341 
Driggers et al.: Distribution of Squatinidae in waters of the western North Atlantic Ocean 
Number of trawls 
Figure 4 
Monthly sampling effort, measured as number of trawls, during the varied time series (1950-2016) of 
7 different fishery-independent surveys (iV=104,957) from which data were examined for this study. 
Gray bars represent effort off the East Coast of the United States, and white bars represent effort 
within the northern Gulf of Mexico. 
victuals were collected at a depth less than 70 m, de¬ 
spite that 80.0% of the total trawling effort occurred 
in shallower water. There was a significant difference 
in the distributions of depths sampled and depths 
where angel sharks were collected in the GOM (K-S 
statistic: 26.93, P<0.01), and no individuals were cap¬ 
tured at depths less than 25 m. However, 97.8% of in¬ 
dividuals were caught between 70 and 474 m where 
19.2% of the total sampling effort occurred (Fig. 3). 
The distribution of squatinids was relatively con¬ 
tinuous throughout outer continental shelf waters of 
the GOM; however, only 2 individuals were observed 
between the Mississippi River Delta and the west¬ 
ern boundary of the Mississippi Canyon (-150 linear 
km, Fig. 5), despite 3600 trawls that were conducted 
within this area. The 2 sharks were caught in 1950 
and 1951 at depths of 73.1 m and 82.3 m, respectively, 
east of Mississippi Canyon. 
Angel sharks off the EC (13.5-19.5°C) and in the 
GOM (15.7-19.4°C) were collected in relatively cool 
waters and showed similar temperature preferences 
(median preferred temperature for EC=17.5°C, median 
for the GOM=17.6°C) (Table 2; Figs. 2 and 3). Depth 
preference for angel sharks was deeper in the GOM 
(92.3-171.9 m; minimum depth observed=25.6 m) than 
off the EC (17.0-94.0 m; minimum depth observed=5.4 
m) (Table 2). Of the sharks captured that had corre¬ 
sponding salinity data available, only 7 out of 2266 
individuals were collected in brackish water (salin¬ 
ity <30.0). In both regions, angel sharks indicated a 
preference for high salinity (Table 2; Figs. 2 and 3); 
however, sharks were caught over a broader range of 
salinity off the EC. 
There were 20,566 stations off the EC and 18,116 
stations in the GOM that had a full complement of 
depth, temperature, and salinity data. Within the GOM, 
there was a significant relationship between tempera¬ 
ture (x 2 =437.76, P<0.01), salinity (x 2 =387.05, P<0.01), 
and positive catch (deviance=2220.71, P<0.01); how¬ 
ever, depth was not significant when included in the 
logistic model (x 2 =0.03, P- 0.87). When excluding depth 
from the model, the relationship between temperature 
(% 2 =1725.18, P<0.01), salinity <x 2 =391.06, P<0.01), and 
positive catch remained significant (deviance=2223.75, 
P<0.Q1). Similarly, off the EC, there was a significant 
relationship between temperature (x 2 =420.35, P<0.01), 
salinity (x 2 =89.82, P<0.01), and positive catch (devi- 
ance=658.72, P<0.01); however, depth (x 2 =1.12, P- 0.29) 
was not a significant factor. The relationship between 
temperature (x 2 =420.35, P<0.01), salinity (x 2 =89.82, 
P<0.01), and positive catch remained significant when 
depth was not included as a factor (deviance=658.72, 
P<0.01). Visual inspection of mapped abiotic conditions 
in the sampled region indicated that relatively high 
temperatures associated with waters off the southern 
Florida peninsula during the winter could represent 
a barrier to movements of squatinids between the EC 
and GOM (Fig. 6). There was no indication of a barrier 
to movements between the EC and the northern GOM 
in relation to salinity (Fig. 7). 
Discussion 
All current sources describing the distribution of At¬ 
lantic angel sharks off the EC list the species as oc- 
