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Fishery Bulletin 115(3) 
commercial industry: 1) LPUE, which is the number of 
bushels fished per hour; 2) the number of 10' squares 
fished; and 3) the total distance traveled per fishing 
trip (in kilometers). The location of ports and processing 
plants are invariable, consistent with present-day eco- 
nomic limitations that make the movement of processing 
capacity an implausible adaptation. The management 
options include a range of closure locations and dura- 
tions discussed later in this section. 
Alternative hypotheses about population dynamics, 
often termed “states of nature,” such as dispersion and 
abundance of a stock, can cause marked differences in 
the density and disposition of a stock and influence the 
success of management alternatives (Punt and Hilborn, 
1997; McAllister and Kirkwood, 1998; Hilborn, 2003). 
In this study, variations in stock distribution are simu- 
lated as differing degrees of patchiness obtained by in- 
creasing the ratio of the variance in recruitment among 
10' squares to the mean recruitment for the entire 
population, with each degree being a variance-to-mean 
ratio approximately twice the value of the previous 
one (e.g., medium patchiness has a variance-to-mean 
ratio that is approximately twice that of low patchi- 
ness). Stock abundance is representative of present-day 
abundance in 2011 (NEFSC 2 ) based on abundance data 
from the Northeast Fisheries Science Center Atlantic 
surfclam and ocean quahog survey in 2011 (NEFSC 2 ). 
Incidental mortality of clams that remain on the sea 
floor after dredging is investigated by setting incidental 
mortality to 0% and 20% of the clams encountered by 
the dredge but not caught in the dredge. The assump- 
tion that is currently made by NMFS is that incidental 
mortality occurs at an intermediate value of approxi- 
mately 12% (NEFSC 2 ) based on Meyer et al. (1981). For 
each of the degrees of patchiness and for the 2 levels of 
incidental mortality, simulations were performed with 
present-day management (termed “base cases” hereaf- 
ter) for a comparison with simulations of area manage- 
ment options. 
Incorporation and manipulation of various commer- 
cial procedures allow an investigation of the fishery 
and the plausible options for enhancement of economic 
opportunities. Captain behavioral types, closure dura- 
tions, closure locations, and years to harvest (i.e., the 
elapsed time for a small clam of specified size to reach 
a defined market size) have all been identified as per- 
tinent commercial features when considering manage- 
ment strategies. Commercial procedures are based on 
interviews conducted with industry leaders, including 
representatives from processing plants and trade orga- 
nizations, and vessel captains. 
One of 3 captain behavioral types (standard, survey, 
confident) is included in each simulation. Captain be- 
haviors are exclusive to each captain type (e.g., confi- 
dent captains do not use survey data). Standard cap- 
tains do not search for new fishing grounds and do not 
use survey data. Survey captains update their knowl- 
edge every 3 years with data from NMFS population 
surveys. The use of NMFS survey data by captains is 
common practice and has been found to improve per- 
formance in simulation studies (Powell et al., 2015). 
Confident captains spend 20% of fishing time search- 
ing for new fishing grounds. In simulations, searching 
behavior produces similar positive changes in perfor- 
mance because using survey data (Powell et al., 2015) 
and searching is reported as a desirable practice by 
captains. Each individual simulation has a defined 
degree of stock patchiness and captain type (Table 1). 
Nine simulations, 1 simulation for each combination of 
captain type and stock patchiness, constitute 1 set of 
cases, hereafter termed an ennead (Fig. 4). 
Hypotheses of this study are that area manage- 
ment will be beneficial for the Atlantic surfclam stock 
and commercial fishery. A comparison of performance 
metrics between enneads under present-day and those 
under alternative management allowed us to test our 
hypotheses (Fig. 5). Management alternatives consist 
of closures of one 10' square per year during the 76 
simulated fishing years. The management alternatives 
simulate the addition of area closures to the current 
management plan. Area closure locations are based on 
1 of 2 rules; a given rule remains in effect throughout 
the 76 simulated fishing years. If rule 1 is executed, 
the 10' square with the highest ratio of the number 
of small clams to the number of market-size clams is 
closed each year. Rule 1 focuses on the importance of 
the proportional presence of small clams. If rule 2 is 
imposed, the 10' square with the largest density of 
small clams (number of clams per square meter) is 
closed each year. Rule 2 considers the population of 
small clams as a whole over an area. Closure durations 
of 3, 5, and 7 years are compared with no closures. This 
results in 3, 5, or 7 10' squares being closed during 
each of the simulated years once the initial span of 
time specified has elapsed. The closure durations would 
result in 6%, 10%, and 14%, respectively, of the fish- 
able area being closed in any year after the maximum 
number of 10' squares were closed (e.g., for the 5-year 
closure duration, five 10' squares [10% of the fished 
area] would be closed at a given time). 
Success of both of the area management rules for 
closure location varies depending on the definition of 
a small clam (i.e., a clam that is smaller than market 
size). The definition of a small clam implemented in 
the simulations is a value that depends on the time 
required for a clam to grow to market size (120 mm SL; 
NEFSC 2 ). The specified size depends on growth rate, 
which is variable across the domain. This variation al- 
lows clams to grow faster in some regions than in oth- 
ers, depending on water temperature. A range of years 
(from 2 to 5 years) to reach harvest size is investigated 
in this study. The number of small clams is determined 
on the basis of the smallest SL that would reach mar- 
ket size (120 mm SL) in a defined period of time. All 
clams with SL that would reach market size, or larger, 
in the defined amount of time in a 10' square, but <120 
mm SL (i.e., less than market size), are counted to in- 
voke closure location rule 1 or 2 depending on which 
rule is being used for a given set of simulations. For 
convenience, an average of the minimum sizes for all 
