286 Fishery Bulletin 119(4) 
Efficiency 
Efficiency CV 
k parameter 
Depth 
Dredge width 
No. of tows 
Year 
Latitude 
Density 
Density CV 
Figure 5 
Correlogram for depletion experiments that targeted Atlantic surfclams (Spisula solidissima) off the 
mid-Atlantic coast of the United States between 1997 and 2011. Numerals in the squares are Pearson’s 
correlation coefficients. Circles denote significant correlations (P<0.05). White circles indicate positive 
correlations, and gray circles indicate negative correlations. Characteristics used to describe experi- 
ments include dredge efficiency and its coefficient of variation (CV); the k parameter, which is the neg- 
ative binomial dispersion parameter; CV of the k parameter; effective area swept (EAS); depth; dredge 
width; number of tows of the dredge; year; latitude; and clam density and its CV. 
Table 6 
Average and median values of the following Patch model parameters for depletion experiments that were flagged because esti- 
mates were at or above the 80th percentile for each error term: dredge efficiency; clam density; the k parameter, which is the neg- 
ative binomial dispersion parameter; effective area swept (EAS); and overlap score (OS), which describes the overlap of tows of the 
dredge. Standard deviations (SDs) were calculated with the maximum likelihood equation (Equation 5), and CVs were calculated 
with Equation 6. Data used in the model are from depletion experiments conducted during 1997-2011 for populations of ocean 
quahogs (Arctica islandica) and Atlantic surfclams (Spisula solidissima) off the mid-Atlantic coast of the United States. 
Density 
No. of Efficiency (individuals/m?) k parameter 
Type of flagged a EAS 
value experiments Value SD CV Value SD CV Value SD CV (m?) OS 
Average 10 0.514 0.124 26.80 2.26 0.49 214.34 5.41 2.57 88.60 99,871 0.96 
Median 0.567 0.115 24.06 0.67 0.13 193.92 452 1.99 32.24 14,196 0.96 
Average 10 0.464 0.171 134.74 136 5.82 3933.21 20.94 2.91 59.22 99,251 1.00 
Median 0.551 0.109 25.30 0.88 0.23 189.55 6.68 2.24 31.95 10,666 1.10 
Average 9 0.384 0.106 34.09 1.51 0.36 292.30 5.30 : 58.50 6584 0.92 
Median 0.381 0.103 32.08 0.97 0.36 238.35 4.45 : 29.87 6302 
Average 0.419 0.104 31.92 1.15 0.33 273.36 5.34 ‘ 55.78 8134 
Median 0.4385 0.097 27.39 0.92 0.32 205.66 5.07 : 29.91 6400 
