Aucoin et al.: An underwater tool to catch and release Ginglymostoma cirratum 
485 
reside in and around deeper reefs and rocky areas, 
where they tend to seek shelter in crevices and un¬ 
der ledges during the day and leave their shelter at 
night to feed on the seabed in shallower areas (Cas¬ 
tro, 2000). 
Nurse sharks have a wide but patchy geographi¬ 
cal distribution along tropical and subtropical coastal 
waters of the eastern Atlantic Ocean, western Atlantic 
Ocean, and eastern Pacific Ocean (Campagno, 2002; 
Karl et ah, 2012). They have long residency times and 
show strong site fidelity (typical of reef sharks), and 
they are one of the few shark species known to exhibit 
mating-site fidelity (Carrier et ah, 2004). Nurse sharks 
are also exceptionally sedentary, unlike most other 
shark species (Heithaus et ah, 2007; Karl et ah, 2012; 
Whitney et al., 2016). They are targeted directly in 
some fisheries and are considered as bycatch in others. 
The conservation status of the nurse shark is globally 
assessed as being data deficient in the IUCN List of 
Threatened Species owing to the lack of information 
across its range in the eastern Pacific Ocean and east¬ 
ern Atlantic Ocean (Rosa et ah, 2006). They are con¬ 
sidered to be a species of least concern in the United 
States and in The Bahamas, but considered to be near 
threatened in the western Atlantic Ocean because of 
their vulnerable status in South America and reported 
threats throughout many areas of Central America and 
the Caribbean (Rosa et ah, 2006). 
Nurse sharks are known to be robust and able to 
tolerate capture, handling, and tagging extremely well 
(Carrier, 1985; Dooley and Flajnik, 2005) and are an 
important species for shark research (predominantly 
in physiology). Over 30% of current studies from all 
published research on 29 reef shark species have fo¬ 
cused on nurse sharks (Osgood and Baum, 2015). Stud¬ 
ies that involved capturing nurse sharks have success¬ 
fully used fishing nets or baited hook-and-line gear, but 
these methods are not without limitations or problems 
(Garla et ah, 2006; Skomal, 2007; Gallagher et al., 
2014). These traditional capture methods can prolong 
treatment and handling times on account of gear en¬ 
tanglement and recovery delays (Smith, 1992; Mandel- 
man and Farrington, 2007; Morgan and Carlson, 2010) 
or cause severe hooking injuries that increase morbid¬ 
ity and mortality (Bansemer and Bennett, 2010; Danyl- 
chuk et ah, 2014). 
Shark survival and recovery after capture varies 
widely and depends on a variety of factors (reviewed 
in Skomal and Bernal, 2010). Assessing 25 species of 
chondrichthyans (i.e., evaluating >11,000 sharks, rays, 
and chimaeras) in a commercial shark fishery, Brac- 
cini et al. (2012) indicated postcapture survival to be 
generally high. Tracking studies on the postrelease 
mortality of lemon sharks (Negaprion brevirostris) and 
Atlantic sharpnose sharks (Rhizoprionodon terraeno- 
vae) captured by baited hook-and-line gear indicated 
a 10-12.5% postrelease mortality rate for these spe¬ 
cies (Gurshin and Szedlmayer, 2004; Danylchuk et 
ah, 2014), but this may be an underestimate owing to 
either low sample sizes or to short monitoring times, 
or both (i.e., delayed mortality due to infection and 
disease). 
Hooking injuries are considered the primary cause 
of angling-related mortality and are the result of many 
factors, including hook type and hook configuration, as 
well as fishing technique and experience (see Brown- 
scombe et al., 2017). Moreover, evidence indicates that 
cartilaginous skeletons of sharks do not heal properly 
after damage (Ashhurst, 2004), thus hooking trauma to 
cartilaginous structures in the jaw or skull may have 
long lasting impacts. 
In this study, we present technical information on 
a more efficient and less invasive capture method that 
we used to catch and release nurse sharks. The tech¬ 
nique involves hooking the area of the caudal peduncle 
(between the caudal fin and 2 nd dorsal fin) where shark 
skin is thick and posterior musculature has been re¬ 
ported as being the most damage-tolerant area (Towner 
et al., 2012). The tail base is also away from the more 
vascularized tissues and sensory organs concentrated 
anteriorly (e.g., gills, eyes, nostrils, ampullae of Loren- 
zini, mandibular neuromasts; Hueter et ah, 2004). The 
resulting damage to these areas from typical baited 
fishing, as well as gut injuries from swallowed hooks, 
can render sharks more susceptible to late onset mor¬ 
bidity and mortality (Bansemer and Bennet, 2010). Al¬ 
though the remarkable ability of sharks to heal quickly 
from various types of body wall and other types of in¬ 
juries has long been documented (Olsen, 1953; Bird, 
1978; Reif, 1978; Towner et ah, 2012; Kessel et ah, 
2017), we examined wound recovery from this new 
poker-and-hook method for up to a 42-day period to 
validate its use as a minimally invasive capture tech¬ 
nique for sharks. 
Materials and methods 
Study area 
Nurse sharks will occasionally inhabit the seawater 
intake canal at the Florida Power and Light St. Lu¬ 
cie Nuclear Power Plant located on Hutchinson Island, 
Florida (Fig. 1). The offshore intake pipes that draw 
cooling water (365 m offshore, 7 m off the seafloor) use 
velocity caps that effectively deter and reduce fish from 
entering (see review by Fedorenko, 1991), but some 
nurse sharks and other marine wildlife still enter from 
time to time (Bresette et ah, 1998). 
Marine wildlife entering the canal need to be re¬ 
moved by biologists in order to return them to their 
natural habitat. In the past, nurse sharks that en¬ 
tered the canal were captured by traditional baited 
hook-and-line gear (e.g., rod and reel, hand lines), 
but the use of these methods in the canal can take 
hours to land a few individuals, if any. The inefficien¬ 
cy of these methods in this case is due to the ten¬ 
dency of nurse sharks to aggregate at discharge ends 
of the canal intake pipes where strong currents and 
obstructions (e.g., pier columns) occur and can pre- 
