McKinzie and Szedimayer: Mortality estimates for Balistes capriscus based on acoustic telemetry 181 
active while residing at their respective VPS sites and 
were removed (right censored) from the data set when 
they emigrated away from their VPS sites. 
Fishing mortality occurred for 4 tagged gray trigger- 
fish (8%) while they resided at their VPS site (Fig. 2). 
All events of fishing mortality identified with telemetry 
were verified by reports of recapture by fishermen (a 
100% reporting rate). Two additional fish (T20 and T28) 
were reported as captured by fisher- 
men in 2016 after they emigrated from 
their VPS site. Fish T20 was detected 
and tracked intermittently for 443 d at 
the VPS site where it was tagged and 
released, and then it emigrated and was 
caught 693 d after release 2.2 km north- 
west of its VPS site. Fish T28 emigrated 
from its VPS site 12 d after release and 
was caught 249 d after release 0.9 km 
west of its VPS site. Total S from F (S;) 
within the VPS sites over the 241-week 
study period was 0.35 (95% CI: 0.10- 
0.73). Total S adjusted to annual S, 
calculated as St=O0!3 Dea was 0.80; 
therefore, annual fF, calculated as 
F=-1n0.80, was 0.23 (95% CI: 0.07—0.50) 
(Fig. 3). In 2015, 1 gray triggerfish was 
caught, among the 15 fish available for 
recapture at the VPS sites, and F was 
0.29 (95% CI: 0.03-1.44). In 2017, 3 gray 0 
triggerfish were caught, among the 
26 fish available for recapture, and F was 
1.13 (95% CI: 0.29—2.87). No fishing mor- 
o o 
fon) foe) 
Survival from fishing mortality 
oO 
aN 
0.2 
One additional natural mortality was detected for fish T34 
outside the VPS site 199 d after it emigrated, but this fish 
had been removed from analysis. Total S from M (S,,) over 
the entire study period was 0.32 (95% CI: 0.07—0.74). Total 
S adjusted to annual S, calculated as Sy=0.32°”"4)", was 
0.78; therefore, annual M, calculated as —]n0.78, was 0.25 
(95% CI: 0.07-0.57) (Fig. 4). One natural mortality 
occurred in each of the following years: 2013 (M=0.42; 95% 
40 60 80 100 120 140 160 180 200 220 240 
Time (week) 
Figure 3 
talities were detected in 2013 (7 fish at 
liberty), 2014 (11 fish at liberty), or 2016 
(9 fish at liberty) (Table 1). However, CIs 
overlap and indicate no significant dif- 
ferences in F among years. 
During this study, natural mortalities 
were detected for 4 fish (8%), while they 
were active at their VPS site (Fig. 2). 
Weekly survival (S) of gray triggerfish (Balistes capriscus) from fishing mor- 
tality in the northern Gulf of Mexico from 2013 through 2017. The dashed 
lines indicate the proportions of fish surviving fishing mortality after each 
weekly interval. Instantaneous fishing mortality rates were calculated from 
S after 1 year at liberty. Black points indicate conditional estimates of S for 
weekly time intervals when a mortality occurred. Error bars indicate standard 
errors. The annual fishing mortality rate, calculated as -In0.35°”4"", was 0.23 
(95% confidence interval: 0.07—0.50) during the 241-week study period. 
Table 1 
Estimates of instantaneous annual total (Z), fishing (Ff), and natural (VM) mortality rates of gray triggerfish 
(Balistes capriscus) from the use of telemetry methods with Vemco Positioning Systems at reef sites in the northern 
Gulf of Mexico from 2013 through 2017. Mortality rates were estimated for each year and for all 5 years combined by 
using the number of tagged fish available for recapture during each year (n) and the number of days in the fishing 
season for each year. The 95% confidence intervals for mortality rates are provided in parentheses. 
Year Z 
No. of 
F M Season days 
2013 
2014 
2015 
2016 
2017 
Total 
0.42 (0.05—1.95) 
0.12 (0.02—0.69) 
0.69 (0.13—2.09) 
0.22 (0.03—1.17) 
1.13 (0.29-2.87) 
0.48 (0.18—0.85) 
0.00 
0.00 
0.29 (0.03—1.44) 
0.00 
1.13 (0.29-2.87) 
0.23 (0.07—0.50) 
0.42 (0.05—1.95) 
0.12 (0.02-0.69) 
0.41 (0.04—1.87) 
0.22 (0.03-1.17) 
0.00 
0.25 (0.07—0.57) 
1 Jan—9 Jun; 1 Aug—15 Oct 
1 Jan—30 Apr 
1 Jan—6 Feb 
1 Jan—31 May 
Closed 
236 
120 
37 
152 
0 
545 
