Whitney et al.: Mortality of Carcharhinus Hmbatus caught in the Florida recreational fishery 
541 
Overall, we found a relatively low rate of 
postrelease mortality (<10%) and most indi¬ 
viduals recovered from capture stress after 
approximately 11 h. Catch-and-release recre¬ 
ational fisheries may have a low impact on 
blacktip shark survivorship if animals are 
kept in the water and have not sustained se¬ 
rious injury. 
-1- : —i-1-1-1- 
-4 -2 0 2 4 
PCI 
Longer time to recovery “* 
Figure 6 
Principal component analysis of the recovery period of blacktip 
sharks ( Carcharhinus limbatus) caught and released off Flori¬ 
da between September 2011 and April 2013. Increasing values 
along both principal components (PCs) correspond to longer 
times to recovery. Black circles represent individual sharks. PCI 
corresponds to behavioral recovery metrics calculated from aver¬ 
ages (average overall dynamic body acceleration [ODBA], tail- 
beat cycle, tailbeat amplitude, and vertical velocity), and PC2 
corresponds to maximum behavioral exertion metrics (maximum 
ODBA, maximum vertical velocity, and ODBA bursts). Capture 
metrics, such as dissolved oxygen (DO) of the water at capture 
location and precaudal length (PCL), are fit onto the recovery 
period ordination and are displayed as arrows. The direction of 
the arrow shows the direction and magnitude of its correlation 
with the behavioral recovery metrics. 
In this study, hook type did not affect where a shark 
was hooked, animal condition, or the likelihood of the 
fisherman removing the hook. In other recreational 
fisheries, the use of circle-hooks has been found to 
increase the likelihood of common thresher sharks 
and shortfin makos being “mouth hooked” as opposed 
to “gut or foul hooked” (hooked on the fins or trunk) 
(French et al., 2015; Sepulveda et al., 2015), as well as 
increasing the likelihood of jaw-hooking across a range 
of recreationally caught shark species (Willey et al., 
2016). Studies on elasmobranchs captured in commer¬ 
cial fisheries have reported a lower incidence of gut¬ 
hooking with circle-hooks than with J-hooks (Kerstet- 
ter and Graves, 2006), and lower at-haulback mortality 
with circle-hooks (Campana et al., 2009), although the 
magnitude of this discrepancy is also species-specific. 
Acknowledgments 
This study would not have been possible with¬ 
out the expertise and dedication of Captain 
R. Moore. The authors also thank Captains 
G. Rapp and D. Rapp for their support, C. 
Capizzano, H. Marshall, J. Morris, G. Schwi- 
eterman, J. Tyminski, and numerous interns 
and volunteers for their help with fieldwork 
and other logistics, and K. Heym, S. Coy, 
V. Wright-Placeres, and K. Casey (Florida 
Aquarium) for their support in equipment 
maintenance and accounting. This study was 
funded by the NOAA Cooperative Research 
Program, grant no. NA11NMF4540120. This 
report serves as Sea Research Foundation 
publication No. 275. 
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