Voss et al : Factors driving the density of derelict crab pots and associated bycatch in North Carolina 
379 
peeler crab and soft-shell crab add to the value and are 
reported separately. In addition, a substantial recre- 
ational blue crab fishery exists in North Carolina. Crab 
pots are the principal fishing gear for all the hard-shell 
crab fisheries in North Carolina. 
The unharvested “take” of blue crab and other fish- 
ery species in DCPs represents substantial mortality 
(Guillory, 1993; Guillory 4 ) and is a drain on fishery 
catches and incomes. Substantial unintended incidental 
take, or bycatch, of wildlife also occurs in pots meant 
to capture blue crab (Havens et al., 2008; Morris et al., 
2011). We extend the definition of bycatch to include 
blue crab and Florida stone crab (Menippe mercenaria), 
both live and dead, found in DCPs because the DCP 
catch is rendered unavailable to the fishery. 
In a NCDMF 1 study during 2002-2005, the capture, 
mortality, and escapement rates of blue crab in DCPs 
in 4 regions (Alligator River, Pamlico River, Bogue 
Sound, and Middle Sound) of coastal North Carolina 
were estimated at an average yearly catch of 40.4 indi- 
viduals/DCP for legally marketable blue crab. In that 
study, the overall mortality for blue crab in DCPs was 
45%, and the estimated annual escapement of blue crab 
from DCPs was 55%; estimated annual finfish mortal- 
ity was 2.5 individuals/DCP. In Virginia, Havens et al. 
(2008) estimated that about 50 marketable blue crab 
are killed per DCP each year. Other fishery and non- 
fishery species have been found either in or entangled 
by DCPs (Havens et al., 2011; NCDMF 1 ; Guillory et 
al. 2 ). Both actively fished crab pots (AFCPs) and DCPs 
pose a significant threat of drowning to diamondback 
terrapin ( Malaclemys terrapin), a coastal species of con- 
cern in the states of Connecticut, Delaware, Maryland, 
Massachusetts, New Jersey, New York, North Carolina, 
Rhode Island, and Virginia (Roosenburg et al., 1997; 
Grosse et al., 2009). Organisms that die in a DCP can 
attract additional organisms that can become bycatch 
until that DCP is no longer capable of retaining organ- 
isms (degrades) or is removed. 
The demographics of DCPs are not yet known for 
North Carolina. One might assume that DCP abun- 
dance is related to the number of AFCPs used in each 
waterbody. Likewise, the number of years that DCPs 
continue to trap animals is unknown. Shively 5 found 
that, depending upon salinity, the functional life ex- 
pectancy of vinyl-coated pots was 2 years or more in 
Texas. The research of Havens et al. (2008) in Virginia 
indicates that lost crab pots trapped animals for more 
than 1 year in higher-salinity areas (annual mean sa- 
linity=20 ) and probably longer in lower-salinity areas 
(annual mean salinity=6), where pots were slower to 
4 Guillory, V. 2001. A review of incidental fishing mortalities 
of blue crabs. In Proceedings: blue crab mortality sympo- 
sium. Gulf States Mar. Fish. Comm. Publ. 90; Lafayette, LA, 
28-29 May 1999 (V. Guillory, H. Perry, and S. Vanderkooy 
(eds.), p. 28-41. [Available at website.] 
5 Shively, J. D. 1997. Degradability of natural materials 
used to attach escapement panels to blue crab traps in Texas, 
18 p. [Available from Natl. Mar. Fish. Serv., Southeast Reg., 
9721 Executive Center Dr., North, St. Petersburg, FL 22702.] 
degrade. The rate at which pots become incapacitated 
can be affected by their rate of decomposition, bioero- 
sion, and engulfment through encrustation by sessile 
organisms. These processes are likely to differ with 
habitat because of variation in salinity, dissolved oxy- 
gen, temperature, and other factors. 
The type of habitat where DCPs are most likely to 
occur is poorly understood. Storms and currents often 
redistribute DCPs (Bishop, 1983), not necessarily to 
places where crabbing has taken place. In North Caro- 
lina, Avissar (2006) found that crabbers relocated their 
crab pots shoreward into shallow-water areas and tidal 
marsh creeks to avoid damage to the pots from sea tur- 
tles attempting to remove the bait, and Grant 6 noted 
that capture rates of diamondback terrapin decreased 
with distance from shore. In Maryland, Roosenburg et 
al. (1999) noted that juvenile and male diamondback 
terrapin were more frequently observed in nearshore 
shallow areas, where they are more likely to interact 
with DCPs. Information about DCP density, transport, 
deposition, and longevity is needed if the limited re- 
sources available for DCP removal efforts are to be 
used more effectively. 
The objectives of this study were to quantify the 
density, distribution, and bycatch of DCPs in 6 selected 
waterbodies on the central and southern coast of North 
Carolina, from Core Sound south to Cape Fear River, 
within 3 habitat types typically fished by crabbers that 
use hard-shell crab pots, marsh creek, margin of the 
Atlantic Intracoastal Waterway (ICW), and estuarine 
edge (within 50 m of shoreline). We test whether the 
density of DCPs differs among these waterbodies and 
the habitats. 
Materials and methods 
Study area and mapping procedure for stratified random 
sampling 
The geographical range of this study spanned from 
Core Sound south to Cape Fear River, an area that 
includes 14 of 29 North Carolina inshore waterbodies. 
The 6 waterbodies that we sampled accounted for, on 
average, 74% of fishery landings of hard-shell crab in 
crab pots and 61% of fishing trips for hard-shell crab 
during which crab pots were used in the area from 
Core Sound south to the South Carolina border (NCD- 
MF 7 ) from 2006 to 2008. The sampled waterbodies, 
listed from north to south, were Core Sound, Newport 
River, Bogue Sound, Topsail Sound, Masonboro Sound, 
and the lower 16 km of the Cape Fear River (Fig. 1). 
6 Grant, G. S. 1997. Impact of crab pot excluder devices on 
diamondback terrapin mortality in commercial crab catch, 
9 p. Unpubl. report. Univ. North Carolina at Wilmington, 
Wilmington, NC. 
7 NCDMF (North Carolina Division of Marine Fisheries). 
2009. Unpubl. data. [Hard crabs and other species report- 
ed in crab pot landings in 2006-2009.] NCDMF, Morehead 
City, NC 28557. 
