Discrimination of bioacoustic signals to the species or population level is critical for using passive acoustic monitoring to study cetacean ecology. Risso's dolphins off southern California have distinctive peaks and notches in their echolocation clicks, but it was unknown whether Risso's dolphins from other geographic areas have similarly distinctive click spectra and whether populations are acoustically distinct. This study investigates using clicks for species and population identification by characterizing the spectral structure of Risso's dolphin echolocation clicks recorded over wide-ranging geographic regions including the U.S. waters of the North Atlantic Ocean, Gulf of Mexico, and North Pacific Ocean; and international waters of the Eastern Tropical Pacific. All recordings with Risso's dolphin clicks exhibited the spectral peak and notch pattern described off southern California, indicating the presence of peak banding patterns is useful for species discrimination. Geographic regions were a significant explanatory factor for variability in the frequencies of click spectral peaks, with relatively higher frequency peaks and notches found off Hawaii compared to California waters and off the southeast U.S. compared to the Gulf of Mexico. In the North Atlantic Ocean, a latitudinal cline in frequencies was evident. Potential causes of acoustic variation within and among acoustic encounters are evaluated.

1.
Au
,
W. W. L.
(
1993
).
The Sonar of Dolphins
(
Springer-Verlag
,
New York)
, 277 pp.
2.
Au
,
W. W. L.
,
Branstetter
,
B.
,
Moore
,
P. W.
, and
Finneran
,
J. J.
(
2012
). “
The biosonar field around an Atlantic bottlenose dolphin (Tursiops truncatus)
,”
J. Acoust. Soc. Am.
131
,
569
576
.
3.
Au
,
W. W. L.
,
Carder
,
D. A.
,
Penner
,
R. H.
, and
Scronce
,
B. L.
(
1985
). “
Demonstration of adaptation in beluga whale echolocation signals
,”
J. Acoust. Soc. Am.
77
,
726
730
.
4.
Baird
,
R. W.
(
2002
).
“Risso's dolphin,”
in
Encyclopedia of Marine Mammals
(
Academic Press
,
San Diego, CA
), pp.
1037
1039
.
5.
Barkley
,
Y. M.
,
Oleson
,
E.
, and
Oswald
,
J. N.
(
2014
). “
Investigating whistle characteristics of three overlapping populations of false killer whales (Pseudorca crassidens) in the Hawaiian Islands
,”
J. Acoust. Soc. Am.
136
,
2154
2154
.
6.
Barlow
,
J.
(
1995
). “
The abundance of cetaceans in California waters. 1. Ship surveys in summer and fall of 1991
,”
Fish. Bull.
93
,
1
14
.
7.
Baumann-Pickering
,
S.
,
McDonald
,
M. A.
,
Simonis
,
A. E.
,
Solsona Berga
,
A.
,
Merkens
,
K. P. B.
,
Oleson
,
E. M.
,
Roch
,
M. A.
,
Wiggins
,
S. M.
,
Rankin
,
S.
,
Yack
,
T. M.
, and
Hildebrand
,
J. A.
(
2013a
). “
Species specific beaked whale echolocation signals
,”
J. Acoust. Soc. Am.
134
,
2293
2301
.
8.
Baumann-Pickering
,
S.
,
Roch
,
M. A.
,
Brownell
,
R. L.
, Jr.
,
Simonis
,
A. E.
,
McDonald
,
M. A.
,
Solsona-Berga
,
A.
,
Oleson
,
E. M.
,
Wiggins
,
S. M.
, and
Hildebrand
,
J. A.
(
2014
). “
Spatio-temporal patterns of beaked whale echolocation signals in the North Pacific
,”
PLoS ONE
9
,
e91383
.
9.
Baumann-Pickering
,
S.
,
Roch
,
M. A.
,
Wiggins
,
S. M.
,
Schnitzler
,
H.-U.
, and
Hildebrand
,
J. A.
(
2015a
). “
Acoustic behavior of melon-headed whales varies on a diel cycle
,”
Behav. Ecol. Sociobiol.
69
,
1553
1563
.
10.
Baumann-Pickering
,
S.
,
Simonis
,
A. E.
,
Oleson
,
E. M.
,
Baird
,
R. W.
,
Roch
,
M. A.
, and
Wiggins
,
S. M.
(
2015b
). “
False killer whale and short-finned pilot whale acoustic identification
,”
Endang. Spec. Res.
28
,
97
108
.
11.
Baumann-Pickering
,
S.
,
Simonis
,
A. E.
,
Wiggins
,
S. M.
,
Brownell
,
J. R. L.
, and
Hildebrand
,
J. A.
(
2013b
). “
Aleutian Islands beaked whale echolocation signals
,”
Mar. Mamm. Sci.
29
,
221
227
.
12.
Baumann-Pickering
,
S.
,
Trickey
,
J. S.
,
Wiggins
,
S. M.
, and
Oleson
,
E. M.
(
2016
). “
Odontocete occurrence in relation to changes in oceanography at a remote equatorial Pacific seamount
,”
Mar. Mamm. Sci.
32
,
805
825
.
13.
Baumann-Pickering
,
S.
,
Wiggins
,
S. M.
,
Hildebrand
,
J. A.
,
Roch
,
M. A.
, and
Schnitzler
,
H.-U.
(
2010
). “
Discriminating features of echolocation clicks of melon-headed whales (Peponocephala electra), bottlenose dolphins (Tursiops truncatus), and Gray's spinner dolphins (Stenella longirostris longirostris)
,”
J. Acoust. Soc. Am.
128
,
2212
2224
.
14.
Branch
,
T. A.
,
Abubaker
,
E.
,
Mkango
,
S.
, and
Butterworth
,
D. S.
(
2007a
). “
Separating southern blue whale subspecies based on length frequencies of sexually mature females
,”
Mar. Mamm. Sci.
23
,
803
833
.
15.
Branch
,
T. A.
,
Stafford
,
K.
,
Palacios
,
D.
,
Allison
,
C.
,
Bannister
,
J.
,
Burton
,
C.
,
Cabrera
,
E.
,
Carlson
,
C.
,
Galletti Vernazzani
,
B.
, and
Gill
,
P.
(
2007b
). “
Past and present distribution, densities and movements of blue whales Balaenoptera musculus in the Southern Hemisphere and northern Indian Ocean
,”
Mamm. Rev.
37
,
116
175
.
16.
Buscaino
,
G.
,
Buffa
,
G.
,
Filiciotto
,
F.
,
Maccarrone
,
V.
,
Di Stefano
,
V.
,
Ceraulo
,
M.
,
Mazzola
,
S.
, and
Alonge
,
G.
(
2015
). “
Pulsed signal properties of free-ranging bottlenose dolphins (Tursiops truncatus) in the central Mediterranean Sea
,”
Mar. Mamm. Sci.
31
,
891
901
.
17.
Calderan
,
S.
,
Wittich
,
A.
,
Harries
,
O.
,
Gordon
,
J.
, and
Leaper
,
R.
(
2013
). “
White-beaked dolphin and Risso's dolphin click characteristics and the potential for classification and species identification
,”
Scottish Natural Heritage Commissioned Report No. 624. Scottish Natural Heritage
, Battleby, Redgorton, Perth, Scotland, 31 pp.
18.
Caldwell
,
D. K.
,
Caldwell
,
M. C.
, and
Miller
,
J. F.
(
1969
). “
Three brief narrow-band sound emissions by a captive male Risso's dolphin, Grampus griseus
,”
Bull. South. Calif. Acad. Sci.
68
,
252
256
.
19.
Carretta
,
J. V.
,
Oleson
,
E.
,
Weller
,
D. W.
,
Lang
,
A. R.
,
Forney
,
K. A.
,
Baker
,
J.
,
Hanson
,
B.
,
Martien
,
K.
,
Muto
,
M. M.
,
Orr
,
A. J.
,
Huber
,
H.
,
Lowry
,
M. S.
,
Barlow
,
J.
,
Lynch
,
D.
,
Carswell
,
L.
,
Brownell
R. L.
, Jr.
, and
Mattila
,
D. K.
(
2013
). “
U.S. Pacific Marine Mammal Stock Assessments, 2013
,” NOAA-TM-NMFS-SWFSC-532 (US Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center, La Jolla, CA),
414
pp.
20.
Castellote
,
M.
,
Clark
,
C. W.
, and
Lammers
,
M. O.
(
2012
). “
Fin whale (Balaenoptera physalus) population identity in the western Mediterranean Sea
,”
Mar. Mamm. Sci.
28
,
325
344
.
21.
Chen
,
I.
,
Watson
,
A.
, and
Chou
,
L.-S.
(
2011
). “
Insights from life history traits of Risso's dolphins (Grampus griseus) in Taiwanese waters: Shorter body length characterizes northwest Pacific population
,”
Mar. Mamm. Sci.
27
,
E43
E64
.
22.
Corkeron
,
P. J.
, and
Van Parijs
,
S. M.
(
2001
). “
Vocalizations of eastern Australian Risso's dolphins, Grampus griseus
,”
Can. J. Zool.
79
,
160
164
.
23.
Cranford
,
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
.
24.
de Boer
,
M. N.
,
Clark
,
J.
,
Leopold
,
M. F.
,
Simmonds
,
M. P.
, and
Reijnders
,
P. J. H.
(
2013
). “
Photo-identification methods reveal seasonal and long-term site-fidelity of Risso's dolphins (Grampus griseus) in shallow waters (Cardigan Bay, Wales)
,”
Open J. Mar. Sci.
3
,
66
75
.
25.
Delarue
,
J.
,
Todd
,
S. K.
,
Van Parijs
,
S. M.
, and
Di Iorio
,
L.
(
2009
). “
Geographic variation in Northwest Atlantic fin whale (Balaenoptera physalus) song: Implications for stock structure assessment
,”
J. Acoust. Soc. Am.
125
,
1774
1782
.
26.
Finneran
,
J. J.
,
Branstetter
,
B. K.
,
Houser
,
D. S.
,
Moore
,
P. W.
,
Mulsow
,
J.
,
Martin
,
C.
, and
Perisho
,
S.
(
2014
). “
High-resolution measurement of a bottlenose dolphin's (Tursiops truncatus) biosonar transmission beam pattern in the horizontal plane
,”
J. Acoust. Soc. Am.
136
,
2025
2038
.
27.
Forney
,
K. A.
, and
Barlow
,
J.
(
1998
). “
Seasonal patterns in the abundance and distribution of California cetaceans, 1991–1992
,”
Mar. Mamm. Sci.
14
,
460
489
.
28.
Frasier
,
K. E.
(
2015
). “
Density estimation of delphinids using passive acoustics: A case study in the Gulf of Mexico
,” Ph.D. dissertation, Scripps Institute of Oceanography,
University of California
,
San Diego, La Jolla, CA
,
315
pp.
29.
Gaspari
,
S.
,
Airoldi
,
S.
, and
Hoelzel
,
A. R.
(
2007
). “
Risso's dolphins (Grampus griseus) in UK waters are differentiated from a population in the Mediterranean Sea and genetically less diverse
,”
Conserv. Gen.
8
,
727
732
.
30.
Green
,
G.
,
Brueggeman
,
J. J.
,
Grotefendt
,
R. A.
,
Bowlby
,
C. E.
,
Bonnell
,
M. L.
, and
K. C. Balcomb
,
I.
(
1992
). “
Cetacean distribution and abundance off Oregon and Washington. Chap. 1
,” in
Oregon and Washington Marine Mammal and Seabird Surveys. OCS Study 91-0093. Final Report prepared for Pacific OCS Region, Minerals 120 Management Service
, edited by
J. J.
Brueggeman
(
U. S. Department of the Interior
,
Los Angeles, CA
), pp.
1
100
.
31.
Henderson
,
E. E.
,
Hildebrand
,
J. A.
, and
Smith
,
M. H.
(
2011
). “
Classification of behavior using vocalizations of Pacific white-sided dolphins (Lagenorhynchus obliquidens)
,”
J. Acoust. Soc. Am.
130
,
557
567
.
32.
Hodge
,
L. E. W.
(
2011
). “
Monitoring marine mammals in Onslow Bay, North Carolina, using passive acoustics
,” Ph.D. dissertation,
Duke University
,
Durham, NC
, 197 pp.
33.
Houser
,
D. S.
,
Helweg
,
D. A.
, and
Moore
,
P. W.
(
1999
). “
Classification of dolphin echolocation clicks by energy and frequency distributions
,”
J. Acoust. Soc. Am.
106
,
1579
1585
.
34.
Huang
,
X.
,
Acero
,
A.
, and
Hon
,
H. W.
(
2001
).
Spoken Language Processing
(
Prentice Hall
,
Upper Saddle River, NJ)
, 960 pp.
35.
Jefferson
,
T. A.
,
Weir
,
C. R.
,
Anderson
,
R. C.
,
Ballance
,
L. T.
,
Kenney
,
R. D.
, and
Kiszka
,
J. J.
(
2014
). “
Global distribution of Risso's dolphin Grampus griseus: A review and critical evaluation
,”
Mamm. Rev.
44
,
56
68
.
36.
Jensen
,
F. H.
,
Wahlberg
,
M.
,
Beedholm
,
K.
,
Johnson
,
M.
,
Soto
,
N. A.
, and
Madsen
,
P. T.
(
2015
). “
Single-click beam patterns suggest dynamic changes to the field of view of echolocating Atlantic spotted dolphins (Stenella frontalis) in the wild
,”
J. Exp. Biol.
218
,
1314
1324
.
37.
Juang
,
B.-H.
,
Rabiner
,
L. R.
, and
Wilpon
,
J. G.
(
1987
). “
On the use of bandpass liftering in speech recognition
,”
IEEE Trans. Acoust. Speech Signal Processing
ASSP-35
,
947
954
.
38.
Kaiser
,
J. F.
(
1990
). “
On a simple algorithm to calculate the ‘Energy’ of a signal
,” in
International Conference on Acoustics, Speech, and Signal Processing
(
IEEE
,
Albuquerque, NM
), pp.
381
384
.
39.
Kandia
,
V.
, and
Stylianou
,
Y.
(
2006
). “
Detection of sperm whale clicks based on the Teager-Kaiser energy operator
,”
Appl. Acoust.
67
,
1144
1163
.
40.
Kruse
,
S.
,
Caldwell
,
D. K.
, and
Caldwell
,
M. C.
(
1999
). “
Risso's dolphin Grampus griseus (G. Cuvier, 1812)
,” in
Handbook of Marine Mammals
, edited by
S. H.
Ridgway
and
R.
Harrison
(
Academic Press
,
Cambridge, UK
), pp.
183
212
.
41.
Lux
,
C. A.
,
Costa
,
A. S.
, and
Dizon
,
A. E.
(
1997
). “
Mitochondrial DNA population structure of the Pacific white-sided dolphin
,”
Rep. Int. Whaling Commission
47
,
645
652
.
42.
Madsen
,
P. T.
,
Kerr
,
I.
, and
Payne
,
R.
(
2004
). “
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
.
43.
Mangels
,
K. F.
, and
Gerrodette
,
T.
(
1994
). “
Report of cetacean sightings during a marine mammal survey in the eastern Pacific Ocean and Gulf of California aboard the NOAA ships McARTHUR and DAVID STARR JORDAN July 28–November 6, 1993
,” NOAA-TM-NMFS-SWFSC-211 (U. S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center, La Jolla, CA),
88 pp
.
44.
Marques
,
T. A.
,
Thomas
,
L.
,
Martin
,
S. W.
,
Mellinger
,
D. K.
,
Ward
,
J. A.
,
Moretti
,
D. J.
,
Harris
,
D.
, and
Tyack
,
P. L.
(
2013
). “
Estimating animal population density using passive acoustics
,”
Biol. Rev.
88
,
287
309
.
45.
Martien
,
K. K.
,
Lang
,
A. R.
, and
Taylor
,
B. L.
(
2015
).
“Report of the meeting on the use of multiple lines of evidence to delineate demographically independent populations,”
NOAA TM-NMFS_SWFSC-538 (U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Southwest Fisheries Science Center, La Jolla, CA), 10 pp.
46.
May-Collado
,
L.
,
Agnarsson
,
I.
, and
Wartzok
,
D.
(
2007
). “
Reexamining the relationship between body size and tonal signals frequency in whales: A comparative phylogenetic approach
,”
Mar. Mamm. Sci.
23
,
524
552
.
47.
McDonald
,
M. A.
,
Messnick
,
S. L.
, and
Hildebrand
,
J. A.
(
2006
). “
Biogeographic characterisation of blue whale song worldwide: Using song to identify populations
,”
J. Cetacean Res. Manage.
8
,
55
65
.
48.
McKenna
,
M.
,
Soldevilla
,
M.
,
Oleson
,
E.
,
Wiggins
,
S.
,
Hildebrand
,
J.
,
Damiani
,
C.
, and
Garcelon
,
D.
(
2009
). “
Increased underwater noise levels in the Santa Barbara Channel from commercial ship traffic and the potential impact on blue whales(Balaenoptera musculus)
,” in
Proceedings of the 7th California Islands Symposium
(
Institute for Wildlife Studies
,
Arcata, CA
), pp. 141–149.
49.
McKenna
,
M. F.
,
Cranford
,
T. W.
,
Berta
,
A.
, and
Pyenson
,
N. D.
(
2012
). “
Morphology of the odontocete melon and its implications for acoustic function
,”
Mar. Mamm. Sci.
28
,
690
713
.
50.
Meiri
,
S.
, and
Dayan
,
T.
(
2003
). “
On the validity of Bergmann's rule
,”
J. Biogeogr.
30
,
331
351
.
51.
Mellinger
,
D. K.
, and
Barlow
,
J.
(
2003
). “
Future directions for acoustic marine mammal surveys: Stock assessment and habitat use
,”
NOAA OAR Special Report, NOAA/PMEL Contribution 2557
, 38 pp.
52.
Mellinger
,
D. K.
,
Stafford
,
K. M.
,
Moore
,
S. E.
,
Dziak
,
R. P.
, and
Matsumoto
,
H.
(
2007
). “
Fixed passive acoustic observation methods for cetaceans
,”
Oceanography
20
,
36
45
.
53.
Miller
,
B.
,
Barlow
,
J.
,
Calderan
,
S.
,
Collins
,
K.
,
Leaper
,
R.
,
Olson
,
P.
,
Ensor
,
P.
,
Peel
,
D.
,
Donnelly
,
D.
,
Andrews-Goff
,
V.
,
Olavarria
,
C.
,
Owen
,
K.
,
Rekdahl
,
M.
,
Schmitt
,
N.
,
Wadley
,
V.
,
Gedamke
,
J.
,
Gales
,
N.
, and
Double
,
M.
(
2015
). “
Validating the reliability of passive acoustic localisation: A novel method for encountering rare and remote Antarctic blue whales
,”
Endang. Spec. Res.
26
,
257
269
.
54.
Mizue
,
K.
, and
Yoshida
,
K.
(
1962
).
“Studies on the little toothed whales in the west sea area of Kyusyu–VIII: About Grampus griseus caught in Goto Is., Nagasaki Pref.,”
Bulletin of the Faculty of Fisheries (Nagasaki University, Nagasaki, Japan), Vol.
12
, pp.
45
52
[in Japanese].
55.
Møhl
,
B.
,
Wahlberg
,
M.
,
Madsen
,
P. T.
,
Heerfordt
,
A.
, and
Lund
,
A.
(
2003
). “
The monopulsed nature of sperm whale clicks
,”
J. Acoust. Soc. Am.
114
,
1143
–1154.
56.
Morisaka
,
T.
, and
Connor
,
R. C.
(
2007
). “
Predation by killer whales (Orcinus orca) and the evolution of whistle loss and narrow-band high frequency clicks in odontocetes
,”
J. Evol. Biol.
20
,
1439
1458
.
57.
Munzel
,
U.
, and
Brunner
,
E.
(
2000
). “
Nonparametric methods in multivariate factorial designs
,”
J. Stat. Planning Inference
88
,
117
132
.
58.
Neves
,
S.
(
2013
). “
Acoustic behavior of Risso's dolphins, Grampus griseus, in the Canary Islands, Spain
,” Ph.D. dissertation,
University of St. Andrews
,
St. Andrews, UK
,
162
pp.
59.
Oswald
,
J. N.
,
Barlow
,
J.
, and
Norris
,
T. F.
(
2003
). “
Acoustic identification of nine delphinid species in the eastern tropical Pacific Ocean
,”
Mar. Mamm. Sci.
19
,
20
37
.
60.
Parks
,
S. E.
,
Clark
,
C. W.
, and
Tyack
,
P. L.
(
2007
). “
Short- and long-term changes in right whale calling behavior: The potential effects of noise on acoustic communication
,”
J. Acoust. Soc. Am.
122
,
3725
3731
.
61.
Peel
,
D.
,
Miller
,
B. S.
,
Kelly
,
N.
,
Dawson
,
S.
,
Slooten
,
E.
, and
Double
,
M. C.
(
2014
). “
A simulation study of acoustic-assisted tracking of whales for mark-recapture surveys
,”
PLoS One
9
,
e95602
.
62.
Picone
,
J. W.
(
1993
). “
Signal modeling techniques in speech recognition
,”
Proc. IEEE
81
,
1215
1247
.
63.
Rabiner
,
L.
, and
Juang
,
B.-H.
(
1993
).
Fundamentals of Speech Recognition
(
Prentice Hall
,
Upper Saddle River, NJ)
, 507 pp.
64.
Rankin
,
S.
,
Oswald
,
J. N.
, and
Barlow
,
J.
(
2008
). “
Acoustic behavior of dolphins in the Pacific Ocean: Implications for using passive acoustic methods for population studies
,”
Can. Acoust.
36
,
88
92
, available at <https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1996>.
65.
Rankin
,
S.
,
Oswald
,
J. N.
,
Simonis
,
A. E.
, and
Barlow
,
J.
(
2015
). “
Vocalizations of the rough-toothed dolphin, Steno bredanensis, in the Pacific Ocean
,”
Mar. Mamm. Sci.
31
,
1538
1548
.
66.
R Core Team
(
2014
).
R: A Language and Environment for Statistical Computing
(
R Foundation for Statistical Computing
,
Vienna, Austria
).
67.
Rendell
,
L.
,
Mesnick
,
S. L.
,
Dalebout
,
M. L.
,
Burtenshaw
,
J.
, and
Whitehead
,
H.
(
2012
). “
Can genetic differences explain vocal dialect variation in Sperm whales, Physeter macrocephalus?
,”
Behav. Gen.
42
,
332
343
.
68.
Rice
,
W. R.
(
1989
). “
Analyzing tables of statistical tests
,”
Evolution
43
,
223
225
.
69.
Richardson
,
W.
,
Greene
,
C. J.
,
Malme
,
C.
, and
Thomson
,
D.
(
1995
).
Marine Mammals and Noise
(
Academic Press
,
San Diego, CA)
.
70.
Roch
,
M. A.
,
Klinck
,
H.
,
Baumann-Pickering
,
S.
,
Mellinger
,
D. K.
,
Qui
,
S.
,
Soldevilla
,
M. S.
, and
Hildebrand
,
J. A.
(
2011
). “
Classification of echolocation clicks from odontocetes in the Southern California Bight
,”
J. Acoust. Soc. Am.
129
,
467
475
.
71.
Roch
,
M. A.
,
Stinner-Sloan
,
J.
,
Baumann-Pickering
,
S.
, and
Wiggins
,
S. M.
(
2015
). “
Compensating for the effects of site and equipment variation on delphinid species identification from their echolocation clicks
,”
J. Acoust. Soc. Am.
137
,
22
29
.
72.
Ross
,
G. J. B.
(
1984
). “
The smaller cetaceans of the southeast coast of southern Africa
,”
Ann. Cape Provincial Museums (Natural History)
15
,
147
400
.
73.
Samarra
,
F. I. P.
,
Deecke
,
V. B.
,
Simonis
,
A. E.
, and
Miller
,
P. J. O.
(
2015
). “
Geographic variation in the time-frequency characteristics of high-frequency whistles produced by killer whales (Orcinus orca)
,”
Mar. Mamm. Sci.
31
,
688
706
.
74.
Sherman
,
K.
, and
Alexander
,
L.
(
1986
).
Variability and Management of Large Marine Ecosystems
(
Westview Press
,
Boulder, CO
), 300 pp.
75.
Širovíc
,
A.
, and
Hildebrand
,
J. A.
(
2011
). “
Using passive acoustics to model blue whale habitat off the Western Antarctic Peninsula
,”
Deep Sea Res. Part II: Top. Stud. Oceanogr.
58
,
1719
1728
.
76.
Širovíc
,
A.
,
Wiggins
,
S. M.
, and
Oleson
,
E. M.
(
2013
). “
Ocean noise in the tropical and subtropical Pacific Ocean
,”
J. Acoust. Soc. Am.
134
,
2681
2689
.
77.
Soldevilla
,
M. S.
,
Henderson
,
E. E.
,
Campbell
,
G. S.
,
Wiggins
,
S. M.
,
Hildebrand
,
J. A.
, and
Roch
,
M. A.
(
2008
). “
Classification of Risso's and Pacific white-sided dolphins using spectral properties of echolocation clicks
,”
J. Acoust. Soc. Am.
124
,
609
624
.
78.
Soldevilla
,
M. S.
,
Wiggins
,
S. M.
, and
Hildebrand
,
J. A.
(
2010a
). “
Spatial and temporal patterns of Risso's dolphin echolocation in the Southern California Bight
,”
J. Acoust. Soc. Am.
127
,
124
132
.
79.
Soldevilla
,
M. S.
,
Wiggins
,
S. M.
, and
Hildebrand
,
J. A.
(
2010b
). “
Spatio-temporal comparison of Pacific white-sided dolphin echolocation click types
,”
Aquat. Biol.
9
,
49
62
.
80.
Soldevilla
,
M. S.
,
Wiggins
,
S. M.
,
Hildebrand
,
J. A.
,
Oleson
,
E. M.
, and
Ferguson
,
M. C.
(
2011
). “
Risso's and Pacific white-sided dolphin habitat modeling from passive acoustic monitoring
,”
Mar. Ecol. Prog. Ser.
423
,
247
260
.
81.
Sveegaard
,
S.
,
Galatius
,
A.
,
Dietz
,
R.
,
Kyhn
,
L.
,
Koblitz
,
J. C.
,
Amundin
,
M.
,
Nabe-Nielsen
,
J.
,
Sinding
,
M.-H. S.
,
Andersen
,
L. W.
, and
Teilmann
,
J.
(
2015
). “
Defining management units for cetaceans by combining genetics, morphology, acoustics and satellite tracking
,”
Global Ecol. Conserv.
3
,
839
850
.
82.
Torres-Florez
,
J. P.
,
Hucke-Gaete
,
R.
,
LeDuc
,
R.
,
Lang
,
A.
,
Taylor
,
B.
,
Pimper
,
L. E.
,
Bedriñana-Romano
,
L.
,
Rosenbaum
,
H. C.
, and
Figueroa
,
C. C.
(
2014
). “
Blue whale population structure along the eastern South Pacific Ocean: Evidence of more than one population
,”
Mol. Ecol.
23
,
5998
6010
.
83.
Van Parijs
,
S. M.
,
Clark
,
C. W.
,
Sousa-Lima
,
R. S.
,
Parks
,
S. E.
,
Rankin
,
S.
,
Risch
,
D.
, and
Van Opzeeland
,
I. C.
(
2009
). “
Management and research applications of real-time and archival passive acoustic sensors over varying temporal and spatial scales
,”
Mar. Ecol. Prog. Ser.
395
,
21
36
.
84.
Wade
,
P. R.
, and
Gerrodette
,
T.
(
1993
). “
Estimates of cetacean abundance and distribution in the Eastern Tropical Pacific
,”
Rep. Int. Whaling Commission
43
,
477
493
.
85.
Walker
,
W. A.
,
Leatherwood
,
S.
,
Goodrick
,
K. R.
,
Perrin
,
W. F.
, and
Stroud
,
R. K.
(
1986
).
“Geographic variation and biology of the Pacific white-sided dolphin, Lagenorhynchus obliquidens, in the north-eastern Pacific,”
in
Research on Dolphins
, edited by
M. M.
Bryden
, and
R.
Harrison
(
Clarendon Press
,
Oxford, UK
), pp.
441
465
.
86.
Waring
,
G. T.
,
Josephson
,
E.
,
Maze-Foley
,
K.
, and
Rosel
,
P. E.
(
2014
). “
U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments - 2013
,” NOAA-TM-NMFS-NE-228 (US Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service, Northeast Fisheries Science Center, Woods Hole, MA),
475
pp.
87.
Wiggins
,
S. M.
,
Hall
,
J.
,
Thayre
,
B. J.
, and
Hildebrand
,
J. A.
(
2016
). “
Gulf of Mexico low-frequency ocean soundscape dominated by airguns
,”
J. Acoust. Soc. Am.
140
,
176
183
.
88.
Wilcox
,
R. R.
(
2005
).
Introduction to Robust Estimation and Hypothesis Testing
, 2nd ed. (
Elsevier
,
Burlington, MA
), 588 pp.
89.
Winn
,
H. E.
,
Thompson
,
T. J.
,
Cummings
,
W. C.
,
Hain
,
J.
,
Hudnall
,
J.
,
Hays
,
H.
, and
Steiner
,
W. W.
(
1981
). “
Song of the Humpback Whale - population comparisons
,”
Behav. Ecol. Sociobiol.
8
,
41
46
.
90.
Zar
,
J. H.
(
1999
).
Biostatistical Analysis
(
Prentice Hall
,
Upper Saddle River, NJ
), 663 pp.
You do not currently have access to this content.