Aucoin et al.: An underwater tool to catch and release Ginglymostoma erratum 
489 
Table 2 
The logistical binary regression applied to data from 
nurse sharks (Ginglymostoma cirratum ) captured with 
the poker-and-hook method in Florida during 2014 to 
ascertain the effects of body size on the likelihood of 
more pronounced skin tears (i.e., circularity <0.5) pro¬ 
duced a significant model (x 2 (D=6.124, P=0.01). The 
model explained 31.7% (Nagelkerke pseudocoefficient of 
determination [pseudo-r 2 ]) of the variance in the out¬ 
come and correctly classified 73.9% of cases. The output 
for variables in the equation indicated that increasing 
body size was associated with a 72% reduction in the 
likelihood of exhibiting more pronounced skin tears 
(odds ratio: 0.279) when the 10/0 barbless J-hook was 
used in our study. The asterisk (*) indicates statisti¬ 
cal significance (a<0.05); B-bets weight coefficient (i.e., 
intercept); SE=standard error; Wald=Wald chi-square 
value; df=degrees of freedom; Exp(p)=exponentiation of 
the coefficients (i.e., odds ratios for the predictors). 
P 
(3 SE Wald df value Exp<P) 
Body size -1.277 0.608 4.411 1 0.036* 0.279 
Constant 14.9 0.524 1.449 1 0.229 1.878 
and circumference. Hook depth (as a proxy for wound 
volume) in relation to wound area, circularity, and cir¬ 
cumference was initially examined. Because the vari¬ 
ables are correlated (different types of measurements 
of the same wound) we first tested for multicollinearity, 
which indicated dropping the variable circumference in 
subsequent analysis. We then tested whether wound 
area predicted hook depth by using ANCOVA. Because 
measurements of shark weight and total length were 
strongly positively correlated, we used a principle com¬ 
ponent analysis to reduce these variables into compo¬ 
nent scores as a better indicator of shark body size 
(i.e., as a covariate) and to increase the degrees of 
freedom available to estimate variability. Nonetheless, 
the model did not reveal any significant relationship 
between wound area and hook depth or body size. 
The logistical binary regression applied to ascer¬ 
tain the effects of body size on the likelihood of more 
pronounced skin tears (i.e., circularity <0.5) produced 
a significant model, indicated by the Omnibus test of 
model coefficients (% 2 ( 1)=6.124, P=0.01), with the Hos- 
mer-Lemeshow test strongly suggesting the model was 
a good fit to the data (P=0.42). The model explained 
31.7% (Nagelkerke pseudo-r 2 ) of the variance in the 
outcome, correctly classified 73.9% of cases, and the 
odds ratio indicated that increasing body size was as¬ 
sociated with a 72% reduction in the likelihood of ex¬ 
hibiting more pronounced skin tears when using the 
10/0 barbless J-hook in our study (Table 2). 
Photos were taken to measure wound and healing 
progression over time; all wounds were nearly or com¬ 
pletely healed after 22 days. Typical healing stages for 
Table 3 
Difference in weight at capture and 22-24 days after 
recapture for 4 nurse sharks (Ginglymostoma cirratum) 
captured by the poker-and-hook method and released in 
Florida during 2014. The remaining sharks sampled for 
this study were weighed only upon their release back 
into the ocean to 
minimize 
handling time. 
Total 
length 
(cm) 
Initial 
weight 
(kg) 
Final 
weight 
(kg) 
Weight 
gain 
(kg) 
Time 
(d) 
Gain 
rate 
(g/d) 
135 
11.8 
12.1 
0.3 
22 
14 
151 
14.9 
15.5 
0.6 
23 
27 
163 
19.8 
20.3 
0.5 
24 
20 
167 
21.2 
22.0 
0.8 
23 
35 
small wounds in nurse sharks begin with mucus secre¬ 
tion, followed by wound contraction, epidermal expan¬ 
sion, and scale neogenesis (Reif, 1978). Figure 4 shows 
typical before-and-after photos of hook wounds from 
sampled nurse sharks. At 9-10 days, wounds showed 
that the dermis had begun regenerating (seen beneath 
its mucus covering; Fig. 4, A and B) or were already 
transitioning to the epidermal expansion stage. At 
22-24 days, repair scales within a fully regenerated 
epidermis were obvious (Fig. 4, C and D) and easily 
identified by their white color (in comparison with fully 
mineralized scales that are brown). At 37-42 days, only 
a small scar remained, and although no histological as¬ 
sessment was performed the formed scales appeared to 
be normal (Fig. 4, E and F), identified by their brown 
color which was due to pigment deposited together 
with inner layers of dentine in the skin (Reif, 1978). 
Table 3 shows before-and-after weights of 4 nurse 
sharks re-assessed after 22-24 days. All individuals 
had gained weight upon recapture (mean: 0.6 kg [stan¬ 
dard deviation 0.2]). The smallest of these 4 sharks, 
which was released into the canal, gained less weight 
than the 3 larger individuals released into the holding 
tank that were fed regularly. 
Discussion 
Studies on the survival of fish after their capture and 
release are technically challenging and the long-term 
effects of physical and physiological trauma associ¬ 
ated with varying capture techniques remain mostly 
unknown (Davis, 2002; Skomal and Bernal, 2010; Gal¬ 
lagher, 2015). Recent studies are beginning to docu¬ 
ment postcapture sharks for extended periods and in¬ 
dicate that capture-related morbidity and mortality in 
sharks varies widely among species (Brill et al., 2008; 
Frick et al., 2010; Heberer et al., 2010; Gallager et al., 
2014). Although postcapture mortality rates for sharks 
are still generally considered to be low (Gurshin and 
