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Fishery Bulletin 115(3) 
remain uncaught with modern high-performance hy- 
draulic dredges (Hennen et aL, 2012; NEFSC 2 ). The 
fate of small clams is effectively unknown. Therefore, 
we investigated the effect of area management under 
the assumption of 0% and 20% incidental mortality. 
Pairwise comparisons of the present-day management 
simulation under the assumption of increased inci- 
dental mortality with simulations implementing area 
management options, also with increased incidental 
mortality, produced performance metrics that were 
then compared with the performance metrics with 0% 
mortality. Additional mortality enhanced the positive 
effect of area management in most situations under 
closure location rule 1. The percentage of simulations 
with enhanced performance metrics under area man- 
agement was greater with increased incidental mor- 
tality. Also, the average percent increase across all 
metrics was enhanced. In most simulations with the 
use of closure location rule 2, increased incidental 
mortality had little effect on the percentage of simu- 
lations with improved performance metrics. The most 
notable difference in the percentage of simulations 
with improved performance metrics in comparisons of 
the 2 levels of incidental mortality is seen in the total 
distance traveled. A larger percentage of simulations 
with increased distance traveled is seen with 0% in- 
cidental mortality in contrast with simulations with 
20 % incidental mortality. A large effect of incidental 
mortality with the use of closure location rule 1 and a 
small effect with closure location rule 2 suggests that 
a combination of the 2 closure location rules could of- 
fer some clarity for determining the real effect of in- 
creased incidental mortality. 
The enhancement of the effect of area management 
at increased levels of incidental mortality can be at- 
tributed to the protection of clams in closed areas. The 
effect of area management is enhanced because 10' 
squares with high clam abundances (regardless of the 
closure rule) are protected, and thus fewer are removed 
from the stock as a result of incidental mortality. When 
incidental mortality is increased from 0% to 20%, mor- 
tality is increased in areas that are fished; however, 
in the closed areas, this mortality is not occurring and 
these regions have the highest number of clams that 
would be subject to this source of mortality. 
Preferred management options 
The importance of the presence and abundance of 
small clams becomes apparent upon examining the 
performance metrics that suggest improvement over 
present-day management. Of the 2 closure location 
rules, the rule that places importance on a population 
dominated by small clams (rule 1) produces a greater 
increase in simulated stock abundance and LPUE over 
time in comparison with a a location closed on the ba- 
sis of the density of small clams (rule 2). An increase in 
the percentage of simulations where fewer 10' squares 
are fished occurs because the closed 10' squares pro- 
duce higher catch rates once open than the 10' squares 
that are not closed. An increase in the distance trav- 
eled during fishing trips is also seen, some of which 
results from closed 10' squares being close to home 
ports and some of which stems from the favorable (i.e., 
higher) LPUEs in recently opened 10' squares farther 
from port. No obvious difference is seen between the 
2 closure location rules for the size of landed clams 
(i.e., the number of clams per bushel). This difference 
between area management and present-day manage- 
ment in the size of clams landed is nonetheless of great 
importance because the lower fishing mortality rate in- 
creases survivorship of large clams and contributes to 
the increase in whole-stock density routinely observed 
in area management simulations, directly and through 
an increase in spawning stock biomass. 
Simulations indicate that the 5-year closure du- 
ration derives the largest benefits for the stock and 
also the commercial fishing industry. Although aver- 
age percent increases in stock density and LPUE are 
greater when closure duration is longer, the percentage 
of simulations showing improvement over present-day 
management is greatest with the 5-year closure du- 
ration. Based on the overall improvements in perfor- 
mance metrics seen with closure location rule 1 and 
the 5-year closure duration simulations, the preferred 
option that simultaneously offers additional opportuni- 
ties for growth of the stock and improvements to the 
commercial fishery is to close areas specified by closure 
location rule 1 for 5 years. Future research into area 
management options should include an investigation of 
an intermediate closure rule or a combination of clo- 
sure rules. Nonetheless, the results of these analyses 
strongly suggest that both the Atlantic surfciam stock 
and fishery would experience a positive change by the 
inclusion of an area management program in the MAB 
region. 
Acknowledgments 
This research was supported by the National Science 
Foundation (NSF) Science Center for Marine Fisher- 
ies (SCeMFiS) under NSF award 1266057 and through 
membership fees provided by the SCeMFiS Industry 
Advisory Board. This article is based, in part, on a 
thesis submitted by the senior author for fulfillment 
of the Master of Science degree at The University of 
Southern Mississippi. The authors thank the SCeMFiS 
member organizations for providing detailed informa- 
tion on vessel characteristics for all vessels targeting 
Atlantic surfclams, which allowed realistic simulations 
of the industry to be performed. 
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