coordination and communication 

10
 

Plan for the next three days 

• Tuesday 

– Technologies to detect pots and traps 

• Occurrences, densities, conditions 

– What works, what doesn’t, recommendations 

• Wednesday 

– Impact assessments 

• Laboratory, controlled, and field observations 

– What works, what doesn’t, recommendations 

• Thursday 

– Utilize information from Tuesday – Wednesday to develop project plans 

for current proposed projects 

11
Project Plans 

1. Quantify the fishing effort in the region, percent of traps lost 

annually, causes of trap loss 

2. Determine the number of derelict traps in study area 

1. Densities correlated with another parameter (habitat type, fishing efforts) 

3. Derelict pot durability and behavior 

1. Rot cord, aging, lifetime, storm impact, navigation and fishing impact 

4. Derelict trap impact quantification 

1. Targeted species mortality rates 

2. bycatch and mortality rates 

3. Habitat impacts 

12
Expected Outcomes 

• Extended Proceedings 

– Abstracts 

– Presentations 

– Discussions and recommendations from workshop 

– Contacts 

• Draft Project Plans 

– Alaska 

– Florida 

– South Carolina 

– Caribbean (USVI) 

13

 

Questions when Deciding on Side Scan Sonar/Things to Keep in Mind 

Peter Murphy, NOAA 

When setting out to locate sub surface targets, there are a number of variables whose answers, 

when taken together, can provide valuable insight on the most likely detection technique to 

provide optimal data. As new and more advanced detection technologies continue to be 

introduced, the list of potential detection techniques continues to grow as well. As presentations 

from experienced field staff during this workshop will demonstrate, the variables which dictate 

best practices can vary significantly both at a regional and local level. However, in order to 

facilitate communication and potential cross comparison, these variables have been collected 

from multiple projects to begin a rough framework of the key factors a user should take into 

account when designing the protocol for their detection effort. This list is not meant to be 

exhaustive, but rather to serve as a starting point for discussion and modification by the 

workshop attendees. 

STEP ONE: 

 How large is the area of study? 

 What level of target detail is required? 

 What data is required from processing of survey results? 

o Focused on pot/trap count and locations, or inclusive of species population data? 

RESULT: Base technology selected – Side scan sonar, Mulitbeam sonar, video survey (ROV or 

tow) 

STEP TWO: 

 What is the depth of the water to be surveyed? 

 What is the expected size of the smallest object necessary to be discovered? 

o For traps, what is the smallest trap or trap fragment which must be reliably 

discovered? 

 What is the bottom topography? 

o Are there obstructions likely to cause acoustic shadowing? 

 What is the bottom habitat? 

o Are there areas of concentrated plant-life? 

 What is the degree of accuracy required for geo-referenced positions of pots?
 

RESULT: Planned base protocol selected, including frequency, planned target survey approach. 

14

 

Abstract 

Playing Hide and Seek with Derelict Pots: 

Lessons learned during the Northwest Straits Initiative’s derelict fishing gear survey and 

removal project. 

Jeff June, Natural Resources Consultants, Inc. and the Northwest Straits Initiative
 

Sidescan sonar has been the mainstay of the derelict pot/trap detection methodology 

during the Northwest Straits Initiative’s (NWSI) derelict fishing gear survey and removal 

project that began in 2002. The method provides a cost effective means of surveying a 

large area of seabed and detecting, and more importantly, accurately identifying and 

locating derelict pots and traps. A 28 foot aluminum skiff equipped with an outboard 

motor and a 600 kHz Marine Sonics® sidescan sonar tows a heavy towfish off a winch 

on the bow. The towfish is suspended approximately 10% of water depth off the seabed 

and towed at speeds of 2.5 to 4.0 knots. Most survey effort is conducted at a 50 m swath 

width (90 m overall coverage) with 20 m used in some situations and when a more 

detailed image is desired. Tracklines are output in Hypack, a marine navigation survey 

software, and area surveyed calculated and plotted on navigation charts with a GIS 

overlay of pot/trap targets detected. Additional equipment employed includes acoustic 

tracking of the towfish position relative to the differential GPS antenna on the vessel and 

inertial motion tracking of the pitch and roll of the vessel to correct for target location in 

deep water situations. Operational adjustments are necessary to correct for temperature 

and salinity aberrations, steep side slope conditions, vessel pitch and roll, towfish layback 

and offset and detection of interference from non-trap/pot targets is discussed. The 

NWSI sidescan sonar surveys produce detailed location information that allows divers to 

return days or even months later to within 2 to 3 m of the pot/trap location and conduct 

removal operations. Since 2002, 50 days of sidescan sonar surveys have detected 5,120 

derelict pots/traps in Puget Sound, Washington. The NWSI methodology has been 

employed to find derelict traps/pots in California and North Carolina. 

15
 

Side Scan Sonar Techniques in Chesapeake Bay - Maryland 

Steve Giordano, NOAA CBO; Ward Slacum, Versar; Jay Lazar, NOAA CBO 

In 2005 the NOAA Chesapeake Bay Office (NCBO) established the Derelict Fishing 

Gear Program (DFGP) to address concerns that derelict crab traps may be negatively 

affecting blue crab and other estuarine species in Chesapeake Bay. In order to effectively 

determine the overall effects of derelict traps, specific information on species mortality 

and injury are required along with the number of derelict traps residing in the system. 

Because traditional observational methods are hindered in the Bay by turbidity, side-scan 

sonar was used to identify and quantify the densities of derelict traps. In Maryland, a 

stratified random sampling design was developed that used side-scan sonar to collect 

transect data within areas of differing fishing activity. The processed sonar data were 

reviewed in a desktop analysis to quantify derelict traps in the imagery. Reviewers were 

trained to identify derelict traps through repeated ground-truthing surveys and reference 

imagery. Placing controls in the final data set assessed the accuracy of trap identification. 

Several lessons were learned throughout this project. Repeated evaluation and refinement 

of survey and groundtruthing methods is advised before during and after project 

completion. 

16
Chesapeake Bay Virginia – Derelict Pot Assessment and Impacts 

Abstract 

Lost or abandoned (derelict) commercial fishing gear, including nets and pots, 

can present safety, nuisance, and environmental impacts in estuarine waters. 

Blue crabs and various fish species that are entrapped and die in derelict traps 

can act as an attractant to crabs resulting in a self-baiting effect. Derelict fishing 

gear damages sensitive habitat and continues to capture both target and bycatch species, leading to reduced fitness and significant acute and delayed 

mortalities (High and Worlund 1979; Guillory 1993; Bullimore et al. 2001; Guillory 

2001; Matsuoka et al. 2005; Havens et al. 2008). Animals captured in derelict 

pots experience starvation, cannibalism, infection, disease, or prolonged 

exposure to poor water quality (i.e., low dissolved oxygen) (Van Engel 1982; 

Guillory 1993). The effect of derelict blue crab pots on diamondback terrapins 

(Malaclemys terrapin) and commercially important finfish has been documented 

(Smolowitz 1978; Guillory 1993; Roosenburg et al. 1997; Guillory and Prejean 

1997). In the Gulf of Mexico, evidence that derelict pots contribute to significant 

mortalities in the blue crab fishery prompted the development of removal 

strategies to reduce the ecologic and economic impacts of derelict traps (Guillory 

et al. 2001). 

In Florida, Alabama, Mississippi, and Louisiana, estimates derived from pot loss 

calculations suggest derelict pots numbered at 605,000 in 1993: though Guillory 

and Perret (1998) state that this number probably is an underestimate. Guillory et 

al (2001) using an annual total number of pots fished commercially at 1 million 

and a 25% loss/abandonment rate suggests 250,000 derelict pots are added to 

the Gulf of Mexico annually. 

Investigations by the project team using side-scan sonar were conducted to 

locate derelict traps and assess their extent and accumulation rate. Additional 

investigations using experimental pots were conducted to calculate catch rates of 

marine organisms, trap degradation rates, and test degradable trap material (rot 

cord, degradable panels). It is estimated that about 20% of deployed traps are 

added annually to the Virginia portion of the Chesapeake Bay derelict pot 

population. Species captured in these lost or derelict pots include blue crab, 

croaker, perch, catfish, spot, red drum, striped bass, flounder, muskrat and 

diamondback terrapins. Derelict pots have been shown to captured between 50 

and 100 blue crabs per trap per season and over a dozen croaker per pot per 

season. Of the blue crabs captured by derelict pots, a significant portion is 

comprised of reproductively viable females that, if they remained in the 

population, could produce 2 to 3 broods of a couple million larvae each. Derelict 

pots continued to capture organisms for over three years after they are lost, 

depending on salinity and energy levels, which suggests derelict pots could affect 

blue crab populations (Havens et al. 2008; Havens, personal observation). 

17

 

An effort to remove derelict crab pots was conducted in Virginia during December 

2008, January, February and March 2009. Fifty eight commercial watermen 

participated using Humminbird Side Imaging units and removed over 8,600 

derelict pots which contained over 5,000 organisms 

(http://ccrm.vims.edu/marine_debris_removal/). This project will continue in the 

winter months for no more than two more years. With an annual accumulation 

rate of derelict pots estimated at about 20%, it is important to have a mechanism 

in place, once the removal program ends, which will render lost or derelict crab 

pots ineffective at capturing organisms. 

In an earlier NOAA Marine Debris program/ National Fish and Wildlife 

Foundation study, “Testing of gear modification for blue crab traps”, the project 

team investigated the use of various degradable components on commercially 

available pots. The project’s four working assumptions were 1) the modification 

must render the pot ineffective of capturing marine life within one season of loss, 

2) the material, once degraded must be environmental neutral, 3) the 

modification must be relatively inexpensive in order to be of practical use and 4) 

the modification must be relatively easy to enforce. Some states along the east 

and gulf coasts (Florida, New Jersey, and Texas) require biodegradable material 

on pots but most (Alabama, Delaware, Georgia, Louisiana, Maryland, 

Mississippi, North Carolina, South Carolina, Virginia, and the Potomac River 

Basin Commission) do not. 

The study found that degradable (rot cord) latch connectors were not as effective 

at allowing escape as degradable cull ring panels. Seventy eight percent of the 

crabs entering pots modified with degradable plastic cull ring panels escaped 

within 1 hour as compared with pots modified with rot cord latches (14%) and 

gapped openings (11%) The odds of escape in the first 4 hours from a trap 

modified with a gapped opening or degradable rot cord are 5 times lower than 

the odds of escape from a trap modified with degradable cull rings. Experiment 

replicate number did not affect the odds of escape within 4 hours (Log-Likelihood 

= -45.188, G = 48.456, df = 4, p-value = 0.0001). Cull rings, or escape rings, 

allow small sublegal crabs to escape pots and commercial watermen must install 

them on pots anyway. In fact, the study found that simply relocating the cull ring 

from the upper chamber wall to flush with the upper chamber floor increased the 

likelihood of escape by undersized crabs by 39 times (Havens et al. In Press). 

The cull ring ‘panels’ expand the size of the units so that, once degraded, the 

hole matches the entrance funnel size. In practical terms, anything that can enter 

the pot would then be able to escape. The study found the best candidate, which 

met all four criteria, was the environmental safe degradable plastic polypropylene 

or polycaprolactone. The degradable plastic timeframe, which degrades in one 

season, coincides with annual removal and repair of pots and will allow for 

seasonal replacement of panels. 

1
 

18
North Carolina Derelict Crab Pots: Shallow Water Side Scan Sonar Efforts 

Andy Wood, Audubon North Carolina 

Side Scan Sonar Survey Efforts 

Several ongoing studies have proven Side Scan Sonar as a valuable tool for locating 

Derelict Crab Pots, though many studies have been conducted in water greater than 12 

feet (four meters). The 2008-09 North Carolina DCP effort is focused on shallow water 

marsh and estuary habitats because a primary goal of this study is learning about impacts 

of DCP to the Diamondback Terrapin, Malaclemys terrapin spp.; a shallow-water reptile 

that is known to enter both active and derelict crab pots. 

Using a Humminbird 1197c Side-Scan Sonar with built-in GPS, we have been able to 

survey more than 150 linear miles of coastline, particularly the Intracoastal Waterway 

and tidal creeks in SE North Carolina. The sonar unit includes a transducer and GPS 

which we mounted to a wooden out-rig that can be modified for use with different boats. 

To date we have run the rig from four separate vessels, though most of our work has been 

conducted from an 18 foot flat-bottom Southern Skimmer. 

Sonar surveys are conducted to locate and record DCP and this information is collected 

on a 4 gigabyte high definition data card for later analysis. The sonar unit records water 

temperature, depth, vessel speed, direction, and GPS location. We carry a hand-held GPS 

to pinpoint DCP that are not accessible by boat. We also record salinity using a hand-held 

refractometer. 

Our study originally attempted to survey selected regions of the entire NC coast but 

owing to inherent challenges including the large expanses of water associated with each 

survey site, a revised plan was developed in order to more fully explore the most likely 

places where commercial and recreational crabbing coincide with suitable terrapin 

habitat. While we were able to access and survey some 23 linear miles of Pamlico Sound 

on and around the dredge islands and shell rakes west of Ocracoke Island on the Outer 

Banks, our work north of there has been curtailed by inclement weather, especially heavy 

winds that create dangerous chop for our shallow-draft vessels. 

Our work around Ocracoke was productive and included locating and removing several 

DCP from colonial waterbird nesting islands. We also observed one large live terrapin; 

one of the few we have seen during the study period. Conversations with former Outer 

Banks watermen, very familiar with the waters and crabbing industry, indicate that many 

DCP are lost due to boat propellers cutting the buoy line. Watermen in the area try to 

retrieve their valuable pots but storm-induced currents move the pots, including pots with 

rebar weight, and many are covered by shifting sands or incorporated into shell rakes; the 

latter example being something we observed during our survey. 

Side-scan sonar was employed around several islands and shell rakes in depths up to 

about 12 feet. Numerous channels meander throughout Pamlico Sound and the challenge 

we faced was staying out of the deep channels (some over 20 feet deep) while not 

19
	 

	 

running aground. Our sonar surveys in deep water were conducted as a means to collect 

images to contrast and compare with shallow water sonar images. The results proved that 

the sonar system could recognizably detect DCP in both deep and shallow water (albeit 

deeper than two feet). 

Conversations with former watermen indicate that commercial crabbing on the Outer 

Banks is an industry in some distress, though for unknown reasons. Many crabbers have 

abandoned the practice without passing the tradition to their offspring. We plan to 

explore a northern part of the Outer Banks near Oregon Inlet in June; an area still 

commercially crabbed. 

South of Pamlico Sound in southeast NC there is still an active commercial crabbing 

industry and it is here that our study has been focused. We have extensively surveyed the 

shallowest waters of Topsail, Wrightsville, and Masonboro Sounds, and the east and west 

sides of the Lower Cape Fear River. In all areas, crab pot buoys are seen in warm weather 

months and our surveys have concentrated in specific fishing spots including crab pot 

lines that flank the Intracoastal Waterway (ICW) and tidal creeks that flow deep enough 

at low tides to allow access to crab boats, as evidenced by pot buoys and DCP. 

Side-scan sonar is most helpful in the ICW and tidal creeks during mid to high tides. In 

very shallow waters less than two feet deep the sonar is less likely to detect DCP. Also, in 

very shallow water we find patches of eel grass and plumes of algae that appear as 

amorphous clouds on the sonar screen. We have frequently investigated geometricshaped patches of algae and been rewarded by finding a DCP within the mass. 

While we are able to visually locate DCP during low tides, the shallow water prevents 

access by boat. This has required use of hand-held GPS units to acquire accurate location 

data. Tidal creeks during tide change are generally turbid to the point that DCP in three 

feet of water may be invisible to the naked eye and it is in these conditions that side-scan 

sonar is most valuable. Most surveys, even in water less than four feet deep, require sonar 

as the only way to locate submerged DCP. That said, pinging a DCP in four feet of turbid 

water does not mean the trap will be retrieved. For this reason we have employed a 

strategy of exploring creeks at high tide for general DCP quantitative analysis and 

returning at low tide for retrieval and examination. 

Once located and accessed, DCP are given a cursory examination to determine associated 

biota around the trap. Upon retrieval, traps are further examined to find small organisms 

able to slip through the trap mesh including shrimps, crabs and fishes. After hauling onto 

the boat or on a shoreline, the trap is opened using various wire cutters and pliers and all 

trapped organisms identified and released. Traps that are intact are either cut open to the 

point they can no longer trap animals, or they are smashed flat and left in place. This is 

the preferred practice for two reasons: 

1.	 the traps are themselves habitat for encrusting marine organisms including oyster, 

sponge, algae, barnacle and worms 

2.	 the quantity of DCP collected is too great for our boats to hold onboard 

20
3.	 cost of landfill disposal can be very high owing to the weight of encrusted traps, 

in addition to transportation difficulty 

Whenever possible, DCP rendered unusable are placed in marsh pools where they will 

not interfere with navigation or migrate into areas that will be used for future recruitment 

study sites. Field observations indicate that DCP displaced in this manner actually 

become important refuge for fishes and other free-moving and encrusting organisms. 

Key challenges with the sonar are related to functional depth for the transducer 

(damaging it while running aground), its ability to define objects in water less than two 

feet deep, and the fact that images appear on the sonar screen several seconds and hence 

several feet after an object has been passed. The latter point is especially frustrating when 

attempting to retrieve DCP even in shallow water. 

In general, use of side-scan sonar is extremely valuable for assessing numbers of DCP in 

deep waters, in addition to being helpful as an augment to visual surveys in shallow 

waters. 

For more information, contact: 

Andy Wood, Education Director 

Audubon North Carolina 

7741 Market Street, Unit D 

Wilmington, NC 28411 

910-686-7527 

awood@audubon.org 

www.ncaudubon.org 

21

 

Towed-Diver Derelict Spiny Lobster Trap Surveys in Florida Keys National Marine 

Sanctuary 

Amy V. Uhrin1 and Thomas R. Matthews2 

1

National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat 

Research, Beaufort, NC 28516 USA 

2

Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute,
 

2796 Overseas Highway, Suite 119, Marathon, FL 33050 USA 

Research Questions 

To effectively manage the spiny lobster trap fishery in the Florida Keys, and the growing 

trap debris problem, improved efforts are needed to quantify the distribution and abundance of 

derelict traps and trap-generated debris and to identify habitats that are sensitive to debris 

accumulation in the region. In this work, we surveyed a range of EFH types from known spiny 

lobster fishing zones to generate estimates of abundance and distribution of derelict traps and 

trap-generated debris in Florida Keys National Marine Sanctuary (FKNMS). The specific 

objectives of this study were to (1) generate estimates of the abundance, type, and spatial 

distribution of spiny lobster trap debris in FKNMS; (2) describe habitat-mediated patterns of trap 

debris accumulation, (3) relate patterns of trap debris accumulation to known patterns of 

commercial trap fishing effort, (4) assess the impact of derelict traps on selected habitat types, 

and (5) calculate mortality and by-catch rates of derelict traps. 

Site Information 

We used a geographic information system (ESRI® ArcGIS®) and a digital database of the 

benthic habitats and bathymetry of the Florida Keys to facilitate spatial delineation of the sample 

universe, sampling strata, and sample units. The sample universe encompassed all benthic 

habitats ≤ 15m deep located within the boundaries of FKNMS, from northern Key Largo to 

southwest of Key West. The sample universe was partitioned into six regions (strata) reflecting 

historic trap-use patterns in FKNMS, consisting of the Upper, Middle, and Lower Florida Keys 

on both the Atlantic Ocean and Florida Bay sides of the Florida Keys island chain. 

Survey Technology / Methodology / Data Recording 

The sample universe was overlain in ArcGIS with grid of 1 minute latitude × 1 minute 

longitude cells. Within each trap-use region, twenty grid cells to be sampled were randomly 

selected a priori from the all-inclusive list, with the center point of each cell serving as the start 

point for a single towed-diver survey transect (sample unit). The center point of each randomly 

selected grid cell was navigated to using a Garmin GPSMAP® 3206 chartplotter. Paired SCUBA 

divers were deployed with tow boards in hand, each equipped with a re-usable data sheet, timing 

device, and pencil. Tow boards were separately attached to the stern cleats of the tow boat using 

a 30 m long, adjustable polypropoline line. The towline was connected to a stainless steel swivel 

shackle attached to the towboard bridle. Placement of the towlines allowed for diver separation 

of 4 m. Divers were given one minute to descend and prepare for towing and towing 

commenced following a pre-arranged acoustic signal, at which point a waypoint was marked in 

the chartplotter to more accurately indicate the start of the tow. Using the chartplotter as a guide, 

the coxswain navigated for 1 km in the direction of a predetermined, randomly selected bearing 

(0 - 360°) while maintaining a speed of 1.6 knots, yielding an effective transect swath of 8 m x 

1000 m (8000 m2

 or 0.8 hectares). Tow direction was altered when necessary to exclude land, 

22
 

 

 

boats, and other navigational hazards. Upon commencement of towing, divers launched their 

respective timing devices and maneuvered the tow boards to maintain approximately 1 m height 

off the bottom. Divers documented the type of habitat encountered at one-minute intervals, 

recorded individual debris items observed within 2 m on either side of their respective towline, 

and noted the habitat type that the debris was residing on. Habitat categories were generalized 

from an existing digital habitat database of the Florida Keys to include bare substrate, seagrass, 

hardbottom, and coral reef in addition to an unmapped algae category. After 1 km, the coxswain 

disengaged the boat engines and delivered a pre-arranged acoustic signal to indicate that the tow 

was complete. Upon cessation of towing, divers recorded the total tow time and used line pulls 

to signify disengagement from the tow boards. The divers then safely ascended to the surface 

and were retrieved by the boat. Immediately following diver retrieval, all data from the tow 

board data sheet was transcribed to an exact replica of the data sheet that had been copied to 

water-proof paper and secured in a dry box. The tow board data sheets were then erased for use 

in subsequent tows. At the conclusion of a field sampling event, the data was entered into an 

electronic database created in Microsoft Access. 

Lessons Learned 

Tow Methodology 

“Quick-release” floats were mounted to the tow boards enabling the divers to indicate the 

location of whole or broken traps to be assessed for habitat impacts at the conclusion of a tow. It 

became apparent early on that this technique was not an effective mechanism to mark traps for a 

number of reasons. The drag forces experienced by the floats during towing caused them to 

come undone on a number of occasions, creating a potential entanglement hazard and leading to 

the termination of the tow. Oftentimes, although the float was released from the tow board, it did 

not completely unravel and thus was not visible at the surface. A number of floats that were 

successfully released were never re-located, particularly during choppy seas when visibility of 

the floats was compromised. 

Data Analysis 

 The inability to effectively mark traps “on-the-fly” for relocation, prevented any 

determination of habitat impacts from existing derelict traps and trap-related debris and led to the 

use of experimentally deployed traps to address this question. The same situation arose for 

attempting to assess by-catch and mortality rates. It is our opinion that this issue will also need 

to be addressed utilizing experimentally deployed traps which can be secured in a known 

location and monitored over time. 

Of 96 total random tows, only 22 had ghost traps present, consisting of both derelict 

stone crab (18) and spiny lobster (17) traps. The non-normal distribution of derelict traps 

observed per transect provides reduced capabilities for extrapolating the number of derelict spiny 

lobster traps Sanctuary-wide. However, we can conduct a power analysis to determine the 

number of tows required to develop a more robust trap loss estimate. 

Data Storage 

Due to differing preferences in software usage between the PI’s, the Microsoft Access 

database was converted to a Microsoft Excel spreadsheet which resulted in a number of duplicate 

data records. As such, a fair amount of time was spent conducting quality control to ensure that 

23
 

the duplicate entries were indeed duplicates and if so, subsequently removed from the 

spreadsheet. 

Recommendations 

Given the location, water quality, and specific questions to be addressed, towed-diver 

transects proved to be an effective method for surveying derelict spiny lobster and stone crab 

traps and trap-generated debris in FKNMS. The status of traps (fishing or not) was easily 

classified and trap-related debris was readily identifiable by divers. Because habitat information 

was gathered “on-the-fly”, ground truthing was not required. Abundance and distribution 

estimates were easily estimated for trap-use regions and habitat type. 

Dual-frequency identification sonar (DIDSON) has been shown to successfully identify 

wire blue crab traps in Pamlico Sound, North Carolina (soft bottom substrate, some vegetation). 

The use of such sonar in FKNMS has yet to be tested and may increase the ability to cover larger 

areas. Although whole-trap detection appears plausible, the ability to identify trap-related debris 

(i.e., slabs, slats, throats) remains to be seen, particularly in reef environments. 

24
Derelict Crab Pot Impact Studies: Impact, morality and loss-rate. 

Jeff June, Natural Resources Consultants, Inc. and the Northwest Straits Initiative 

The Northwest Straits Initiative’s (NWSI) derelict fishing gear survey and removal 

project that began in 2002 takes a science-based approach to derelict fishing gear 

removal. Divers and onboard biologist record information on derelict pots/traps found 

and impacts on marine habitat and animals. Additional studies have been conducted to 

estimate annual mortality of Dungeness crab (Cancer magister) and red rock crab 

(Cancer productus) from derelict crab pots and to estimate pot loss rates in recreational 

and commercial crab fisheries in Puget Sound. 

Information collected during derelict pot/trap removal includes habitat type, water depth, 

number of live and dead animals entrapped by species, pot type (recreational or 

commercial), pot condition (fishing/not fishing) and the use and condition of required 

escape cord. If ownership can be determined, owners are allowed the opportunity to 

recover their pot/trap. Divers have removed 1,652 derelict crab pots during 72 diving 

days and collected data on 1,360 pots including 624 (46%) recreational pots and 736 

(54%) commercial pots. Actively fishing pots totaled 491 (36%) and inactive pots 869 

(64%). Although escape cord is required on pots by state regulation, 277 of the 1,360 

pots (20%) were not equipped with escape cord. A total of 2,225 live and 519 dead 

animals were entrapped in the 1,360 pots. Derelict pots lost in eelgrass habitat were 

found impede eelgrass growth under the pot footprint and, in some cases, result in larger 

areas of eelgrass loss due to current scouring around the derelict pot. In an ongoing 

habitat recovery study, eelgrass density improved about 30% one year area derelict pot 

removal. 

A study of 24 simulated recreational and commercial derelict pots is ongoing but 

preliminary information indicates that derelict pots without escape cord may kill between 

0.062 to 0.083 Dungeness crab per day or 22 to 30 crabs per year until the pot 

deteriorates and stops fishing and use of escape cord may decrease mortality by 70%. 

Subareas within two popular recreational and commercial Dungeness crab fishing areas 

were surveyed for derelict pots with sidescan sonar and divers removed all of the derelict 

pots. The areas were resurveyed after one fishing season and the number of newly lost 

pots provided an estimate of loss rate of crab pots per unit of seabed. In Dungeness Bay, 

a rather secluded bay with very little no fishing vessel traffic, pot loss rates ranged from 

5.3 pots/km2

 between 2003 and 2004 to 13.4 pots/km2 between 2007 and 2008. In Port 

Gardner, near the entrance to an active urban marina and on an industrial marine vessel 

transit zone, pot loss was over ten fold higher at117.9 pots per km2

. 

25
Chesapeake Bay, Maryland – Derelict Pot Assessment and Impacts 

Steve Giordano, NOAA CBO; Ward Slacum, Versar; Jay Lazar, NOAA CBO) 

In 2005 the NOAA Chesapeake Bay Office (NCBO) established the Derelict Fishing 

Gear Program (DFGP) to address concerns that derelict crab traps may be negatively 

affecting blue crab and other estuarine species in Chesapeake Bay. Two types of 

information were being collected in the Maryland Bay to determine overall effects. A 

side-scan sonar survey was conducted in areas of the Bay where the commercial hard 

crab fishery occurred (1,785 km2

) to quantify derelict traps from the imagery, and a field 

experiment simulating derelict traps was also conducted to provide data on species 

mortality and other vital details. Based on the sonar survey it is estimated that nearly 

85,000 traps could be on the bottom of the Maryland Bay and that the majority of these 

are near river mouths and in shallow to intermediate depths (1-8 m). Blue crab mortality 

was 19 crabs/trap/year in experimental traps and several species of bycatch were also 

documented including white perch, oyster toadfish, and spot. In the context of population 

impacts, the mortality rates of blue crab may not be significant when compared to 

commercial harvest or the overall abundance of crab in Chesapeake Bay. However, most 

of the areas that exhibit high derelict trap densities can be consider sensitive and 

ecologically important habitats for blue crab and other species. Therefore, targeted 

derelict trap retrieval efforts are recommended in addition to extensive education and 

outreach efforts to the public and commercial fishing industry. 

26
 

Derelict Blue Crab Traps in the Virginia Portion of the Chesapeake Bay 

David Stanhope, Kory Angstadt, Kirk J. Havens, Donna Marie Bilkovic 

Center for Coastal Resources Management Virginia Institute of Marine Science 

www.ccrm.vims.edu 

See Abstract pages 17-18 

27
 

	 

	 

	 

	 

	 

North Carolina Derelict Crab Pots 101: shallow water efforts 

David S. Lee, The Tortoise Reserve 

 For the past year Audubon North Carolina and The Tortoise Reserve have been 

working under a NOAA contract on issues related to abandoned and derelict crab pots in 

shallow water (<12 feet) portions of estuaries in North Carolina. Fortunately, NC Marine 

Fisheries has been looking into the problems associated with derelict pots for a number of 

years so we have a lot of unpublished back ground information that they have kindly 

shared. Our first contract year was primarily devoted to developing survey and removal 

methodology and identifying possible solutions. The main focus of our effort has been 

the effect of crab pots on local diamondback terrapin populations. 

 Terrapins are particularly vulnerable to drowning in crab pots, and because of their 

limited annual reproduction, slow growth, and longevity populations can quickly become 

depleted. Studies by others have shown that several decades of crabbing can deplete 

terrapin populations to the point that they will not recover. Terrapins suffer from a 

number of other conservation issues, but crab pots are believed by terrapin researchers to 

have a greater negative impact on local populations than all other factors combined. Most 

activity for diamondback terrapins occurs in shallow waters within 50 yards of land. 

Locating and removing pots from shallow water has resulted in some unanticipated 

challenges. 

Surveys: 

Two air surveys for crab pots were conducted during our study period. These surveys 

covered the area from the NC/SC line northward to Topsail Island, about 1/3 of the North 

Carolina coast. From these surveys we learned the following: 

	 Surveys need to be conducted from late winter through spring when water clarity 

is best. 

	 Surveys conducted during low tide on sunny days, with light to no wind, yield 

better results due to greater visibility. 

	 Air surveys are not appropriate for many areas because water depth, turbidity 

around inlets and the mouths of rivers, and other local conditions negatively affect 

trap visibility. 

	 Because of the extensive amount of land under military control in our study area 

large portions of the state’s coastal areas, including many of the sounds, are off 

limits to private aircraft. 

	 Federal aviation rules prevent low elevation flights in heavily developed coastal 

communities, which include some of the key crabbing areas. 

28
 

	 

	 

 Accurate GPS readings for derelict pots are not possible from the air because the 

plane cannot be directly over the pots when pots are spotted. 

	 Slow moving (75-80 mph) aircraft flying at 300-500 feet can detect buoys of 

active pots as well as abandoned crab pots in clear shallow water. Approximate 

locations of abandoned crab pots can be identified on maps or in relation to fixed 

objects (bridges, boating channels, water towers, residential homes, etc.) The 

square nature of the pots can be seen from above and they stand out rather well. 

Pots that are damaged or covered irregularly with growth are not as apparent. 

 Air surveys would appear to be a quick and cost efficient way of locating areas of 

abandoned crab pot concentrations because extensive areas of coastline, marshes, tidal 

creeks, and sounds can be surveyed in hours. Air surveys give a quick overview as to 

where pots are being actively fished and thereby can be used as a reference of likely 

places to search for derelict pots even when derelict pots cannot be seen from the air. 

Actively fished pots have buoys that can be spotted from the air at all seasons regardless 

of water depth and turbidity. 

 In that all abandoned pots are not likely to be spotted from the air and pots in <3feet of 

water (depending on conditions) are not likely to be seen, air surveys are not 

recommended as a substitute for boat and/or side-scan sonar surveys. They should be 

most useful for locating areas of concentrations of abandoned pots for removal when time 

and other resources are limited and one wants to obtain maximum efficiency in pot 

removal in a short time period. 

 Visual surveys from boats are an effective way to locate, examine and remove 

shallow water derelict crab pots. Pots are most easily detected during low tide but the 

shallow nature of most tidal creeks within the marsh makes access difficult until high 

tide. Entering creeks during falling tides can lead to stranding of boats of crews, damage 

to the boat and to side-scan sonar units. Timing by season is also critical; water is clearest 

from mid winter through mid spring. During warmer seasons we found that pots were 

often not visually detected even when in as little as 12-18 inches of water. The warm 

estuarine waters support massive blooms of microorganisms that cloud the water. Visual 

surveys are the only way to detect partly submerged traps immediately adjacent to land 

and discarded ones that had been tossed into the marshes. 

Results of our side-scan sonar detection surveys have been presented in an 

accompanying abstract (Andy Wood). For a variety of reasons side-scan sonar is not 

totally effective in extreme shallow water areas.

 Discussions with local fishermen were helpful in learning about local crabbing 

locations, seasons, and methods and indicate that the fishermen are aware of the issues of 

ghost crab pots and the fact that they are competing with them for fisheries resources. 

However, few accept any personal responsibility for the problem, as it is always other 

people’s traps or recreational boaters cutting lines with props that are causing the 

29
problems. Historically, watermen generally resist regulation changes that would alter pot 

design or placement. 

Crab Pots and By-catch: 

 Over one million commercial crab pots are fished annually in North Carolina waters. 

Estimates of annual commercial trap loss have been made by NC Marine Fisheries. They 

estimate an average 17% annual loss with a range of 14 to 21%. Loss of peeler pots 

averages 11% per year. The number of fished pots has increased annually from 350,000 

in 1983 to 1,285,748 in 2000. With a conservative estimate of 5-6 years of trap life for 

abandoned vinyl coated wire pots the number of viable ghost pots probably exceeds one 

million. In one study area in the southeastern part of the state we documented an 8-15 to 

1 ratios of ghost to actively fished pots. Discussions with one fisherman indicated a loss 

of all but 8 of 30+ pots he had set the previous season. 

 Removal of abandoned and derelict pots is limited to a 15-day closure period in mid 

winter. During this time NC Marine Fisheries typically removes 5,000-8,000 pots per 

year with a ratio of about 4 to 1 of abandoned to ghost pots, as the ghost pots are more 

difficult to locate. They only cover a small portion of the state in any given year. For 

several regulatory and safety reasons the general public is not allowed to participate in 

crap pot clean up activities. 

 Information we recorded on derelict pots included location, depth/tide, water 

temperature, salinity, condition of the pot, by-catch, and trap associates. We also noted 

wire color, presence of cull rings, and when possible reason for trap loss. A large 

proportion of the loss seems to be from lines run over by recreational boaters as the 

crabbers often set traps immediately adjacent to the Inter-coastal and other waterways. 

NC Marine fisheries reported major trap loss after various hurricanes in the 90’s. 

Recreational pot loss appears to result mostly from faulty knot tying and neglect. 

 The state of abandoned and derelict traps is variable. Our data is mostly from traps 

recovered from 0-3 feet of water where trap decomposition is probably accelerated due to 

tidal exposure and an unknown percentage of damaged traps being ones tossed into 

shallow water and into intertidal areas to ‘dispose’ of them. We scored traps on a scale of 

0-10 with 0 being intact new traps and 10 being rusted piles of wire. In shallow water 

zones less than 30% of the ghost pots were active, while 60-85% of the abandoned pots 

were actively capturing estuarine organisms. 

 The major by-catch species of ghost crab pots is the blue crab (91% of by-catch), with 

fin-fish making up 9%. Ghost pots catch 40-60 crabs per year although there is a 50% 

escape rate. By-catch is higher in peeler pots as escape rings are not required by state 

regulation. As a ball park figure, based on annual trap loss, trap life span of neglected 

pots, and number of crabs trapped per pot per year, minus a 50% escape rate, a 

conservative estimate of annual market sized blue crabs lost to ghost fishing is 10-15 

million crabs in NC. The actual loss is certainly much higher. The blue crab supports the 

30
	 

	 

	 

largest fishery in North Carolina with an average of over 43 million pounds per year 

landed since 1994. 

 Recreational crabbing in many aspects has more of an impact on terrapin by-catch 

issues than does commercial crabbing. Water front rental properties often provide crab 

pots and the renters have little knowledge of estuarine environments and proper use of 

such traps. Pots can remain deployed and unchecked for weeks, and lost pots tend to pile 

up under docks and are not recovered as the rental agents simply replace them with new 

ones. Recreational pots tend to be fished almost exclusively in shallow water and close to 

shore and in some areas do considerable damage to local terrapin populations. These 

same issues may also apply to the peeler crab fishery but we have not yet had the 

opportunity to look into this. 

Recommendations: 

 From an ecological perspective there are some advantages to derelict crab pots, after 

less than two to three years in the water the substrate provided by the wire allows for 

substantial colonization of encrusting marine organisms. Oysters and ribbed mussels 

represent the major component of the biomass; we use the sizes of the former as a means 

for estimating the time the trap has been submerged. The traps produce miniature hard 

bottom real estate that is used by a variety of sponges and marine alga. Brittle stars, sea 

urchins, mud crabs, hermit crabs, various types of other crustaceans, tunicates, gobies, 

pinfish, oyster toadfish and other estuarine species inhabit the traps or a regular basis, and 

often in considerable numbers. Because of this traps we locate that are no longer 

functional have been for the most part left in place. Intact pots with impressive 

assemblages of associated marine biota are made inoperable and left in place. 

 Based on what we have learned to date we will make the following recommendations 

to N C Marine fisheries regarding proposed crabbing regulation changes in 2010. 

	 Revise regulations to require By-catch Reduction Devices for terrapins. The need 

and practically of these devises has already been established in studies both in 

North Carolina and other states. These devices should be required on all 

commercially sold pots, all recreational pots and any commercial pots fished in < 

12 feet of water and/or within 100 yards of land. Traps used for peeler crabs are 

set in spring in shallow water and would benefit from even smaller sized opening 

in reduction devices. These would not affect the size or number of peeler crabs 

caught. It would be best if the excluders were installed at time of manufacture. 

We feel it is unlikely that recreational or commercial crabbers will install the 

excluders themselves. 

	 Soak times of 3 days or les are recommended. 

	 Biodegradable panels on all new traps sold in North Carolina should be required. 

31
	 

	 

	 

	 

	 Identification of trap ownership needs to be attached to the trap itself as well as 

the marker buoys. 

	 Permits to remove derelict pots should not be required, and permission for 

removal of abandoned and unidentified pots during the 15-day closure period 

should not be required. As it now stands waterfront property owners and coastal 

conservation groups cannot legally remove ghost or abandoned pots. 

	 Counties need to change regulations so that pots that are removed can be disposed 

of in public landfills for no charge. 

	 The current practice of out of season stacking and storage pots on estuarine 

islands and other water front areas needs to be discontinued as often pots are not 

retrieved and winter storms wash pots into the adjacent waters. 

Research and Education: 

 While the overall effort will clearly benefit from additional research much can be 

learned from research into crab pot and terrapin issues already conducted both in North 

Carolina and nearby states. We discourage continuation of duplicate studies as awaiting 

for results only further delays a State-wide decision process. It is clear that the derelict 

pot issue is of both commercial and conservation concern and needs to be actively dealt 

with. Several local key studies have been conducted in the 1980-90’s that indicate the 

need for regulatory change. In addition to our work, several terrapin studies are currently 

in progress by UNC-Wilmington and NC Marine Fisheries continues to collect data on 

derelict crab pots. 

 Inventories of by-catch under estimate the total amount of damage done by a single 

pot due to decomposition and predation rates of the various trapped organisms. In 2010 

we will be studying the decomposition rates of terrapins and other by-catch species at 

different water temperatures and salinities and with different predatory by-catch 

associates, as well as rates of trap breakdown. These studies will be in controlled tidal 

lagoons in partnership with the Institute of Marine Science. We will also examine rates of 

ghost trap recruitment in specific areas once all ghost pots have been located and cleaned 

out of specific study areas. 

 In order to prevent this from being an ongoing problem be believe that local 

education efforts and involvement of a broad conservation community should be the 

major focus of long-term solutions. Of prominent importance are the education of 

waterfront property owners and the commercial fishing community. We have made 

presentations and participated in a number of regional and local meetings of 

herpetological groups, have set up displays and given talks at weekend coastal events, 

and currently had a class at a coastal elementary school adopt the terrapin/crab pot issue 

as a two year project. We have developed a statewide working group represented by state 

and federal agencies, coastal military bases, National Sea Shores and Wildlife Refuges, 

32
 

academic institutions, public aquaria and museums, conservation organizations, and 

individuals in the private sector. Through this working group an educational flyer has 

been prepared. Additionally, we have a web site (www.Tortoisereserve.org) and a list 

serve for information sharing among members of our state network. Audubon produced a 

video about the North Carolina terrapin/crab pot issue that has been widely circulated on 

the Internet. 

Tortoise Reserve, P.O. Box 7082, White Lake, North Carolina 28337 

TorResInc@aol.com 

Appendix I: By-catch species reported from abandoned and ghost crab pots in 

North Carolina, those in bold make up a significant portion of the total by-catch. 

Fishes 

Blue Catfish 

Blue Fish 

Bowfin 

Brown Bullhead 

Chubsucker 

Conger Eel 

Filefish 

Gag Grouper 

Goosfish 

Hake 

Hogfish 

Northern Puffer 

Northern Searobin 

Oyster Toadfish 

Pigfish 

Pilotfish 

Pinfish 

Pumpkinseed 

Red Drum 

Raked Solefish 

Remora 

Searobbin 

Shark Sucker 

Sheepshead 

Southern Flounder 

Southern Hake 

Spadefish 

Speckled Trout 

Spiny Toadfish 

Striped Bass 

33
Striped Mullet 

Summer Flounder 

Spiny Puffer 

Spot 

Stingray 

Warmouth 

White Catfish 

White Perch 

Yellow Perch 

Other vertebrates 

Eastern Mud Turtle 

Diamondback Terrapin 

River Otter 

Muskrat 

Grebe (sp.) 

Hooded Merganser 

Common Tern 

Various shorebirds and rails 

Reported additional mortality to Bottle-nosed Dolphins, Loggerhead, Kemp’s 

Ridley, and Green seaturtles mostly through crab pot rope entanglement. 

Invertebrates 

Blue Crabs 

Conch (whelks) 

Florida Horse Conch 

Octopus 

Flat-clawed Hermit Crab 

Horseshoe Crab 

Miscellaneous jellyfishes 

Purple sea urchins 

Red Umbrella Jellyfish 

Snails 

Spider Crab 

Stone Crab 

Rock Lobster 

Spiny Lobster 

34
Lobster Trap Loss, Ghost Fishing, and Impact on Natural Resources in Florida Keys 

National Marine Sanctuary 

Thomas R. Matthews1

and Amy V. Uhrin2 

1

Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, 

2796 Overseas Highway, Suite 119, Marathon, FL 33050 USA 

2

National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat 

Research, Beaufort, NC 28516 USA 

Lost trap estimates 

Estimates of the number of lost lobster traps are available from fishery dependent and 

fishery independent methods. Commercial trappers responding to mail surveys conducted at the 

end of each fishing season report non-hurricane trap losses from 10% to 28%. The proportion of 

traps lost did not change despite the progressive decrease as the number of traps in the fishery 

was reduced from 750,000 to 499,000. Trap loss was higher during years with tropical storms or 

hurricanes; for example fishermen reported losing most of their traps during 2005 as a result of 

Hurricanes Katrina, Rita, and Wilma. These estimates suggest that, at the present time, trap 

losses range from approximately 50,000 to 140,000 annually. A fishery-independent survey 

conducted during 2007 yielded a similar estimate. Towed-divers surveyed 96 0.8 ha transects in 

the heavily fished 500,000 hectare portion of Florida Keys National Marine Sanctuary east of 

Key West and recorded 5.4 incidences of trap debris per hectare. Approximately 6% of these 

incidences were of ghost traps capable of catching and confining lobsters. Extrapolation of the 

observed number of ghost traps to the total area surveyed suggests that the number of such traps 

is approximately 100,000 in that area of the Sanctuary. 

Derelict Trap Condition 

The vast majority of lobster traps in the Florida Keys are constructed of wood (90%). The 

remaining traps are wood-frame traps with one or more wire sides (8%), or all wire-sided traps 

with a wood top (2%). Interviews with fishermen suggest that wood traps have a serviceable 

lifespan of 2 to 4 years before they degrade beyond repair. This variability arises from some 

fishermen using their traps for only 4 months of the 8 month fishing season. 

A study to evaluate the length of time a lost trap may ghost fish after being lost was 

conducted using new traps and traps that had been fished for six months. Of the 13 new traps, 12 

remained fishing after three months and 9 after 6 months, and 5 after one year. Three remained 

fishing after 16 months when the study ended due to the disruption of Tropical Storm Fay. Of 

the 11 used traps, 5 remained fishing after three months. 2 after 6 months, and 1 after one year. 

This trap also was still fishing after 16 months. These studies indicate that lost traps can remain 

fishing for extended time frames. 

During surveys by towed divers, trap debris was found in varying states of decay. As 

previously discussed, intact traps were 5.9% of the trap debris encountered, while broken traps 

(12.4%), pieces of wood (32.9%), concrete slabs (14.3%), wire (2.5%), plastic (5%), and rope 

(26.9%) made up the remainder of trap debris. 

Ghost fishing Mortality and Habitat Impact 

Estimates of lobster mortality in ghost traps are not available. However inferences can be 

made based on studies of lobster mortality in actively fished traps. Lobsters confined in actively 

fished traps have a mortality rate (Fc) ranging from 0.078 to 0.099. Given the potential 

35
 

magnitude of the number of ghost fishing traps, ghost fishing is likely a substantial source of 

lobster mortality. In contrast, mortality of fish bycatch in actively fished lobster traps was rare. 

Mortality rates (Fc) observed from over 100,000 fishing traps indicates fish mortality is <0.001. 

Although juvenile fish are commonly seen in and around wooden trap debris, these fish are not 

confined in the traps and fish may be using the debris as habitat. The role of trap debris as 

settlement habitat for juvenile fish remains to be evaluated. 

A survey of the distribution of traps fished on the Atlantic ocean side of the Florida Keys 

revealed that approximately 13% we on hardbottom habitat and 2.5% we on coral reef habitats. 

Routine deployment and pulling of traps placed on those habitats caused an average of 1.28 

injuries to coral, gorgonians, and sponges resulting in injury to 52 cm2 of live tissue. Most 

damage to these habitats occurs as traps moved during storms with sustained high winds for 

multiple days. On average, 18 such storms occur each fishing season. In our studies, these 

storms cause traps on hardbottom and reefs to move and reduce percent living cover by 10% to 

20% in an average 2.9m2 impact area. 

Implications for Overall Impact 

The lobster fishery in the Florida Keys has existed for decades. It appears likely that the 

current ecosystem reflects long-term impacts from the fishery. Increased hurricane frequency is 

likely to cause greater trap loss and trap movement which may exacerbate impacts to the 

ecosystem. More work is required to assess the potential increased fishery yield if ghost fishing 

mortality can be reduced. Our recent observations and evaluation of the mechanisms that cause 

trap impacts on habitat have provided the needed insight fishermen and fishery managers need to 

develop more environmentally friendly traps and lobster fishing techniques to protect sensitive 

habitats. 

36
APPENDIX A: Workshop Agenda 

37
 

 


 


 

NOAA Submerged Derelict Trap Detection Methods Workshop
	

June 2-4, 2009 

Courtyard by Marriott 

Silver Spring, Maryland 

Agenda
	

June 2, 2009 

Side Scan Sonar and Towed Diver Techniques 

8:00-8:30 Registration 

8:30-9:15 Welcome and Purpose of the Workshop 

Holly Bamford, NOAA 

9:15-9:45 Questions when Deciding on Side Scan Sonar/Things to Keep in Mind 

Peter Murphy, NOAA 

9:45-10:30 Side Scan Sonar Techniques in Puget Sound, Washington 

Jeff June, Natural Resource Consultants, Inc. 

10:30-10:45 Break 

10:45-11:30 Side Scan Sonar Techniques in Chesapeake Bay - Maryland 

Steve Giordano, NOAA; Ward Slacum, Versar; Jay Lazar, NOAA 

11:30-12:15 Side Scan Sonar Techniques in Chesapeake Bay – Virginia 

David Stanhope and Kory Angstadt, Virginia Institute of Marine Science 

12:15-1:45 Lunch 

1:45-2:30 Side Scan Sonar Techniques in Inshore North Carolina 

Andy Wood, Audubon North Carolina 

2:30-3:15 Diver Tow Surveys in the Florida Keys, Florida 

Amy Uhrin, NOAA and Tom Matthews, FL Fish and Wildlife Conservation 

Commission 

3:15-3:30 Break 

3:30-5:00 Q&A and Structured Discussion 

Sampling designs, pot identification, density estimates 

38
 

June 3, 2009 

Impact Studies 

8:30-9:15 Recap of what was captured from first day of discussion (looking closely at notes) 

9:15-9:45 MDP Needs and Goals 

Holly Bamford, NOAA 

9:45-10:30 Puget Sound, Washington – Derelict Pot Assessment and Impacts 

Jeff June, Natural Resource Consultants, Inc. 

10:30-10:45 Break 

10:45-11:30 Chesapeake Bay, Maryland – Derelict Pot Assessment and Impacts 

Steve Giordano, NOAA; Ward Slacum, Versar; Jay Lazar, NOAA) 

11:30-12:15 Chesapeake Bay, Virginia – Derelict Pot Assessment and Impacts 

David Stanhope and Kory Angstadt, Virginia Institute of Marine Science 

12:15-1:45 Lunch 

1:45-2:30 Inshore North Carolina – Derelict Pot Assessment and Impacts 

David Lee, Tortoise Reserve 

2:30-3:15 Florida Keys, Florida – Derelict Pot Assessment and Impacts 

Amy Uhrin, NOAA and Tom Matthews, FL Fish and Wildlife Conservation 

Commission 

3:15-3:30 Break 

3:30-5:00 Q&A and Structured Discussion 

Experimental designs 

June 4, 2009 

2009 Project Plans drafted 

39
APPENDIX B: Workshop Participants 

40
First name Last name Email Street City State Zip Phone 

Kory Angstadt kory@sweethall.wetlan.vims.edu 1208 Greate Rd. Gloucester Point VA 23062 804-684-7844 

Courtney Arthur Courtney.Arthur@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-2989 

Holly Bamford Holly.Bamford@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-2989 

Nir Barnea Nir.Barnea@noaa.gov 7600 Sand Point Way NE Seattle WA 98115 206-526-6943 

Laurie Bauer laurie.bauer@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-3028 x236 

Joan Browder joan.browder@noaa.gov 75 Virginia Beach Dr. Miami FL 33149 305-361-4270 

Steve Giordano Steve.Giordano@noaa.gov 410 Severn Avenue Annapolis MD 21403 410-267-5647 

Chris Haney CHaney@defenders.org 1130 17th Street, NW Washington D.C. 20036 202-682-9400 

Jeff June jjune@nrccorp.com 4039 21st Avenue 

#404 

Seattle WA 98194 206-285-3480 

Chris Kinkade Chris.Kinkade@noaa.gov 410 Severn Avenue Annapolis MD 21403 410-295-3157 

Jay Lazar jay.lazar@noaa.gov 410 Severn Avenue Annapolis MD 21403 410-295-3143 

David Lee Torresinc@aol.com P.O. Box 7082 White Lake NC 28337 910-532-6599 

Jacek Maselko Jacek.Maselko@noaa.gov 17109 Pt Lena Loop Road Juneau AK 99801 907-789-6067 

Tom Matthews Tom.Matthews@MyFWC.com 2796 Overseas Hwy 

Suite 119 

Marathon FL 33050 305-289-2330 

Charlie Menza Charles.Menza@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-3028 

Sarah Morison Sarah.Morison@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-2989 

Peter Murphy Peter.Murphy@noaa.gov 7600 Sand Point Way NE Seattle WA 98115 206-526-4661 

Sarah Opfer Sarah.Opfer@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-2989 

Neal Parry Neal.Parry@noaa.gov SSMC 4 

1305 East-West Hwy Silver Spring MD 20910 301-713-2989 

Ward Slacum wslacum@versar.com 410-215-6824 

David Stanhope stanhope@sweethall.wetlan.vims.edu 1208 Greate Rd. Gloucester Point VA 23062 804-684-7844 

Amy Uhrin amy.uhrin@noaa.gov 101 Pivers Island Road Beaufort NC 28516 252-728-8778 

Andy Wood awood@audubon.org 7741 Market Street 

Unit D Wilmington NC 28411 910-686-7527 

41