Little is known about the vocalizations of Irrawaddy dolphins (Orcaella brevirostris) in the Gulf of Thailand. The present study first described the echolocation clicks of Irrawaddy dolphins in Trat Bay, in the eastern Gulf of Thailand, using a broadband hydrophone system. Over 2 h of acoustic recordings were collected during 14-day study periods in December 2017 and December 2018. Several criteria were used to judge if a click was on axis or as close to the acoustic axis as possible. To calculate the distance of dolphins, a low-budget localization method based on arrival time differences between the direct and indirect signals was used in the present study. The clicks had a mean peak-to-peak source level of 192 ± 3 dB re 1 μPa, an energy flux density source level of 131 ± 3 dB re 1 μPa2s, a mean centroid frequency of 98 ± 10 kHz, a mean duration of 16 ± 2 μs, and a −3 dB bandwidth of 79 ± 13 kHz. The click parameters of the Irrawaddy dolphins in Trat Bay were slightly different from the clicks recorded from the dolphins in Sundarbans, Bangladesh. The present study provided a basic description of the click characteristics of Irrawaddy dolphins in Trat Bay, which could contribute to the management and conservation strategies for local Irrawaddy dolphins, and a basic reference for the proper input parameters in passive acoustic monitoring and detection.
References
1.
Akamatsu
, T.
, Teilmann
, J.
, Miller
, L. A.
, Tougaard
, J.
, Dietz
, R.
, Wang
, D.
, Wang
, K.
, Siebert
, U.
, and Naito
, Y.
(2007
). “Comparison of echolocation behavior between coastal and riverine porpoises
,” Deep Sea Res. II
54
, 290
–297
.2.
3.
Au
, W. L.
(2004
). “Echolocation signals of wild dolphins
,” Acoust. Phys.
50
, 454
–462
.4.
Au
, W. L.
, Floyd
, R. W.
, Penner
, R. H.
, and Murchison
, E.
(1974
). “Measurement of echolocation signals of Atlantic bottlenose dolphin, Tursiops truncatus Montagu, in open waters
,” J. Acoust. Soc. Am.
56
, 1280
–1290
.5.
Au
, W. L.
, Kastelein
, R. A.
, Rippe
, T.
, and Schooneman
, N. M.
(1999
). “Transmission beam pattern and echolocation signals of a harbor porpoise (Phocoena phocoena)
,” J. Acoust. Soc. Am.
106
, 3699
–3705
.6.
Aubauer
, R.
, Lammers
, M. O.
, and Au
, W. L.
(2000
). “One-hydrophone method of estimating distance and depth of phonating dolphins in shallow water
,” J. Acoust. Soc. Am.
107
, 2744
–2749
.7.
Bahl
, R.
, Ura
, T.
, Inoue
, T.
, Sugimatsu
, H.
, Sakamaki
, T.
, Kojima
, J.
, Akamatsu
, T.
, Takahashi
, H.
, Pattnaik
, A.
, Khan
, M.
, Behera
, S.
, and Kar
, S.
(2006b
). “Observation studies based on echolocation click signals of Irrawaddy dolphins in Chilika lagoon
,” J. Acoust. Soc. Am.
120
, 3014
–3021
.8.
Bahl
, R.
, Ura
, T.
, Sugimatsu
, H.
, Inoue
, T.
, Sakamaki
, T.
, Kojima
, J.
, Akamatsu
, T.
, Takahashi
, H.
, Behera
, S. K.
, Pattnaik
, A. K.
, Khan
, M.
, and Kar
, S. K.
(2006a
). “Acoustic survey of Irrawaddy dolphin populations in Chilika lagoon: First test of a compact high-resolution device
,” in OCEANS 2006 Asia-Pacific, pp. 1
–6
.9.
de Freitas
, M.
, Jensen
, F. H.
, Tyne
, J.
, Beider
, L.
, and Madsen
, P. T.
(2015
). “Echolocation parameters of Australian humpback dolphins (Sousa sahulensis) and Indo-Pacific bottlenose dolphins (Tursiops aduncus) in the wild
,” J. Acoust. Soc. Am.
137
, 3033
–3041
.10.
de Freitas
, M.
, Smith
, J. N.
, Jensen
, F. H.
, Beedholm
, K.
, and Madsen
, P. T.
(2018
). “Echolocation click source parameters of Australian snubfin dolphins (Orcaella heinsohni)
,” J. Acoust. Soc. Am.
143
, EL2564
–EL2569
.11.
DeRuiter
, S. L.
, Hansen
, M.
, Koopman
, H. N.
, Westgate
, A. J.
, Tyack
, P. L.
, and Madsen
, P. T.
(2010
). “Propagation of narrow band high frequency clicks: Measured and modeled transmission loss of porpoise like clicks in porpoise habitats
,” J. Acoust. Soc. Am.
127
, 560
–567
.12.
Granford
, T. W.
, Amundin
, M.
, and Norris
, K. S.
(1996
). “Functional morphology and homology in the odontocete nasal complex: Implications for sound generation
,” J. Morphol.
228
, 223
–285
.13.
Hines
, E.
, and Jumchumpoo
, C.
(2014
). “Coastal marine mammals along the eastern gulf of Thailand (2014)
,” Final Report to Australian Marine Mammal Centre Grants Program, Kingston, Tasmania, Australia.14.
Hines
, E. M.
, Strindberg
, S.
, Junchumpoo
, C.
, Ponnampalam
, L. S.
, Ilangakoon
, A. D.
, Jackson-Ricketts
, J.
, and Monanunsap
, S.
(2015
). “Line transect estimates of Irrawaddy dolphin abundance along the eastern Gulf Coast of Thailand
,” Front. Mar. Sci.
2
, 63
.15.
Hoffman
, J. M.
, Ponnampalam
, L. S.
, Araújo-Wang
, C.
, Kuit
, S. H.
, Hung
, S. K.
, and Wang
, J. Y.
(2017
). “Description of whistles of Irrawaddy dolphins (Orcaella brevirostris) from the waters of Matang, Peninsular Malaysia
,” Bioacoust.
26
, 15
–24
.16.
Ingale
, C. B.
, and Lokhande
, S.
(2015
). “Habitat impact on echo-location characteristics of Irrawaddy dolphins from Chilika Lake and Sunderbans
,” Int. J. Sci. Res.
4
, 2249
–2252
.17.
IUCN
(2012
). IUCN Red List of Threatened Species, Version 2012.1.18.
Jensen
, F. H.
, Rocco
, A.
, Mansur
, R. M.
, Smith
, B. D.
, Janik
, V. M.
, and Madsen
, P. T.
(2013
). “Clicking in shallow rivers: Short range echolocation of Irrawaddy and Ganges River Dolphins in a shallow, acoustically complex habitat
,” PLoS One
9
, e101427
.19.
Junchompoo
, C.
, Monanunsap
, S.
, and Penpein
, C.
(2014
). “Population and conservation status of Irrawaddy dolphins (Orcaella brevirostris) in Trat Bay, Trat Province, Thailand
,” in Proceedings of the Design Symposium on Conservation of Ecosystem
, Vol. 2, pp. 32
–38
.20.
Jutapruet
, S.
, Intongcome
, A.
, Wang
, X.
, Kittiwattanawong
, K.
, and Huang
, S.-L.
(2017
). “Distribution of three sympatric cetacean species off the coast of the Central Western Gulf of Thailand
,” Aquat. Mammals
43
, 465
–473
.21.
Kamminga
, C.
, Wiersma
, H.
, and van Heel
, D.
(1983
). “Investigations on cetacean sonar VI. Sonar sounds in Orcaella brevirostris of the Mahakam River, East Kalimantan, Indonesia; the first descriptions of the acoustic behavior
,” Aquat. Mammals
10
, 83
–94
.22.
Kyhn
, L. A.
, Tougaard
, J.
, Jensen
, F. H.
, Wahlberg
, M.
, Stone
, G.
, Yoshinaga
, A.
, Beedholm
, K.
, and Madsen
, P. T.
(2009
). “Feeding at a high pitch: Source parameters of narrow band, high frequency clicks from echolocation off-shore hourglass dolphins and coastal Hector's dolphins
,” J. Acoust. Soc. Am.
125
, 1783
–1791
.23.
Kyhn
, L. A.
, Tougaard
, J.
, Thomas
, L.
, Duve
, L. R.
, Stenback
, J.
, Amundin
, M.
, Desportes
, G.
, and Teilmann
, J.
(2012
). “From echolocation clicks to animal density—Acoustic sampling of harbor porpoises with static data loggers
,” J. Acoust. Soc. Am.
131
, 550
–560
.24.
Li
, S. H.
, Wang
, K. X.
, Wang
, D.
, and Akamatsu
, T.
(2005
). “Echolocation signals of the free-ranging Yangtze finless porpoise (Neophocaena phocaenoides asiaeorientialis)
,” J. Acoust. Soc. Am.
117
, 3288
–3296
.25.
Madsen
, P. T.
, Kerr
, I.
, and Payne
, R.
(2004a
). “Echolocation clicks of two free-ranging, oceanic delphinids with different food preferences: False killer whales Pseudorca crassidens and Risso's dolphins Grampus griseus
,” J. Exp. Biol.
207
, 1811
–1823
.26.
Madsen
, P. T.
, Kerr
, I.
, and Payne
, R.
(2004b
). “Source parameter estimates of echolocation clicks from wild pygmy killer whales (Feresa attenuata)
,” J. Acoust. Soc. Am.
116
, 1909
–1912
.27.
Madsen
, P. T.
, and Wahlberg
, M.
(2007
). “Recording and quantification of ultrasonic echolocation clicks from free-ranging toothed whales
,” Deep Sea Res.
54
, 1421
–1444
.28.
Muhamad
, H. M.
, Xu
, X. M.
, Zhang
, X. L.
, Jaaman
, S. A.
, and Muda
, A. M.
(2018
). “Whistle description of Irrawaddy dolphins (Orcaella brevirostris) in Bay of Brunei, Sarawak, Malaysia
,” J. Acoust. Soc. Am.
143
, 2708
–2714
.29.
Nowacek
, D. P.
, Christiansen
, F.
, Bejder
, L.
, Goldbogen
, J. A.
, and Friedlaender
, A. S.
(2016
). “Studying cetacean behavior: New technological approaches and conservation applications
,” Animal Behav.
120
, 235
–244
.30.
Ponnampalam
, L. S.
, Hines
, E. M.
, Monanunsap
, S.
, Ilangakoon
, A. D.
, Junchompoo
, C.
, Adulyanukosol
, K.
, and Morse
, L.
(2013
). “Behavioral observations of coastal Irrawaddy dolphins (Orcaella brevirostris) in Trat Province, Eastern Gulf of Thailand
,” Aquat. Mammals
39
, 401
–408
.31.
Rasmussen
, M. H.
, Miller
, L. A.
, and Au
, W. L.
(2002
). “Source level of clicks from free-ranging white-beaked dolphins (Lagenrhynchus albirostris, Gray 1846) recorded in Icelandic waters
,” J. Acoust. Soc. Am.
116
, 1826
–1831
.32.
Rocco
, A.
(2009
). “Vocal characteristics of Irrawaddy dolphins from the Sundarban mangrove forest and Bay of Bengal, Bangladesh
,” Ph.D. dissertation, University of St. Andrews
, Fife, Scotland.33.
Smith
, B D.
, Ahmed
, B.
, Mowgli
, R. M.
, and Strindberg
, S.
(2008
). “Species occurrence and distributional ecology of near shore cetaceans in the Bay of Bengal, Bangladesh, with abundance estimates for Irrawaddy dolphins Orcaella brevirostris and finless porpoises Neophocaena phocaenoides
,” J. Cetacean Res. Manag.
10
, 45
–58
.34.
Smith
, B. D.
, Braulik
, G.
, Strindberg
, S.
, Ahmed
, B.
, and Mansur
, R.
(2006
). “Abundance of Irrawaddy dolphins (Orcaella brevirostris) and Ganges River dolphins (Platanista gangetica gangetica) estimated using concurrent counts made by independent teams in waterways of the Sundarbans mangrove forest in Bangladesh
,” Marine Mammal Sci.
22
, 527
–547
.35.
Stacey
, P. J.
, and Arnold
, P. W.
(1999
). “Orcaella brevirostris
,” Mamm. Spec.
616
, 1
–8
.36.
Stacey
, P. J.
, and Leatherwood
(1997
). “The Irrawaddy dolphin, Orcaella brevirostris: A summary of current knowledge and recommendations for conservation action
,” Asian Mar. Biol.
14
, 195
–214
.37.
Svarachorn
, T.
, Kettratad
, J.
, Thubthong
, N.
, and Chansue
, N.
(2016
). “Sound characteristics and primary descriptions of vocalizations associated with behaviours of captive Irrawaddy dolphins (Orcaella brevirostris)
,” Aquat. Mammals
42
, 519
–530
.38.
Teoh
, S. W.
, Jaaman
, S. A.
, and Palaniappan
, P. M.
(2013
). “A preliminary study of population size of Irrawaddy dolphins (Orcaella brevirostris) in Cowie Bay, Sabah, Malaysia
,” J. Trop. Biol. Conserv.
10
, 23
–26
.39.
Tongnunui
, S.
, Wattanakornsiri
, A.
, Pachana
, K.
, Beamish
, F.
, and Tongsukdee
, S.
(2011
). “Preliminary investigation of Irrawaddy dolphin (Orcaella brevirostris) in the Bangpakong Estuary, inner Gulf of Thailand
,” Environ. Nat. Res. J.
9
, 48
–57
.40.
41.
Van Parijs
, S. M.
, and Corkeron
, P. J.
(2001
). “Vocalizations and behavior of pacific humpback dolphins Sousa chinensis
,” Ethology
107
, 701
–716
.42.
Van Parijs
, S. M.
, Parra
, G. J.
, and Corkeron
, P. J.
(2000
). “Sounds produced by Australian Irrawaddy dolphins, Orcaella brevirostris
,” J. Acoust. Soc. Am.
130
, 2263
–2274
.43.
Wahlberg
, M.
, Jensen
, F. H.
, Soto
, N. A.
, Beedholm
, K.
, Beider
, L.
, Oliveira
, C.
, Rasmussen
, M.
, Simon
, M.
, Villadsgaard
, A.
, and Madsen
, P. T.
(2011
). “Source parameters of echolocation clicks from wild bottlenose dolphins (Tursiops aduncus and Tursiops truncatus)
,” J. Acoust. Soc. Am.
108
, 1938
–1940
.44.
Williams
, R.
, Wright
, A. J.
, Ashe
, E.
, Blight
, L. K.
, Bruintjes
, R.
, Canessa
, R.
, Clark
, C. W.
, Cullis-Suzuki
, S.
, Dakin
, D. T.
, Erbe
, C.
, Hammond
, P. S.
, Merchant
, N. D.
, O'Hara
, P. D.
, Purser
, J.
, Radford
, A. N.
, Simpson
, S. D.
, Thomas
, L.
, and Wale
, M. A.
(2015
). “Impacts of anthropogenic noise on marine life: Publication patterns, new discoveries, and future directions in research and management
,” Ocean Coastal Manage.
115
, 17
–24
.© 2019 Acoustical Society of America.
2019
Acoustical Society of America
You do not currently have access to this content.