312 
Fishery Bulletin 115(3) 
Table 3 
Evaluation of model simulations in 
which closure location rule 1 
was 
used to examine the 
influence of area management 
on the stock and commercial fishery of Atlantic surfclam ( Spisula solidissima ) 
in the Mid-Atlantic Bight. Tabulated are the 
proportion of simulations where metrics used to evaluate the Atlantic surfclam population and commercial fishery were 
significantly greater under present-day management or 
alternative management under closure location rule 1 and with 
present-day abundance. Rule 1 mandates that the cell with the highest ratio of the number of small clams to the number 
of market-size clams be closed each 
year. There were 9 simulations per percentage. Any fraction over 
0.11 (1 significant dif- 
ference out of 9) is unlikely to occur by chance (exact binomial test: oc= 
=0.05; Conover 
, 1980). Size of clams 
is given 
as shell 
length (SL) in millimeters, closure duration is measured in years, and LPUE means ! 
landings per unit of effort. 
Definition of a small clam 
104 mm 
SL 
93 
mm 
SL 
80 mm SL 
64 mm SL 
Closure duration (yr) 
3 
5 
7 
3 
5 
7 
3 
5 
7 
3 
5 
7 
Stock density 
Present management 
0.44 
0.44 
0.11 
0.11 
0.11 
0.00 
0.22 
0.11 
0.11 
0.33 
0.22 
0.56 
Alternative management 
Number of clams per bushel 
0.44 
0.33 
0.56 
0.44 
0.67 
0.44 
0.56 
0.56 
0.44 
0.22 
0.33 
0.33 
Present management 
0.56 
1.00 
1.00 
0.22 
1.00 
1.00 
0.22 
1.00 
1.00 
0.22 
1.00 
1.00 
Alternative management 
LPUE 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
0.00 
Present management 
0.00 
0.11 
0.11 
0.00 
0.00 
0.11 
0.11 
0.00 
0.11 
0.00 
0.00 
0.44 
Alternative management 
Number of 10' squares fished 
0.44 
0.33 
0.56 
0.67 
0.56 
0.44 
0.78 
0.78 
0.33 
0.56 
0.89 
0.44 
Present management 
0.44 
0.56 
0.67 
0.33 
0.44 
0.56 
0.44 
0.56 
0.44 
0.44 
0.44 
0.56 
Alternative management 
Total distance traveled 
0.22 
0.00 
0.11 
0.11 
0.00 
0.00 
0.11 
0.00 
0.00 
0.33 
0.00 
0.00 
Present management 
0.11 
0.00 
0.00 
0.11 
0.00 
0.00 
0.00 
0.11 
0.00 
0.11 
0.00 
0.00 
Alternative management 
0.33 
0.56 
0.78 
0.11 
0.44 
0.67 
0.33 
0.44 
0.44 
0.22 
0.44 
0.44 
resulting in average stock density increases of 7-8% 
over the range of closure durations and definitions of 
a small clam. 
Number of clams per bushel As the closure dura- 
tion increased, the catch contained fewer clams per 
bushel; however, this effect did not vary significantly 
with a change in the definition of a small clam. The 
percentage of simulations that showed significantly 
more clams per bushel under present-day management 
reached the highest average of 97% (range: 89-100%; 
Table 7) for 7-year closure durations. With a 7-year clo- 
sure duration, the number of clams per bushel was 3% 
higher under present-day management (Fig. 8, Table 
6). The trend of fewer clams per bushel in area man- 
agement options was muted by an increase in inciden- 
tal mortality. Fewer simulations had significantly more 
clams per bushel under present-day management. The 
number of clams per bushel averaged 4% higher under 
present-day management than under the 7-year clo- 
sure duration. 
Landings per unit of effort All of the examined closure 
durations resulted in average increases of 8% in LPUE 
(Fig. 8, Table 6). The 3-year closure duration resulted 
in an increase in LPUE in an average of 64% of simu- 
lations (range: 56-89%; Table 7) when compared with 
LPUE under present-day management. The 5-year clo- 
sure duration showed significantly enhanced LPUE 
in an average of 56% of simulations and resulted in 
significant increases in LPUE in an average of 64% of 
simulations (range: 44-78%; Table 7) when compared 
with LPUE under present-day management. The 7-year 
closure duration resulted in the least number of simu- 
lations having significantly increased LPUE (average: 
42%; range: 22-67%; Table 7). The longest closure hav- 
ing the least amount of simulations with significantly 
improved LPUE might be attributed to the locations of 
closure. A closure based on the number of small clams 
per square meter might result in closure of some 10' 
squares with the most total clams (i.e., small and mar- 
ket-size clams). As the closure duration increases, more 
10' squares are closed at a time. With the 7-year clo- 
sure duration, more of the 10' squares with high clam 
densities might be closed, thus causing a lower average 
LPUE. 
Increased incidental mortality resulted in fewer 
simulations having significantly increased LPUE (Ta- 
ble 8). However, of the simulations where LPUE was 
significantly enhanced by alternative management, the 
