Voss et al.: Factors driving the density of derelict crab pots and associated bycatch in North Carolina 
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■ Blue crab 
□ Florida stone crab 
M Sheepshead 
Black sea bass 
Waterbody 
U Creek Edge ICW 
Habitat type 
Figure 4 
Abundance of 4 fishery species per km 2 — 
the blue crab (Callinectes sapidus), Florida 
stone crab (Menippe mercenaria), sheeps- 
head ( Archosargus probatocephalus ), and 
black sea bass ( Centropristis striata ) — 
found among the bycatch of derelict crab 
pots (A) by waterbody and (B) by habitat 
type from April to November 2010 in 6 
waterbodies (Bogue, Core, Masonboro, and 
Topsail sounds and Cape Fear and New- 
port rivers) of North Carolina. 
6 retrieved DCPs, 2 were estimated to have been in 
the water for at least 2 years, on the basis of degree 
of fouling and size of attached eastern oysters. Three 
other introduced DCPs, each estimated to have been 
in the water for 1-1.5 years, were heavily fouled with 
algae and tunicates and were still capable of capturing 
bycatch. Live adult blue crab (5), Florida stone crab (8), 
and an oyster toadfish (1) were found in the 6 recov- 
ered DCPs, but they were not included in our bycatch 
database. One DCP was thought to have become der- 
elict within a few months of retrieval because its rebar 
was still intact. 
Discussion 
The occurrence of DCPs is a serious problem through- 
out North Carolina and in other states where the blue 
crab fishery that uses hard-shell crab pots contrib- 
utes to the local heritage and economy. We were able 
to produce quantitative estimates of DCP density and 
abundance and of bycatch by waterbody and habitat in 
North Carolina. Our results document the magnitude 
of the problem and may help focus future cleanout ef- 
forts. This study shows that DCPs are introduced into 
areas not necessarily associated with crabbing activity 
because pots were probably transported by tides and 
storm currents. Further, a previously unrecognized 
source of mortality for fishery species and other wild- 
life — stacked pots stored on the marsh — was observed. 
Derelict crab pots were abundant in 5 of the 6 wa- 
terbodies (Table 1) and were present in each of the 3 
types of habitat surveyed (Table 1; Fig. 3), despite cur- 
rent crab pot regulations, management efforts to lim- 
it pot loss or abandonment, and programs to remove 
derelict gear. Lack of a significant difference in DCP 
density among habitat types may have been a result 
of the ecological similarity of the 3 habitats examined. 
All were situated in shallow water, they were adjacent 
to one another, and each was a likely focus of crabbing 
effort. Crabbers traditionally set lines of pots along the 
shallow edge of deeper water areas (such as channels) 
or in areas adjacent to salt marshes. Avissar (2006) 
found that crabbers moved their pots into shallower 
waters at the estuarine edge or toward the heads of 
marsh creeks to avoid pot damage caused by sea tur- 
tles seeking the enclosed bait. Hence, we expected to 
find higher DCP densities in marsh creek or estuarine 
edge habitats. Of all observed DCPs, 50% were dis- 
covered in marsh creek habitat; however, this finding 
could result from lower sampling effort overall in ICW 
habitat or from the lack of appropriate ICW habitat in 
2 of the studied waterbodies (Table 1). 
We sampled with replacement for a selection of cells 
to represent each habitat type within each waterbody. 
This procedure resulted in 23 randomly selected cells 
being surveyed as 2 different habitat types, effectively 
duplicating results in 46 of the 201 sampled cells and 
possibly hindering our ability to detect differences in 
DCP density among habitat types. However, analysis of 
the subset of 155 single-habitat cells yielded the same 
patterns found in the analysis of the complete 201-cell 
data set, with significant differences in DCP densities 
found among the 6 waterbodies but not among the 3 
habitat types and with no differences in AFCP densi- 
ties detected among these factors. 
Found in 46% of the 201 sampled cells, AFCPs were 
much more widely distributed than DCPs, which were 
found in only 9% of the sampled cells. This difference 
may have resulted from the 11-fold higher number of 
