280 
Fishery Bulletin 119(4) 
Table 3 
Parameters from 19 simulations that were most comparable with data from the depletion exper- 
iment SC04-01. Type of clam distribution is denoted as vertical bands (P), clams in half the area 
(HP), and diagonal across the area (T). Characteristics used to describe the experiments are the 
effective area swept (EAS), the coefficient of variation (CV) for the efficiency estimate (CV,), and 
the CV of the k parameter (CV), which is the negative binomial dispersion parameter. The esti- 
mated efficiency of depletion experiment SC04-01 is 0.53334. The data set used in the simulations 
came from depletion experiments conducted during 1997-2011 for Atlantic surfclams (Spisula 
solidissima) off the mid-Atlantic coast of the United States. See Figure 1 for the locations where the 
experiments were conducted. 
Simulation and SC04-01 values 
Average values from simulations 
Values from SC04-01 
Mean absolute error in efficiency estimate: 
CV, CVx 
14.564 25.703 
19.835 28.085 
0.1471 Range: 
Parameter 
EAS (m?) 
16,443.2 
12,824.4 
0.0000-0.5817 
Parameter 
Error in 
efficiency 
estimate 
Density Clam 
(individuals/m”) — distribution 
0.3083 1.50 
0.2533 1.50 
0.4250 3.00 
0.4633 3.00 
0.4133 3.00 
0.2533 0.75 
0.4450 0.75 
0.3250 0.75 
0.2233 1.50 
0.3467 1.50 
0.0867 1.50 
0.0033 3.00 
0.3400 3.00 
0.4167 3.00 
0.0317 1.50 
0.0250 1.50 
0.0083 3.00 
0.0383 0.75 
0.0233 1.50 
222 
wUSsSs geese eeHeHeH aS 
uniform distribution across the depletion rectangle (NP), 
patches oriented across the narrow dimension (P), patches 
oriented longitudinally (HP), and patches of a triangular 
nature emanating from one side of the rectangle (T) 
(Fig. 2). The fraction of chosen simulations assigned to 
each field experiment falling into each of these categories 
was obtained to describe possible similarities in clam dis- 
persion characteristics in the area occupied by the field 
depletion experiment. 
Comparisons between field experiments and simula- 
tions were made by using 4 error terms chosen to deter- 
mine which of the field depletion experiments diverged the 
most from the most comparable simulations identified with 
the 4-integer test. Two error terms, henceforth referred to 
as Errl and Err2, describe how closely the 4 experiment 
True CVE CVE 
efficiency 
EAS (m?) 
estimate Estimate 
24.2038 
26.1968 
27.2515 
18.3371 
18.7500 
19.0160 
14.9942 
13.2075 
19.2098 
19.9257 
23.6196 
23.4114 
26.5866 
26.7742 
26.4758 
26.4220 
26.8293 
28.5385 
28.6364 
28.5484 
28.5821 
28.7838 
28.9172 
28.8820 
19.9005 28.8194 
14.7059 28.0702 
1.7609 25.3618 
1.3886 26.9719 
1.3091 24.6763 
2.4398 26.3924 
2.2964 25.0700 
20,807.33 
20,807.33 
16,443.15 
12,824.38 
18,932.27 
19,145.44 
18,949.80 
18,931.71 
18,729.82 
18,815.12 
18,931.71 
18,581.26 
18,815.12 
18,891.53 
18,729.82 
18,932.27 
18,891.53 
18,757.88 
13,600.72 
measures derived from the field experiments (EAS, CVj, 
CVx, and OS) agreed with the same measures obtained 
from the extracted subset of the simulations: 
ae s abs(observed — expected) a (9) 
it expected 
= 2 
Err? = we (observed — expected) (10) 
Jal expected 
where the observed measurement value is obtained from 
the field experiment and the expected measurement is the 
average value of the extracted simulations. 
The error term Err3 is the average percent error from 
the simulation subset obtained by comparing the field 
