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Abstract

The use of olfactory stimuli and the provision of food are a common practice to prompt artificial aggregations of emblematic wild species and ensure the economic viability of the wildlife-watching industry. Several elasmobranch species have been targeted by such operations in a variety of locations for over four decades. A recent review succinctly addressed the potential effects of shark diving tourism, including shark provisioning, on shark individual behavior and ecology, but the general paucity of data on the ecology of elasmobranchs precluded general statements. By using a functional framework, we reviewed the findings of the 22 available studies that investigated the behavioral, physiological, and ecological response of 14 shark and three ray species targeted by artificial provisioning. Focusing on the underlying processes that rule the response of targeted elasmobranch species, we report further effects acting beyond the individual-scale and their cross-scale relationships. We suggest that the most commonly described alterations of individual movement patterns have cascading effects through the group and community-scale, ultimately resulting in altered health condition and individual behavior toward humans. We conclude by stressing the potential for provisioning activities to support the investigation of complex ecological and behavioral processes in elasmobranchs.
MARINE ECOLOGY PROGRESS SERIES
Mar Ecol Prog Ser
Vol. 53 8: 273 –283, 2015
doi: 10.3354/meps11492 Published October 28
INTRODUCTION
The flourishing growth of nature-based tourism
can partly be explained by the need for current gen-
erations to reconnect with nature (Miller 2005).
Specifically, the viewing of emblematic wildlife has
increased in popularity (Knight 2009), and the pro-
moters of wildlife-watching point out various bene-
fits, ranging from financial inputs to local economies
to enhancing education and environmental aware-
ness (Orams 2002), that contribute towards the con-
servation of showcased species and their environ-
ments (Walpole & Thouless 2005). The economic
via bi lity of commercial wildlife viewing depends on
the predictable and constant sightings of wild ani-
mals (Whittaker 1997), which can be enhanced by at -
tracting them. In particular, the use of appetitive
stimuli is a common practice to ensure animals are
viewable to tourists (Knight 2009), but there are con-
cerns regarding possible negative consequences for
the targeted animals and their ecosystems. Orams
(2002), Newsome & Rodger (2008) and Burgin &
Hardiman (2015) reviewed a number of studies that
characterized the alteration of behavioral and physi -
o logical parameters in terrestrial vertebrates, ceta -
ceans, and fish, including but not limited to altered
health condition and increased aggression toward
humans.
© Inter-Research 2015 · www.int-res.com*Corresponding author: p.brena@live.fr
REVIEW
Shark and ray provisioning:
functional insights into behavioral, ecological and
physiological responses across multiple scales
Pierpaolo F. Brena*, Johann Mourier, Serge Planes, Eric Clua
USR 3278 CNRS-EPHE-UPVD, Centre de Recherche Insulaire et Observatoir e de l’Environnement (CRIOBE), BP 1013,
98729 Papetoai, Moorea, French Polynesia
ABSTRACT: The use of olfactory stimuli and the provision of food are a common practice to
prompt artificial aggregations of emblematic wild species and ensure the economic viability of the
wildlife-watching industry. Several elasmobranch species have been targeted by such operations
in a variety of locations for over 4 decades. A recent review succinctly addressed the potential
effects of shark diving tourism, including shark provisioning, on shark individual behavior and
ecology, but the paucity of data on the ecology of elasmobranchs precluded general statements.
By using a functional framework, we reviewed the findings of the 22 available studies that inves-
tigated the behavioral, physiological, and ecological response of 14 shark and 3 ray species tar-
geted by artificial provisioning. Focusing on the underlying processes that rule the response of tar-
geted elasmobranch species, we report further effects acting beyond the individual scale. We
suggest that the most commonly described alterations of individual movement patterns have cas-
cading effects through the group and community scales, ultimately resulting in altered health con-
dition and individual behavior toward humans. We conclude by stressing the potential for provi-
sioning activities to support the investigation of complex ecological and behavioral processes in
elasmobranchs.
KEY WORDS: Anthropogenic disturbance · Ecological effects · Management · Non-consumptive
exploitation · Shark conservation · Wildlife provisioning
Resale or republication not permitted without written consent of the publisher
Mar Ecol Prog Ser 538: 273–283, 2015
Shark and ray provisioning is an umbrella term
encompassing various practices (Richards et al. 2015)
ranging from solely using an olfactory stimulus to
feeding varying amounts of food, in order to facilitate
encounters between tourists and elusive elasmo-
branch species. These activities generate large rev-
enues for tourist operators and related businesses
worldwide (Gallagher & Hammerschlag 2011, Cis-
neros-Montemayor et al. 2013) and promote the non-
extractive value of elasmobranchs (Brunnschweiler
2010, Clua et al. 2011, Vianna et al. 2012). They are
also assumed to increase environmental awareness
and enhance positive attitudes toward this threat-
ened taxon, thereby promoting its conservation
(Topelko & Dearden 2005).
The ecological consequences of elasmobranch pro-
visioning activities have received relatively little
attention to date. A recent review by Gallagher et al.
(2015) on the effects of shark diving tourism suc-
cinctly describe some impacts of artificial provision-
ing on shark individual behavior, but does not in -
clude the responses of rays, nor cover the effects of
provisioning beyond the individual scale. Few eco-
logical aspects have been studied across enough spe-
cies to allow comparison and establish common ef -
fects (Table 1). This patchy information prevents
general conclusions being drawn from findings that
depend on the interplay between (1) the frequency
and type of activities, (2) the focal species, character-
ized by a wide variety of site-dependent natural be -
haviors and ecology, and (3) the general ecology of
the viewing site (Duffus & Dearden 1990). Moreover,
logistical constraints imposed by the study of elusive
species often preclude classical approaches: control
sites and baseline data on the ecology of the target
population are seldom available. Therefore, focusing
on the underlying processes that rule the response of
targeted species is crucial to characterizing the im -
pact of provisioning activities.
Here, we adopt a functional framework to synthe-
size the effects of provisioning operations on the eco -
logy, behavior and physiology of elasmobranchs
beyond the individual scale. We gathered the 22
available studies that investigated the behavioral,
physiological, and ecological response of 14 shark
and 3 ray species at 11 sites around the world where
aggregations were conducted using appetitive stim-
uli (Fig. 1). Given the shared ecological and biologi-
cal features of sharks and rays (Carrier et al. 2012),
an exhaustive review of elasmobranch responses to
provisioning ought to benefit our understanding of
the underpinning mechanisms in action. This proce-
dure allows us to (1) suggest a complementary ap -
proach to the review provided by Gallagher et al.
(2015), that includes additional references and dis-
cusses further described impacts; (2) to highlight the
putative connections between every impact de -
scribed in isolation, across the individual, group and
community scales; and (3) to illustrate the potential
for provisioning activities to support the investigation
of key ecological and behavioral processes in elas-
mobranchs.
WHY INCLUDE SHARKS AND RAYS?
Our review covers the effects of provisioning of
both sharks and rays. Like most shark species, some
ray species are carnivorous and are privileged tar-
gets for artificial provisioning activities. Most of the
individual responses by sharks to provisioning re -
ported in Gallagher et al. (2015) have also been
described in rays. In this section, we briefly justify the
inclusion of both sharks and rays in our review by (1)
highlighting their key similar responses to provision-
ing, and (2) discussing how the comparison of differ-
ent responses can help address key research ques-
tions on the impact of provisioning.
Similar individual responses by sharks and rays
Horizontal movement patterns in fed sharks and
rays are affected by provisioning at both local spatial
and short-term temporal scales. Sharks and rays ex -
posed to provisioning operations generally show a
reduced horizontal activity. By tracking the fine-
scale distribution of great white sharks Carcharodon
carcharias in the vicinity of cage-diving operations at
Neptune Islands, South Australia, Huveneers et al.
(2013) showed that the area where individuals spend
50% of their time decreased by 28% during berley-
ing operations. Similarly, female southern stingrays
Dasyatis americana fed at a tourist site in Grand Cay-
man displayed smaller activity spaces than non-fed
rays, in addition to reversed diel activity patterns
(Corcoran et al. 2013). Furthermore, several studies
report that the centers of activity of tracked sharks
and rays align with areas and hours of active provi-
sioning (Newsome et al. 2004, Clarke et al. 2011,
Bruce & Bradford 2013, Huveneers et al. 2013).
Some studies describe the emergence of an antici-
patory response by fed sharks and rays. The learning
capabilities of elasmobranchs are now widely recog-
nized (Guttridge et al. 2009), and the regular expo-
sure to an olfactory stimulus, sometimes followed by
274
Brena et al.: Shark and ray responses to provisioning 275
Model species Studied concept
Individual Individual Site Dietary Abundance Community Group Competitive Individual Behavior
horizontal vertical occupancy habits composition structure interference health to humans
distribution distribution patterns
C. albimarginatus nys nys Brunnschweiler nys nys Brunnschweiler nys nys nys nys
et al. (2014) et al. (2014)
C. amblyrhynchos nys nys Brunnschweiler nys Clarke Brunnschweiler nys nys nys nys
et al. (2014) et al. (2013) et al. (2014)
Clarke et al. Clarke
(2013) et al. (2013)
C. carcharias Bruce & Bruce & Bruce & nys Bruce & nys nys nys nys nys
Bradford (2013) Bradford (2013) Bradford (2013) Bradford
Huveneers Laroche et al. Huveneers et al. (2013)
et al. (2013) (2007) (2013)
Laroche et al.
(2007)
C. falciformis Clarke et al. nys Clarke et al. nys Clarke et Clarke et nys Clarke et nys Clarke et
(2011) (2011) al. (2013) al. (2013) al. (2013) al. (2013)
C. galapagensis nys nys Meyer et al. nys Meyer et al. Meyer et al. nys nys nys nys
(2009) (2009) (2009)
C. leucas Brunnschweiler nys Brunnschweiler nys Brunnschweiler Brunnschweiler nys nys nys nys
& Barnett (2013) & Barnett (2013) & Baensch & Baensch (2011)
Brunnschweiler (2011) Brunnschweiler
et al. (2014) et al. (2014)
C. melanopterus nys nys Brunnschweiler nys nys Brunnschweiler Mourier et al. nys nys nys
et al. (2014) et al. (2014) (2013b)
C. perezi nys nys Maljkovi & Maljkovi nys nys nys Maljkovi nys nys
Côté (2011) & Côté (2011) & Côté (2011)
C. plumbeus nys nys Meyer et al. nys Meyer et al. Meyer et al. nys nys nys nys
(2009) (2009) (2009)
G. cuvier nys nys Brunnschweiler nys nys Brunnschweiler nys nys nys nys
et al. (2014) et al. (2014)
N. acutidens nys nys Brunnschweiler nys Clua et al. Brunnschweiler nys Clua et al. nys Clua et al.
et al. (2014) 2010b et al. (2014) (2010a) (2010a)
Clua et al.
(2010a & b)
N. ferrugineus nys nys Brunnschweiler nys nys Brunnschweiler nys nys nys nys
et al. (2014) et al. (2014)
R. typus nys nys Araujo et nys nys nys nys nys Araujo et nys
al. (2014) al. (2014)
T. o besus nys Fitzpatrick Brunnschweiler nys nys Brunnschweiler nys nys nys nys
et al. (2011) et al. (2014) et al. (2014)
D. americana Corcoran et al. nys Corcoran et al. Semeniuk nys nys nys Newsome Semeniuk & Newsome
(2013) (2013) et al. (2007) et al. (2004) Rothley (2008) et al. (2004)
Newsome et al. Semeniuk & Semeniuk et Semeniuk
(2004) Rothley al. (2009) & Rothley
(2008) (2008)
H. fai Gaspar et al. nys Gaspar et al. nys nys nys nys nys nys nys
(2008) (2008)
M. australis nys nys Newsome et nys nys nys nys Newsome et nys nys
al. (2004) al. (2004)
Table 1. Overview of the ecological concepts investigated in the literature on shark and ray feeding. nys: not yet studied
Mar Ecol Prog Ser 538: 273–283, 2015
276
easy access to food, can drive individuals into a re -
peated and predictable use of the provisioning site.
At locations where provisioning operations take
place daily at regular times, several authors wit-
nessed sharks and rays arriving at provisioning sites
in anticipation of the process, even before bait is sup-
plied or with no bait at all (Gaspar et al. 2008, Meyer
et al. 2009, Bruce & Bradford 2013, Clarke et al. 2013,
Corcoran et al. 2013). In cases when no anticipatory
response is reported, individuals responded much
faster to the stimulus after baiting was initiated
(New some et al. 2004, Johnson et al. 2006).
Overall, all studies demonstrate that the propensity
to respond to provisioning operations varies both
among elasmobranch species and among individuals
within each species (Laroche et al. 2007, Gaspar et al.
2008, Brunnschweiler & Barnett 2013, Huveneers et
al. 2013, Brunnschweiler et al. 2014). Sharks and rays
display inter-individual variation in patterns of resi-
dency and habitat use: while some individuals show
year-round site attachment, others are only oppor-
tunistic visitors and are consequently less likely to be
affected by provisioning operations (Clua et al.
2010a, Clarke et al. 2011, Maljkovi & Côté 2011,
Araujo et al. 2014).
Insights provided by different responses:
diet and foraging behavior
In their list of recommended research questions for
the field of shark diving tourism, Gallagher et al.
(2015) stress the need to better understand the im -
pact of provisioning on sharks’ trophic features but
deplore the paucity of data available on the topic. Al -
though the amount of food distributed is seldom reli-
ably reported, the inclusion of the ray literature gives
a broader perspective on the effects of provisioning
regimes on the dietary habits of elasmobranchs.
To our knowledge, only 2 studies have investigated
possible disturbances to dietary habits of elasmo-
branchs resulting from provisioning operations. Malj -
kovi and Côté (2011) used stable isotope analysis to
investigate isotopic signatures of fed Caribbean reef
sharks Carcharhinus perezi in the Bahamas and de-
tected a putative change in their dietary habits. A
small number of large individuals accessed more than
50% of the bait offered and showed a 15N tissue en-
richment, which can be explained by their frequent
access to high-trophic level food. Nevertheless, some
authors extrapolated the energy requirements of free-
ranging sharks from simple bioenergetic models de-
Fig. 1. Distribution of provisioning operations targeting sharks and rays. Map shows the countries/states where the impact of
shark and ray provisioning operations have been studied
Brena et al.: Shark and ray responses to provisioning
veloped from similar species, and concluded that pro-
visioning was unlikely to constitute the sole source of
energy for fed sharks (Malj kovi & Côté 2011, Ham-
merschlag et al. 2012). Conversely, Semeniuk et al.
(2007) used fatty acid (FA) profile analysis to investi-
gate human-induced physiological changes in south-
ern stingrays fed with squid in the Caribbean. The FA
profiles of fed individuals turned out to be markedly
distinct from those of unfed stingrays and showed a
strong similarity with the FA compositions of squid,
suggesting that conditioned stingrays rely on provi-
sioning operations as their main food source. They
also showed that provisioned squid does not provide a
similar nutritional lipid composition to the stingrays’
natural prey. Still, the detrimental consequences of
depending on provisioned food on the ability of indi-
viduals to feed independently (Orams 2002) remain
undetermined. However, Newsome et al. (2004) ob-
served that regularly fed southern stingrays maintain
active foraging and natural hunting behaviors when
provisioning operations do not occur, even though
their rate of success in predatory actions is unknown.
These findings suggest that the extent to which fed
individuals rely on provisioned food is linked to the
practices involved (Richards et al. 2015). Moreover,
comparing the response of elasmobranch species to
different feeding regimes (i.e. whether the amount of
food is restricted or not) can contribute to determin-
ing not only how they are impacted by provisioning
activities, but also how they tune their feeding strate-
gies according to fluctuating contexts.
GROUP-SCALE EFFECTS
Aggregation effects
The primary purpose of provisioning operations is
to aggregate sharks and rays at a particular location,
sometimes where the target species are already nat-
urally abundant (e.g. Vianna et al. 2012). A number
of studies report that tour operators have achieved
the goal of increasing abundances of targeted spe-
cies at the provisioning sites over prolonged periods
(Meyer et al. 2009, Clua et al. 2010b, Brunnschweiler
& Baensch 2011, Bruce & Bradford 2013, Clarke et al.
2013). Most notably, Brunnschweiler & Baensch
(2011) noticed a 6-fold increase in the bull shark Car-
charhinus leucas population in Fiji over 7 yr. Indeed,
Bruce & Bradford (2013) state that the changes de -
scribed in fed elasmobranch groups can be directly
linked to provisioning operations. The authors ob -
served that great white shark sightings near Neptune
Islands, South Australia, significantly increased fol-
lowing the growth of shark cage diving operations.
Provisioning operations can influence group com-
position in terms of species and genders that are ag -
gregated. Using an olfactory stimulus can lead to the
gathering of both gregarious and solitary species.
Aggregations of naturally sociable blacktip Carcha -
rhinus melanopterus (Mourier et al. 2012) or whitetip
Triaen odon obesus (Fitzpatrick et al. 2011) reef sharks
and silky sharks Carcharhinus falciformis (Clarke et
al. 2011) are described in the literature. Likewise,
gatherings of solitary tiger shark Galeocerdo cuvier
(Hammerschlag et al. 2012), whale (Araujo et al.
2014), bull (Brunnschweiler & Baensch 2011), and
great white sharks (Bruce & Bradford 2013), sicklefin
lemon sharks Negaprion acutidens (Clua et al. 2010a)
and southern stingrays (Semeniuk & Rothley 2008)
have been reported. Moreover, Mourier et al. (2013b)
show that the sexual segregation of blacktip reef
sharks around Moorea, French Polynesia does not oc -
cur on the northern coast of the island, where feeding
operations regularly take place, although this pattern
could not be clearly linked to provisioning activities.
Effects on natural cycles
As shown in Gallagher et al. (2015), the impact of
provisioning operations on natural cycles and behav-
ior is hard to assess in elasmobranchs because of the
general lack of baseline data on reproductive cycles
and migrations for most of the species involved
(Brunn schweiler & Baensch 2011). Nevertheless,
pro visioning platforms can represent useful tools for
investigating such aspects (Meyer et al. 2009, Clua et
al. 2010a, Brunnschweiler & Baensch 2011, Araujo et
al. 2014). The observed seasonality in the abundance
of sharks at several provisioning sites indicates that
individuals maintain their natural migrations and
that provisioning activities are unlikely to perma-
nently alter them (Laroche et al. 2007, Meyer et al.
2009, Clua et al. 2010a, Brunnschweiler & Baensch
2011). The seasonal changes in abundance at the
provisioning site and the patterns of habitat use de -
scribed in long-term surveys are attributed to breed-
ing migrations (Meyer et al. 2009, Clua et al. 2010a,
Brunnschweiler & Baensch 2011, Hammerschlag et
al. 2012). On the north shore of Moorea, French Poly-
nesia, female resident blacktip reef sharks that are
exposed to provisioning migrate to breeding grounds
located on distant islands, showing that provisioning
activities do not seem to alter short-term reproduc-
tive migrations (Mourier & Planes 2013).
277
Mar Ecol Prog Ser 538: 273–283, 2015
Effects on competitive interference
Multi-species aggregations can lead to inter-
specific interactions in the form of bites, chases and
other forms of aggression, as has been reported be -
tween eagle rays Myliobatis australis and southern
stingrays (Newsome et al. 2004). Individuals are
likely to display dominance signaling in the presence
of competitors, as agonistic interactions constitute an
important factor in hierarchy establishment (Martin
2007, Clua et al. 2013). Group hierarchies described
in fed elasmobranch aggregations are thought to be
size-dependent (Newsome et al. 2004, Clua et al.
2010a, Maljkovi & Côté 2011), as has been stated in
past studies on shark social behavior (Allee & Dickin-
son 1954, Myrberg & Gruber 1974). Provision of a
limited amount of food is therefore thought to gener-
ate inter- and intraspecific dominance interactions
between competing individuals (Ritter 2001, Clua et
al. 2010a). However, Semeniuk & Rothley (2008) also
reported a significant increase of conspecific bite
marks in southern stingrays when unlimited food
was distributed, presumably linked to indiscriminate
biting in a high density population. The potential for
simultaneous competition related to food and repro-
duction is also discussed in the case of sicklefin
lemon sharks in French Polynesia (Clua et al. 2010a)
and southern stingrays in the Caribbean (Semeniuk
& Rothley 2008) to explain the rise in seasonal intra-
specific agonistic behaviors.
COMMUNITY-SCALE EFFECTS
Effects on distribution of predators and prey
It is now recognized that predators affect prey
demo graphy and trophic interactions through both
direct predation and induced behavior (i.e. non-
consumptive effects) that may cascade through com-
munities (e.g. Preisser et al. 2005, Creel & Christian-
son 2008, Heithaus et al. 2008). In this regard, some
authors discuss the potential consequences of provi-
sioning operations on the distribution of the elasmo-
branch predators and prey.
As reported in Gallagher et al. (2015), it has been
hypothesized that the provisioning of sharks and rays
is likely to reduce predation pressure on their natural
prey. On the other hand, even when predation efforts
are limited in clustered predators, the structure of lo-
cal prey communities can be affected if predators are
not fed to satiation (Clarke et al. 2011, Corcoran et al.
2013). However, there is currently no empirical data
to support either hypothesis, and Maljkovi & Côté
(2010) showed no evidence that long-term baiting af-
fects the feeding ecology of Caribbean reef sharks.
Moreover, provisioning operations may also influ-
ence the ecology of predators that prey on the tar-
geted fed species. For example, Corcoran et al.
(2013) noted increased sightings of great hammer-
head sharks Sphyrna mokarran in the vicinity of a
southern stingray feeding site in the Cayman Islands,
and suggest that the sharks are attracted by unnatu-
ral aggregations of their habitual prey. Aggregated
elasmobranchs are therefore likely to influence the
distribution of other species, either through con-
sumptive or non-consumptive effects, or by attracting
them as potential prey.
Effects on elasmobranch communities
A handful of studies discuss modifications of local
elasmobranch community composition as another pu -
ta tive consequence of regular provisioning, as com-
petitive interference is known to influence distribution
of sharks over small spatial scales through competitive
exclusion (Papastamatiou et al. 2006) and behaviorally
mediated indirect interactions (Heit haus et al. 2008).
Brunnschweiler et al. (2014) monitored the abun-
dance of 8 shark species at a feeding site in Fiji over
several years. They observed a rapid increase in the
population of bull sharks, whitetip and blacktip reef
sharks, along with a decrease in nurse Nebrius ferru -
gineus, silvertip Carcharhinus albimarginatus, tiger
and sicklefin lemon sharks. In this case, the rapidly
expanding population of bull sharks is thought to
exclude all other species through competitive exclu-
sion. Similarly, it has been suggested that increas-
ingly abundant large sharks exclude smaller species
from provisioning sites at several other locations
(Meyer et al. 2009, Clarke et al. 2013), but no clear
cause-and-effect relationships have been established
so far. The extent to which accumulations of large
predatory sharks play a role in altering community
dynamics remains undetermined (Clarke et al. 2011)
and de serves further attention, given the fundamen-
tal role of elasmobranchs in structuring and main-
taining healthy marine ecosystems (Ruppert et al.
2013). Moreover, the use of olfactory stimuli and/or
food items can also aggregate non-targeted marine
species, such as predatory fish, and potentially con-
tribute to local community changes.
The effects of artificial provisioning on the fertility
of exposed populations remains unknown. Some
authors suggest that sedentary behaviors of sharks
278
Brena et al.: Shark and ray responses to provisioning
and rays could favor inbreeding on the long term
(Clua et al. 2010a), especially in small populations
with naturally low genetic diversity (Mourier et al.
2013a, Mourier & Planes 2013). On the other hand,
the potential role of repeated artificial aggregations
in promoting mating has yet to be addressed.
CASCADING EFFECTS ON INDIVIDUAL
HEALTH AND BEHAVIOR
In this section, we treat altered health condition
and behavior of fed species separately, since they are
considered as potential end results of several effects
discussed earlier. Whereas impacts on individual
health have mainly been documented in rays, with
several altered health parameters described, all re -
sulting in lowered body condition, the emergence of
inquisitive behaviors towards humans is described
for both sharks and rays.
Altered health condition
Rays exposed to regular provisioning have a higher
probability of being injured. Semeniuk & Rothley
(2008) compared the prevalence of injured southern
stingrays between a routine feeding spot and a
control site in the Cayman Islands and demonstrated
that 85% of fed rays were injured, compared to 30%
of non-fed rays. At the feeding site, injuries included
conspecific bite marks, predator wounds (interpreted
as an increased predation risk), and a wide range of
boat-related injuries caused by anchors, chains and
propellers (Semeniuk & Rothley 2008). Similarly,
Arau jo et al. (2014) reported a 47% incidence of boat-
propeller scars in whale sharks, although these were
not attributable solely to provisioning operations.
Increased parasite transmission has been noticed
among fed rays (Semeniuk & Rothley 2008, Semeni uk
et al. 2009). High group densities during feeding
events are likely to favor parasite transmission, re -
sulting in a higher number of parasites per ray (Seme-
niuk & Rothley 2008). This issue has also been sug-
gested to affect surrounding fish communities and
possibly sharks as secondary hosts (Vignon et al. 2010).
While investigating a range of physiological para -
meters in regularly fed rays, Semeniuk et al. (2009)
reported decreased hematocrit and total serum pro-
teins, which were related to increased parasites and
infection as well as to differential leukocrit/leukocyte
reactions, indicating oxidative stress. According to
the authors, these multiple degraded physiological
parameters in fed rays are likely to lead to a decrease
in survival (Semeniuk et al. 2009), but no long-term
investigation of putative detrimental effects of feed-
ing on individual fitness has been undertaken so far.
Effects on behavior to humans
Although no correlation has been demonstrated so
far between provisioning operations and unprovoked
shark and ray bites (Meyer et al. 2009), the dense ag -
gregations of sharks and rays targeted by tourist oper-
ations lead to increased interactions with humans,
sometimes resulting in bites (Levine et al. 2014).
While the Shark Attacks and Related Incidents File
(SARIF) database (2014; http://sharkattacksurvivors.
com/ shark_attack/) provides 10 cases of sharkbite oc -
curring during shark provisioning operations between
1968 and 2014, these incidents are significantly unre-
ported and must be treated with caution. In fact, Mail-
laud & Van Grevelynghe (2005) reviewed 54 cases of
shark bite that occurred between 1979 and 2001 in
French Polynesia (none of which were re ported in
the SARIF database) and reported that up to 25 cases
(45%) were linked to shark provisioning operations
involving fish blood or flesh close to the victim. Like-
wise, the practice of hand-feeding seems to enhance
the risk of a bite, and most victims in this case review
were the feeding operators themselves (Maillaud &
Van Grevelynghe 2005).
A possible association between tourist presence,
food rewards and subsequent attraction to humans
has been described in southern stingrays in Hamelin
Bay, Western Australia (Newsome et al. 2004). More-
over, fed individuals can develop very inquisitive atti-
tudes (Clua et al. 2010a), sometimes displaying pushy
behaviors or ramming toward tourists with food (Se-
meniuk & Rothley 2008). Similarly, group size and
corresponding competition could be a potential factor
leading to aggression toward tourists. For example,
Clarke et al. (2013) described context-dependent be-
havior of fed silky sharks toward humans, with indi-
viduals acting more boldly as group size increased.
Overall, the relationship between shark provisioning
operations and in creased risk of shark bites on recre-
ational ocean users is still being discussed (Meyer et
al. 2009). However, naturally increased aggression
be tween individuals in the breeding season, combined
with competition for provisioned food, can be an im-
portant factor contributing to bites on humans during
provisioning events, as reported in male sicklefin
lemon sharks (Clua et al. 2010a), and should therefore
be taken into account in managing the activity.
279
Mar Ecol Prog Ser 538: 273–283, 2015
DISCUSSION
Exhaustively reviewing the available literature on
the response of elasmobranchs to provisioning activ-
ities not only allowed us to report group-scale and
community-scale effects, but also to highlight puta-
tive cross-scale relationships between the described
effects and to discuss potential underlying mecha-
nisms. The synoptic functional framework (Fig. 2)
presented here illustrates the potential for provision-
ing activities to support the investigation of complex
ecological and behavioral processes in elasmo-
branchs.
A frame of bound multiple-scale effects
The described effects of provisioning on elasmo-
branchs occur across individual, group, and commu-
nity scales, and interact in a framework of theoretical
relationships (Fig. 2). Modification of local-scale acti -
v ity patterns is the most frequently described impact.
In particular, reduced horizontal activity and in -
creased residency of fed elasmobranchs are common
features. At the individual scale, the disruption of
natural movement patterns is likely to have negative
effects on animals’ energy budgets and overall
health, as reported in whales (Lusseau 2004).
The impact of provisioning on individual activity
patterns can also have group-scale repercussions,
including increased abundances over both short and
long time scales, and the aggregation of both natu-
rally solitary and gregarious species. Seasonal repro-
ductive cycles do not seem to be impacted in the
short term, although this aspect has only been stud-
ied in a few species. Long-term studies are needed to
better address this question, as it is already known in
terrestrial species that disruptions in natural cycles
can influence the fertility and demography of the
focal species (Boutin 1990, Orams 2002).
The potential community-scale effects of provision-
ing operations have not been expressly studied, but
investigation of the relative abundance of species at
provisioning sites may help to elucidate this topic.
The influence of regular provisioning on the dietary
habits of elasmobranchs depends in all likelihood on
the focal species and practices. Although the lack of
data precludes cross-study comparisons or general
conclusions, one striking case among the few avail-
able studies on the subject shows that stingrays rely
heavily on unnatural food items provided by tourists
(Semeniuk et al. 2007).
Moreover, although the sanitary implications of
provisioning operations remain insufficiently investi-
gated, individual health appears to be negatively af -
fected as a potential end-result of several impacts
listed above. Repetitive gathering of regularly fed
large groups is likely to favor parasite transmission
and injuries resulting from competition, predation,
and interactions with humans. Physiological costs of
artificially enhanced group living have been clearly
established in one study (Semeniuk et al. 2009) on
stingrays, which should encourage similar studies of
more species in different contexts. Finally, the rise in
competition for food in multi-species
aggregations and the elicitation of
conditioned responses to tourist pres-
ence can alter the natural behavior of
the target species, potentially leading
to inquisitive attitudes toward hu -
mans and accidental bites.
A case of ecological trap?
Various hypotheses have been pro-
posed to explain persisting aggregat-
ing behaviors in spite of the deleteri-
ous effects described. Instinctive be -
havior drives an individual’s response
to appetitive stimuli (i.e. the bait
scent). Operant conditioning can hap-
pen when individuals access food and
the response to the stimulus is posi-
tively reinforced with a reward (Skin-
280
Fig. 2. Multi-scale framework of concepts investigated in impact assessment
studies of shark and ray feeding. Arrows show theoretical relationships be-
tween impacted concepts at the individual, group/species and community-
scale. Data collected so far do not indicate that natural cycles are impacted
Brena et al.: Shark and ray responses to provisioning
ner 1938). In this case, fed individuals only perceive
the short-term benefits of responding to the stimulus,
but incur greater costs in the long term, a phenome-
non defined as an ecological trap (Schlaepfer et al.
2002). However, the extent to which provisioning
activities provide an easy-to-access resource greatly
depends on the ratio between food amount and num-
ber of competitors. When the amount of food is lim-
ited, only a few individuals will benefit, and we sug-
gest that aggregating behaviors may persist due to
social amplification.Indeed, socialinformation canbe
vicariously acquired and used as an indirect means to
evaluate environmental cues (Danchin et al. 2004). It
is reasonable to assume that individuals interpret the
presence of conspecifics as positive feedback, adding
to their individual instinctive response to the appeti-
tive stimulus. As more conspecifics ag gregate at the
provisioning site, the probability of another individual
coming in creases (Sumpter 2006). From this perspec-
tive, Bejder et al. (2009) suggests the need for inte-
grated models incorporating individual decision mak-
ing as the theoretical basis for understanding how
human disturbances influence animal behavior.
Unveiling natural processes and informing
sustainability
The mitigation of sharkhuman conflicts is critical
to the promotion of shark conservation, and includes
(1) implementing the sustainable exploitation of
shark species and (2) the prevention of shark bites on
humans (Neff & Yang 2013). The popularity of shark
and ray provisioning operations among the public
provides an incentive to preserve the targeted spe-
cies from commercial exploitation by fisheries in
areas where sharks and rays are not protected. Sup-
plementary feeding can also be perceived as an arti-
ficial support to the targeted species by providing
easy-to-access resources (Clua et al. 2010a, Laroche
et al. 2007), allowing individuals to allocate more en -
ergy to other activities such as reproduction (Orams
2002). However, most effects of provisioning ap pear
to be either neutral or detrimental. The im ple men ta -
tion of sustainable practices in elasmobranch tourist
provisioning, as well as in other forms of elasmo-
branch exploitation, requires a solid body of knowl-
edge on how elasmobranch species interact with
their environment.
As stated in most of the studies reviewed here, in -
cluding the recent summary on individual-scale ef -
fects of shark provisioning by Gallagher et al. (2015),
the general lack of baseline data on the biology, eco -
logy and physiology of elasmobranchs complicates
the interpretation of available findings on the effects
of artificial provisioning. Here, we considered the lit-
erature on both shark and ray responses to provision-
ing and used the findings to develop a functional
framework showing the interactions of the described
effects across multiple scales. This procedure ought
to benefit our understanding of the natural mecha-
nisms underpinning the response of elas mo branchs
to provisioning activities, and to a broader extent, the
interaction between elasmobranch individuals and
their environment. Shark and ray provisioning activ-
ities could therefore provide opportunities to support
the investigation of several fundamental concepts in
elasmobranch ecology. Such investigations are usu-
ally curbed by practical and financial constraints that
restrict the number of individuals and the type of re -
sponse variables that can be sampled (Bejder et al.
2009). We suggest that provisioning operations could
support studies on short-term behavioral features at
both the individual and group scales (Beale & Mon-
aghan 2004, Higham & Shelton 2011), as well as on
long-term ecological and physiological processes
that may affect the response of the focus species not
only to provisioning, but also to other environmental
cues, provided that the necessary precautions are
adopted when interpreting the findings.
More specifically, the phenomena determining
shark behavior toward humans are of great concern
for the mitigation of sharkhuman conflicts, and
shark conservation more generally. Indeed, shark
bites receive tremendous coverage in the media,
which can lead to any or all of the following: (1) neg-
ative perceptions and attitudes among the public; (2)
reduced compliance with conservation policies; and
(3) populist political decisions that may not be effec-
tive. In addition to putative impacts on individual fit-
ness, actively feeding elasmobranchs can influence
their behavior toward humans. Excited and compet-
ing individuals can become less wary of people and
eventually cause an accident, as has been described
in a range of other fed terrestrial wildlife species
(Aggi marang see 1993, Kamal et al. 1997). Levine et
al. (2014) recently suggested a possible connection
between hand-feeding practices by scuba divers and
a series of unprovoked attacks in the Red Sea. How-
ever, based on the partial data provided, their con-
clusions seem highly speculative, and we suggest
that more evidence is needed before feeding prac-
tices can be reliably linked to unprovoked shark bite
incidents. As previously discussed in this review,
sharks’ individual behavior to humans can be viewed
as the consequence of several ecological and physio-
281
Mar Ecol Prog Ser 538: 273–283, 2015
logical features occurring at multiple scales, investi-
gation of which should be deepened to inform sus-
tainable practices, and promote the role of shark and
ray provisioning toward their conservation.
Acknowledgements. This study benefited from the financial
support of the Ministère de l’Ecologie, du Développement
durable et de l’Energie (MEDDE) of France, the Fonds
Français pour l’Environnment Mondial (FFEM) and the Délé-
gation Régionale à la Recherche et à la Technologie (DRRT)
of French Polynesia. We also thank R. Dixon, L. Minetti and
J. L. Rummer for their help in improving the manuscript.
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Editorial responsibility: Jake Rice,
Ottawa, Ontario, Canada
Submitted: January 30, 2015; Accepted: September 18, 2015
Proofs received from author(s): October 16, 2015
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... To ensure reliable experiences can be offered to paying clients, the provisioning of food to attract sharks to divers is commonplace (Meyer et al., 2021). This has led to debate within the public and scientific community as to whether the potential economic and conservation advantages outweigh the possible negative impacts, which might include changes in shark behavior, increased human-wildlife conflict, increased prevalence of disease, or a possible reliance of sharks on provisioned food sources (Semeniuk and Rothley, 2008;Brena et al., 2015;Gallagher et al., 2015;Macdonald et al., 2017). At face value, shark ecotourism appears to be a conservation "winwin" providing localized protection to species, while generating local income and employment (of particular importance in developing countries) and raising public awareness of imperiled species (Apps et al., 2018). ...
... At face value, shark ecotourism appears to be a conservation "winwin" providing localized protection to species, while generating local income and employment (of particular importance in developing countries) and raising public awareness of imperiled species (Apps et al., 2018). Since the initial boom of these tourism operations, considerable research effort has focused on the potential ecological impacts of this industry, resulting in a number of species-specific studies exploring the influence of shark dive tourism on movement ecology (Hammerschlag et al., 2012), residency patterns (Mourier et al., 2020), trophic ecology (Abrantes et al., 2018), community composition (Clarke et al., 2013), field metabolic rates (Barnett et al., 2016), and harmful human-wildlife encounters such as shark bites [see Brena et al. (2015), Gallagher et al. (2015) for reviews]. On balance, each operation, as well as each species/ecosystem response to dive ecotourism are different. ...
... While the impacts of provisioning on individual shark behavior appears to vary both within and among species (Brena et al., 2015), impacts at the group level on species that form aggregations (groups of sharks forming on a regular to semiregular basis) or engage in social association behavior (i.e., non-random co-occurrence in space and time) are less well studied (Becerril-García et al., 2019). With increasing numbers of shark populations found to feature social associations (Jacoby et al., 2012;Mourier et al., 2018) and compelling evidence that conditioning can occur leading to anticipatory behaviors at dive sites (Bruce and Bradford, 2013;Clarke et al., 2013;Heinrich et al., 2021), understanding both the direct and indirect impacts of provisioning on the potential social structuring of shark groups remains an important and unexplored area of research. ...
Article
Full-text available
Shark dive ecotourism is a lucrative industry in many regions around the globe. In some cases, sharks are provisioned using bait, prompting increased research on how baited dives influence shark behavior and yielding mixed results. Effects on patterns of habitat use and movement seemly vary across species and locations. It is unknown, however, whether wide-ranging, marine apex predators respond to provisioning by changing their patterns of grouping or social behavior. We applied a tiered analytical approach (aggregation-gregariousness-social preferences) examining the impact of provisioning on the putative social behavior of tiger sharks (Galeocerdo cuvier) at a dive tourism location in The Bahamas. Using network inference on three years of acoustic tracking data from 48 sharks, we tested for non-random social structure between non-provisioned and provisioned monitoring sites resulting in 12 distinct networks. Generally considered a solitary nomadic predator, we found evidence of sociality in tiger sharks, which varied spatiotemporally. We documented periods of both random (n = 7 networks) and non-random aggregation (n = 5 networks). Three of five non-random aggregations were at locations unimpacted by provisioning regardless of season, one occurred at an active provisioning site during the dry season and one at the same receivers during the wet season when provision activity is less prevalent. Aggregations lasted longer and occurred more frequently at provisioning sites, where gregariousness was also more variable. While differences in gregariousness among individuals was generally predictive of non-random network structure, individual site preferences, size and sex were not. Within five social preference networks, constructed using generalized affiliation indices, network density was lower at provisioning sites, indicating lower connectivity at these locations. We found no evidence of size assortment on preferences. Our data suggest that sociality may occur naturally within the Tiger Beach area, perhaps due to the unusually high density of individuals there. This study demonstrates the existence of periodic social behavior, but also considerable variation in association between tiger sharks, which we argue may help to mitigate any long-term impacts of provisioning on this population. Finally, we illustrate the utility of combining telemetry and social network approaches for assessing the impact of human disturbance on wildlife behavior.
... Moreover, attracting wildlife has a range of potential impacts and ethical considerations. Details about the impacts of provisioning have been reviewed in Newsome and Rodger (2008), Brena et al. (2015), Patroni, Simpson, et al. (2018a), Healy et al. (2020), and the ethics of wildlife tourism discussed in Garrod (2007), Fennell (2011), Burns (2017), Ziegler et al. (2018), Patroni, Day, et al. (2018), Patroni et al. (2019). Such considerations have also been incorporated in management frameworks including in Higginbottom et al. (2003) and Meyer et al. (2021). ...
... Additional publications were sourced from the reference lists of both single-site papers and broad tourism review papers (e.g. Brena et al., 2015;Orams, 2002;Trave et al., 2017). Subsequently, searches for 'tourism' AND 'provisioning' OR 'attracting' OR 'feeding' OR 'habitat modification' were paired with search terms for different taxa (e.g. ...
Article
Wildlife tourism uses various stimuli to attract species and facilitate close encounters. Such activities are often referred to as provisioning, however the term is used interchangeably, and sometimes erroneously, with attracting, feeding, luring, and chumming, all of which lack consistent definitions. Here, we review the current use of provisioning-associated terminology in marine bird, teleost (bony fish), marine mammal, marine reptile, ray and shark tourism, within the scientific literature and on tourism operator webpages. We then propose to reclassify provisioning into Feeding, Attracting, and Modifying habitat, providing eight specific terms that reflect: (1) if the stimulus exploits wildlife appetite or search for preferred habitat; (2) the nature of the attractant (consumable or not); (3) the intention of the activity if using consumable attractants (direct, indirect, or incidental feeding) or modified habitat (intentional or repurposed modification); and (4) which species are affected by the activity (target or non-target species). We applied these terms to wildlife tourism around the world to gain better insight into tourism practices across taxa. Clarifying the terminology describing these wildlife interactions ensures they can be accurately described in the scientific literature, which will in turn help resource managers and industry groups to systematically assess these diverse activities.
... However, feeding or attracting wildlife with food to enable better viewing opportunities by ecotourists (i.e. provisioning tourism) has the potential to alter the natural behaviour and physiology of animals (reviewed by Brena et al., 2015;Cox & Gaston, 2018;Patroni et al., 2018;Trave et al., 2017). For instance, in the presence of tourismbased provisioning, northern Bahamian rock iguanas, Cyclura cychlura, experienced a greater incidence of endoparasitic infection and indicators of a nutritionally unbalanced diet (Knapp et al., 2013). ...
Article
While a growing body of literature has shown that tourism provisioning can influence the behaviour of wildlife, how physiological state might be related to the nature and magnitude of these effects remains poorly understood. Physiological state, including reproductive and nutritional status, can have profound effects on an individual's behaviour and decision making. In the present study, we used multiple physiological markers related to reproductive (testosterone, 17β-oestradiol and progesterone), metabolic (corticosteroids) and nutritional ecology (stable isotopes and fatty acids), integrated with ultrasonography and passive acoustic telemetry to explore the possible relationship between physiological condition and space use of tiger sharks, Galeocerdo cuvier, exposed to dive tourism provisioning. Large, nongravid female tiger sharks, with higher plasma steroid levels (i.e. testosterone, 17β-oestradiol, relative corticosteroid), enriched δ¹⁵N and elevated nutritional status (in terms of fatty acids) spent proportionally more time at food provisioning sites compared to conspecifics. Testosterone levels also were positively correlated with the proportion of time spent at provisioning sites. Based on these results, we speculate that physiological condition plays a role in shaping the spatial behaviour of female tiger sharks within the context of food provisioning, whereby larger individuals, exhibiting higher testosterone levels and elevated nutritional status, show selective preferences for provisioning dive sites, where they outcompete conspecifics of relatively smaller size, lower testosterone levels and depressed nutritional state. While more studies are needed to explore whether sharks are making these decisions because of their physiological state or whether spending more time at provisioning sites results in altered physiological state, our findings highlight the importance of considering animal life stage, endocrine regulation, and nutritional condition when evaluating the biological impacts of provisioning tourism.
... In The Bahamas, the sex ratio favored females at Cape Eleuthera and South Eleuthera, as in previous studies (Brooks et al. 2013;Talwar et al. 2020), whereas it was more balanced in the Exumas and favored males in Andros. In Bimini, the sex ratio might have favored females because most fishing occurred near a provisioning site where sizebased dominance hierarchies may occur (Brena et al. 2015). Similarly, a female-biased sex ratio was observed at a provisioning site near New Providence (Maljkovic and Côté 2011), whereas it was more balanced around the whole of New Providence in this study. ...
Article
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The Caribbean reef shark (Carcharhinus perezi) is an economically important species in The Bahamas, where it is protected from fishing and is a mainstay for the shark dive tourism industry. Significant declines in abundance are suspected throughout much of its range, making the study of its life history and spatial ecology important for effective fisheries management and conservation planning. We used tag-recapture data collected in The Bahamas between 2008 and 2020 to investigate the species’ linear movements, population characteristics, life history, and growth. Sharks moved little between tag and recapture events (range: 0 to 8 km) despite multiple years at liberty for many sharks (range: 2 days to 7.1 years). We found no evidence of seasonal migration. We used a combined-sex von Bertalanffy growth function to estimate an asymptotic mean length at age (TL∞) of 205.8 cm total length and a growth coefficient (k) of 0.06. Theoretical maximum longevity was 43.3 to 57.8 years. Median male length at maturity (L50) was 148.9 cm total length (95% CI: 146.1–151.5 cm), which likely occurs around 14.8 years of age. Our results indicate slower growth of the Caribbean reef shark in The Bahamas than previously estimated in Venezuela. Our results suggest the Caribbean reef shark may be more vulnerable to overfishing and extirpation at the northern extent of its range than previously considered and that large no-take areas may be an effective conservation tool for this species.
... Wildlife provisioning also creates unprecedented opportunities for scientific data collection, aggregating animals that are difficult to study without baiting due to their low density, solitary behavior, or pelagic environment (Bègue et al., 2020;Brena et al., 2015Brena et al., ,2018Gallagher & Hammerschlag, 2011;Meyer et al., 2009). Flourishing shark and ray watching also promotes the development of participatory science, involving tourists in the production of scientific research and raising their awareness on elasmobranch conservation (Gallagher et al., 2015;Mieras et al., 2017;Ward-Paige et al., 2020). ...
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The tourism activities linked to artificial provisioning of blacktip reef sharks (Carcharhinus melanopterus) and pink whiprays (Pateobatis fai) on a specific site in French Polynesia were suddenly and completely stopped due to a COVID-19 lockdown that lasted 6 weeks from March 20 until April 30, 2020. Using both drone footage and underwater counting, we were able to track the abundance of those two species before, during, and after reopening and thus investigate the impact of provisioning on wild shark populations. The absence of any stimulus during this long period resulted in almost total desertion of the site by the elasmobranchs. However, 1 day prior to reopening, some individuals of both species positively reacted to the single acoustic stimulus of an engine boat, showing the resilience of conditioning, and some elasmobranchs reacted to acoustic and olfactive stimuli linked to the provisioning practice from the first day after reopening. During the first 2 weeks after reopening, the abundance of both species remained at reduced levels comparable to those observed between 2008 and 2010 for sharks; i.e., around 9 animals in the presence of local tourists. Pre-lockdown abundance levels, reaching approximatively 15 individuals for sharks and 10 for rays, were considered restored 1 and 2 months after reopening for blacktip reef sharks and pink whiprays, respectively. These findings improve our capacity to better understand the potential effects of artificial provisioning tourism on the abundance of elasmobranchs by showing that conditioning is resilient for several weeks, suggesting that intermittent interruption of elasmobranchs feeding would not really help to decrease its impact on animal welfare.
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Marine wildlife tourism is increasing in popularity, with operations targeting a wide range of taxa globally. While previous studies have mostly focused on assessing the effects of provisioning from tourism on focal species, non-focal species that unintentionally feed on supplemental food sources have largely been overlooked. This study improves our understanding of the effects of shark-cage-diving tourism on the movements and behaviours of a non-focal pelagic fish. We used acoustic tracking to determine the effects of shark-cage-diving tourism on the residency and space use of 17 yellowtail kingfish Seriola lalandi at the Neptune Islands, South Australia. We revealed that while cage-diving did not affect the overall or weekly residency and space use of kingfish, daily time spent at the islands and location of kingfish was influenced by the presence of operators. Acoustic attractant did not affect kingfish behaviours, but operators using food-based attractants increased the average time spent at the Neptune Islands by ~27% (from 230.6 ± 6.8 to 293.8 ± 5.5 min). Kingfish were also observed closer to operators using food-based attractants (217 ± 4.82 m from vessel) compared to an acoustic attractant (412 ± 29.5 m from vessel). Our findings identify changes in the daily behaviour of kingfish at the Neptune Islands as a result of food-based attractants from shark-cage-diving, which demonstrates that non-focal large pelagic species can be affected by shark-diving tourism. These effects may lead to long-term effects on the physiological condition and energetic responses of these individuals.
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Shark depredation, the full or partial removal of a hooked fish by a shark before it is landed, is anecdotally increasing in the United States. Perceptions of depredation by anglers and fishing guides may influence their behavior and have cascading effects on sharks and recreational fisheries. However, to date, these perceptions have not been broadly quantified. To better understand how anglers and guides respond to shark depredation in recreational fisheries, we used an online survey open to saltwater anglers in North America, distributed electronically via social media and online platforms. Of the 541 respondents, 77% had experienced depredation in nearshore and pelagic fisheries in the last five years, with depredation more commonly reported in the southeastern United States. Emotional responses to depredation were significantly different between anglers and guides, with the latter feeling more intense negative emotions. Behavioral changes in response to depredation, such as targeting and harvesting sharks, were driven largely by negative emotional responses and perceptions of sharks as threats to target species, while changes to protect target species varied with positive emotional responses and angler demographics. Guides were predominantly concerned about increased mortality to their target species and loss of trophy fish from the population. In fact, 87% of guides experienced depredation when fishing with clients and overwhelmingly reported that depredation has a negative effect on their livelihood. Overall, these results can be used to help inform strategies to reduce depredation while accounting for the values of stakeholder groups, particularly anglers and those advocating for shark conservation.
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Over the past 4 decades there has been a growing concern for the conservation status of elasmobranchs (sharks and rays). In 2002, the first elasmobranch species were added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Less than 20 yr later, there were 39 species on Appendix II and 5 on Appendix I. Despite growing concern, effective conservation and management remain challenged by a lack of data on population status for many species, human−wildlife interactions, threats to population viability, and the efficacy of conservation approaches. We surveyed 100 of the most frequently published and cited experts on elasmobranchs and, based on ranked responses, prioritized 20 research questions on elasmobranch conservation. To address these questions, we then convened a group of 47 experts from 35 institutions and 12 countries. The 20 questions were organized into the following broad categories: (1) status and threats, (2) population and ecology, and (3) conservation and management. For each section, we sought to synthesize existing knowledge, describe consensus or diverging views, identify gaps, and suggest promising future directions and research priorities. The resulting synthesis aggregates an array of perspectives on emergent research and priority directions for elasmobranch conservation.
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Whale shark (Rhincodon typus) tourism is increasingly popular wherever the species occur, including a fledgling industry on the South Atlantic island of St. Helena. We interviewed 154 people to elicit the social and economic value of whale shark tourism on the island. Additionally, 77 survey participants were queried about their willingness to pay, 32% of those responding indicated that they would be willing to pay at least £10 more, a 20% increase from existing charges. Tourists also supported the concept that the local population should pay less for whale shark snorkel tours. Perceptions among visitors and locals were that the marine environment was well managed on St. Helena and that protecting it was important. Results from this study could help inform St. Helena Government policy and support MWT operators on the island to further develop a sustainable and equitable whale shark tourism industry.
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We investigated spatial use patterns of 77 Caribbean reef sharks (Carcharhinus perezi) at Lighthouse Reef Atoll, Belize over 7 years using residency patterns, kernel density (KD) estimation and network analysis. We found a high degree individual variation in spatial use of the atoll, but there were significant differences in residency and activity space between sexes, with females being overall more resident. Ontogenetic shifts in movement and residency were largely limited to females, as the residency index increased and activity space estimates decreased as females matured, while for males there was no relationship between space use or residency and size. KD analysis revealed many mature females were highly resident to discrete locations, and average activity space of the intermediate-sized sharks was significantly larger than that of the adults, but not the smallest sharks. Markov chain analyses indicated that the southwestern portion of the atoll was the most important movement corridor for all sharks. Both the Blue Hole and Half Moon Caye Natural Monuments provide some protection for larger Caribbean reef sharks; however, a gear ban on longlines on the southwestern forereef between Long Caye and the channel entrance to the Blue Hole would maximize the benefits for all sharks.
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This study examines the frequentation of feeding sites by the pink whipray (Himanturafai) in the lagoon of Moorea (French Polynesia) from April 2005 to March 2006. Six multidirectional hydrophones (VEMCO VR 2) were deployed at 1.5-3 m depth in the North-western area of the Moorea lagoon in which two ray feeding sites were set up for tourism purposes in 1995 and 1999. The study area (1.9 km2) is part of a marine reserve created by the French Polynesian government in October 2004. Fourteen individuals (6 males, 8 females; disc width DW: 73-114 cm) were surgically implanted with individually coded ultrasonic transmitters (VEMCO V8-SC and V13-1H) and presence/absence data were collected for up to 340 days. One ray was never detected. Of the other 13 animals, 7 (4 males, 3 females) showed a maximum presence time on one feeding site (Sand bank) and 4 (1 male, 3 females) favoured the other one (Motu); 2 rays (1 male, 1 female) were detected less than 10% of their total detection time at either of the feeding sites. Both receivers located on the feeding sites detected all 12 individuals during the data collection period and detected a fish an average of 89% of the time daily, whereas the mean daily detection time of the other four receivers-located outside of any feeding area-ranged from 27 to 60%. Only one ray was detected by all 6 receivers in the same day. We observed different frequentation patterns between individuals at each feeding site. Daily bimodal pattern related to feeding time is shown but with no correlation with tourist or feeding numbers. Rays show anticipation on feeding times (one or two hours before feeding hours) but they are conditioned and come on sites with or without feeding activity occurring on the selected day. Even if our study suggests that site fidelity exists for 11 individuals out of 13, the long-term impact of feeding on ray behaviour, reproduction and health still needs to be explored.
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Brunnschweiler & McKenzie (2010; Mar Ecol Prog Ser 420: 283-284) expressed reservations over the findings of Clua et al. (2010; Mar Ecol Prog Ser 414: 257-266), mostly related to the lack of a reference site or a control group in the methodology. In our study, we distinguished between 39 individuals of sicklefin lemon sharks Negaprion acutidens, mainly based on photo-identification. Our study was based on the field-survey approach, with time (a continuous variable) as the source of variation, and thus a control group was not necessary. We provide here additional data that support the notion that abundance of lemon sharks on the provisioning site was increasing, both in their number and fidelity. We maintain our conclusion that sicklefin lemon shark provisioning off Moorea Island can continue, but should be more intensely controlled.
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Many shark populations are experiencing critical declines from overfishing, triggering potentially detrimental cascade effects on marine ecosystems. Silky sharks, Carcharhinus falciformis, have experienced some of the most severe declines, yet little information exists on their behavioural ecology to inform management decisions. In the present study, the movement patterns of a sexually segregated subpopulation of female silky sharks on reefs in the Central Red Sea were investigated using acoustic telemetry to characterise habitat-use and residency patterns. Frequent baiting of sharks at a particular reef-site significantly increased time spent in the vicinity, although no increases in use of other reef areas 5-10 and 50-60 km away were recorded, and regular use of all three reef areas persisted in the absence of bait. Observed residency patterns varied considerably, from being present almost year-round to visiting only intermittently. The sharks spent significantly longer times at study reefs during daylight hours, even within bait-free regions, suggesting the diel bias is normal. This pattern became less distinct nearer the full moon when there is more ambient light. The regular, perennial use of these reefs by mature and near-mature female silky sharks highlights the importance of this habitat in the Red Sea for recruitment into the local shark population.
Book
Winner of Choice Magazine’s Outstanding Academic Title award, January 2005! Sharks and their relatives are the subjects of tremendous interest. The public’s fascination is influenced by their roles in movies and popular literature, while the media races to cover stories of predators endangering helpless humans. The alarming threat to shark populations is also garnering significant publicity and leading to a worldwide increase in conservation initiatives. Finally, technological advances are impacting every area of shark research and revealing incredible secrets about these mysterious animals. These major factors indicate the need for a timely synthesis of the biology of sharks and their relatives. Biology of Sharks and Their Relatives brings together the latest information on the phylogeny, physiology, behavior, and ecology of sharks and their relatives, the skates, rays, and chimaeras. Written by a “Who’s Who” lineup in North American elasmobranch research, this single-source review of elasmobranch fishes presents cohesive and integrated coverage of key topics and discusses technological advances used in modern shark research. The text establishes relationships among the sharks and their relatives that dominate the Chondrichthyes, describes their functions and physiological processes, and examines issues relevant to managing depleted and threatened fisheries. Each of the 19 chapters includes a comprehensive review of the subject with extensive up-to-date citations. This authoritative book provides a synopsis of the current understanding of elasmobranch fishes while identifying gaps in our knowledge to stimulate further study. Its broad coverage and inclusive nature make this an important resource for marine and conservation biologists, fishery scientists, biological oceanographers, zoologists, ecologists, environmental planners, and students.
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Behavioral activities of a colony of 10 bonnethead sharks, Sphyrna t. tiburo, held under semi-natural conditions, were examined over a period of six months. All sharks had attained, or were approaching, sexual maturity. Objectives of the study were to describe species-typical motor patterns and postures, to analyze the diurnality of patrolling activity and to characterize pattern(s) of organization underlying social interactions noted within the colony. Eighteen postures and patterns of movement were described, almost half of them having apparent social relevance. In specific instances, functional significance of a pattern was cautiously given. Patrolling activity appeared to have a diurnal rhythm, with a peak occurring in the late afternoon; smaller individuals were more erratic in their patrolling. Finally, a clear but subtle social organization, based on a straight-line, size-dependent, dominance hierarchy was found. Though position within the hierarchy was not determined by sex, data indicated that all individuals tended to shy away from larger males. Sexual differences in the performance of certain patterns of movement were also established.
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There is a lack of studies on how provisioning may influence shark numbers and behaviour. The effects of long-term provisioning were investigated at a Red Sea reef, where both grey reef shark (Carcharhinus amblyrhynchos) and silky shark (Carcharhinus falciformis) occurred. Initially, grey reef sharks outnumbered silky sharks, but over 6 years, silky shark numbers increased almost 20-fold, whereas grey-reef sightings decreased >90%. Following this, silky-shark sightings also declined considerably (>80%). It is suggested that these declines could relate to local overfishing. Many silky sharks were identified individually through distinctive markings or conventional tagging. Some individual silky sharks were recorded regularly over 2 years or more, but most appeared to be transient visitors. Sighting records indicated that provisioning extended the residency of transient individuals. If visiting silky sharks were drawn from a larger regional population, this would explain both their initial accumulation and why, to begin with, sightings were sustained despite local fishing pressure. Conversely, the site fidelity typical of grey reef sharks would have made them more susceptible to local depletion. Silky sharks were recorded as behaving more boldly when present in greater numbers, but the decline in grey reef sharks appears to be unrelated to the initial increase in the numbers of silky shark.