The Global Economic Impact of Manta Ray Watching Tourism

Abstract

As manta rays face increased threats from targeted and bycatch fisheries, manta ray watching tourism, if managed properly, may present an attractive economic alternative to consumptive use of these species. Both species in the genus Manta (Manta alfredi and Manta birostris) are classified by the International Union for the Conservation of Nature Red List as species Vulnerable to extinction in the wild, and are considered unsustainable as fisheries resources due to their conservative life history characteristics, which considerably reduce their ability to recover population numbers when depleted. Utilising dive operator surveys, Internet research, and a literature review, this study provides the first global estimate of the direct economic impact of manta ray watching tourism and examines the potential socio-economic benefits of non-consumptive manta ray watching operations relative to consumptive use of manta rays as a fishery resource. In the 23 countries in which manta ray watching operations meeting our criteria were identified, we estimated direct revenue to dive operators from manta ray dives and snorkels at over US$73 million annually and direct economic impact, including associated tourism expenditures, of US$140 million annually. Ten countries account for almost 93% of the global revenue estimate, specifically Japan, Indonesia, the Maldives, Mozambique, Thailand, Australia, Mexico, United States, Federated States of Micronesia and Palau. In many of the areas where directed fisheries for manta rays are known to occur, these activities overlap with manta ray tourism sites or the migratory range of the mantas on which these sites depend, and are likely to be unsustainable and detrimental to manta ray watching tourism.

Full text

The Global Economic Impact of Manta Ray Watching
Tourism
Mary P. O’Malley
1,2,3
*, Katie Lee-Brooks
2
, Hannah B. Medd
3
1WildAid, San Francisco, California, United States of America, 2The Manta Trust, Dorchester, United Kingdom, 3Shark Savers, New York, New York, United States of
America
Abstract
As manta rays face increased threats from targeted and bycatch fisheries, manta ray watching tourism, if managed properly,
may present an attractive economic alternative to consumptive use of these species. Both species in the genus Manta
(Manta alfredi and Manta birostris) are classified by the International Union for the Conservation of Nature Red List as
species Vulnerable to extinction in the wild, and are considered unsustainable as fisheries resources due to their
conservative life history characteristics, which considerably reduce their ability to recover population numbers when
depleted. Utilising dive operator surveys, Internet research, and a literature review, this study provides the first global
estimate of the direct economic impact of manta ray watching tourism and examines the potential socio-economic benefits
of non-consumptive manta ray watching operations relative to consumptive use of manta rays as a fishery resource. In the
23 countries in which manta ray watching operations meeting our criteria were identified, we estimated direct revenue to
dive operators from manta ray dives and snorkels at over US$73 million annually and direct economic impact, including
associated tourism expenditures, of US$140 million annually. Ten countries account for almost 93% of the global revenue
estimate, specifically Japan, Indonesia, the Maldives, Mozambique, Thailand, Australia, Mexico, United States, Federated
States of Micronesia and Palau. In many of the areas where directed fisheries for manta rays are known to occur, these
activities overlap with manta ray tourism sites or the migratory range of the mantas on which these sites depend, and are
likely to be unsustainable and detrimental to manta ray watching tourism.
Citation: O’Malley MP, Lee-Brooks K, Medd HB (2013) The Global Economic Impact of Manta Ray Watching Tourism. PLoS ONE 8(5): e65051. doi:10.1371/
journal.pone.0065051
Editor: Simon Thrush, National Institute of Water & Atmospheric Research, New Zealand
Received January 20, 2013; Accepted April 20, 2013; Published May 31, 2013
Copyright: ß2013 O’Malley et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: This study was conducted on a volunteer basis by the three authors. The authors have no support or funding to report.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: maryomalley@mac.com
Introduction
While some conservation biologists assert that the intrinsic value
of nature should provide sufficient ethical justification for its
conservation [1,2,3], environmental policy decision makers are
nevertheless challenged with balancing the needs of numerous
stakeholders amid increasing competition for the use of valuable
and diminishing natural resources [4]. Accordingly, interest in
exploring the benefits of marine recreational activities as non-
consumptive uses of marine resources has grown considerably in
recent years [5–7]. One such non-consumptive option is ecotour-
ism, which can be defined as ‘‘non-consumptive travel with
minimal negative impact that results in increased conservation and
sustainability of natural and sociocultural resources and contrib-
utes to the well-being of local people’’ [8]. Ecotourism in the
marine realm, focused on large marine species (megafauna), can, if
properly managed, potentially offer one solution that provides
long-term, sustainable benefits for both the people and animals
involved [9,10].
Marine species involved in such activities range from whales, to
turtles, to seals, to sharks and rays, and interactions range from
simply observing these animals from a boat or from shore to in
water dive and snorkel experiences [10–15]. These activities have
expanded, becoming increasingly popular since the 1980s
[7,10,16,17], and have been shown to generate significant
economic benefits, both in their own right and to the supporting
businesses within the local economies in which they operate [5,18–
20]. While management of wildlife-centred marine ecotourism
presents its own challenges [21], well-managed models have
proven to generate sustainable livelihoods, potentially providing a
long-term solution for conserving marine megafauna [9,22]. In
some locations, marine ecotourism operations provide significant
financial benefits to communities where few alternative sources of
income exist [5,23]. In many countries, manta ray interactions are
proving to be a highly sought-after experience for divers and
snorkelers [11,24–26], with tourists in the Maldives willing to pay
more for excursions involving mantas than either sharks or turtles
[27], and the number of visitors on tours to see manta rays
surpassing those looking for whale sharks in Western Australia’s
Bateman Bay on Ningaloo Reef [25].
Manta rays belong to the family Mobulidae, a small, but
diverse, family of planktivourous elasmobranchs (2 species within
the genus Manta and 9 species within the genus Mobula, collectively
referred to as ‘‘mobulids’’) with a global distribution across
tropical, subtropical and temperate waters [28]. The genus Manta,
collectively known as manta rays, has recently been re-described
and comprises two recognised species, the reef manta, Manta
alfredi, and the giant manta, Manta birostris, with a third putative
species, Manta cf birostris, believed to occur in the Caribbean Sea,
Gulf of Mexico and the east coast of the United States [29]. M.
birostris is the largest of all the mobulids reaching wingspans
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(referred to as disc width or DW) of over 7 m with the slightly
smaller M. alfredi growing to around 5 m DW [29]. All 11 mobulid
species are harmless to humans, feeding predominantly on
zooplankton, with the Manta species in particular often aggregating
predictably and seasonally to feed, visit cleaning stations or mate
[28]. Their large size, predictable patterns of occurrence, and
perceived friendly and curious nature combined with the relative
safety of interacting with a harmless animal has resulted in the
aforementioned popularity with divers. A detailed study of manta
ray watching in the Maldives estimated tourist expenditures of
US$8.1 m annually for manta ray dives and snorkels [11].
Unfortunately these same characteristics that attract divers and
snorkelers (i.e. predictable nature, propensity for surface feeding,
large size and lack of human avoidance), also make them a
relatively easy target species for fishers in some parts of the world
[28]. Both species of manta ray are considered unsustainable as a
fishery resource due to several elements of their life history such as
late maturity, long lives and exceptionally low fecundity (only one
pup on average every two to three or more years [28,30,31] (G.
Stevens, pers. comm.)). These characteristics not only make them
vulnerable, but also considerably reduce their ability to recover
population numbers when depleted [28,30–34]. Populations in a
number of countries’ waters could be vulnerable to local extinction
[30,31,33–36], and certain monitored subpopulations, including
Gulf of California, Mexico, Indonesia and the Philippines, have
been rapidly depleted [37–39]. While the meat of these animals is
deemed to be of poor quality and is worth little [11,28,35,40], the
gill plates or branchial filaments have become highly sought after
in Asian markets [30,31,35–37] where they are utilised in a tonic
marketed to treat a wide variety of conditions [35]. A 2011 report
on this trade estimated the value of this market at US$11.3 m per
year across all mobulid species [35], with an estimated US$5m
from Manta species alone (S. Heinrichs, pers. comm.). As further
evidence of increased fishery pressure on these species, the FAO
reported that mobulid catches increased from 900 to 3300 tonnes
over the period 2000–2007 [41], with additional unreported
catches likely [37]. While manta rays face other threats, including
bycatch in non-target fisheries, boat strikes, entanglement and
natural predation [28], it is targeted fisheries, which pose the
greatest threat to their survival.
Although legal protection for manta rays has been limited and
not always well enforced, recent measures adopted by two
important international treaties governing the conservation and
trade of threatened species, represent significant progress and
indicate a greatly increased level of awareness of manta rays as
species of international conservation concern. In response to a
proposal by Ecuador, in November 2011, the giant manta was
included on both Appendix I and II of the Convention on
Migratory Species (CMS), a non-binding agreement of 116
governments to ‘‘strive towards strictly protecting’’ the species.
In March 2013, a proposal sponsored by Ecuador, Brazil and
Colombia to include the genus Manta on Appendix II of the
Convention on International Trade in Endangered Species of
Wild Fauna and Flora (CITES) was adopted by the 16
th
Conference of the Parties. The 178 Parties to this binding treaty
will now be required, following the implementation period, to
demonstrate that any exports of manta rays or their parts have
been obtained from legal and sustainable sources. Laws prohib-
iting the catch or trade of one or both Manta species have been
passed in one region (the European Union), six countries
(Ecuador, Mexico, Philippines, Maldives, New Zealand, and
Australia), two US States (Hawaii and Florida), two US Territories
(Guam and the Commonwealth of the Northern Mariana Islands),
the state of Yap, Federated States of Micronesia (FSM), and a few
small Marine Park Areas. These national and local measures only
cover a small proportion of the ranges of these highly migratory
species, however, leaving them vulnerable to a number of
unregulated fisheries.
In light of the threats that exist to these animals, this study aims
to provide the first global estimate of the direct economic impact of
manta ray watching tourism and examine the potential socio-
economic benefits of non-consumptive manta ray watching
operations relative to consumptive use of manta rays as a fishery
resource.
Methods
Study Definitions and Terms
The following definitions refer to the key terms used throughout
this study. Manta ray watching refers to recreational activities
undertaken to view manta rays in the wild, which for this study
includes dives and snorkels at manta ray dive sites, but could also
potentially include observing manta rays from a boat. Manta ray
watching locations are identified as locations where commercial
operations conduct dives and/or snorkels at dive sites where
manta rays are a primary attraction, consistent with criteria used
in other tourism valuation studies (e.g. [10,11]). Locations and
individual dive sites where divers encounter manta rays opportu-
nistically were not considered as manta ray watching activities,
and in keeping with the conservative approach taken by Anderson
et al. [11], visits to manta ray sites during times of year when
manta rays are not seen consistently were also excluded. Direct
economic impact of manta ray watching comprises direct expenditures
(we used gross expenditures as have most of the comparable
economic valuation studies reviewed [5,6,11,12,14,17,19,20,42–
46]) to dive businesses from manta ray dives and snorkels (referred
to hereafter collectively as manta dives) and associated tourism
expenditures, which together provide a conservative estimate of
total tourist expenditures on manta ray watching activities [17].
Associated tourism expenditures include the proportion of tourist
expenses, such as lodging, food and other purchases that can be
attributed to the manta dives [17,19,20,47]. While we only
considered in-country expenditures to estimate direct economic
impact per country, considering the remote locations of most
manta watching locations, it is likely that a large proportion of
manta ray watching tourists travel long distances, and therefore
international travel expenses not included in this analysis may
contribute substantially to economic impact globally.
Data Collection
From August 2011 to August 2012, data on the extent of manta
ray watching and expenditures on manta dives were collected
through primary and published research (Table 1) using a five step
process; (1) literature review to identify existing published and
unpublished estimates of manta dive expenditures, using Google
Scholar, the Manta Trust group on Mendeley.com, and the
resource pages of manta ray research organisations’ websites, (2)
broad level Internet research to identify manta ray watching
locations, conducted through review of manta ray research
organisations’ websites and the IUCN Red List assessments for
both Manta species to identify countries and locations where manta
ray sightings have been documented, (3) location specific Internet
research to identify dive operators and manta dive sites, conducted
with the Google search engine using key word terms: ‘‘location+-
manta ray dives’’, ‘‘location+dive sites+manta’’, ‘‘location+dive
operators’’, ‘‘location+dive shops’’, ‘‘location+live aboard diving’’,
‘‘location+dive resorts’’, (4) questionnaires emailed to dive
operators (File S1) to collect information on manta dive
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expenditures and additional data, and (5) personal interviews with
select operators and area experts to review and verify results for
each location. Depending on the quality of information available
via the different data collection methods in each destination,
subsequent stages of investigation were adapted to allow compa-
rable quality of data to be collected for all countries and locations.
For example where dive operator websites provided very detailed
information, the area specific Internet research was the primary
source of data, with survey responses and personal interviews used
for verification. In other locations, especially those with a small
number of operators or where only limited information was
available online, survey responses and personal interviews were the
primary data sources.
For each manta ray watching location we focused on obtaining
the following details; (1) number of operators offering manta dives,
(2) dive sites considered to be primarily manta dive sites, (3)
seasons that manta rays are present (if seasonal), (4) number of
trips made to manta dive sites per year, (5) maximum number of
divers per trip (capacity) and average occupancy rates, (6) price per
dive, (7) the number or proportion of dives/days lost due to poor
weather or other factors, and (8) operator perceptions with regard
to the importance of manta rays to their business and the local
community and how manta rays rank among sea life that divers
most want to see. As an additional verification step, operators were
also asked if they knew how many other dive operators visited the
manta dive site(s) and if they were able to estimate the total
number of dives to the site(s). Two survey versions were designed,
one for day boat operations and one for live-aboard boats, and
questions were often personalised to reflect any data already
gathered or specific questions that arose through the Internet
research. Most surveys were conducted in English, but for some
areas were translated to the local language.
To estimate associated tourism expenditures, a benefits transfer
approach was employed based on methods used by Hoyt [17] to
estimate direct economic impact of whale watching in locations
where detailed data on associated tourist expenditures were not
available. Hoyt [17] applied ratios of ‘‘total expenditures’’ (whale
watching tickets plus associated tourist expenditures) to ‘‘direct
expenditures’’ (whale watching tickets) based on estimates of total
expenditures from published whale watching studies for whale
watching in comparable locations. Economic valuation literature
supports use of the benefits transfer approach (or ‘‘value transfer’’)
in the absence of primary data (i.e. data collected directly from the
study site), yet stresses the importance of ensuring that values are
transferred across comparable sites or that adjustments are made
to reflect differences in characteristics from the original study site
to the site to which the values are being transferred [47,48]. To
ensure the values transferred would be comparable, we used
expenditure data from studies focused on similar marine tourism
activities, mainly shark diving or whale watching, and transferred
values from the same countries (and regions within the country
where available) or, in a few cases, to countries with similar
tourism industry characteristics. Our study collected country
specific data on dive tourist expenditures from one country
tourism authority report [49], 10 published studies on the
economic impact of tourist trips focused on viewing sharks
[6,10,12,18,19,42–44,46,50], and one study on the economic
impact of whale watching tourism [20]. From each of these
studies, we extracted average total expenditure per trip (and/or
per day) and average expenditure on dives/whale watching tickets
for each location analysed.
Data Analysis
Depending on the amount and quality of data collected for each
location, two methods were employed to estimate manta dive
expenditures; Analysis 1- sum of the estimated annual manta dive
expenditure values for each operator in the area [17,20] and
Analysis 2- estimate based on the total number of boats and divers
visiting the manta dive site(s) from dive operator surveys and
interviews, adapted from Anderson et al. [11]. The first calculation
method was used for all areas for which we were able to collect
sufficient data to calculate individual estimates for each operator.
Analysis 1 used two formulas, one for day boat dive operations
(manta dives per week 6weeks per season 6average price per
dive 6average number of guests per dive) and one for live-aboard
dive operations (cost per trip/number of dives per trip = cost per
dive; cost per dive 6number of manta dives per trip 6average
number of divers per trip 6number of trips per season). Analysis 2
used the following formula, and averaged the results when input
from more than one operator was available: Number of boat visits
to the manta dive site(s) per week (number of boats 6visits per
week) 6Average number of guests per boat 6Number of weeks in
the season = Estimated manta ray dive revenue per season. For
both methods any time lost due to poor weather conditions or
other factors was factored in to ensure that expenditures were not
over estimated.
Table 1. Data Collection: Details collected and sources.
Details Internet research Operator surveys Other sources*
Manta watching tourism locations x x
Number of operators offering manta dives x x x
Dive sites considered to be primarily manta dive sites x x x
Seasons that manta rays are present (if seasonal) x x x
Number of trips made to manta dive sites per year x x x
Maximum number of divers per manta dive trip x
Average number of divers per manta dive trip x x
Average number of divers visiting manta sites x x
Price per manta dive x x x
Number or proportion of dives/days lost due to poor weather or other factors x x
Operator perception questions x
*Other sources include manta ray researchers and dive travel booking agents.
doi:10.1371/journal.pone.0065051.t001
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Analysis of raw data and/or estimates of manta dive expendi-
tures provided by local researchers employed the same or more
precise methods. The Yap estimate was based on actual data from
the largest operator plus his estimate for the other operators (B.
Acker, pers. comm.), and the data source for the W. Australia
estimate was government figures for the actual number of dives at
the manta ray site multiplied by the average cost per dive trip,
which was relatively constant across operators (F. McGregor, pers.
comm.). Researchers in Kona, Hawaii collected actual manta dive
expenditure data through a survey process, involving a phone call
or personal visit to every manta ray dive operator in the area (J.
McLaughlin, pers. comm.), and the Japan revenue figure was
obtained by summing estimates provided by a local expert of the
number of boats, dives and snorkels visiting each of the manta ray
dive sites for every day of the year. The expert providing these
estimates (T. Ito) has been diving these sites almost daily for the
past 30 years (T. Kashiwagi, pers. comm.).
To calculate estimates of direct economic impact including
associated tourism expenditures, we determined ratios from the
reviewed literature that would best represent average local
expenditures by manta ray watching tourists compared with their
average expenditures on manta dives. We applied these ratios to
the manta dive expenditure figures to estimate the direct economic
impact of manta ray watching for each country. For example,
Vianna et al. [50] provided details on average dive tourist
expenditures for diving focused trips in Palau of $2,081 per trip,
and expenditure on dives of $749 per trip, resulting in a ratio of
2.78:1, that is $2.78 being spent across all trip expenditures for
every dollar spent directly on diving. Applying this ratio to the
expenditures on manta dives in Palau from our study, we were
able to estimate the direct economic impact of manta ray watching
for Palau. Since data on diver expenditures were not available for
every manta ray watching location, we calculated ratios for most
countries using total daily expenditure for whale watchers from
O’Connor et al. [20] and modified these figures to account for the
higher costs of manta dive trips compared with whale watching
trips. For example, in Mozambique, the average daily cost of
whale watching per participant was $58 for the whale watching
ticket plus $85 in associated expenditures for a total direct
economic impact of $143 per participant per whale watching day,
a ratio of 2.46:1. Modifying these figures to account for the higher
cost of manta dives, the total direct economic impact comes to
$203 ($118 cost of manta dives+$85 associated expenditures) per
manta ray watching day and a ratio of 1.71:1 ($203/$118).
In order to verify that ‘‘our methods were robust and our
estimates plausible as compared with other similar studies’’ [51],
we reviewed 26 published studies and reports estimating the
economic value of marine based tourism activities, most of which
focused on marine megafauna viewing operations [5–7,10–
12,14,17–20,42–47,49–57], and checked results by comparing
estimates and important data points obtained from multiple
sources. As an additional verification step, we compared estimates
obtained from both methods for 4 locations (Palau; Madagascar;
Bora Bora, Fr. Polynesia; Yap, FSM) and checked data points
from our estimates against official figures where available (Palau
[5,50,58]; Raja Ampat, Indonesia [59]; Similan-Surin Islands,
Thailand [60]; FSM [61]). Finally, all values have been converted
into US$for consistency using current exchange rates from www.
xe.com.
Results
From the literature review, we identified a single peer-reviewed
published estimate on manta ray watching in the Maldives [11].
Manta researchers and local experts provided estimates of manta
ray watching dives and expenditures or sufficient details to enable
us to calculate estimates for Bateman Bay, Western Australia (F.
McGregor), Yap, FSM (B. Acker), Yaeyama Islands, Japan (T.
Kashiwagi, T. Ito) and Kona, Hawaii, United States (Manta
Pacific Research Foundation). Data and estimates for all other
locations were obtained from Internet research and dive operator
surveys.
Extent of Manta Ray Watching Tourism
This study identified and investigated operations in 31 countries
where manta dives were found to take place. Of these countries,
25 met our criteria to be eligible for estimation of manta dive
expenditures, and of these, we were able to make or locate
estimates for 23. In five of the six countries excluded from analysis
(Egypt, South Africa, Sri Lanka, New Zealand and Tonga), despite
the fact that manta rays were seasonally encountered and were
considered to be an important motivation for a proportion of
clients selecting these locations, no primarily manta dive sites had
been established and manta rays were not seen with enough
regularity to enable dive operations to market manta ray specific
dives. In the case of Sri Lanka, the political history of the country
has meant that dive tourism is at present only an emerging
industry, and while no cleaning stations or other sites where manta
rays can be encountered reliably have yet been identified, efforts to
locate such sites were reported to be underway. In the Cook
Islands, the area where manta rays aggregate, Suwarro Bay, is only
accessible currently by private yacht and no commercial dive
tourism has been established to date. In Tanzania, Internet
research confirms manta ray watching tourism, but we were
unable to collect sufficient data to make an expenditure estimate.
In two emerging manta ray watching locations, Laje de Santos in
Brazil and Isla de la Plata in Ecuador, socio-economic studies are
underway by local researchers, but expenditure estimates are not
yet available.
This study showed manta ray watching tourism to be widely
distributed, present across 6 continents and numerous island
nations, specifically occurring at approximately 200 different
identified manta dive sites (Figure 1). Of the 23 countries
examined, we estimated over one million manta ray dives and
snorkels per year (Table 2, Table S1). Through our Internet
research and surveys, we identified 386 operators that take divers
and snorkelers to manta sites in these countries, studied the
websites of 319 of these operators (82.6%), and sent surveys to 244
(63.2%). Ninety-four of the surveys were completed and returned
(39% response rate). In addition to providing data on their
operations, the dive operators who responded were frequently very
helpful with reporting additional operators we had not located
through web research and filling in gaps in data.
Direct Expenditures on Manta Dives
This study estimated direct expenditures on manta dives in the
23 countries analysed at over US$73 million annually, with ten
countries accounting for almost 93% of the global expenditure
estimate, specifically Japan, Indonesia, Maldives, Mozambique,
Thailand, Australia, Mexico, United States, Federated States of
Micronesia and Palau (Table 2, Table S1). Estimates from Japan
alone accounted for over 15% of the total estimate with manta
dive expenditures in this country estimated at $11.4 million
generated from 3 dive locations. In Indonesia expenditures of over
$10.6 million were estimated from 11 sites in four key locations,
and in contrast Anderson et al. [11] estimated expenditures of $8.1
million from 91 sites in 12 atolls in the Maldives.
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Direct Economic Impact of Manta Ray Tourism
Direct economic impact of manta ray watching tourism was
estimated at $140 million annually (Table 3, Table S2). Analysis of
the expenditure data from the dive studies and country report
from 6 countries resulted ratios ranging from 1.676to 3.436and
a median value of 2.006to 2.466. These sources provided trip
expenditure data for 7 of the 23 manta ray watching countries
(Australia, Fiji, French Polynesia, Palau and Thailand, including
Myanmar and India, as manta dive trips to these countries
originate in Thailand with Thai operators), values from O’Connor
et al. [20] were used to calculate ratios for an additional 13
countries (Costa Rica, Ecuador, FSM, Indonesia, Japan, Mada-
gascar, Maldives, Mexico, Mozambique, New Caledonia, Philip-
pines, Sudan (based on Egypt as these trips originate in Egypt with
Egyptian operators) and United States), and we applied ratios from
countries with similar tourism characteristics for the remaining 3
countries (Kiribati, Papua New Guinea, Solomon Islands). The
ratios calculated from the whale watching studies (and adjusted for
manta dive costs) ranged from 1.426to 3.316with a median
value of 1.846to 1.916, indicating that associated expenditures
related to diving and whale watching appear to be comparable.
Verification of Results
Our verification measures showed that our results were
comparable across the techniques we used and to the official data
available. In Palau, for example, we compared manta ray dive
expenditure results from summing individual operator estimates
(Analysis 1) to two calculations from estimates of total number of
boats and divers provided by a local researcher and one of the dive
operators (Analysis 2). These three estimates were comparable
with only slight variations (Researcher: $2.44 m; Dive Operator:
$2.71 m; Surveys: $2.45 m). In Yap, one operator completed our
dive survey in addition to supplying his own estimate for all of
Yap, with the two resulting estimates differing by only 1%. Where
available, we also checked data and estimates against official
sources. For Raja Ampat, we compared the number of divers from
Raja Ampat 2011 entrance fee records (7,667) [59] to our estimate
of the total number of divers (6,472), and found only an 18%
variance in the two numbers. For Palau, we also compared this
study’s estimated number of divers to published data [5,50,58]. In
this case, our calculation yielded an estimate of 39,280 divers as
compared to the average number of divers from 2007–9 of 40,976
from Vianna et al. [5,50] and 55,619 divers in 2011 from Palau
Visitors Bureau data (assuming 51% of total visitors are divers per
Vianna et al. [5,50]), indicating that both of these estimates were
conservative.
Dive Operator Survey Responses
Operator responses (N = 94) gave valuable insights into the
perceived value of manta rays to their businesses and local
communities and the motivation of tourists who chose to
participate in these activities (Table 4). All dive operators
responding to our survey ranked manta rays as one of the top
five attractions for divers with 87% (N = 82) ranking them in the
top 3 and 29% (N = 27) ranking manta rays as the number one
attraction for divers. One international live aboard dive company
with operations in top dive destinations throughout Asia and the
Pacific reported that across all locations customer requests for
manta rays were second only to whale sharks (S. Erbe, pers.
comm.). All of the operators surveyed perceived manta rays to be
important to their business and to the local community, and many
added that customers frequently ask about manta rays and
consider the opportunity to see them as important in their decision
to book a dive trip. One operator from Raja Ampat, Indonesia
reported that telling potential guests about the nearby manta ray
cleaning station is a ‘‘clincher’’ to the guest confirming a trip (M.
Miners, pers. comm.). In Indonesia, because manta rays are often
sighted during low tourism season, operators in Bali and Komodo
described manta rays as ‘‘vital to keeping the business going’’
during otherwise slow times (L. Harding pers. comm., B.
Pilkington-Vincett pers. comm.). Fishermen and local hotels on
Nusa Lembongan (Bali) have also been able to supplement their
Figure 1. Global distribution and direct economic impact (DEI) of manta watching tourism. Direct economic impact comprises estimated
tourist expenditures on manta ray dives and associated expenditures, such as lodging, food and local transportation, which can be attributed to
manta ray diving.
doi:10.1371/journal.pone.0065051.g001
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income by taking snorkelers to see manta rays (C. Guillevic, pers.
comm.). A dive operator, who runs trips to the Revillagigedos
Islands in Mexico, stated that while 100% of the dives on these
trips are not ‘‘manta dives’’, without manta rays, they would have
no business at this destination (M. Lever, pers. comm.).
Of the 94 responses received, 70 (74.5%) provided additional
comments in response to the following general request: ‘‘Please
provide any other comments you’d like to add that might be helpful with
assessing the value of manta rays to your business and to the local community
overall’’. Fifty comments (71.4%) reiterated the importance of
mantas to operators’ businesses and the high level of interest in
manta encounters expressed by clients, and reported participation
in local conservation efforts. Sixteen of the comments (22.9%)
reported manta fishing (legal and illegal) in the vicinity of manta
dive sites, perceived declines in manta sightings, and perceived
negative impact to their business from decreased manta encoun-
ters. Specifically, operators from Indonesia (3) and the Philippines
(2) reported seeing manta rays in local fish markets, while
operators from Mozambique (3) reported targeting of manta rays
near manta sites (even ‘‘on the house reef’’), and operators from
Thailand (1) and Mexico (2) reported witnessing illegal fishing of
manta rays near manta dive sites in Mu Koh Similan National
Marine Park in Thailand and in two locations in Mexico, where
manta rays are legally protected. The one dive operator in Kiribati
reported devastating declines in the local manta ray population as
a result of bycatch from gill nets targeting other species placed in a
channel frequented by mantas. Finally, four comments (5.7%)
expressed concern about possible negative impacts of overcrowd-
ing at dive sites and some operators’ lack of compliance with
established guidelines. Because these comments were not submit-
ted in response to standard questions, they do not provide a
scientific measure, but do represent issues the operators perceived
to be important to assessing the value of manta rays to their
business and the local community.
Discussion
Direct Economic Impact of Manta Ray Watching Tourism
Direct economic impact estimates from this study confirm that
manta ray watching tourism generates significant economic
benefits in the countries where it is based. These estimates are
likely to be conservative in that they only take into account the
number of manta dives as a percentage of total dives per dive trip
and dive operator surveys confirmed that manta rays were an
Table 2. Manta Ray Watching Tourism Extent and Dive Expenditure Estimates (US$).
Country
Number of Manta
Dive Sites
Estimated Total Annual
Manta Dives
Estimated Total Annual
Expenditure (US$) Sources
Japan 3 145,158 $11,400,103 T. Kashawagi, pers. comm.
Indonesia 11 139,594 $10,655,022 Internet and Surveys
Maldives 91 157,000 $8,100,000 Anderson et al., 2011
Mozambique 18 129,102 $7,640,351 Internet and Surveys
Thailand 3 121,767 $7,418,750 Internet and Surveys
Australia 14 75,393 $6,529,435 Internet, Surveys & F.McGregor, pers.
comm.
Mexico 4 40,680 $5,084,600 Internet and Surveys
United States 3 50,912 $4,661,938 Manta Pacific Research Foundation, pers.
comm.
Federated States of Micronesia 6 67,872 $4,091,520 B. Acker, pers. comm.
Palau 2 35,390 $2,455,108 Internet and Surveys
French Polynesia 3 17,550 $1,367,625 Internet and Surveys
Philippines 8 18,463 $863,479 Internet and Surveys
Ecuador* 1 2,557 $726,126 Internet and Surveys
Fiji 5 14,967 $630,148 Internet and Surveys
New Caledonia 2 5,100 $524,988 Internet and Surveys
Solomon Islands 3 2,908 $319,332 Internet and Surveys
Madagascar 1 5,426 $206,498 Internet and Surveys
India 2 979 $198,890 Internet and Surveys
Papua New Guinea 2 2,012 $175,561 Internet and Surveys
Myanmar 3 2,158 $157,606 Internet and Surveys
Costa Rica 2 2,184 $109,200 Internet and Surveys
Kiribati 2 350 $17,500 Internet and Surveys
Sudan 1 181 $13,506 Internet and Surveys
TOTAL 190 1,037,703 $73,347,286
*Ecuador has a second manta dive site in Isla de la Plata, but dive expenditures for this site are not included in the Ecuador estimate.
doi:10.1371/journal.pone.0065051.t002
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important factor in participants’ decision making and the only
reason or the overriding reason in several top manta locations
(Revillagigedos Islands, Mexico; Christmas Island, Kiribati; Yap
and Pohnpei, Federated States of Micronesia; and Sangalaki,
Indonesia).
Our research also suggests that manta ray watching provides
additional economic benefits, which are not as easily quantified.
For example, indirect economic impacts, ‘‘economic multipliers’’,
are the ripple effects tourism businesses generate throughout a
local economy from purchasing goods and services and employing
people, who in turn spend their wages to purchase goods and
services in the community [14,47,62]. In Gansbaai, a popular
shark viewing destination in South Africa, local retailers and other
service businesses reported that tourists account for approximately
Table 3. Direct Economic Impact of Manta Ray Watching Tourism.
Country
Manta Dive Expenditure
Estimate (US$) Trip Expenditure : Dive Expenditure Direct Economic Impact Estimate
Japan $11,400,103 1.56 $17,784,161
Indonesia $10,655,022 1.42 $15,130,131
Maldives $8,100,000 1.91 $15,471,000
Mozambique $7,640,351 1.71 $13,065,000
Thailand $7,418,750 1.67 $12,389,313
Australia $6,529,435 2.23 $14,560,640
Mexico $5,084,600 2.01 $10,220,046
USA $4,661,938 3.31 $15,431,015
FSM $4,091,520 1.92 $7,855,718
Palau $2,455,108 2.78 $6,825,200
Fr. Polynesia $1,367,625 2.71 $3,706,264
Philippines $863,479 1.64 $1,416,106
Ecuador $726,126 2.56 $2,009,411
Fiji $630,148 2.52 $1,587,973
New Caledonia $524,988 2.21 $1,160,223
Solomon Islands $319,332 1.92 $613,117
Madagascar $206,498 1.84 $379,956
India $198,890 1.67 $332,146
Papua New Guinea $175,561 1.92 $337,077
Myanmar $157,606 1.67 $263,202
Costa Rica $109,200 2.50 $273,000
Kiribati $17,500 1.92 $33,600
Sudan $13,506 1.69 $22,825
Totals $73,347,286 $140,716,597
doi:10.1371/journal.pone.0065051.t003
Table 4. Responses to Survey Questions on Dive Operator Perception Questions.
Number of Responses Percentage of Respondents
1. Importance of manta rays to business and local communities (n = 84)
Yes 84 100%
No 00%
2. Manta rays’ rank among sea life that divers most want to see (n = 94)
Top 1 27 28.7%
Top 3 55 58.5%
Top 5 12 12.8%
Total respondents ranking mantas in top 5 94 100%
doi:10.1371/journal.pone.0065051.t004
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50% of their annual sales, thus providing significant economic
benefits and jobs to businesses ranging from petrol stations to
grocery stores to agricultural production [46]. Stoeckl et al. [51]
notes that direct economic impact estimates for small regional
economies can be viewed as estimates of total economic impact
that are biased downwards by up to 25%. The marketing value of
manta rays may also be considerable, as evidenced by the manta
ray photos featured prominently on operator websites in all of the
manta ray watching tourism areas included in this study. Even
many areas that were excluded due to inconsistent manta ray
sightings advertised the possibility of manta ray encounters,
demonstrating the perceived value to dive businesses of even
limited opportunities for manta ray encounters. In addition, the
future growth potential for this industry could be substantial, as
some of the most popular sites for viewing marine megafauna have
only been discovered in recent years [56,63], and our research
identified locations in India, Sri Lanka, Indonesia, the Cook
Islands, Marshall Islands and Tonga where manta rays are
encountered, but tourism operations and infrastructure are still
very limited or manta dives sites have not yet been identified.
Potential Negative Impacts from Manta Ray Watching
Tourism
Four of the operators surveyed reported concern about
overcrowding at some manta sites, fearing possible negative
impacts to the manta rays’ behaviour, and one also noted that
manta ray sightings had decreased at very crowded sites. While
some studies on marine megafauna tourism have suggested that
improperly managed tourism might have negative implications for
these animals [11,21,64], the results from studies that have
attempted to quantify the effects of disturbance due to human
interactions, have not yielded conclusive results [21,64,65]. In
addition, much discussion surrounds the understanding of the
terms involved in qualifying disruptive behaviour or harassment of
animals, with people imposing their own values when interpreting
such terms [66]. Further, in light of the substantial economic and
conservation benefits attributed to marine megafauna ecotourism
[10,20,52,67], Hammerschlag et al. [68] recommend that sensi-
tivities to disturbance be examined on a species by species basis in
order to develop best practices for ecotourism most applicable to
each species. In the Maldives studies have been carried out
specifically to gain a better understanding of human-manta
interactions and reactions, and to date disturbance to these
animals appears to be minimal (Manta Trust, unpublished data).
The findings from these studies will be used to inform a
scientifically sound code of conduct for these species (G. Stevens,
pers. comm.). Such guidelines, combined with educational and
interpretive briefings, have been demonstrated to minimize
tourists’ impacts on the environment and marine life while also
enhancing their enjoyment of the experience [21,69], and ‘user
pays’ policies can be employed to cover the costs of these programs
[9]. Deployment of such models in all manta ray tourism locations
could ensure the welfare of the animals as well as continued
customer satisfaction and business success.
Direct Economic Impact of Manta Tourism Relative to
Fisheries and Trade
It is increasingly evident that large charismatic marine animals
are more valuable as long-term sources of tourism revenue than as
onetime revenues to fisheries [5,6,10,11,26,33,45,67]. For manta
rays this study’s global estimate of direct economic impact of $140
million per year from tourism greatly exceeds the trade in manta
ray gill plates estimated at $5 million per year (S. Heinrichs, pers.
comm.; total trade in mobulid gill plates estimated at US$11
million [35]). Indonesia ranked as one of the top 3 destinations in
the world for manta ray watching, with estimates of manta dive
expenditures close to US$10.7 million and direct economic impact
over US$15 million per year. Yet fishery surveys conducted in
Indonesia over the past ten years provide evidence of unsustain-
able mobulid fisheries and associated population declines [35–37]
(Setiasih et al. unpublished data), which may threaten these
valuable manta ray watching tourism businesses. Based on analysis
of landings data collected through surveys of ports in Lombok,
Pelabuhanratu, Cilacap, Kedonganan, Lombok and Lamakera
[35,37] (Setiasih et al. unpublished data), the total annual income
from manta ray fisheries in Indonesia is estimated at approxi-
mately US$442,000 (estimated 94% from gill plates for export; 6%
from other products sold locally), less than 3% of the annual
expenditures on manta ray watching tourism (M. O’Malley
unpublished data). Additionally the tourism revenue figures
estimated in this study only account for existing manta ray
watching operations, without considering potential for develop-
ment of these activities in other parts of the country. These figures
also do not account for consumer surplus, though dive operator
surveys in this study suggest that consumer surplus clearly exists for
manta rays as an input to a recreational experience. Overlooking
this important aspect of economic value may greatly understate
the comparative benefit of non-consumptive use, since competitive
conditions likely eliminate any producer surplus in consumptive
use (D. Letson, pers. comm.).
As another means of demonstrating the disparity between the
revenue iconic species can generate for tourism relative to
consumptive use, published studies have used various methods to
calculate the estimated lifetime tourism value per animal
[5,6,11,26,63,64]. However, these comparisons have been criti-
cized as being simplistic [11], and might potentially be construed
as weakening rather than strengthening the case for conservation,
since a smaller number of animals yields a higher per animal value
(70). Nevertheless per animal estimates can provide an effective
means of communicating the worth of these animals to tourism
compared with a fishery, which can be easily understood by policy
makers and the general public [6]. Norman and Catlin [63]
estimated the lifetime tourism value per whale shark in Australia at
US$282,000, while the average landed price for a whale shark in
Taiwan has been reported as US$3,500 [71]. This estimate was
derived by dividing the estimated value of the whale shark tourism
industry in Ningaloo Reef, Western Australia, the longest
established whale shark watching destination, by the number of
whale sharks associated with the site, and then multiplying by the
generation time for this species, which approximates the number
of years it takes for an animal to replace itself in the population.
Applying this method to manta rays in Yap, which is likely to be
the longest established manta ray watching tourism destination,
based around a stable population of approximately 100 reef manta
rays [72], and the estimated generation time for manta rays of 25
years [30,31], the lifetime value of each manta in Yap can be
estimated at approximately US$1.9 million ($7.68 m/100625).
Anderson et al. [11] used a more conservative method to estimate
individual values for a core group of manta rays that frequent a
popular manta dive site in the Maldives at US$100,000 per animal
over a 20-year period. Despite the varied results obtained from
different calculation methods and different locations, both
demonstrate the stark contrast to the average price for a whole
manta ray (2.5 m DW) sold in a fish market in Sri Lanka, which is
reported as US$41 [40], or the approximately US$200 a fishing
crew in Lamakera, Indonesia receives for a large manta ray (5 m
DW) [35].
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Potential Socio-economic Benefits of Manta Ray Tourism
Relative to Manta Ray Fisheries
While the economic impact argument in favour of manta ray
tourism relative to manta ray fisheries is clear, the socio-economic
realities involved with communities shifting from manta ray fishing
to manta ray tourism are more complex. However, potential
negative impacts of manta fisheries on sustainable and more
valuable manta tourism businesses that are important to other
communities, and recent international agreements to protect
manta rays and require strict regulation of trade, highlight the
importance of investigating alternative sources of income for
communities that derive a portion of their income from manta
fisheries and trade. As fishing is a traditional way of life in many
coastal communities, it’s important to note that presenting
ecotourism as an alternative to unsustainable fisheries does not
suggest that tourism replace all fisheries. Ecotourism can be
compatible with these traditions and even help to support
sustainable fisheries, as Vianna et al. [5] demonstrated that local
fishers could earn more from supplying fish to feed shark diving
tourists than from fishing for sharks. However, fishing that targets
the iconic species tourists are coming to see and experience, is not
compatible with ecotourism. For example, Orams [14] found that
substantial tourism revenues from whale watching in Tonga would
be severely impacted if whaling activities were resumed there.
In locations where mantas can be encountered reliably,
ecotourism may provide one alternative to help communities shift
towards more sustainable sources of income. In Lamakera, a small
village in the Nusa Tenggara Timur Province, Indonesia, research
suggests that a seasonal fishery targeting manta and mobula rays
for the gill plate export trade may be the world’s largest manta ray
landing site [35], and contributes significantly to the annual
income of a small number of fishers (Setiasih et al. unpublished
data). Located along an important pelagic corridor, seasonal
migrations of manta and mobula rays and other megafauna highly
valued in marine tourism, including whale sharks and several
cetacean species [73,74,75], could potentially support the devel-
opment of ecotourism in this location (Setiasih et al. unpublished
data). While infrastructure investment would be required and
there would be cultural challenges to overcome, tourism develop-
ment in cooperation with fishing communities has been successful
in Indonesia and other countries, in areas where manta rays and
sharks are now important tourist attractions [22] (A. and M.
Miners, pers. comm). In West Papua Province, Indonesia, manta
rays and sharks are among the top tourist attractions in a 1220
square kilometre conservation zone, which was established
through lease agreements between villages, who own the fishing
rights for the area, and a dive eco-resort, which is built on an
island previously used as a shark finning camp. Locally-hired
rangers, some of whom were formerly engaged in shark finning
and other unsustainable fishing practices, enforce the conservation
zone, and the villages benefit from lease fees, employment
(supporting 80 families from the local villages), the resort’s
purchases of local produce and fish, community projects and skills
training programs, and improved fishing in the waters surrounding
the no-take areas of the conservation zone (A. and M. Miners,
pers. comm.). Recognition of the value and potential of marine
ecotourism and the importance of marine megafauna to this
industry has since led to adoption of legal protection at the Raja
Ampat Regency level for manta and mobula rays, sharks, turtles
and dugongs. Such community level agreements, in which dive
operators and/or non-governmental organisations pay communi-
ties to restrict fishing in designated areas or adhere to agreed upon
sustainable guidelines, can protect valuable species and habitats,
while ensuring broader distribution of tourism benefits throughout
the community, including to those not directly employed by dive
resorts [22]. In the Maldives, even without such agreements, many
fishermen shifted from shark fishing to more sustainable employ-
ment in dive tourism, as evidenced by 19 shark fishing boats on the
Island of Dhangethi in south Ari Atoll in July 1991 and 22 boats
involved in tourism and only 4 involved in shark fishing by August
1998 [45].
While development of manta tourism may not be a feasible
alternative to manta fishing in all areas, measures to curtail these
fisheries should nevertheless be pursued and other economic
alternatives investigated. Most manta fisheries are reported to be
somewhat opportunistic and not primary sources of income to the
fishermen involved [40] (K. Forsberg, pers. comm., S. Heinrichs,
pers. comm.), but offers from foreign traders of relatively large
amounts of money for mobulid gill plates, especially those from
large manta rays, have provided incentive for fishers to
supplement their regular income by targeting manta rays they
encounter during fishing trips [40] (S. Heinrichs, pers. comm.).
However, this income is not likely to be sustainable in the long
term, due to manta rays’ low reproductive capacity, and these
fisheries will soon be required to demonstrate that they are
sustainable and legal to comply with new export requirements,
which may not be possible. In addition, Indonesian fishermen
have reported targeting mobulids in the range of manta tourism
areas in Indonesia and Australia (Setiasih et al. unpublished data),
and dive operator survey responses and published reports suggest
negative impacts to manta tourism operations where manta fishing
activities overlap or are within the migratory range of the mantas
on which the tourism operations depend. Operators reported
targeted fishing and bycatch of manta rays in the vicinity of manta
dive sites and significantly decreased manta ray sightings in
locations in Indonesia, Thailand, the Philippines, Mozambique
and Kiribati. Manta researcher observations and published studies
also suggest large declines in diver sightings of one or both manta
species in areas that overlap with manta fishing activities in
Australia (F. McGregor, pers. comm.), Mozambique [76] and the
Philippines [77].
Potential Sources of Error
Due to the global scope of this study and resource limitations
precluding extensive onsite surveys and data collection in all of the
23 manta watching countries identified, the figures presented in
this study should be considered as estimates. As the first study to
attempt such a global estimate of the direct economic impact of
manta ray watching tourism, however, these estimates are still
valuable to demonstrate the economic importance and potential of
this activity and the benefits of conserving manta rays, even if only
for economic reasons. We recommend further in-depth local
socio-economic studies of manta ray tourism, which would enable
more accurate estimates of economic impacts, including direct
assessment of manta dive participants’ motivations for visiting the
locations and their willingness to pay for the opportunity to see
manta rays, to enable researchers to quantify estimates of
consumer surplus. In locations with manta fisheries, local studies
could also better assess the feasibility of manta tourism as an
alternative to manta fisheries, and investigate other sustainable
alternatives at the community level.
Conclusions
The slow reproductive rate of manta rays and evidence of large
declines associated with directed manta ray fisheries strongly
suggest that revenues from catch and trade are likely to diminish
and disappear over time. On the other hand, the demand for
ecotourism focused on marine megafauna is reported to be
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growing [10,20,52], and the global tourism industry overall
forecasts significant growth over the next twenty years [78].
Tourism is not expected to solve all the complex issues associated
with unsustainable manta ray fisheries and the international trade
in these threatened species, yet development of well managed
manta ray watching tourism may offer a promising alternative in
some of the areas where manta rays are still targeted.
While tourism operations must be managed properly and make
efforts to reduce their ecological footprint, fisheries must do the
same by not targeting species that cannot be fished sustainably,
and taking sensible management measures to ensure that the
species they do target are not depleted. Coastal communities
depend heavily upon their surrounding marine resources and it is
crucial that they strive to manage these resources wisely for
themselves and future generations. For those communities in
areas, which are frequented by manta rays, manta ray watching
tourism can be an important aspect of their marine resource
management plan that, if properly managed, can potentially
provide sustainable benefits for many generations.
Supporting Information
Table S1 Manta Ray Watching Tourism Extent and
Dive Expenditure Estimates. Research results used to
calculate the country totals summarized in Table 2.
(PDF)
Table S2 Direct Economic Impact of Manta Ray
Watching Tourism. Research results used to calculate ratios
of total expenditures to dive only expenditures to produce the
country direct economic impact estimates summarized in Table 3.
(PDF)
File S1 Dive Operator Surveys. Survey questions sent to live
aboard dive operators and land-based dive operators.
(PDF)
Acknowledgments
We thank Manta Pacific Research Foundation, Tom Kashiwagi, Takashi
Ito, Frazer McGregor, Bill Acker, and Ric Parker for providing revenue
estimates and data for this study. We also greatly appreciate the review and
valuable comments and advice from Professor David Letson and Dr.
Simon Pierce. We also thank Briana Rivera, Daniela Morales, Marit
Miners, Becky Pilkington-Vincett, Lydie Couturier and Kathy Townsend
for their assistance with identifying and surveying dive operators. And
finally we are very grateful to all the dive operators who took the time to
respond to our surveys and answer follow up questions.
Author Contributions
Conceived and designed the experiments: MO HM KB. Performed the
experiments: MO HM KB. Analyzed the data: MO HM KB. Wrote the
paper: MO HM KB.
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