French et al.: Strong relationship between catch of Hippoglossus hippoglossus and availability of habitat for juveniles 
119 
Table 4 
Depth, slope, and bottom temperature (summer, winter, and range) were used as predictor 
variables to model the distribution and availability of suitable habitat for Atlantic halibut 
(Hippoglossus hippoglossus ) by using data from trawl surveys conducted from 2001 to 2013 in 
the northwest Atlantic Ocean. Empirical cumulative distributions (ECDs), which describe the 
odds that a positive survey set occurred (Atlantic halibut were present) across the available 
range of environmental conditions, for each predictor variable, were calculated for 3 regions in 
the northwest Atlantic Ocean: Nova Scotia and U.S. waters (NS and U.S.), Newfoundland and 
Labrador (NF), and the northern and southern Gulf of St. Lawrence (GSL). Values in the 10% 
and 90% columns provide the range for the majority (middle 80%) of the positive sets in each 
region, and the D statistics from Kolmogorov-Smirnov (K-S) tests are all close to 0, supporting 
the notion that there is no statistically significant difference between environmental conditions 
at the locations of positive sample data sets and the entire data set and that both data sets are 
drawn from the same range of variables. B. temp=bottom temperature. 
Region 
Variable 
ECD 
K-S test 
10% 
90% 
D statistic 
P-value 
NS and U.S. 
Depth (m) 
-193.4 
-65.0 
0.0026 
1 
NF 
Depth (m) 
-556.1 
-88.7 
0.0010 
1 
GSL 
Depth (m) 
-281.0 
-30.2 
0.0022 
1 
NS and U.S. 
Slope (% rise) 
0.0 
1.5 
0.0000 
1 
NF 
Slope (% rise) 
0.1 
4.6 
0.0000 
1 
GSL 
Slope (% rise) 
0.1 
1.5 
0.0000 
1 
NS and U.S. 
Summer b. temp. (°C) 
4.2 
8.7 
0.0002 
1 
NF 
Summer b. temp. (°C) 
2.9 
6.7 
0.0001 
1 
GSL 
Summer b. temp. (°C) 
1.5 
5.8 
0.0004 
1 
NS and U.S. 
Winter b. temp. (°C) 
3.7 
7.7 
0.0002 
1 
NF 
Winter b. temp. (°C) 
2.6 
5.4 
0.0001 
1 
GSL 
Winter b. temp. (°C) 
-0.2 
3.7 
0.0004 
1 
NS and U.S. 
B. temp, range (°C) 
-0.7 
2.1 
0.0002 
1 
NF 
B. temp, range (°C) 
-0.4 
1.4 
0.0001 
1 
GSL 
B. temp, range (°C) 
-0.1 
5.3 
0.0004 
1 
a much wider distribution of sample depths in NF, 
this analysis could benefit from a higher sampling ef¬ 
fort in deeper waters across the range; however, with 
the highest suitability falling well within the depth 
range of the survey strata, we do not believe that the 
depth limitation hindered the prediction of suitable 
habitat for juveniles. Summer bottom temperature 
had the highest contribution to the NS and U.S., and 
NF models, whereas winter bottom temperature con¬ 
tributed the most to the GSL model (Suppl. Fig. 1, 
D-F) (online only). The majority of fish caught in NS 
and U.S. were caught between summer temperatures 
of 4.2°C and 8.7°C; a slightly increased prevalence 
occurred toward the warmer temperatures (Table 4, 
Suppl. Fig. 2). In NF there was a similar range with 
a shift toward colder summer temperatures; the mid¬ 
dle 80% of juveniles were found in waters from 2.9°C 
to 6.7°C (Table 4). Alternatively, in GSL, there was 
a lean toward cooler summer temperatures, between 
1.5°C and 5.8°C (Table 4, Suppl. Fig. 2) (online only). 
These temperature windows are similar to those from 
GSL pop-up satellite archival tagging studies from Le 
Bris et al. (2017) and Murphy et al. (2017). Among 
regions, the environmental variable windows of oc¬ 
currence of juveniles overlap with slight variations in 
temperature and depth at the extremes. Lower and 
upper values correspond with regional differences 
in habitat characteristics that are evident when the 
empirical cumulative distributions of reginal samples 
are compared (Suppl. Fig. 2) (online only). 
SH-based shares were directly related to abundance- 
based shares (survey data), supporting the idea that 
the 1:1 line can be considered a baseline for expected 
productivity from each region (Fig. 3A). In turn, both 
suitable habitat shares and abundance-based shares 
(survey data) were related to abundance-based shares 
(landings) in historical (1953-54) and recent commer¬ 
cial fisheries (2010-14) (Fig. 3, B-D). The recent abun¬ 
dance-based shares (landings: 2010-14) from the hali¬ 
but fishery were also very similar to abundance-based 
shares (survey data) from 2010 through 2013 (Fig. 3C), 
and when plotted against suitable habitat availability, 
relations fell very close to the 1:1 line of expected pro¬ 
ductivity (Fig. 3B). 
There was a strong spatial overlap between halibut 
fishery landings and suitable habitat (Fig. 4; Butler 
and Coffen-Smout, 2017). The highest proportion of the 
2010 through 2014 catch occurred in division 4X, which 
