Karczmarski, L

TIONGSON, AJC

Marine Biodiversity Records

HKU Scholars Hub

Title The Indo-Pacific bottlenose dolphin (Tursiops aduncus) inTañon Strait, central PhilippinesAuthor(s) TIONGSON, AJC; Karczmarski, LCitation Marine Biodiversity Records, 2016, v. 9, p. 85:1-4Issued Date 2016URL http://hdl.handle.net/10722/235362RightsMarine Biodiversity Records. Copyright © BioMed Central Ltd.;This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 DOI 10.1186/s41200-016-0088-4MARINE RECORD Open AccessThe Indo-Pacific bottlenose dolphin(Tursiops aduncus) in Tañon Strait, centralPhilippinesAngelico Jose C. Tiongson and Leszek Karczmarski*AbstractPrevious sightings of bottlenose dolphins in Tañon Strait, central Philippines, in the late 1980’s to early 1990’s werelimited to the southern section of the strait, in waters <500 m deep, and the species was formerly identified asTursiops truncatus. Photo-identification surveys (n = 117) conducted in 2014 and 2015 in Tañon Strait resulted in 50encounters of Indo-Pacific bottlenose dolphins Tursiops aduncus. No common bottlenose dolphin T. truncatus wasseen. The Indo-Pacific bottlenose dolphin has only recently been confirmed to occur in coastal waters in thePhilippines and thus very little is known of its local distribution and ecology. In Tañon Strait, the species was seenacross a wide range of water depth (4–668 m, x ̅ = 309 m) in groups ranging from 1 to ~60 individuals. We providea photographic verification of this species and first evidence of a seemingly small population in a tropical protectedseascape in the Philippines.Keywords: Indo-Pacific bottlenose dolphin, Tursiops aduncus, Tañon Strait, PhilippinesIntroductionThe Indo-Pacific bottlenose dolphin (Tursiops aduncus,Ehrenberg 1833) occurs throughout warm temperateand tropical coastal waters, usually less than 100 m deep,in the Indian Ocean and western Pacific (Wang andYang 2009). In the Philippines, the species was first con-firmed only recently from a stranding in Luzon(Aragones et al. 2010). Opportunistic sightings by Wangand Yang (2009) suggested that this species may be dis-tributed throughout the Philippine seas in discrete popu-lations in coastal areas. However, actual sighting recordsremain sparse.In the Philippines, first studies of marine mammalsdate back to the late 1980’s and focused primarily onspecies diversity and distribution (Leatherwood et al.1992). Tañon Strait, located between the islands ofNegros and Cebu in the central Philippines (Fig. 1) wasfound to have a considerably high diversity of cetaceans,given its relatively small area (Leatherwood et al. 1992;Dolar et al. 1994, 2006), which has led to the establish-ment of a nationally protected seascape, Tañon Strait* Correspondence: leszek@hku.hkThe Swire Institute of Marine Science, School of Biological Sciences, TheUniversity of Hong Kong, Cape d’Aguilar, Shek O, Hong Kong© 2016 The Author(s). Open Access This articInternational License (http://creativecommonsreproduction in any medium, provided you gthe Creative Commons license, and indicate if(http://creativecommons.org/publicdomain/zeProtected Seascape (TSPS), in 1998. The strait is 220 kmlong and 27 km at its widest, with steep slopes on bothsides that rapidly descend to >500 m deep in the middlesection (Hayasaka et al. 1982). The shallow bathymetricsill in the southern opening of the strait (125 m deep)and the many small islands (Bantayan group of islands)in the shallow northern opening separate the strait fromBohol Sea and Visayan Sea.Bottlenose dolphins have previously been sighted inthe southern section of Tañon Strait, but the speciesidentity remained unclear. Leatherwood et al. (1821)identified them as Tursiops truncatus (Montagu 1821)based on the formerly monospecific genus Tursiops.Dolar et al. (2006) identified them only up to the genuslevel, but subsequently recognised that they were mostlikely T. aduncus (M.L.L. Dolar pers. comm.). Althoughboth Leatherwood et al. (1992) and Dolar et al. (2006)surveyed the entire Tañon Strait, their sightings ofbottlenose dolphins were limited only to the southernsection of the strait, near the opening. A short-termfollow-up study by Callanta (2009) reported a similarpattern. Our recent work (L. Karczmarski and A.J.C.Tiongson, study in progress) confirms the identity of thespecies and indicates its considerably wider distribution.le is distributed under the terms of the Creative Commons Attribution 4.0.org/licenses/by/4.0/), which permits unrestricted use, distribution, andive appropriate credit to the original author(s) and the source, provide a link tochanges were made. The Creative Commons Public Domain Dedication waiverro/1.0/) applies to the data made available in this article, unless otherwise stated.Fig. 1 Map of the Philippines and the Tañon Strait study site (inset) showing the locations of sightings of Indo-Pacific bottlenose dolphins in 2014(black circles) and 2015 (open circles). The gray lines indicate the survey tracks for 2014 and 2015Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 2 of 4Materials and methodsBoat-based photo-identification surveys (n = 117) wereconducted from April through July of both 2014 and2015 with start off points at Dumaguete City onNegros Island and Moalboal on Cebu Island (Fig. 1).Four small boats of similar size were used (8.5–9.8 m,powered with 40 and 75 HP outboard engines), ran-ging from one to three boats at a time, during everygood-weather day (no precipitation and sea state ≤3in Beaufort scale) and following a commonly acceptedfield protocol (similarly as in Karczmarski et al.2005). The northernmost range of surveys were atBarili (10.2310°N, 123.5487°E) on Cebu Island andVallehermoso (10.3102°N, 123.3326°E) on NegrosIsland, while the southernmost range were at Apo Island(9.0607°N, 123.2551°E) off Negros Island and Santander(9.4103°N, 123.3443°E) on Cebu Island (Fig. 1).Each time a dolphin group was sighted, the animalswere slowly approached and their speed and general dir-ection were matched with that of a research vessel tominimise any potential impact caused by the boat pres-ence. Once the dolphins were in a range sufficientlyclose for species identification, the start time and loca-tion of the encounter was recorded using a handheldGarmin 78 s GPS. Group size estimates were made atthe beginning and the end of an encounter, and in regu-lar intervals throughout the encounter. Dolphins’ dorsalfins and their upper body were photographed usinghigh-speed digital cameras fitted with 100–400 mmimage stabilized lenses. At each encounter, a consciousattempt was made to photograph all individuals in thegroup and, whenever possible, capture both sides of thedorsal fin. The unique body marks and notches ondorsal fins were used for individual identification (e.g.Table 1 Water depth associated with sightings of Indo-Pacific bottlenose dolphins in Tañon Strait in 1995 and 2014–2015Source Survey year n Depth range (m) Mean depth (m) SDDolar et al. 2006 1995 3 24–328 141 133~this study 2014– 2015 50 4–668 309 172Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 3 of 4Karczmarski and Cockcroft 1998) and, subsequently, thesoftware program DISCOVERY (Gailey and Karczmarski2012) was used for photo-ID database management.Results and discussionA total of 669 h were spent at sea, during 92 survey daysacross two field seasons. Indo-Pacific bottlenose dol-phins Tursiops aduncus were seen throughout the studyperiod, at all times of the day from dusk to late after-noon, in varying distance from shore ranging from 20 mto 11 km offshore, and throughout a wide range of waterdepth (Table 1). Photo-ID data were obtained during 50encounters. Individual sighting frequencies ranged fromone (n = 21) to ten (n = 1), with the majority of the 121Fig. 2 The Indo-Pacific bottlenose dolphin in Tañon Strait, showing (a) the reand (b) ventral spots around the genital area of a mature femalecatalogued individuals (82 %, n = 99) seen more thanonce. Group sizes ranged from a solitary individual to~60 dolphins, with a mean of 11 and median of 10dolphins per group (±10.5 SD). Groups frequently con-sisted of all age classes, including calves and neonates,although adult-only groups were also seen.Although bottlenose dolphins were known to occur inPhilippine waters (Leatherwood et al. 1992; Dolar et al.1994, 2002, 2006), they were usually identified as T. trun-catus. The similarities between Tursiops truncatus and T.aduncus (Rice 1998) make their identification in the fieldchallenging, especially in areas where they occur sympatri-cally. Our photographic data confirms the species of Tur-siops seen at each of our encounters as T. aduncus (Fig. 2).latively long snout (indicated with arrow) characteristic of the species,Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 4 of 4At present, the Indo-Pacific bottlenose dolphin isnot listed in the Philippines’ Fisheries AdministrativeOrder 208 (FAO 208) of 2001 which sets out the pro-tection of aquatic species, and it is classified as DataDeficient by the regional Red List assessment (Dolaret al. 2012) and the IUCN Red List of ThreatenedSpecies (Hammond et al. 2012). An amendment tothe Philippines’ Fisheries Administrative Order 208that includes T. aduncus is pertinent and urgentlyneeded for the consistency with other protective mea-sures in the Philippines (e.g. Republic Act 8550, 9147,FAO 185/185-1). An appropriate recognition of thespecies is important as it remains little known notonly in the Philippines but across most of its range.Their discontinuous distribution in tropical Philippine wa-ters and apparently small population sizes warrants conser-vation concern, especially in the face of climate change inthe region (Dolar and Sabater 2011). Furthermore,lobomycosis-like disease and other skin disorders haverecently been observed in Tañon Strait (A.J.C. Tiongsonand L. Karczmarski, unpublished data), likely indicative ofthe deteriorating habitat quality.Our preliminary results indicate that the popula-tion of Indo-Pacific bottlenose dolphins in TSPS isnot large, with considerable site fidelity in the area,although ranging further north and into deeper wa-ters than previously thought. Although the species isknown to generally prefer coastal shallow waters,sightings in deeper waters of Tañon Strait are notsurprising because the strait’s bathymetry limits thecoastal shallow waters to a narrow strip and bringsdeep waters close to shore. The presence of calves andneonates indicate that the dolphins are reproducing in thestrait. The Tañon Strait Protected Seascape (TSPS) isunder the National Integrated Protected Area Systems(NIPAS) Act, with a purpose to conserve the biodiversityof the area and implement sustainable development. Thisprovision makes the strait excellently suited for researchinvestigating the bottlenose dolphin population under arapidly changing environment and such study should beencouraged.AcknowledgementsThis work was partially funded through a research grant from Ocean ParkConservation Foundation Hong Kong (OPCFHK, grant no. MM05-1415) andinternal funding of the Cetacean Ecology Lab at the Swire Institute of MarineScience (SWIMS), The University of Hong Kong. Research clearance (No.2014-0000-04) was obtained from the TSPS-Protected Area ManagementBoard. The following people are gratefully acknowledged for their assistanceat various stages of our field work: Stephen C.Y. Chan, Yuen-WaHo, Mark dela Paz, Edna Sabater and a dedicated team of volunteers. We thank JanetEstacion of Silliman University’s Institute of Environmental and Marine Sci-ences for her invaluable help; and Louella Dolar of Tropical Marine Researchfor Conservation (TMRC) for providing access to her earlier data. RaphaelVirchaux and Rudy Poitier are gratefully acknowledged for their support, andthe staff and crew of ‘Dolphin House’ and ‘Easydiving PH’ are thanked fortheir assistance during boat surveys.Authors’ contributionsBoth authors contributed equally to this study. AJCT performed this study aspart of his ongoing postgraduate research. LK designed the project, securedfunding, and supervised the study. Both authors read and approved the finalmanuscript.Competing interestsThe authors declare that they have no competing interests.Received: 20 June 2016 Accepted: 21 June 2016ReferencesAragones LV, Roque MAA, Flores MB, Encomienda RP, Laule GE, Espinos BG,Maniago FE, Diaz GC, Alesna EB, Braun RC. The Philippine marine mammalstrandings from 1998 to 2009: animals in the Philippines in peril? AquatMamm. 2010;36(3):219–33.Callanta LS. Residence patterns and range characteristics of Indo-Pacificbottlenose dolphins (Tursiops aduncus) and other small cetaceans in thesouthern Tañon Strait, Central Visayas, Philippines. MSc thesis. SillimanUniversity, Philippines; 2009Dolar MLL, Sabater ER. Potential impact of climate change on marine mammalbiodiversity in Southeast Asia: a review. Silliman J. 2011;52(1):91–113.Dolar MLL, Leatherwood SJ, Wood CJ, Alava MNR, Hill CL, Aragones LV. Directedfisheries for cetaceans in the Philippines. Report of the International WhalingCommission. 1994;44:439–49.Dolar MLL, Perrin WF, Gaudiano JP, Yaptinchay AASP, Tan JML. Preliminary reporton a small estuarine population of Irrawaddy dolphins Orcaella brevirostris inthe Philippines. The Raffles Bulletin of Zoology Supplement. 2002;10:155–60.Dolar MLL, Perrin WF, Taylor B, Kooyman G, Alava MNR. Distributional ecology ofcetaceans in the central Philippines. J Cetacean Res Manag. 2006;8:93–111.Dolar MLL, Sabater ER, Gaudiano JPA, Bagarinao TU, Sorongon PME, BarcelonaALB, Tagarino AP, Daclan JMO, Santos MD. Tursiops aduncus. In: Alava MNR,Dolar MLL, Sabater ER, Aquino MTR, Santos MD, editors. Red list status ofmarine mammals in the Philippines. Manila: Bureau of Fisheries and AquaticResources-National Fisheries Research and Development Institute;2012. p. 106–9.Gailey G, Karczmarski L. DISCOVERY: A photo-identification data managementsystem for individually recognizable animals. The Swire Institute of MarineScience, The University of Hong Kong; 2012. Available at: http://www.biosch.hku.hk/ecology/staffhp/lk/Discovery/.Hammond PS, Bearzi G, Bjørge A, Forney KA, Karczmarski L, Kasuya T, Perrin WF,Scott MD, Wang JY, Wells RS, Wilson B. Tursiops aduncus. The IUCN Red Listof Threatened Species. Version 2015.2. 2012. Available at: http://www.iucnredlist.org/details/full/41714/0. Accessed 17 Oct 2015.Hayasaka S, Saisho T, Kakinuma Y, Shinomiya A, Oki K, Hamada T, Tanabe K, KanieY, Hattori M, VandeVusse F, Alcala L, Cordero PAJ, Cabrera JJ, Garcia RG. Fieldstudy on the habitat of Nautilus in the environs of Cebu and Negros islands,the Philippines. Memoirs of the Kagoshima University Research Center forthe South Pacific, Occasional Publications. 1982;3(1):67–137.Karczmarski L, Cockcroft VG. Matrix photo-identification technique applied instudies of free-ranging bottlenose and humpback dolphins. Aquat Mamm.1998;24(3):143–7.Karczmarski L, Würsig B, Gailey G, Larson KW, Vanderlip C. Spinner dolphins in aremote Hawaiian atoll: social grouping and population structure. Behav Ecol.2005;16:675–85.Leatherwood S, Dolar MLL, Wood CJ, Aragones LV, Hill CL. Marine mammalspecies confirmed from Philippine waters. Silliman J. 1992;36:65–86.Rice DW. Marine mammals of the world: Systematics and distribution, no. 4.Kansas: Special publications of the Society for Marine Mammals, The Societyfor Marine Mammalogy, Lawrence; 1998. p. 231.Wang JY, Yang SC. Indo-Pacific bottlenose dolphins, Tursiops aduncus. In: PerrinWF, Würsig B, Thewissen C, editors. Encyclopedia of marine mammals.San Diego: Academic; 2009. p. 602–8.

The Indo-Pacific bottlenose dolphin (Tursiops aduncus) in Tañon Strait, central Philippines

Angelico Jose C. Tiongson

Leszek Karczmarski

Springer - Publisher Connector

Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 
DOI 10.1186/s41200-016-0088-4MARINE RECORD Open AccessThe Indo-Pacific bottlenose dolphin
(Tursiops aduncus) in Tañon Strait, central
Philippines
Angelico Jose C. Tiongson and Leszek Karczmarski*Abstract
Previous sightings of bottlenose dolphins in Tañon Strait, central Philippines, in the late 1980’s to early 1990’s were
limited to the southern section of the strait, in waters <500 m deep, and the species was formerly identified as
Tursiops truncatus. Photo-identification surveys (n = 117) conducted in 2014 and 2015 in Tañon Strait resulted in 50
encounters of Indo-Pacific bottlenose dolphins Tursiops aduncus. No common bottlenose dolphin T. truncatus was
seen. The Indo-Pacific bottlenose dolphin has only recently been confirmed to occur in coastal waters in the
Philippines and thus very little is known of its local distribution and ecology. In Tañon Strait, the species was seen
across a wide range of water depth (4–668 m, x ̅ = 309 m) in groups ranging from 1 to ~60 individuals. We provide
a photographic verification of this species and first evidence of a seemingly small population in a tropical protected
seascape in the Philippines.
Keywords: Indo-Pacific bottlenose dolphin, Tursiops aduncus, Tañon Strait, PhilippinesIntroduction
The Indo-Pacific bottlenose dolphin (Tursiops aduncus,
Ehrenberg 1833) occurs throughout warm temperate
and tropical coastal waters, usually less than 100 m deep,
in the Indian Ocean and western Pacific (Wang and
Yang 2009). In the Philippines, the species was first con-
firmed only recently from a stranding in Luzon
(Aragones et al. 2010). Opportunistic sightings by Wang
and Yang (2009) suggested that this species may be dis-
tributed throughout the Philippine seas in discrete popu-
lations in coastal areas. However, actual sighting records
remain sparse.
In the Philippines, first studies of marine mammals
date back to the late 1980’s and focused primarily on
species diversity and distribution (Leatherwood et al.
1992). Tañon Strait, located between the islands of
Negros and Cebu in the central Philippines (Fig. 1) was
found to have a considerably high diversity of cetaceans,
given its relatively small area (Leatherwood et al. 1992;
Dolar et al. 1994, 2006), which has led to the establish-
ment of a nationally protected seascape, Tañon Strait* Correspondence: leszek@hku.hk
The Swire Institute of Marine Science, School of Biological Sciences, The
University of Hong Kong, Cape d’Aguilar, Shek O, Hong Kong
© 2016 The Author(s). Open Access This artic
International License (http://creativecommons
reproduction in any medium, provided you g
the Creative Commons license, and indicate if
(http://creativecommons.org/publicdomain/zeProtected Seascape (TSPS), in 1998. The strait is 220 km
long and 27 km at its widest, with steep slopes on both
sides that rapidly descend to >500 m deep in the middle
section (Hayasaka et al. 1982). The shallow bathymetric
sill in the southern opening of the strait (125 m deep)
and the many small islands (Bantayan group of islands)
in the shallow northern opening separate the strait from
Bohol Sea and Visayan Sea.
Bottlenose dolphins have previously been sighted in
the southern section of Tañon Strait, but the species
identity remained unclear. Leatherwood et al. (1821)
identified them as Tursiops truncatus (Montagu 1821)
based on the formerly monospecific genus Tursiops.
Dolar et al. (2006) identified them only up to the genus
level, but subsequently recognised that they were most
likely T. aduncus (M.L.L. Dolar pers. comm.). Although
both Leatherwood et al. (1992) and Dolar et al. (2006)
surveyed the entire Tañon Strait, their sightings of
bottlenose dolphins were limited only to the southern
section of the strait, near the opening. A short-term
follow-up study by Callanta (2009) reported a similar
pattern. Our recent work (L. Karczmarski and A.J.C.
Tiongson, study in progress) confirms the identity of the
species and indicates its considerably wider distribution.le is distributed under the terms of the Creative Commons Attribution 4.0
.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
ive appropriate credit to the original author(s) and the source, provide a link to
changes were made. The Creative Commons Public Domain Dedication waiver
ro/1.0/) applies to the data made available in this article, unless otherwise stated.
Fig. 1 Map of the Philippines and the Tañon Strait study site (inset) showing the locations of sightings of Indo-Pacific bottlenose dolphins in 2014
(black circles) and 2015 (open circles). The gray lines indicate the survey tracks for 2014 and 2015
Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 2 of 4Materials and methods
Boat-based photo-identification surveys (n = 117) were
conducted from April through July of both 2014 and
2015 with start off points at Dumaguete City on
Negros Island and Moalboal on Cebu Island (Fig. 1).
Four small boats of similar size were used (8.5–9.8 m,
powered with 40 and 75 HP outboard engines), ran-
ging from one to three boats at a time, during every
good-weather day (no precipitation and sea state ≤3
in Beaufort scale) and following a commonly accepted
field protocol (similarly as in Karczmarski et al.
2005). The northernmost range of surveys were at
Barili (10.2310°N, 123.5487°E) on Cebu Island and
Vallehermoso (10.3102°N, 123.3326°E) on Negros
Island, while the southernmost range were at Apo Island
(9.0607°N, 123.2551°E) off Negros Island and Santander
(9.4103°N, 123.3443°E) on Cebu Island (Fig. 1).Each time a dolphin group was sighted, the animals
were slowly approached and their speed and general dir-
ection were matched with that of a research vessel to
minimise any potential impact caused by the boat pres-
ence. Once the dolphins were in a range sufficiently
close for species identification, the start time and loca-
tion of the encounter was recorded using a handheld
Garmin 78 s GPS. Group size estimates were made at
the beginning and the end of an encounter, and in regu-
lar intervals throughout the encounter. Dolphins’ dorsal
fins and their upper body were photographed using
high-speed digital cameras fitted with 100–400 mm
image stabilized lenses. At each encounter, a conscious
attempt was made to photograph all individuals in the
group and, whenever possible, capture both sides of the
dorsal fin. The unique body marks and notches on
dorsal fins were used for individual identification (e.g.
Table 1 Water depth associated with sightings of Indo-Pacific bottlenose dolphins in Tañon Strait in 1995 and 2014–2015
Source Survey year n Depth range (m) Mean depth (m) SD
Dolar et al. 2006 1995 3 24–328 141 133
~this study 2014– 2015 50 4–668 309 172
Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 3 of 4Karczmarski and Cockcroft 1998) and, subsequently, the
software program DISCOVERY (Gailey and Karczmarski
2012) was used for photo-ID database management.
Results and discussion
A total of 669 h were spent at sea, during 92 survey days
across two field seasons. Indo-Pacific bottlenose dol-
phins Tursiops aduncus were seen throughout the study
period, at all times of the day from dusk to late after-
noon, in varying distance from shore ranging from 20 m
to 11 km offshore, and throughout a wide range of water
depth (Table 1). Photo-ID data were obtained during 50
encounters. Individual sighting frequencies ranged from
one (n = 21) to ten (n = 1), with the majority of the 121Fig. 2 The Indo-Pacific bottlenose dolphin in Tañon Strait, showing (a) the re
and (b) ventral spots around the genital area of a mature femalecatalogued individuals (82 %, n = 99) seen more than
once. Group sizes ranged from a solitary individual to
~60 dolphins, with a mean of 11 and median of 10
dolphins per group (±10.5 SD). Groups frequently con-
sisted of all age classes, including calves and neonates,
although adult-only groups were also seen.
Although bottlenose dolphins were known to occur in
Philippine waters (Leatherwood et al. 1992; Dolar et al.
1994, 2002, 2006), they were usually identified as T. trun-
catus. The similarities between Tursiops truncatus and T.
aduncus (Rice 1998) make their identification in the field
challenging, especially in areas where they occur sympatri-
cally. Our photographic data confirms the species of Tur-
siops seen at each of our encounters as T. aduncus (Fig. 2).latively long snout (indicated with arrow) characteristic of the species,
Tiongson and Karczmarski Marine Biodiversity Records  (2016) 9:85 Page 4 of 4At present, the Indo-Pacific bottlenose dolphin is
not listed in the Philippines’ Fisheries Administrative
Order 208 (FAO 208) of 2001 which sets out the pro-
tection of aquatic species, and it is classified as Data
Deficient by the regional Red List assessment (Dolar
et al. 2012) and the IUCN Red List of Threatened
Species (Hammond et al. 2012). An amendment to
the Philippines’ Fisheries Administrative Order 208
that includes T. aduncus is pertinent and urgently
needed for the consistency with other protective mea-
sures in the Philippines (e.g. Republic Act 8550, 9147,
FAO 185/185-1). An appropriate recognition of the
species is important as it remains little known not
only in the Philippines but across most of its range.
Their discontinuous distribution in tropical Philippine wa-
ters and apparently small population sizes warrants conser-
vation concern, especially in the face of climate change in
the region (Dolar and Sabater 2011). Furthermore,
lobomycosis-like disease and other skin disorders have
recently been observed in Tañon Strait (A.J.C. Tiongson
and L. Karczmarski, unpublished data), likely indicative of
the deteriorating habitat quality.
Our preliminary results indicate that the popula-
tion of Indo-Pacific bottlenose dolphins in TSPS is
not large, with considerable site fidelity in the area,
although ranging further north and into deeper wa-
ters than previously thought. Although the species is
known to generally prefer coastal shallow waters,
sightings in deeper waters of Tañon Strait are not
surprising because the strait’s bathymetry limits the
coastal shallow waters to a narrow strip and brings
deep waters close to shore. The presence of calves and
neonates indicate that the dolphins are reproducing in the
strait. The Tañon Strait Protected Seascape (TSPS) is
under the National Integrated Protected Area Systems
(NIPAS) Act, with a purpose to conserve the biodiversity
of the area and implement sustainable development. This
provision makes the strait excellently suited for research
investigating the bottlenose dolphin population under a
rapidly changing environment and such study should be
encouraged.Acknowledgements
This work was partially funded through a research grant from Ocean Park
Conservation Foundation Hong Kong (OPCFHK, grant no. MM05-1415) and
internal funding of the Cetacean Ecology Lab at the Swire Institute of Marine
Science (SWIMS), The University of Hong Kong. Research clearance (No.
2014-0000-04) was obtained from the TSPS-Protected Area Management
Board. The following people are gratefully acknowledged for their assistance
at various stages of our field work: Stephen C.Y. Chan, Yuen-WaHo, Mark de
la Paz, Edna Sabater and a dedicated team of volunteers. We thank Janet
Estacion of Silliman University’s Institute of Environmental and Marine Sci-
ences for her invaluable help; and Louella Dolar of Tropical Marine Research
for Conservation (TMRC) for providing access to her earlier data. Raphael
Virchaux and Rudy Poitier are gratefully acknowledged for their support, and
the staff and crew of ‘Dolphin House’ and ‘Easydiving PH’ are thanked for
their assistance during boat surveys.Authors’ contributions
Both authors contributed equally to this study. AJCT performed this study as
part of his ongoing postgraduate research. LK designed the project, secured
funding, and supervised the study. Both authors read and approved the final
manuscript.
Competing interests
The authors declare that they have no competing interests.
Received: 20 June 2016 Accepted: 21 June 2016
References
Aragones LV, Roque MAA, Flores MB, Encomienda RP, Laule GE, Espinos BG,
Maniago FE, Diaz GC, Alesna EB, Braun RC. The Philippine marine mammal
strandings from 1998 to 2009: animals in the Philippines in peril? Aquat
Mamm. 2010;36(3):219–33.
Callanta LS. Residence patterns and range characteristics of Indo-Pacific
bottlenose dolphins (Tursiops aduncus) and other small cetaceans in the
southern Tañon Strait, Central Visayas, Philippines. MSc thesis. Silliman
University, Philippines; 2009
Dolar MLL, Sabater ER. Potential impact of climate change on marine mammal
biodiversity in Southeast Asia: a review. Silliman J. 2011;52(1):91–113.
Dolar MLL, Leatherwood SJ, Wood CJ, Alava MNR, Hill CL, Aragones LV. Directed
fisheries for cetaceans in the Philippines. Report of the International Whaling
Commission. 1994;44:439–49.
Dolar MLL, Perrin WF, Gaudiano JP, Yaptinchay AASP, Tan JML. Preliminary report
on a small estuarine population of Irrawaddy dolphins Orcaella brevirostris in
the Philippines. The Raffles Bulletin of Zoology Supplement. 2002;10:155–60.
Dolar MLL, Perrin WF, Taylor B, Kooyman G, Alava MNR. Distributional ecology of
cetaceans in the central Philippines. J Cetacean Res Manag. 2006;8:93–111.
Dolar MLL, Sabater ER, Gaudiano JPA, Bagarinao TU, Sorongon PME, Barcelona
ALB, Tagarino AP, Daclan JMO, Santos MD. Tursiops aduncus. In: Alava MNR,
Dolar MLL, Sabater ER, Aquino MTR, Santos MD, editors. Red list status of
marine mammals in the Philippines. Manila: Bureau of Fisheries and Aquatic
Resources-National Fisheries Research and Development Institute;
2012. p. 106–9.
Gailey G, Karczmarski L. DISCOVERY: A photo-identification data management
system for individually recognizable animals. The Swire Institute of Marine
Science, The University of Hong Kong; 2012. Available at: http://www.biosch.
hku.hk/ecology/staffhp/lk/Discovery/.
Hammond PS, Bearzi G, Bjørge A, Forney KA, Karczmarski L, Kasuya T, Perrin WF,
Scott MD, Wang JY, Wells RS, Wilson B. Tursiops aduncus. The IUCN Red List
of Threatened Species. Version 2015.2. 2012. Available at: http://www.
iucnredlist.org/details/full/41714/0. Accessed 17 Oct 2015.
Hayasaka S, Saisho T, Kakinuma Y, Shinomiya A, Oki K, Hamada T, Tanabe K, Kanie
Y, Hattori M, VandeVusse F, Alcala L, Cordero PAJ, Cabrera JJ, Garcia RG. Field
study on the habitat of Nautilus in the environs of Cebu and Negros islands,
the Philippines. Memoirs of the Kagoshima University Research Center for
the South Pacific, Occasional Publications. 1982;3(1):67–137.
Karczmarski L, Cockcroft VG. Matrix photo-identification technique applied in
studies of free-ranging bottlenose and humpback dolphins. Aquat Mamm.
1998;24(3):143–7.
Karczmarski L, Würsig B, Gailey G, Larson KW, Vanderlip C. Spinner dolphins in a
remote Hawaiian atoll: social grouping and population structure. Behav Ecol.
2005;16:675–85.
Leatherwood S, Dolar MLL, Wood CJ, Aragones LV, Hill CL. Marine mammal
species confirmed from Philippine waters. Silliman J. 1992;36:65–86.
Rice DW. Marine mammals of the world: Systematics and distribution, no. 4.
Kansas: Special publications of the Society for Marine Mammals, The Society
for Marine Mammalogy, Lawrence; 1998. p. 231.
Wang JY, Yang SC. Indo-Pacific bottlenose dolphins, Tursiops aduncus. In: Perrin
WF, Würsig B, Thewissen C, editors. Encyclopedia of marine mammals.
San Diego: Academic; 2009. p. 602–8.


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The Indo-Pacific bottlenose dolphin (Tursiops aduncus) in Tañon Strait, central Philippines

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