Stevens and Guida: Biological parameters of Chaceon quinquedens in the Mid-Atlantic Bight 
349 
Table 4 
Total biomass density (kg/ha) of red deepsea crab (Chae- 
con quinquedens) at each site and depth stratum sam- 
pled in the Mid-Atlantic Bight during 2011-2013, and 
summaries across sites and depth strata are provided. 
Sampling occurred at 3 depth strata, shallow (250—450 
m), middle slope (450-700 m), and deep (700-850 m), 
at 4 sites. Block Island Canyon (BIC), Hudson Canyon 
(Hud), Baltimore and Washington Canyons (BWC), and 
Norfolk Canyon (Nor). 
Depth stratum 
Year 
Site 
Shallow 
Middle 
Deep 
Mean 
2011 
Hud 
39.8 
126.8 
105.1 
2011 
Nor 
0 
92.5 
92.5 
2012 
BIC 
0 
18.9 
25.2 
14.7 
2012 
Hud 
16.0 
21.6 
17.9 
2012 
BWC 
0.0 
241.4 
17.9 
86.4 
2012 
Nor 
0.0 
72.8 
15.9 
29.5 
2013 
Hud 
0.0 
0.0 
9.7 
3.2 
2013 
BWC 
1.0 
128.4 
64.2 
2013 
Nor 
32.0 
25.3 
29.8 
Mean 
13.6 
95.6 
18.8 
47.4 
Size of crab 
Carapace length was measured on all sampled crabs 
except for 133 crab from site BIC in 2012; for those 
crab, CL was calculated from the regression of CL on 
SW and used in all further analyses. The mean size 
of male crab captured (79.4 mm CL [SD 14.7], range: 
31.6-126.5 mm CL) was significantly greater (^=11. 62, 
df=1974, F<0.0001) than that of female crab (73.7 mm 
CL [SD 10.1], range: 26.5-103.6 mm CL). Mean size 
of males differed between years (weighted F, Table 5) 
and was lower in July 2013 (73.9 mm CL [SD 17.5]) 
than in January 2011 (80.5 mm CL [SD 10.6]) or 2012 
(83.2 mm CL [SD 13.6]). Mean size of females also dif- 
fered between years (weighted F, Table 5), but pairwise 
comparisons among years were not significant. Lack of 
sampling at some sites and depths prevented making 
annual comparisons among all samples; therefore, fur- 
ther comparisons were made by combining data across 
years. Mean weights determined from 13 subsampled 
tows (for which sexes were weighed in aggregate) were 
294 g (SD 68) for males and 227 g (SD 71) for females. 
Length-frequency distribution of males showed a 
mode in the range of 80-90 mm CL, and a distinct drop 
in abundance at sizes >90 mm CL (Fig. 2). Hard-shell 
crab predominated below 70 mm CL, old-shell crabs 
were more abundant from 75 to 100 mm CL, and most 
crabs >100 mm CL were classified as very-old-shell. 
Female crab exhibited a mode at 70-75 mm CL. Hard- 
shell females predominated below 60 mm CL, and old- 
shell females were more abundant in all size groups 
above 60 mm CL. 
Morphometries 
Sex did not affect the relationship between CL and 
SW; therefore, a combined regression equation was 
derived for both sexes (Tables 5 and 6; Fig. 3A). The 
inverse relationship was also determined and used to 
predict CL for 133 crab that were missing CL measure- 
ments. The relationship between ChL and CL differed 
between sexes with a significant interaction (Table 5); 
males had longer chelae at sizes >50 mm CL, but fe- 
males had longer chelae below 50 mm CL (Fig. 3B). 
Males had an allometry coefficient (the log-transformed 
slope) of 1.09, indicating isometric growth, whereas fe- 
males had an allometry coefficient of 0.862, implying 
slight negative allometry. Among male crab, the rela- 
tionship between ChH and CL had an allometry co- 
efficient of 1.16, indicating slightly positive allometry 
(Table 6, Fig. 3C), and the relationship between ChH 
and ChL had an allometry coefficient of 1.06 (Fig. 3D). 
Neither the relationship between ChL and CL nor the 
relationship between ChH and ChL revealed any ap- 
parent inflections in the growth pattern that could be 
used to determine maturity. The relationship between 
female AW and CL was significant but did not differ 
with maturity status (Table 5). Nonetheless, there was 
a significant interaction effect; therefore, combined and 
separate equations for immature and mature females 
are presented in Table 6. 
Distribution by depth, temperature, crab size, and shell 
condition 
Females were more abundant than males at depths 
from 400 to 650 m, but males predominated at great- 
er depths (Fig. 4). Weighted ANOVA showed that size 
varied with both depth and sex, and a significant in- 
teraction occurred (Table 5). Mean CL of male crab de- 
creased with depth: 83.1 mm CL (SD 13.7), 79.7 mm 
CL (SD 11.6), and 78.2 mm CL (SD 17.9) in the shal- 
low, middle slope, and deep strata, respectively (Fig. 
5A). Mean CL for males differed significantly between 
the shallow and deep strata (pairwise t-test, P<0.05 
with Bonferroni correction), but the values for neither 
strata differed from the middle slope stratum. Mean 
CL of females also decreased with depth to a greater 
degree than it did for males (Table 5, Fig. 5B): 80.6 mm 
CL (SD 10.1), 73.8 mm CL (SD 9.1), and 67.0 mm CL 
(SD 12.8) in the shallow, middle slope, and deep stra- 
ta, respectively, and all differed significantly (P<0.05). 
Mean CL of male crab did not differ between sites (Ta- 
ble 5, Fig. 6C), whereas mean CL of female crab was 
significantly greater at site Nor than at all other sites 
(P<0.05; Fig. 6D). 
Mean shell condition for males was significantly less 
in stratum 1 (2.2) than in stratum 2 (2.6) or stratum 3 
(2.5), but the latter 2 strata did not differ significantly 
(Fig. 6A). Mean shell condition for females was signifi- 
cantly greater in stratum 2 (2.8) than in either stra- 
tum 1 or 3 (both 2.4), but strata 1 and 3 did not differ 
significantly (Fig. 6B). New-shell male crab were most 
