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Fishery Bulletin 106(1 ) 
stranded bottlenose dolphins that were found spatially 
and temporally concurrent with the spot fishery exhib- 
ited entanglement lesions (Friedlaender et al., 2001). In 
the current study, stranding thresholds were exceeded 
twice coincident in time (October and November) and 
place (south of Cape Lookout) with the typical gillnet 
season for spot (Steve et al., 2001), spanning both MU 
seasons. The disparity between bycatch and stranding 
data likely is due, in part, to low observer effort in 
nearshore waters of southern NC where the spot fishery 
is most active (Rossman and Palka 1 ). In 2006, NMFS 
implemented an Alternative Platform Observer Program 
in NC whereby observers use an independent vessel to 
find and observe gill nets fished from small boats, which 
are commonly used in nearshore waters (Kolkmeyer et 
al., 2007) but difficult for traditional observers to get 
onboard. There is no observer program, however, for 
recreational gill nets, which are not regulated by the 
MMPA (MMPA 16 U.S.C. 1362 [20] ) but are commonly 
used in NC to target spot (NCMFC, 2003); thus, it is 
not known if or at what level bycatch occurs in the rec- 
reational fishery. Given the rate of HI-FI strandings, 
it is reasonable to assume that the PBR level was ap- 
proached or exceeded because of mortality in the spot 
fishery during some years. However, one importance of 
a threshold value is to represent periods when fishery- 
related mortality does not exceed levels the population 
can sustain (i.e., PBR levels). In the case of the spot 
fishery, it is likely that the threshold values used in 
the present study are too high. Establishing threshold 
values is an iterative process, whereby values are ad- 
justed according to changes in either PBR or bycatch 
estimates. 
Management actions for the spiny dogfish fishery had 
unintentional but beneficial consequences on the by- 
catch of bottlenose dolphins. State and federal regula- 
tions severely decreased fishing effort off the NC coast 
(Federal Register, 2000b; ASMFC 2 ), essentially closing 
the NC fishery in November 2000. For the 2003-04 
season, NC was allowed a 227-t quota of spiny dogfish 
from state waters, about 7% of the average annual 
landings in NC before November 2000. Fishing effort 
occurred almost exclusively in January and February 
of 2004. Only two HI-FI stranded dolphins occurred 
in these months, one of which was wrapped in a large- 
mesh gill net (20.3-cm stretch mesh) more indicative of 
the striped bass ( Morone saxatilis ) fishery than spiny 
dogfish fishery (Steve et al., 2001). No bycatch was 
reported by federal observers on fishing vessels dur- 
ing the 2003-04 spiny dogfish fishery off NC (Ross- 
man and Palka 1 ). The soak times were shorter in the 
2003-04 season than during previous years (Rossman 
and Palka 1 ) due to trip limits imposed by the NCDMF 
and these likely contributed to a lower bycatch rate. 
Quota shares were not allocated on a state-by-state 
basis for the next fishing year (May 2004-April 2005) 
(ASMFC 2 ) and, as a result, landings of spiny dogfish 
in NC were almost nonexistent. 
Independently, managers enacted fisheries regulations 
for spiny dogfish that inadvertently decreased bottle- 
nose dolphin bycatch. The opposite situation conceivably 
could occur; that is, fisheries regulations could alter 
fishing practices or effort in a manner that could in- 
crease dolphin bycatch. Gillnetters in NC are dynamic, 
altering their fishing practices in response to a vari- 
ety of factors including changes in fishery regulations 
(Steve et al., 2001). Thus, researchers and managers 
need to be proactive, working towards managing spe- 
cies as an interrelated community and considering how 
regulations for one species may affect others. 
These analyses indicate that, at least in some situa- 
tions, strandings can serve as a near real-time indica- 
tor of fishery bycatch. Absolute estimates of bycatch 
mortality must be obtained using observer data, but the 
multi-year time lag associated with obtaining those es- 
timates prevents real-time mitigation of that mortality. 
Near real-time detection of increased bycatch can also 
be used to direct observer effort to areas of potentially 
high bycatch. Thus, observer coverage and stranding 
investigations can be used in concert for more effective 
management. 
Acknowledgments 
We are grateful for the dedicated participants in the 
North Carolina Marine Mammal Stranding Network. 
We also thank the North Carolina Division of Marine 
Fisheries, Statistics Division, for providing NC fisheries 
data and P. Rosel (National Marine Fisheries Service 
[NMFS], Southeast Fisheries Science Center [SEFSC], 
Layfayette, LA) for providing results for the stranding 
database on the six strandings genetically confirmed as 
the offshore morphotype. L. Hansen, M. Prager, and D. 
Vaughan (NMFS/SEFSC, Beaufort, NC), M. Rossman 
(NMFS/Northeast Fisheries Science Center, Woods Hole, 
MA), M. Scott (Inter-American Tropical Tuna Commis- 
sion, La Jolla, CA), and three anonymous reviewers 
provided thoughtful comments on the manuscript. E. 
Griffith (contract employee with NMFS/SEFSC) assisted 
with statistical analyses. 
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