Hawaiian Melon-headed Whale (Peponacephala electra)

Mass Stranding Event of July 3-4, 2004 

Brandon L. Southall, Robert Braun, Frances M.D. Gulland, Ashley D. 

Heard, Robin W. Baird, Sarah M. Wilkin, and Teri K. Rowles 

Photo by Gretchen Johnson 

U.S. Department of Commerce 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

NOAA Technical Memorandum NMFS-OPR-31 

April 2006 
THIS PAGE INTENTIONALLY LEFT BLANK
Hawaiian Melon-headed Whale (Peponacephala electra)

Mass Stranding Event of July 3-4, 2004 

Brandon L. Southall, Ph.D.1 

Robert Braun, D.V.M.2 

Frances M.D. Gulland, Vet. MB, MRCVS, Ph.D.3 

Ashley D. Heard4 

Robin W. Baird, Ph.D.5 

Sarah M. Wilkin, M.S.6 

Teri K. Rowles, D.V.M., Ph.D.6 

1

Director, NOAA Oceans Acoustics Program, National Marine Fisheries Service, Office of Science and Technology, 

1315 East West Highway, SSMC III, Silver Spring, MD 20910 2 Hawaiian Islands Stranding Response Group, 47-928 Kamakoi Road, Kane’ohe, Hawaii 96744 3

 Director, Research and Veterinary Services, The Marine Mammal Center, Marin Headlands, 1065 Fort Cronkhite, 

Sausalito, California 94965 

4 University of Hawai‘i at Hilo, 200 W. Kawili St., Hilo, HI, 96720 

5

 Cascadia Research, 218 1⁄2 W 4th Avenue, Olympia, Washington 98501 6

 Marine Mammal Health and Stranding Response Program, Office of Protected Resources, NOAA National Marine 

Fisheries Service, 1315 East West Highway, Silver Spring, Maryland 20910 

NOAA Tec Me andum NMFS-OPR-31 hnical mor

April 2006 

U.S. Department of Commerce 

Carlos Gutierrez, Secretary 

National Oceanic and Atmospheric Administration 

Vice Admiral Conrad C. Lautenbacher, Jr. USN (Ret), 

Under Secretary for Oceans and Atmosphere 

National Marine Fisheries Service 

William T. Hogarth, PhD., Assistant Administrator for Fisheries 
Suggested citation: 

Southall, B. L., R. Braun, F. M. D. Gulland, A. D. Heard, R. W. Baird, S. M. Wilkin and 

T. K. Rowles. 2006. Hawaiian melon-headed whale (Peponocephala electra) mass 

stranding event of July 3-4, 2004. NOAA Technical Memorandum NMFS-OPR-31. 73 

pp.

A copy of this report may be obtained from: 

Office of Protected Resources 

NOAA, NMFS, F/PR2 

1315 East West Highway 

Silver Spring, Maryland 20910 

Or online at: 

http://www.nmfs.noaa.gov/pr/
Table of Contents

Page 

Executive Summary.............................................................................................................1 

Introduction .........................................................................................................................3 

Background on species and sightings..................................................................................4 

 Historical strandings 

 

Overview of events............................................................................................................12 

Post-Mortem Examination.................................................................................................18 

 Imaging 

 Gross Findings 

 Histopathology 

 Biological Factors 

Environmental Analysis.....................................................................................................26 

 Physical Factors 

 Wind and sea surface temperatures 

 Harmful Algal Blooms 

Military Exercises..............................................................................................................31 

Acoustic Analysis..............................................................................................................37 

Conclusion.........................................................................................................................43 

Literature Cited..................................................................................................................48 

Appendices........................................................................................................................56 
Executive Summary 

On July 3-4, 2004, between 150-200 melon–headed whales (Peponocephala electra) 

occupied the shallow waters of Hanalei Bay, Kaua‘i, Hawai‘i for over 28 hours. Attendees of a 

canoe blessing observed the animals entering the Bay in a single wave formation at 0700 hrs1

(local time) on July 3, 2004. The animals were observed moving back into shore from the 

mouth of the Bay at 0900 hrs. The usually pelagic animals milled in the shallow confined bay 

and were returned to deeper water with human assistance. The animals were herded out of the 

Bay with the help of members of the community, the Hanalei Canoe Club, local and federal 

employees, and volunteers/staff with the Hawaiian Islands Stranding Response Group 

beginning at 0930 on July 4, 2004 and were out of visual sight by 1030 hrs. 

Only one animal, a calf, was known to have died (on July 5, 2004) following this 

event. The animal was noted alive and alone in the Bay on the afternoon of July 4, 2004 and 

was found dead in the Bay the morning of July 5, 2004. On July 7, 2004, a full necropsy, 

magnetic resonance imaging, and computerized tomography examination were performed on 

the calf to determine the manner and cause of death. The combination of imaging, necropsy 

and histological analyses found no evidence of infectious, internal traumatic, congenital, or 

toxic factors. Although cause of death could not be definitively determined, it is likely that 

maternal separation, poor nutritional condition, and dehydration contributed to the final 

demise of the animal. Although we do not know when the calf was separated from the female, 

the movement into the Bay, the milling and re-grouping may have contributed to the 

separation or lack of nursing especially if the maternal bond was weak or this was a 

primiparous calf. 

Environmental factors, abiotic and biotic, were analyzed for any anomalous 

occurrences that would have contributed to the animals entering and remaining in Hanalei 

Bay. The bathymetry is similar to many other sites within the Hawaiian Island chain and 

dissimilar to that which has been associated with mass strandings in other parts of the U.S. 

The weather conditions appear to be normal for this time of year with no fronts or other 

significant features noted. There was no evidence for unusual distribution or occurrence of 

predator or prey species, or unusual harmful algal blooms. Weather patterns and bathymetry 

that have been associated with mass strandings elsewhere were not found to occur in this 

instance. 

This event was spatially and temporally correlated with Rim of the Pacific Exercises 

(RIMPAC) which is a biennial, sea control/power projection fleet exercise that has been 

conducted since 1968 and involves U.S. forces and forces from various Rim-of-the-Pacific 

nations. Official sonar training and tracking exercises in the Pacific Missile Range Facility 

(PMRF) warning area did not commence until approximately 0800 hrs (local time) on July 3 

and were thus ruled out as a possible trigger for the initial movement into the Bay. 

However, the six naval surface vessels transiting to the operational area on July 2 

intermittently transmitted active sonar [for ~ 9 hours total from 1315 to 0030] as they 

approached from the south. The potential for these transmissions to have triggered the 

whales’ movement into Hanalei Bay was investigated. Analyses with the information 

available indicated that animals to the south and east of Kaua‘i could likely have detected 

active sonar transmissions on July 2, and reached Hanalei Bay on or before 0700 on July 3, 

 

1

 This time is set by reliable observations and a canoe blessing ceremony 

1
2004. However, data limitations regarding the position of the whales prior to their arrival in 

the Bay, the magnitude of sonar exposure, behavioral responses of melon-headed whales to 

acoustic stimuli, and other possible relevant factors preclude a conclusive finding regarding 

the role of sonar in triggering this event. Propagation modeling suggest that transmissions 

from sonar use during the July 3 exercise in the PMRF warning area may have been detectable 

at the mouth of the Bay. If the animals responded negatively to these signals, it may have 

contributed to their continued presence in the Bay. The U.S. Navy ceased all active sonar 

transmissions during exercises in this range on the afternoon of July 3, 2004. Subsequent to 

the cessation of sonar use, the animals were herded out of the Bay. 

While causation of this stranding event may never be unequivocally determined, we 

consider the active sonar transmissions of July 2-3, 2004, a plausible, if not likely, 

contributing factor in what may have been a confluence of events. This conclusion is based 

on: (1) the evidently anomalous nature of the stranding; (2) its close spatiotemporal correlation 

with wide-scale, sustained use of sonar systems previously associated with stranding of deepdiving marine mammals; (3) the directed movement of two groups of transmitting vessels 

toward the southeast and southwest coast of Kaua‘i; (4) the results of acoustic propagation 

modeling and an analysis of possible animal transit times to the Bay; and (5) the absence of 

any other compelling causative explanation. The initiation and persistence of this event may 

have resulted from an interaction of biological and physical factors. The biological factors 

may have included the presence of an apparently uncommon, deep-diving cetacean species 

(and possibly an offshore, non-resident group), social interactions among the animals before or 

after they entered the Bay, and/or unknown predator or prey conditions. The physical factors 

may have included the presence of nearby deep water, multiple vessels transiting in a directed 

manner while transmitting active sonar over a sustained period, the presence of surface sound 

ducting conditions, and/or intermittent and random human interactions while the animals were 

in the Bay. 

 

2
MASS STRANDING EVENT IN HANALEI BAY, 

KAUA‘I, JULY 3-4, 2004 

Introduction 

On July 3-4, 2004, between 150 and 200 melon–headed whales (Peponocephala electra) 

occupied the shallow waters of Hanalei Bay, Kaua‘i, Hawai‘i for over 28 hours. The group 

was observed by attendees of a canoe blessing quickly entering the Bay as a wave across the 

mouth of the Bay with animals side by side at 0700 hrs2

 (local time) on July 3, 2004. The 

animals made at least one movement out of the Bay before 0900 because they were observed 

moving back to shore from the mouth of the Bay at 0900 hrs by a life guard reporting for duty 

(Souza, interview with life guard). Once back in the Bay, the animals exhibited spy hopping 

and tail slapping behaviors, as well as vocalizations. The usually pelagic animals stayed in the 

shallow, confined Bay and were returned to deeper water with human assistance. With the 

help of volunteers and staff of the Hawaiian Islands Stranding Response Group, the Hanalei 

Canoe Club, community members and the federal and state authorities, the group of animals 

was herded out of the Bay beginning at 0930 on July 4, 2004 and was out of visual sight by 

1030 hrs. On the afternoon of July 4, a lone animal was observed swimming in the Bay. A 

melon-headed whale calf was found dead in Hanalei Bay on July 5, 2004 and the carcass was 

flown to California for scanning and necropsy, which occurred on July 7, 2004. This event 

was coincident with military training exercises in the Hawaiian Islands, and therefore 

immediate interaction between the National Marine Fisheries Service and the US Navy 

commenced on the day of the event initiation. By evaluating factors for which there was 

information, this investigation focused on the overall event and its three sub-portions: 1) Why 

did the animals move into the Bay?; 2) Why did the animals remain in the Bay?; and 3) Why 

did the calf die? 

 

2

 This time is set by reliable observations and a canoe blessing ceremony 

3
Background on species and sightings 

Melon-headed whales (Peponocephala electra) are small odontocetes found in tropical and 

warm-temperate waters throughout the world (Perryman et al., 1994) with a general 

distribution from 20°S to 20°N (Jefferson and Barros, 1997). Melon-headed whales prefer 

deep, equatorial ocean waters (Watkins et al., 1997), and are thought to feed deep in the water 

column because one of their primary prey, mesopelagic squid, are found in waters up to 1,500 

m (4,920 ft) deep (Jefferson and Barros, 1997). Most knowledge about the biology of this 

species comes from mass strandings (Perryman et al., 1994). 

Melon-headed whales have been seen over a range of depths (255-4,407 m) off all the main 

Hawaiian Islands (Shallenberger, 1981; Baird et al., 2003; Huggins et al., 2005). An analysis 

of sighting distribution in relation to effort from 2000-2005 indicates that melon-headed 

whales in Hawai‘i are found more frequently in depths greater than 2,000 m (Huggins et al., 

2005). Huggins et al. (2005) reported that only one of 18 encounters with melon-headed 

whales occurred off the island of Kaua‘i in these surveys (Table 1). However only about 11% 

of the total search effort was off that island, and much of the search effort was in relatively 

shallow water (Baird, unpublished). Aerial surveys for humpback whales from 1993-1999, 

reported only three sightings with a total number of 127 animals observed (Mobley et al., 

1999a). From 2001 – 2004 the same surveyors reported only one sighting of 10 individuals 

(Mobley 2001, 2002, 2003, 2004). However, discriminating between melon-headed whales 

and pygmy killer whales in the field is difficult and may have lead to misidentifications in 

these aerial surveys. 

Median melon-headed whale group size around the main Hawaiian Islands from boat-based 

surveys was 305 individuals, with a range from 17-800 animals (Huggins et al., 2005). 

Watkins et al. (1997) reported groups of only 10-14 for the Caribbean. Although no studies of 

social organization have been undertaken, it appears that large groups tend to consist of many 

closely-spaced subgroups (Jefferson and Barros, 1997) that come together to socialize or for 

calving. Melon-headed whales are often seen with other species of cetaceans, including 

Fraser’s dolphins (Lagenodelphis hosei) (Mullin et al., 1994), rough-toothed dolphins (Steno 

bredanensis) (Huggins et al., 2005), and short-finned pilot whales (Globicephla 

macrorhynchus) (Migura and Meadows, 2002). Little is known about this species elsewhere in 

its range, due to its inaccessibility and apparent avoidance of vessels (Huggins et al., 2005). 

Two abundance estimates have been reported from Hawaiian waters. Based on a shipboard 

line-transect survey of the entire Hawaiian Islands Exclusive Economic Zone (EEZ) in 2002, 

Barlow (2006) calculated an estimate of 2,950 melon-headed whales in Hawaiian waters, 

though the estimate is very imprecise (CV = 1.17). Data from 12 aerial surveys in 1993, 1995, 

and 1998, were used to estimate abundance, resulting in an estimate of only 154 melon-headed 

whales (CV = .88) (Mobley et al., 2000). This study underestimated the total number of 

melon-headed whales within the U.S. EEZ off Hawai‘i, because areas around the 

Northwestern Hawaiian Islands (NWHI) and beyond 25 nautical miles (46.3 km) from the 

main Hawaiian Islands were not surveyed. Since melon-headed whales are found more 

frequently in waters deeper than 2,000 m, the aerial surveys likely covered only the inshore

4
Table 1. Search effort by island area from Baird/Cascadia Research small-boat surveys 

(Huggins et al., 2005; Baird, unpublished). Effort is greatest and in deeper water off the island 

of Hawai‘i than around other islands, which is reflected in differences in number of sightings. 

# km on 

effort 

# days 

effort 

# hrs on 

effort Island area Dates 

Apr 2002 1,089 10 75 

Sep/Oct 2002 1,649 20 154 

May 2003 1,791 15 108 

Hawai‘i Oct 2003 2,495 24 173 

Sep-Dec 2004 4,656 42 290 

Jan/Feb 2005 2,089 17 124 

Sub-total 13,769 128 922 

May/Jun 2003 3,222 24 195 

Kaua‘i/Ni‘hau Oct/Nov 2005 2,194 24 145 

Sub-total 5,416 48 340 

Feb -Apr 2000 1,600 23 158 

Nov/Dec 2000 2,032 21 150 

Jan-Mar 2001 2,102 28 203 Maui/Lana‘i Apr 2002 785 9 64 

May 2003 1,659 16 107 

Sub-total 8,178 97 682 

Apr/May 2002 860 9 57 

O‘ahu May 2003 1,789 13 111 

Sub-total 2,649 22 168 

Total 30,012 295 2,114 

part of the range of this population. Ongoing photo-identification efforts from 2000-2005 have 

documented over 300 distinctive individual melon-headed whales from around the main 

Hawaiian Islands (Huggins et al., 2005). Photographs are available for a mark-recapture 

population estimate around the main Hawaiian Islands, but these analyses have not yet been 

undertaken (Baird, unpublished). Inter-island movements from Kaua‘i to Hawai‘i have been 

documented based on photo-identified individuals, and genetic samples from at least 82 

animals are available for future stock structure analyses (Baird, unpublished). Even though 

increased attention has been paid to this species in recent years, detailed information about the 

population structure and abundance of these animals is still largely unknown (Huggins et al., 

2005). 

5
a. 

18.5

19

19.5

20

20.5

21

21.5

22

22.5

-161 -160 -159 -158 -157 -156 -155

Longitude (degrees W)

Latitude (degrees N) 

Kaua‘i 

O‘ahu 

Maui 

20.5

20.7

20.9

21.1

21.3

21.5

21.7

21.9

22.1

1 -160.5 -160 -159.5 -159 -158.5 -158

Longitude (degrees W)

Latitude (degrees N) 

22.3

22.5

-16

b.

18.8

19

19.2

19.4

19.6

19.8

20

20.2

20.4

-156.5 -156.3 -156.1 -155.9 -155.7 -155.5

Longitude (degrees W)

Latitude (degrees N)

Hawai‘i 

Hawai‘i 

c. 

Kaua‘i 

Figure 1. Maps showing distribution of melon-headed whales (green diamonds) and survey 

effort (red lines) from small boat surveys a) around the main Hawaiian Islands, b) off the coast 

of Hawai‘i, and c) off the coast of Kaua‘i from 2000 through 2005 (Baird, unpublished). 

Historical Strandings

Marine mammals that mass strand are usually more social and pelagic animals which are often 

less accustomed to shallow or in-shore habitats (Geraci and Lounsbury, 1993; 2005). The 

causes of mass strandings are varied and more often than not unexplained. They may occur 

when animals move into shallow waters following specific weather or oceanographic events, 

extreme tidal events, predator detection at the outlet of the area, due to illness or injury of 

individuals, when animals become trapped or confused chasing prey, or the effort of a group 

to help an already injured or stranded member. 

6
Minimum 

Number Date Location Scenario References 

60 1841 Hilo Bay, Hawai‘i 

Animals driven 

ashore CDD; Peale 1848; Tomich 1986 

109 Oct 1957 Heng-chun, Taiwan Live Stranding Yang 1964, 1976; Wang et al. 2001 

Dawbin 1963; Dawbin et al. 1970; 

150 Aug 1958 Crowdy Heads, Australia Live Stranding Noble and Fraser 1970 

4 Apr 1964 Palmyra Atoll, Line Islands Stranding Brownell et al. 2006 

Animals in 

bay; driven 

ashore 3 250 23 Mar 1965 Suruga Bay, Japan Nishiwaki and Norris 1966 

231 Nov 1972 Malekula Island, Vanuatu Live Stranding Rancurel 1973,1974; CSLP 1973 

Stranding 

Questionable 

 Best & Shaughnessy 1981; 

6 Sep 1974 Aldabra Atoll, Seychelles Leatherwood et al. 1991. 

Large # 

animals 

nearshore; Live 

87 11 Aug 1976 Stranding 

Moreton Island, Queensland, 

Australia 

Bryden et al. 1977; Bannister et al.

1996; Cannon 1977. 

2000 animals 

in bay; 

148 13 Oct 1976 Playa Tambor, Costa Rica Stranding Lodi et al. 1990 

135 6 Jan 1982 Aoshima Beach, Japan Live Stranding Miyazaki 1983; Morimitsu 1983 

Da Silva et al. 1987; Lodi et al.1990; 

240 16 Apr 1987 Piracanga Beach, Brazil Live Stranding Siciliano et al. 1987. 

30 19 Feb 1990 Akashi Beach, Japan Live Stranding Brownell et al. 2006 

Animals in 

lagoon 1-2 wks 

prior; Live 

5 Nov 1993 Stranding 

Kwajelein Atoll, Marshall 

Islands Reeves et al. 1999 

Before Oct 

6 1994 Lembel Strait, Indonesia Stranding Rudolph et al. 1997 

Point Plomer, New South 

7 Nov 1995 Wales, Australia Live Stranding Bannister et al. 1996 

120 Dec 1997 

Eurong Beach, Fraser Island, 

Australia Live Stranding Anonymous 1999. 

3 17 Feb 1998 Playa Tucacas, Venezuela Live Stranding Bolanos and Villarroel 2003. 

50 11 Feb 2001 Hasaki, Japan Live Stranding Cetacean News 2001 

Live Stranding 

[some of same 

animals as 11 

15 14 Feb 2001 Oarai, Japan Feb] Brownell et al. 2006. 

171 10 Mar 2001 Nakatane, Japan Live Stranding Brownell et al. 2006 

24-25 Feb 

2002 

Live and Dead 

91? Hasaki, Japan Stranding Brownell et al. 2006 

 

3

 It was reported that 500 animals came into the bay and half were captured. Other details unknown. 

7
4 150+ 3 Jul 2004 Hanalei Bay, Hawai‘i Live Stranding This report 

Sal Island, Cape Verde 

9 1 Nov 2005 Archipelago Live Stranding Brownell et al. 2006 

26 22 Jan 2006 Asahi, Japan Live Stranding Brownell et al. 2006 

3 22 Feb 2006 Ichinomiya and Isumi, Japan Live Stranding Brownell et al. 2006 

120 28 Feb 2006 Ichinomiya, Japan Live Stranding Brownell et al. 2006 

> 20 animals 

nearshore; live 

and dead 

stranding 

26-29 Mar 

2006 

Vero Beach and Hutchinson 

5 Island, Florida NMFS stranding database 

Table 2. List of melon-headed whale (Peponocephala electra) mass strandings worldwide, as 

recorded in the Cetacean Distribution Database, National Museum of Natural History, 

Smithsonian Institution. 

Melon-headed whales are known to strand both in single stranding events and in mass 

stranding events in numbers of 100 or more individuals per event (Miyazaki et al., 1995). A 

mass stranding is an event which involves two or more cetaceans (excluding female/calf pairs) 

which are found ashore alive or dead and which are spatially and temporally correlated 

(Wilkinson, 1991; Geraci and Lounsbury, 1993). Table 2 provides a list of mass stranding 

events of more than three individuals of melon headed whales using data obtained from cited 

references, the Cetacean Distribution Database (Smithsonian Institute), and Brownell et al.

(2006). A recent report (Brownell et al, 2006) lists a total of 25 mass stranding events or near 

mass stranding events from 1841 to 2006 including this event with 6 of those events reported 

after 2004 (Table 2). In many cases, actual beach mass strandings for this species are 

preceded by large numbers of live animals near shore or in bays or lagoons. The actual 

number of animals that beach stranded or died in these events has ranged from 4 to 250 

animals. At least 50% of the reported mass strandings have included more than 100 animals 

per event. Mass stranding events were documented involving more than 200 melon-headed 

whales on Piracanga Beach, Brazil in 1987 (Da Silva et al., 1987) and 231 animals in 

Malekula Island, Vanuatu in 1972 (Rancurel, 1973). There was one additional mass event in 

Hawaii in 1841 which was described as animals driven ashore in Hilo Bay, Hawai‘i (Peale, 

1848). The only other mass events involving 3 or more of this species in the United States 

were animals that were seen close to the shores of Sebastian, Florida on March 26, 2006 and 5 

animals that stranded on Vero Beach and in Stuart, Florida on March 29, 2006. 

Historically, of the 17 species of cetaceans regularly documented around the main Hawaiian 

islands, the most commonly stranded species in Hawai‘i are the humpback whale (Megaptera 

novaeangliae), the spinner dolphin (Stenella longirostris), the pygmy sperm whale (Kogia 

breviceps), the striped dolphin (Stenella coeruleoalba), and the sperm whale (Physeter 

5 macrocephalus) . Melon headed whales are not a common species to strand in Hawai‘i, with 

 

4

 This is considered a live stranding. 

5

 These data were obtained from the Cetacean Stranding Database, compiled by National Marine Fisheries 

Service, Office of Protected Resources, NOAA. 

8
Minimum 

Number Date Location Scenario Sources 

60 1841 Hilo Bay, Hawai‘i 

Animals 

driven ashore 

CDD; Peale 1848; Tomich 

1986 

1 Before 1875 Hawai‘i Unknown 

True 1889; Van Beneden and 

Gervais 1880 

1 24 Mar 1955 Wailupe Circle, O‘ahu Stranding CDD; Shallenberger 1981 

CDD; Nishiwaki and Norris 

1966; Dawbin, Noble and 

1 27 Jun 1964 Kahuku, O‘ahu Stranding Fraser 1970. 

CDD; Nishiwaki and Norris 

1 15 Jun 1965 Lahaina, Maui Stranding 1966; Maldini et al. 2005 

1 17 Dec 1966 Off Mahukona, Hawai‘i Capture Anon 1966 

1 27 Aug 1971 Keehi Lagoon, O‘ahu Stranding CDD; Shallenberger 1981 

1 17 Sep 1971 Kahuku, O‘ahu Stranding CDD; Shallenberger 1981 

Dead 

1 14 Jul 1976 Punaluu, O‘ahu Stranding CDD; SEAN 2001 

1 26 Sep 1978 12 miles off Waianae, O‘ahu Capture CDD 

1 26 Oct 1978 15 miles off Pokai Bay, O‘ahu Capture RLB 

1 12 Aug 1982 Kihei, Maui Stranding RLB 

1 Jun 1983 Makaha, O‘ahu Stranding 

Nitta 1991; Maldini et al.

2005 

CDD; Consiglieri 1985; 

1 26 Aug 1985 Mokuleia, O‘ahu Live Stranding Maldini et al. 2005 

Dead 

Stranding 

CDD; Consiglieri 1986; 

1 24 Mar 1986 Paia, Kuau Bay, Maui Maldini et al. 2005 

Nitta 1991; Maldini et al.

1 15 Oct 1988 Mokueia, O‘ahu Stranding 2005 

Dead 

Stranding 

CDD; NMFS 1993; Maldini 

1 10 Jan 1993 Ko Olina Resort, O‘ahu et al. 2005 

1 Jun 1995 Brennecke's Beach, Kaua‘i Stranding Maldini et al. 2005 

1 May 1996 Makaha, O‘ahu Stranding Maldini et al. 2005 

1 11 Apr 1998 Keauhou Bay, Hawai‘i Live Stranding Maldini et al. 2005 

NMFS Stranding Database; 

1 10 Sept 2001 Mokuleia, O‘ahu Stranding Maldini et al. 2005 

2 19 Aug 2003 Hauula Beach, O‘ahu Live Stranding NMFS Stranding Database 

1 25 Aug 2005 Waimanalo, O‘ahu Stranding NMFS Stranding Database 

Table 3. List of melon-headed whale (Peponocephala electra) strandings and captures in Hawai‘i 

as recorded in the Cetacean Distribution Database, National Museum of Natural History, 

Smithsonian Institute and the Marine Mammals Stranding Database, National Marine Fisheries 

Service. This table also includes captures from near shore waters as a minimal indication of species 

presence in near shore waters. 

9
only 17 confirmed strandings of 18 individuals recorded for all the Hawaiian islands from 

1964 to 2005 (Table 3 and Fig. 2)6

. However, there was no major effort to report strandings 

until the late 1970s, and even then, there was not continuous consistent effort for detection or 

reporting of marine mammal strandings through the 1980s and early 1990s. From the mid1990s to present there has been an organized network and regional attention paid to consistent 

reporting and documentation of strandings. From 1995 to 2005 (excluding this event), 7 

individual melon headed whales have been reported stranded, 5 on O‘ahu, 1 on Kaua‘i, and 1 

on Hawai‘i. It must be noted that in the historic reports, most strandings have occurred on 

O‘ahu which has had more consistent historical reporting effort. Previously there have been 

three mass events involving melon-headed whales reported in Hawai‘i, a suspected drive 

fishery or hunt in 1841 in which 60 whales were driven ashore by natives in Hilo Bay, Hawai‘i 

(Peale, 1848), a capture of two individuals in 1978 in O‘ahu, and a live stranding of two adult 

males in August 2003 in O‘ahu. The exact details of the animals in the 1841 event milling in 

shallows or near shore before the capture or drive are unknown. Despite records of melonheaded whale strandings elsewhere in the world, there has been only one other mass event in 

the United States in the last thirty years. Therefore, the Hanalei Bay stranding event of 2004 

was anomalous for the U.S.

 

6

 These data were obtained from the Cetacean Distribution Database, compiled by the Marine Mammal Program, 

National Museum of Natural History, Smithsonian Institution, the Cetacean Stranding Database, compiled by 

NMFS, Office of Protected Resources, NOAA, and Brownell et al. 2006. 

10
Figure 2. All recorded instances of melon whale strandings and captures in: a) the main 

Hawaiian Islands; b) on O‘ahu and Kaua‘i, and c) on O‘ahu. These data are summarized in 

Table 3. Red circles are strandings of single animals, the yellow circle is a mass stranding of 2 

adult males, and the green diamonds represent captures of live animals, both at sea and near 

shore. Bathymetry data from the GEBCO Digital Atlas, British Oceanographic Data Centre. 

a 

Kaua‘i 

O‘ahu

Maui

Hawai‘i 

Kaua‘i 

O‘ahu 

O‘ahu

b c

11
Overview of Events 

The group of melon–headed whales entered the Bay at around 0700 hrs (local time) July 

3, 2004, a time fixed by a canoe blessing ceremony and reliable observations (personal 

communication from beach interviews). The animals entered the Bay side by side in a 

single wave formation. The animals initially came into the SSW portion of the Bay and 

were first spotted approximately 91 m (100 yards) off shore from the Pine Trees area (see 

Fig. 3a). Table 4 provides a timeline of the activities and the progression of the event 

and Figures 4 and 5 provide images of the event (provided by Jean Souza). 

People were entering the water intermittently and chaotically throughout the day and 

interacting with the whales. During this time, the animals separated into as many as four 

subgroups, with individuals moving between groups. At approximately 1600 hrs Kaua‘i 

police and Division of Conservation and Resources Enforcement (DOCARE) arrived and 

ordered people from the water. During most of the day, the animals stayed between the 

Pavilion and pine trees areas with approximately 550-731 m (6-800 yards) between 

groups (see Figure 3b). The smaller groups coalesced back into one large group once 

Table 4. Timeline of melon-headed whale movements in this event as reported in field 

reports received by NMFS. 

Event Time Date 

Group of whales enter SW part of Bay – 91 m from shore 0700 July 3, 2004 

0900 (when 

lifeguard 

came on 

duty) 

Group of whales moved cohesively from East side of Bay to 

center and then headed out of Bay, but immediately turned 

around and returned to the East side of the Bay July 3, 2004 

The large group split into up to 4 smaller subgroups, which 

spread out over 600-800 yards between the Pavilion and the Pine 

Trees to the South; public (human) interaction with whales 

Throughout 

day July 3, 2004 

Kaua‘i police and DOCARE ordered public away from animals; 

animals reformed into one cohesive group within 100 yards of 

shore near Pavilion beach Park 1600 July 3, 2004 

Animals noted swimming in tight circles After 1600 July 3, 2004 

NMFS and HSRG personnel arrived in Kaua‘i, assessed 

situation, and noted that no animals had stranded; developed 

intervention plan 2030 July 3, 2004 

Throughout 

night 

July 3-4, 

Volunteers hold beach watch near group 2004 

Herding of group to open water begins (8 canoes and 30+ 

kayaks) 0930 July 4, 2004 

Group of whales departed Bay and were no longer in sight 1030 July 4, 2004 

First reports of lone young animal (calf) in Bay 1300 July 4, 2004 

Animal stranded and pushed back out Before 0900 July 5, 2004 

Calf found dead 0900-1000 July 5, 2004 

Calf shipped via Federal Express to California afternoon July 5, 2004 

Calf necropsied N/A July 7, 2004 

12
people left the water. When the group was spotted 69 m (75 yards) from the Pavilion on 

the Southeast part of the Bay at around 1920 hrs (local time), the animals were observed 

to be swimming in tight circles (Fig. 4a). There were no reports of fresh injuries on the 

animals or of any predators (e.g., sharks or killer whales) seen in and at the mouth of the 

Bay. Tail slapping behavior, large amounts of whistling vocalization and some spy 

 

a b

Pavilion 

Pine Trees 

 

c d

Figure 3. Maps of animal movements in the Hanalei Bay stranding event. Aerial photograph 

from the US Geologic Survey. a) The animals entered the Bay and were first observed at 0700 

on July 3 (red star); b) Between 0930-1600 the animals moved (red ellipse) in several 

subgroups between the Pavilion and the pine trees (yellow circles), forming back up into a 

cohesive group around 1600 (red star); c) At dawn on July 4, animals were observed near the 

pier (open circle); After 0930, using the lau, the animals were herded across the Bay and out 

into deeper water; d) The calf was first observed by the pier at 1300 on July 4 (red dot), was 

found stranded at Lumahai Beach on the morning of July 5, pushed out, and later stranded on 

July 5 by the pier in Hanalei Bay (red star). 

13
hopping continued for several hours. The animals remained in the Bay overnight, and on 

the morning of July 4, 2004, were observed south of the pier and within 182 -274 m (2-

300 yards) of the boats that extended from the end of the pier to the SW. The animals 

made little effort to move south and west along the shore. 

Due to the coincidence of this event with the Rim of the Pacific naval exercises, NMFS 

initiated discussions with the US Navy early in the event and continued discussions with 

the U.S. Navy throughout the event. The findings and actions relative to U.S. Navy 

activities are discussed later in this document. 

At daylight on July 4, 2004 the animals were observed in the same position in one large 

group. Therefore the decision was made to implement the plan to herd the animals out of 

the Bay with coordinated human intervention. On July 4, 2004, at 0930 hrs (local time) a 

‘lau’ or floating strand of woven vines (Fig. 4b) about 213 m (700 feet) long was tied 

between two canoes and used to herd animals out of the Bay (Fig. 3c). A further 30-40 

kayaks were positioned behind the canoes and lau to assist in encouraging the animals 

out from inside the pier and moored boats. Once the lau drifted within 9 m (10 yards) of 

the group, the animals moved toward it. After calmly investigating the lau, nosing up to 

it, the animals turned NNW away from the lau toward the opposite shore. Three to five 

larger animals swam ahead of the group toward the far side of the Bay where they found 

shallow water again and then turned north toward open water. As the lead animals and 

group gathered speed additional canoes and the kayaks extended the U–shape of the 

towed lau and moved north toward open water behind the animals. The animals exited 

the Bay at a rapid pace exhibiting porpoising behavior into deeper water and were out of 

sight of the beach observers at approximately 1030 hrs. 

14
photo by Gretchen Johnson 

a 

Photo by Jean Souza, NOAA 

b

Photo by David Boynton 

c 

15

Figure 4. Photos of the events surrounding the strandings. a) animals swimming in tight circles; b) 

Kainoa Forrest of Hanalei Canoe Club demonstrates twisting the beach morning glory vine to make 

the lau; c) and d) deploying the lau; e) NOAA staff tracking the movements of the whales out of 

Hanalei Bay 

photo by David Boynton 

e

d

photo by Jean Souza, NOAA 
 

f 

 

photo by Jean Souza, NOAA 

g

photo by Jean Souza, NOAA 

h 

photo by 

 Jean Souza 

 NOAA 

Figure 5. Photos of the events surrounding the strandings con’t. f) impromptu public 

outreach and education station set up by NOAA staff; g) Marlee Breese of the Hawaiian 

Islands Stranding Response Group (HISRG) giving media interviews; h) Dr. Bob Braun of 

HISRG and Kainoa Forrest of Hanalei Canoe Club addressing the community volunteer 

participants. 

16
A single small cetacean was first reported at 1300 hrs (local time; approximately 2.5 hours 

after the group left the Bay) on July 4, 2004 alone near the pier. The animal was observed for 

approximately an hour and then it was lost from sight as it traveled from the Hanalei Bay area 

northwest to Lumahai Beach. The animal was found stranded alive on Lumahai Beach early in 

the morning on July 5, 2004, but was pushed back into the water (Fig. 3d). The animal was 

then found dead at around 0900 – 1000 hrs (local time) again near the pier in Hanalei Bay 

(Fig. 6). The carcass was retrieved and held in cold storage until shipment to California for 

diagnostic imaging (not available in Hawaii), for necropsy and for tissue collection. 

Figure 6. A young melon-headed whale calf was found dead on July 5, 2004 in 

Hanalei Bay. Photo by Gretchen Johnson.

17
Post-Mortem Examination 

The animal was a Code 2 (fresh dead) male, 115 cm in length with vibrissae present along the 

rostrum (see Level A form in Appendix 1). The animal weighed 17.5 kg. Fetal folds were 

evident along the body, and the umbilical slit was partially closed. These features indicate that 

this animal was young and likely approximately one week old. The calf was stored on ice 

(July 5, 2004), was shipped to the Marine Mammal Center (TMMC), Sausalito, California. 

Once the carcass arrived at the Marine Mammal Center, it was taken to Raytel Imaging, San 

Francisco, for magnetic resonance imaging and computerized tomography (CT) scanning (July 

7, 2004). After scanning, the carcass was taken back to the Marine Mammal Center for gross 

necropsy and collection of tissues for histopathology, bacteriology and banking. 

Histopathology was completed at the University of California, Davis. 

Imaging

Magnetic resonance imaging (MRI) prior to dissection was performed using a GE Genesis 

Signa 1.5T MRI using GE XL 9.0 software. T1-weighted scans of the sagittal and axial planes 

were collected for the head. In addition, the following pulse sequences were performed: T2* 

gradient echo in the coronal and axial planes, T2 fast spin echo (FSE) in the coronal plane, and 

T2 fluid attenuation inversion recovery (FLAIR) in the coronal and axial planes. T2-weighted 

axial and T2 FSE coronal scans were collected for the thoracic region. Computed tomography 

(CT) was performed with a GE Lightspeed CT. Images collected of the chest region (source 

of 140 kV at 120 mA) were contiguous and collimated to 5 mm. Images of the temporal bone 

(source of 120 kV at 100 mA) were also contiguous but collimated to 1 mm. Both imaging 

modalities were used to evaluate morphology prior to gross necropsy to visualize and evaluate 

auditory and auditory pathway pathology in light of the coincidence with RIMPAC activities. 

Images showed incomplete cerebral myelination that was consistent with the neonatal 

developmental stage. Localized hemorrhages were not observed in the parenchyma, 

subarachnoid spaces, or intraventricular spaces; there was no indication of subdural hematoma 

formation (Fig. 7). Hemorrhage was not apparent in any of the acoustic fats (i.e., melon and 

fats associated with the lower jaw). The auditory bullae appeared grossly normal and the 

persistence of cochlear fluid permitted the cochlea to be visualized (Fig.8). Associated sinuses 

and Eustachian tubes appeared clear except for a localized region of hyperintensity involving 

the Eustachian tube and associated air spaces of the right auditory bulla, potentially 

corresponding to localized fluid accumulation (measuring 7 x 9 x 10 mm). Although partially 

located within the pneumatized bone, it is not contiguous with the cochlea. Airspace 

consolidative changes characterized by hyperintensity were observed in approximately 75% of 

the right lung (Fig. 9) and to a lesser extent in the ventral (caudal) portion of the left lung lobe. 

The main bronchi appeared clear and free of debris. The skeletal system was free of fractures, 

and structural or congenital deformities of either the soft tissue or skeletal system were not 

detected. There was no evidence of internal trauma. 

18
Right

Left

Dorsal

Ventral

A B

Figure 7. Images demonstrating normally developed brain without indication of hemorrhage, 

lesion or subdural hematoma. (A) CT scan and (B) T2* GRE scan through the brain, auditory 

bullae, and associated air spaces. 

Right

Left

Anterior

Posterior Right

Right

Left

Left

Dorsal

Ventral

Anterior

Posterior

Figure 8. Coronal MRI image collected with the T2 FLAIR pulse sequence. The red arrow 

indicates the position of the cochlea. Some localized fluid accumulation appears in the 

Eustachian tube and associated sinus. 

A B

Figure 9. (A) CT and (B) MRI collected with T2 FSE pulse sequence demonstrating 

consolidative changes of the right lung, and to a lesser degree, in the left lung. 

19
Gross Findings

In several areas the skin was flaking off the underlying tissue (interpreted as post mortem 

decomposition). The body was thin with concavity caudal to the skull. The melon was poorly 

developed. The esophagus, all of the chambers of the stomach, and the intestines were empty. 

There was scant adipose tissue in the abdominal cavity, around the kidneys, and in the 

coronary groove. Therefore, this young whale likely had not nursed for some time prior to its 

death. It was not possible to determine whether this animal had ever nursed; however the 

amount of zymogen depletion and overall condition of the calf indicate that it was not nursing 

well prior to the morning of July 3, 2004. The thymus was well developed, and there was no 

evidence of atrophy or depletion that can occur if there is poor nutrition or stress early in 

neonatal life. This calf was known to be separated from the female upon exit of the group from 

the Bay, but it cannot be determined whether separation from the female occurred while the 

animals were in the Bay or prior to the group’s entrance into the Bay. The empty 

gastrointestinal tract and the poor body condition do not necessarily mean separation from the 

female but they do indicate abnormal nursing or maternal care. 

 

Approximately 6-8 circumferential fetal folds were found present along the body (Figs. 10 and 

11) and the flukes were folded under at the tips. The umbilical vein, the urachus and umbilical 

arteries were partially patent. The umbilicus was absent (Fig. 12) and the umbilical slit was 

partially closed. The umbilicus had begun to regress and the ductus arteriosus was completely 

closed. Along the inner body wall, the umbilical slit was surrounded by a small amount of 

fibrous tissue (Fig. 13) consistent with healing. Several vibrissae were present along the 

rostrum. These features indicate that the animal was young, but not newborn. 

 Figure 10. Left lateral view of whale carcass 

Figure 11. Fetal folds on right side of carcass 

20
Figure 12. Umbilical scar on ventrum of carcass 

Figure 13. Internal view of healing umbilical scar. 

Several, 1.0 - 5.0 cm long, linear, depressed areas of skin with slightly raised, dark grey edges 

were found along the chin and ventral mandible. Several, shallow, gray linear depressions 

were present along the ventrum, at midline and adjacent to the umbilicus and genital slits. 

Rake marks were present on the right side of the head lateral and anterior to the right eye and 

over the body. A single circumferential, linear depression extended circumferentially around 

Figures 14a and b. Circumferential linear lesion in skin. 

the head at the level of the eye (Figs. 14a and b). There was no evidence of hemorrhage 

associated with this single circumferential linear depression. 

There was a small amount of light tan, foamy fluid in the distal trachea and main stem 

bronchi. The right lung lobes were slightly collapsed, diffusely mottled dark red and purple, 

rubbery and exuded foamy fluid and a large amount of blood on cut section (Fig. 15). The 

anterioventral, medial dorsal and margins of the left lung lobes were markedly collapsed, and 

21
approximately 50-60% of the left lung was dark purple and rubbery. The remaining areas of 

left lung were dark pink and aerated. All sections of lung floated in formalin. The heart 

weighed 141 g (0.8 % of body weight), the right ventricle was 0.8 cm thick, the left ventricle 

was 1.0 cm thick, and the interventricular septum was 1.0 cm thick. The ductus arteriosus was 

closed and the foramen ovale was fenestrated. The thymus extended partially up the trachea 

and several lobes were observed just distal to the larynx. 

 

Figure 15. Dorsal view of lungs removed from thorax. 

The head was sectioned transversely at 1 to 2 cm increments and the sections examined 

grossly. Selected sections were also examined histologically. There was no evidence of 

hemorrhage along the mandibular adipose tissue, skeletal muscle, within the sinuses, or inner 

ear cavities (Fig. 16). 

 

22
Figure 16. Sagittal section of the frozen, formalin-fixed head at the level of the ears, showing 

absence of hemorrhage. The scale is on the right side and indicates 1 cm. 

Based on the presence of fetal skin folds, presence of vibrissae, degree of umbilical regression, 

length (reported birth lengths for melon headed whales are around 100 cm), and appearance of 

organs, the calf was estimated to be approximately a week old. All tissues examined were 

appropriately developed for a newborn cetacean including immature testes and brain. Sections 

of lung were either fully or partially aerated. The meconium had been completely excreted, 

which occurs within the first few days of life in most species. The umbilicus had begun to 

regress and the ductus arteriosus was completely closed. All of these findings are consistent 

with a young animal. 

Histopathology

Samples of the lungs, heart, trachea, aorta, thymus, salivary gland, thyroid glands, tongue, 

esophagus, stomach, duodenum, jejunum, ileum, colon, pancreas, spleen, liver, kidney, ureter, 

urinary bladder, blubber, adrenal glands, skin (multiple sites), eye, blubber, muscle (multiple 

sites), testes, brain, and the mediastinal, sternal, axillary, and mesenteric lymph nodes were 

examined histopathologically. 

Histopathological review of the lungs indicated the calf had bronchopneumonia and passive 

congestion. Bronchopneumonia is a common finding in stranded cetaceans (Lowenstine, 

personal observations) and in mild cases is often related to the act of stranding or being 

trapped in shallow water. There was leukocytosis in the lungs and in a few places, the 

interstitial walls were mildly expanded by neutrophils (acute interstitial pneumonia). These 

interstitial changes were interpreted to be secondary to acute systemic inflammation. The left 

lung lobes were partially atelectic. This could be related to acute constriction or plugging of 

the left main stem bronchi or partial failure of alveolar expansion after birth (atelectasis 

23
neonatorum). The right lung lobes were diffusely congested and edematous consistent with 

lying in right lateral recumbency (Fig. 17) [note this animal was packed and shipped 

immediately after finding the carcass, therefore this may be a result of the position during 

transport]. Small numbers of aspirated squames are normally found in the lungs of neonatal 

animals and can be present in the lungs weeks after birth. 

Figure 17. Hemotoxylin and eosin stained section of right lung showing congestion and 

atelectasis. 

Acute myofiber degeneration and necrosis was found in the heart. This is a common finding in 

stranded animals and has been attributed to elevated endogenous catecholamine release in 

other animals and humans (Turnbull and Cowan, 1998). Mild hepatic lipidosis, which is often 

related to inanition or poor in utero nutrition in young animals, was found in the liver. There 

was marked lymphoid depletion in the spleen. The lymphoid atrophy may be related to the 

mild inflammation in the skin, lungs, or small intestine, or could be reflective of the animal’s 

poor nutritional condition and debilitation, though the thymus was not similarly depleted. The 

presence of moderate extramedullary hematopoiesis found in the animal’s spleen is a normal 

finding in cetaceans. Superficial bacterial colonization and necrosis of the distal umbilical 

vein and artery with fibroplasia confirmed the grossly-observed normal regress of the 

umbilicus; and testes morphology was consistent with an infantile developmental state. Other 

findings included: meningeal congestion in the brain, congestion in the kidneys, inflammation 

in the jejunum, and mild zymogen depletion in the pancreas. The zymogen depletion also 

supports the young age or inanition. Congestion and mild hemorrhages in multiple organs are 

common non-specific terminal findings in stranded odontocetes.

The skin lesions on the ventral mandible were acute and suggestive of external trauma. 

Interestingly, there was epithelial necrosis and adjacent intracellular edema in addition to the 

abrasions and ulcerations. These lesions can be associated with toxic injury to keratinocytes. 

Given the underwater topography of the area in which this animal stranded, this change could 

have been related to contact with coral. Similar lesions have been reported in humans 

following contact with coelenterates (Letot et al., 1990). The thin linear indention extended 

circumferentially around the head and was not associated with inflammation histologically. 

The indention was associated with sub-lethal cellular changes indicating that the changes 

24
probably occurred ante-mortem. The exact etiology of this skin lesion is not known; however, 

similar facial clefts due to constriction by amniotic bands have been described in human 

infants, and can be induced experimentally in lambs and mice (Rowsell, 1989). This indention 

was considered a separate entity from the fetal folds common in neonatal cetaceans which 

were also present in this young whale. There was no inflammation associated with the rake 

marks examined histologically, suggesting that at least some of the rake marks occurred after 

death. 

There was a moderate drainage reaction in several of the lymph nodes examined and in the 

axillary and cervical lymph nodes there was sinusoidal neutrophilia and lymphadenitis. Again, 

these changes were very mild and, given the location of the lymph nodes, the inflammation 

may be related to the acute skin lesions. In several of the peripheral and thoracic lymph nodes 

examined there were small mineralized concretions in the capsule and fibrous tissue septa of 

the node. In some areas these concretions were associated with the capillary endothelial cell 

lining. The significance of this finding is not known. Similarly, the adrenal cortex was much 

thinner than expected and from what has been noted in other cetacean species. Again, the 

significance of this change is unknown, and it may be an anatomic variation of this species or 

related to age. 

All of the inflammatory changes noted in the tissues examined were regarded to be mild, acute 

(6-12 hours old), and could have been secondary to injuries acquired during stranding or from 

being trapped in shallow water. There was no evidence of hemorrhage in the brain or in the 

cervical, cranial, or mandibular tissues and blubber. There was no evidence of viral or 

bacterial disease, including viral inclusions, lymphoid depletion, cytolytic changes, etc, in the 

tissues examined. Although cause of death could not be definitively determined, it is highly 

likely that maternal separation, dehydration, and poor nutritional condition contributed to this 

calf’s death. The reasons for the maternal separation, dehydration and poor nutritional state of 

the calf are not known. 

Disease and Other Biological Factors

Historically there have been many reasons for single or mass strandings, although most cases 

have unknown causes. In some cases pelagic animals are found near shore or in embayments 

when they are obviously chasing prey, being chased by predators, or are feeding. Once in 

shallow waters these pelagic species may strand. Many potential mass strandings have been 

prevented in the Cape Cod region of Massachusetts by herding the animals using small vessels 

and acoustic devices (Touhey, 2003). Unlike the recent North Carolina mass stranding of pilot 

whales, minke whale and dwarf sperm whales (Hohn et al., 2006), observations of this group 

showed maintenance of the group cohesion under the adverse conditions in shallow unfamiliar 

waters and the rapid coalescence into a larger group once people left the water. It is likely 

that the group cohesion contributed to the circumstances under which these animals entered 

the Bay and remained there throughout the day. 

Another factor which is reported to be responsible for mass strandings is disease or injury of 

one or more key individuals of a group who may lead animals into shallow waters, near shore 

25
or into embayments or lagoons (Robson, 1984). In some cases, once the injured or sick 

animal is removed from the area, the remaining members of the group have been successfully 

herded out to sea. In this case, no reports were received of freshly injured animals in the Bay, 

such as might have occurred with recent predation attacks. No animal was observed dead on 

the shallow areas of the Bay during the event or following the animals’ return to the sea; 

although no survey for carcasses underwater was performed. It is unlikely that the poor 

condition of the young animal would contribute to the group’s movement into the Bay. 

However, since no other animals were stranded or examined during this event it is impossible 

to discern whether any other animals were sick, potentially contributing to the stranding event. 

Finally, based on interviews with fishermen, Hanalei Canoe Club members, NOAA biologists, 

life guards, and State of Hawaii Department of Land and Natural Resources biologists, no 

biological indicators such as predators or prey items that would explain the movement of the 

whales into the Bay or remaining there for over 28 hours were observed. However no real 

scientific effort was undertaken at the time of the event to perform the surveys and veterinary 

exams necessary to rigorously document the above mentioned factors. 

Environmental Analysis 

Several studies have determined positive correlations between environmental factors and the 

sites of cetacean strandings, particularly mass strandings. Coastal topography (Brabyn and 

McLean, 1992), large-scale climate events (Evans et al., 2005), and wind effects on nearshore 

circulation (Walker et al., 2005) have all been investigated in relation to cetacean strandings. 

In addition, harmful algal blooms and their associated biotoxins have been associated with 

unusual mortality events and strandings but have not been associated with unusual inshore 

congregations of pelagic animals (HARNESS, 2005). 

Physical features

The bathymetry and coastal topography of Hanalei Bay was compared with the benthic 

features around Kaua‘i and the other main Hawaiian islands (Figure 20a). In their analysis 

utilizing data from New Zealand, Brabyn and McLean (1992) determined that mass strandings 

were more common in areas with gently sloping sandy beaches, an adjacent protruding section 

of coastline, and shallow bays where the coastline was less indented. These features are not 

found in Hanalei Bay. Hanalei Bay is the most distinct indented body of water along the 

northern coastline of Kaua‘i, and there are no adjacent protruding areas of coastline. 

Both Brabyn and McLean (1992) and Walker et al. (2005) found that mass strandings of other 

species occured significantly more often on beaches that were in proximity to deep water. 

This particular bathymetric feature is similar to that of Hanalei Bay; only a few miles offshore 

26
a. 

Kaua‘i

O‘ahu 

b.

Hanalei Bay

Kaua‘i

Figure 18. Bathymetry maps of a) Oahu and Kauai, and b) the north of Kauai. Contours are 

shown at 500-meter intervals. Bathymetry data from the GEBCO Digital Atlas, British 

Oceanographic Data Centre, plotted using the Maptool utility at seaturtle.org. 

27
28

of Hanalei Bay, the bottom drops to over 2000 meters. However this is not a feature unique to 

the Bay. The volcanic islands of the Hawaiian chain rise sharply from the ocean floor; very 

deep waters can be found a short distance from the beach in most of the archipelago (Figure 

20b). Thus, bathymetry does not help explain why this mass stranding occurred in Hanalei 

Bay at this time. 

Wind and sea surface temperature features

Wind and sea surface temperature have also been examined in relation to cetacean stranding 

events (Evans et al., 2005, Walker et al., 2005). Walker et al. (2005) found that in all mass 

stranding events of cetaceans analyzed (n=15), a change in wind direction from upwellingfavorable to downwelling-favorable condition occurred in the week prior to the event. They 

hypothesized that the whales were tracking frontal convergences created by an upwelling 

front, either directly or indirectly, following prey migrations. We analyzed environmental 

data for the area for the time period preceding the stranding event, to examine factors that may 

have caused the animals to enter Hanalei Bay, and the days of the event, for factors that would 

cause the animals to remain in the Bay. 

Sea surface temperature plots were created for the area around O‘ahu and Kaua‘i using data 

from the NOAA GOESS archive (Figure 19). An integrated map was also created for the 3 

days surrounding the event (Figure 21; note different color scale). While some different 

temperature water masses can be seen with the exaggerated color scale in Figure 21, the 

maximum temperature difference in the map area was approximately 2 degrees. The waters 

around O‘ahu and Kaua‘i were almost uniformly warm (average 26.5°C) for the days 

preceding and during the stranding event. No major fronts were detectable. 

Wind data from the National Weather Service were also analyzed for the four days preceding 

the event to assess variability (Figure 20). Along the north shore of Kaua‘i, the observed wind 

conditions are the prevailing trade winds from the east at approximately 12-14 knots, which is 

considered normal and expected for this late June-July time period (Andy Nash, NWS 

Honolulu, pers. comm). No changes in wind direction or strength which would contribute to 

front formation or dissolution were observed. July 3 and 4 were also studied to determine if 

any changes occurred that would cause the animals to remain in shallow waters, and again no 

anomalies or differences were detected. 

In conclusion, the environmental factors of bathymetry, sea surface temperature and wind 

were analyzed for this stranding event. The bathymetry is similar to many other sites within 

the Hawaiian Island chain. The weather conditions appear to be normal for this time of year 

with no fronts or other significant features noted. The analysis of environmental features does 

not appear to provide an explanation for the cause of this event, or the reason the animals 

remained in Hanalei Bay. 
June 30, 2004 July 1, 2004 June 29, 2004 

July 2, 2004 July 3, 2004 July 4, 2004 

Figure 19. Sea surface temperature Jun 29 - Jul 4, 2004, the four days immediately preceding the stranding evsurface temperature is represented in degrees Celsius. Sea surface temperature data are from NOAA’s GOES dsource data have a nominal spatial resolution of 6km and have been validated to be within 0.5C of actual SST. 

program from seaturtle.org. 

29
30

Figure 20. Wind speed and direction from Jun 29 - Jul 3, 2004, the four days immediately preceding the strandevent. Wind speed is in knots. Note that the wind speed color scales are not identical among plots. Wind data Service (NWS) NCDC NOMADS site and plots were made by the NWS Research Scientific Services Division, 
Harmful Algal Blooms

The on-site team evaluated potential biotic factors, including the presence of unusual 

chlorophyll signals from satellite imagery and phytoplankton in the water. There was no 

evidence of unusual chlorophyll imagery for this area and time frame (Seki, pers. comm.). 

Water samples were obtained by the US Coast Guard station near Lihue and sent to the 

University of Hawaii for identification. The water samples showed essentially a pure 

assemblage of the photosynthetic cyanobacteria, Trichodesmium spp. (Brown, email report). 

This colonial phytoplankton is large enough to be visible to the naked eye and is commonly 

found in tropical and subtropical waters of the world oceans. One species of Trichodesmium

has been found to produce a biotoxin, but with the minimal sampling done during this event it 

is not known whether that species was present. Other species have been associated with deaths 

of marine organisms (generally, neurotoxins have impacted organisms tested --mostly 

zooplankton) (Sellner, 1997). Trichodesmium is generally not grazed well, but there is a 

harpacticoid copepod that feeds on some of this phytoplankton. Trichodesmium blooms are a 

common occurrence in Hawaii in July (Karl et al., 1997), and most likely did not contribute to 

the unusual behavior of the melon-headed whales of entering or staying in the Bay. 

Military Exercises 

This event occurred during the 2004 Rim of the Pacific Exercises (RIMPAC) which is a 

biennial, sea control/power projection fleet exercise that has been conducted since 1968 and 

involves US forces and forces from various Rim-of-the-Pacific nations. Due to the presence 

and scope of military exercises being conducted during the Hanalei Bay marine mammal 

stranding event, contact with U. S. Navy officials was made during this event. Requests for 

stand down of active sonar use were made following initial discussions and the U. S. Navy 

responded very quickly to cease transmissions following this request (see Table 5). 

An investigation of the possible relationship between military training exercises, active sonar 

transmissions, and movement of the animals into the Bay and remaining there was conducted 

focusing on active sonar use before and during the exercises on July 3, 2004. Initial 

investigation focused on the official training events of July 3, but was extended to consider the 

sonar transmissions of a group of six naval surface vessels (four U.S. and two Japanese ships) 

involved in training and tracking exercises while transiting toward the island of Kaua‘i from 

the south on the afternoon and evening on July 2, 2004 as well (Fig. 21). Official active sonar 

exercises on or near PMRF did not commence until approximately 0800 hours (local time) on 

July 3 (Fig. 22). From what is known to the authors of this report regarding the scope and 

nature of previous RIMPAC exercises and other naval exercises in Hawai‘i the active sonar 

transmissions on July 2-3 were not particularly unusual for the area and time of year in 

question. 

31
Figure 21. Vessel movement and sonar transmissions on July 2-3, 2004 prior to RIMPAC 

exercises. Red stars indicate transmission locations for which sound propagation analyses were 

conducted 

Figure 22. Vessel movement and sonar transmissions on July 3, 2004 during RIMPAC 

exercises. 

32
For the past decade, the potential role of acoustic exposure, particularly to tactical midfrequency, military active sonar, in marine mammal stranding events has been a subject of 

relatively intense consideration and debate (e.g., Richardson et al., 1995; NRC, 2000; 2003; 

2005). Globally, four marine mammal mass stranding events, generally involving various 

species of beaked whales, have occurred in which active military sonar appears to have been 

the most likely causative factor. These include strandings in Greece in 1996 (Frantiz, 1998), 

Bahamas in 2000 (NOAA/US Navy Joint Interim Report, 2001), Madeira in 2000 (ICES 

AGISC 2005), and the Canary Islands in 2002 (Fernandez et al., 2005). Although melonheaded whales were not involved in any of these previously reported events, they have similar 

habitat requirements and life history characteristics (e.g., relatively deep diving) to most of the 

species involved in these four events. The beaked whale mass strandings noted above were 

relatively small numbers (<30) of animals per event as compared to the more typical mass 

stranding of melon-headed whales which may be a reflection of the difference in group size 

for melon-headed whales melon-headed whales (median group size 305 individuals) as 

compared to beaked whales (maximum group size observed 9 individuals; Huggins et al.

2005, Baird et al., 2004). 

Recent data suggest that under certain, though still unknown, conditions, at least one cetacean 

species (Cuvier’s beaked whale: Ziphius cavirostris) exposed to active mid-frequency sonar 

may develop a pathological condition with lesions similar to decompression sickness in 

humans (NMFS, 2002; Jepson et al., 2004; Fernandez et al., 2005). These cases may be 

related to direct ensonification and/or changes in diving behavior, resulting in lesions 

associated with nitrogen bubble formation (Cox et al., 2006). Similar lesions were observed 

in a Blainsville’s beaked whale (Mesoplodon densirostris) studied following the Bahamas 

(2000) stranding event (Rotstein, unpublished). It is important to bear in mind that key 

questions regarding the conditions in which nitrogen bubble formation may occur in the 

presence of active sonar, and a number of other important issues bearing on the interpretation 

of observed lesions, remain unanswered (Piantadosi and Thalmann 2004). However, given the 

apparent occurrence of this phenomenon in certain deep-diving species (e.g., beaked whales), 

it is appropriate to address whether it may occur in species with similar diving patterns and 

habitat requirements (e.g., melon-headed whales) when they experience similar acoustic 

exposures. It must be noted that this event is dissimilar from those reported beaked whale 

events in that only one animal died and was examined, it did not have lesions consistent with 

the observed lesions in the Bahamas, and only one species stranded. 

Behavioral responses to sound may play a role in marine mammal stranding events, whether 

they are related to physiological changes (e.g., changes in diving inducing nitrogen bubble 

formation) or direct beaching behavior (Cox et al., 2006). Extreme avoidance behaviors 

arising from acoustic exposure have been documented for some cetaceans other than melonheaded whales. For example, Geraci and Lounsbury (2005) report that coastal whalers have 

used certain species’ tendency to flee in a straight line from a source of danger to successfully 

drive striped dolphins (Stenella coeruleoalba) and pilot whales (Globicephla macrorhynchus) 

ashore using impulsive sounds. Arguably, behavioral reactions of some cetaceans to active, 

mid-frequency military sonar have recently been observed. For instance, on May, 2003, in 

situ observations of altered behavior of killer whales (Orcinus orca), and a minke whale

(Balaenoptera acutorostrata) were reported in the area of tactical sonar use during a military 

33
exercise while transiting the eastern Strait of Juan de Fuca and Haro Strait (Bain, 2003; 

Balcomb, 2003; US Navy, PacFleet, 2004; NMFS, 2005). It is important to note here again 

that our knowledge of the effects of anthropogenic acoustic events on marine mammal health, 

behavior and mortality is still in its infancy. Relative to this event, virtually nothing is known 

about melon-headed whale reactions. 

34
Table 5. Timeline of event, NMFS activities and naval activities relative to this event in 

Hanalei Bay. 

Melon-headed whale 

Activities 

NMFS and Network 

Activities 

Navy Activities 

Time Date 

JMSDF P-3 dropped 6 

active sonobuoys 30 nm 

SE of Kaua‘i 0730 July 2, 2004 

Active sonar used 

intermittently during 

transit approaching either 

side of the island 1015-2359 July 2, 2004 

2 RIMPAC units test 

active SONAR (Fig. 21) at 

PMRF Underwater Range 0645-0715 July 3, 2004 

Group of whales enter SW 

part of Bay – 91 m from 

shore 0700 July 3, 2004 

RIMPAC exercise begins 

(Fig. 22) 0800 July 3, 2004 

RIMPAC units training on 

PMRF Underwater Range, 

Antisubmarine Warfare 

training 0800-1700 July 3, 2004 

Group of whales moved 

cohesively from east side of 

Bay to center and then 

headed out of Bay but 

immediately turned around 

and returned to the east side 

of the Bay 

Ocean Safety Board 

relay report from 

Lifeguards regarding 

whales and harassment 

by people 

0930 July 3, 2004 

10:30 Lifeguards, 

Police Dispatch trying 

to prevent human 

interactions in Bay; 

members of the public 

report calling PMRF 

regarding this event 

Smaller subgroups (up to 4) 

spread out over 6-800 yards 

between the Pavilion and the 

Pine Trees to the south; 

public interacting with 

whales 

Throughout 

day July 3, 2004 

Animals reformed into one 

cohesive group within 100 

yards of shore near Pavilion 

beach Park 

Kaua‘i police and 

DOCARE ordered 

public away from 

animals; 1600 July 3, 2004 

NMFS informs 

RIMPAC Battle Watch 

Captain (BWC) of 

stranding situation 1645 July 3, 2004 

BWC directs all ships to 

cease all active sonar 

transmissions 1647 July 3, 2004 

CPF BWC/CDO notified 1650 July 3, 2004 

CPF/CCTF RIMPAC 

decides to send OPREP-3 

N/B 1730 July 3, 2004 

35
Melon-headed whale 

Activities 

NMFS and Network 

Activities 

Navy Activities 

Time Date 

NMFS and HSRG 

personnel arrived in 

Kaua‘i, assessed 

situation, noted that no 

animals had stranded, 

and developed 

intervention plan 2030 July 3, 2004 

Volunteers hold beach 

watch near group 

Throughout 

night July 3-4, 2004 

RIMPAC units continue 

non-active sonar events 

operating on PMRF 0900 July 4, 2004 

Herding of group to 

open water begins (8 

canoes and 30+ kayaks) 0930 July 4, 2004 

Group of whales departed 

Bay and were no longer in 

sight 1030 July 4, 2004 

NMFS reports 

departure of whales to 

NAVY 1050 July 4, 2004 

Lone young animal in Bay 1300 July 4, 2004 

NMFS reports sighting 

of one juvenile still in 

Bay to NAVY 1515 July 4, 2004 

Animal stranded and pushed 

back out Before 0900 July 5, 2004 

Calf found dead 0900-1000 July 5, 2004 

Calf packed on ice for 

shipment to California via 

Federal Express 

Early 

afternoon July 5, 2004 

Calf necropsied N/A July 7, 2004 

36
Acoustic Analysis 

A detailed sound propagation analysis was conducted of sonar transmissions from both U.S. 

and Japanese naval vessels transiting from Pearl Harbor on O‘ahu toward the island of Kaua‘i 

on the afternoon and evening of July 2, 2004. Predicted sound fields were calculated for five 

positions along the ship’s tracks coinciding with known transmissions of two types of midfrequency sonar (indicated with red stars in Fig. 21). These positions were selected to 

approximate the range of possible conditions arising from the fact that the vessels were 

moving closer to Hanalei Bay. 

 

For each of the five positions, transit speeds required for hypothetical animals to travel from 

the south and east of Kaua‘i and reach Hanalei Bay by 0700 on July 3, 2004 were determined. 

These transit rates were then compared with the predicted sound fields to estimate whether 

animals exposed to military sonar transmissions could physically arrive in Hanalei Bay in the 

known time period. Detailed modeling analysis of the July 3 transmissions have been 

conducted by the U.S. Navy and are discussed below as well. 

Propagation Analysis 

A standard ray-tracing, sound propagation model (using the Bellhop Gaussian beam/finite 

element ray-tracing model available at: www.hlsresearch.com/oalib) was used to estimate 

acoustic conditions resulting from sonar transmissions at five specific times and locations of 

known transmissions of U.S. and Japanese vessels on the evening of July 2, 2004 to the south 

and southeast of Kaua‘i: 

1330: USS Paul Hamilton initial sonar transmissions (21° 15’ N, 158° 20’ W) 

1900: USS Lake Erie sonar transmissions (21° 30’ N, 159° 08’ W) (Figure 21) 

2000: JDS Inazuma and Haruna initial sonar transmissions (21° 35’ N, 159° 20’ W) (Figure 22) 

2200: JDS Inazuma and Haruna sonar transmissions nearest Hanalei Bay (21° 45’ N, 159° 0’ W) 

2300: USS Paul Hamilton sonar transmissions nearest Hanalei Bay (21° 45’ N, 158° 40’ W) 

The propagation analysis models used average environmental features for July (bathymetry 

and nominal sound velocity profiles expected in that area for that time of year). The U.S. 

Navy provided NMFS specific measurements of these features (which can dramatically affect 

transmission ranges) from an area to the south and east of Kaua‘i on July 2, 2004. These data 

indicate that sound propagation conditions were very similar to typical conditions for July, as 

indicated in the Generalized Digital Environmental Model (available at: 

https://128.160.23.42/gdemv/gdemv.html) database that underlies the propagation model used 

to conduct this investigation. In addition to bathymetric and environmental variables, 

information regarding variable operational characteristics of the various sonar systems was 

used in propagation analyses. According to technical data provided by U.S. Navy to NMFS 

following the stranding event, U.S. naval vessels were equipped with SQS-53C mid-frequency 

sonar systems (center transmission frequency: 3.5 kHz; nominal source level: 235 dBRMS re: 

1μPa) and Japanese naval vessel used OQS-5 and OQS-3 tactical systems (center transmission 

frequency: 5.0 kHz; nominal source level: 225 dBRMS re: 1μPa). 

37
Our calculations are believed to roughly approximate conditions present during military sonar 

transmissions on July 2, 2004. However, the propagation model used assumes that sound 

propagates omnidirectionally from the source. Tactical sonars can be focused to some extent 

in a particular direction. The fact that such information was not included in the analysis here 

is acknowledged to be a potentially significant limiting factor. Our analyses are thus 

appropriate for certain portions of zones surrounding the ships, depending on which 

operational mode the sonar was being used in and the exact orientation and targeting of the 

ship at each ping (information not currently available to NOAA). In the directional “beam” of 

the sonar (where it is pointed), received levels can, under certain conditions, exceed those 

predicted by an omnidirectional model. It is thus acknowledged that the current analysis is 

most accurate only for a sub-set of the area surrounding transmitting vessels. 

For the purposes of visualizing sound fields resulting from active sonar transmissions for this 

analysis, 120, 140, and 160 dBRMS re: 1μPa received level isopleths were arbitrarily selected. 

These received levels are not presumed to have any particular biological relevance for melonheaded whales or other cetaceans. These zones of similar estimated received level were 

determined by calculating maximum received levels in the 0-500m depth regime along eight 

directional radials (45o angular separation) relative to each transmission location at each 

bearing (N, NW, W, SW, S, SE, E, and NE). That is, the isopleths indicate the loudest 

estimated received level within the portion of the water column within which the animals 

would reasonably be expected to occur. It should be noted that this is a quite conservative 

Figure 23. Representation of five active sonar transmissions on July 2, 2004 modeled in this 

analysis. Isopleths representing 120, 140, and 160 dBrms re: 1uPa are shown in green, 

black, and red respectively. 

38
means of estimating received level isopleths; animals moving through the water column likely 

never experience the maximum received level in this depth band as calculated here. A 

composite representation of all five modeled transmissions with each of the three defined 

isopleths is shown in Fig. 23. 

Determination of Ranges and Swim Speeds 

Radial distances from Hanalei Bay to the south and east of Kaua‘i were estimated (Fig. 24). 

These spatial zones were then converted into average swimming speeds for each of the five 

transmissions analyzed to assess the feasibility of animals arriving in Hanalei Bay at 0700 on 

July 3 following active sonar exposure on the afternoon and evening of July 2. This 

approximation presumes that the pod was located to the south or east of Kauai’i on July 2, 

which may or may not have been the case. As noted earlier, this is one of the areas where 

melon-headed whales have previously been sighted with minimal effort in the Hawaiian 

Islands. 

The spatial analysis was an admittedly simplistic approximation using nautical charts. Our 

calculations of distance from Kaua‛i at various transmission points agree closely, however, 

with those given in the charts provided in the Navy’s analysis. It is also important to note that 

it is highly unlikely a more detailed mapping analysis would alter the conclusions reached in 

this report. 

Figure 24. Map depicting estimated distance isopleths from Hanalei Bay at points to the south 

and east of Kaua‘i. 

39
Assuming an 0700 arrival time (July 3) for the whale group in Hanalei Bay, necessary transit 

speeds coinciding with these transit ranges were determined for each of the five transmissions 

analyzed, accounting for transmission time and estimated sound fields. Two examples of 

these calculations are given in Figs. 25 and 26. 

Figure 25. Approximate swim speeds necessary for the group of Peponacephala electra to 

reach Hanalei Bay following exposure to approximate sound fields from USS Lake 

Erie active sonar transmissions at 1900 on July 2, 2004. 

Figure 26. Approximate swim speeds necessary for group to reach Hanalei Bay following 

exposure to approximate sound fields from JDS Inazuma and Haruna at 2000 on 

July 2, 2004.

40
Relationship Between Estimated Sound Fields and Required Transit Speeds

 

Estimated sound fields were compared with transit speeds necessary to reach Hanalei Bay by 

the target arrival time for each of the five modeled active sonar transmissions. The combined 

results of these analyses indicate that the group would have had to travel approximately 1.4 to 

4.0 m/s over 6.5 to 17.5 hours after receiving sonar sounds ranging from 120 to >160 dBRMS

re: 1μPa to reach the Bay at 0700 on July 3, 2004. It is important to note that in many cases, 

the position of the vessels themselves overlaps with required transit speeds on the order of 2.0 

m/s from animals in the relatively near vicinity (again, the analysis considers exposure of 

animals in the vicinity of naval vessels to the south and east of Kaua‘i only). Although no 

published data are available on cruising speeds in Peponocephala, cruising speeds in other 

cetaceans of approximately 1.8 to 3.1 m/s are sustainable over relatively long periods (Costa 

and Williams, 1999). Whether a mixed pod of melon-headed whales, including very young 

individuals would be capable of sustaining such a pace over a period of many hours is 

unknown but it is likely that the presence of young animals could limit transit speeds if the 

group remained together. 

 

It should be noted that in some conditions, areas that include plausible transit speeds 

overlapped with the physical position of the military vessels. Thus, received sonar levels 

approaching the source level of the system could have been received by individuals to the 

south and east of Kaua‘i, who would have reached Hanalei Bay by 0700 on July 3, 2004. 

Consequently, the precision of the acoustic analysis, as well as the precise level at which 

behavioral reactions occur, is arguably irrelevant. It is noteworthy that other cetaceans 

(beluga and narwhal) have been documented rapidly swimming away from other human noise 

sources at large distances (up to 80 km) in other areas (LGL and Greeneridge, 1986; NRC, 

2005). This is thought to be a predator-fleeing response; humans hunt these species in the 

Arctic areas where the observations occurred. If a behavioral response in this situation was 

triggered at a received level just above the ambient noise level, the group could have moved 

much slower (< 1.0 m/s) and reached the Bay by 0700 on July 3, 2004. However, it is not 

known whether marine mammals may perceive tactical mid-frequency sonar signals as similar 

to those of potential predators (e.g., social signals of killer whales) and react in a similar 

fleeing manner at low received levels (NRC, 2005). Further, it is arguably unlikely that such 

profound reactions at low levels would be expected in an area with relatively common military 

activity if animals were present at the same time and in the same vicinity or that if they were 

they would not have been previously detected. 

 

Sonar Exposure on July 3, 2004 within Hanalei Bay

 

Acoustic propagation modeling was conducted by NMFS using nominal sound velocity 

profiles for the area to the north and west of Kaua‘i for the month of July and the times and 

locations of July 3 operations at The Pacific Missile Range Facility (PMRF) provided by U. S. 

Navy. The results indicated generally that received levels near the mouth of Hanalei Bay were 

estimated to range from near or below likely ambient noise to perhaps 20-30 dB above it (~ 

41
125 dBRMS re: 1μPa was the maximum estimated received level near the mouth of the Bay). 

Detailed modeling was conducted by U. S. Navy, 3rd Fleet (2006) using in situ sound velocity 

profiles (obtained in the July 6-21 timeframe) to estimate the received sound levels in Hanalei 

Bay on July 3 from active sonar operations. The presence of a “weak” surface propagation 

duct (described as similar to the nominal condition) was noted. The Navy analyses were in 

agreement with NMFS results in suggesting that under certain conditions, sounds from active 

sonar transmissions could be detected by cetaceans near or in Hanalei Bay. However, the 

Navy analyses estimate higher received levels, particularly in the top 25m of the water column 

where the surface duct apparently occurred (U. S. Navy, 3rd Fleet, 2006). Estimated mean 

received levels from transmissions of various vessels at various times ranged from 

approximately 138-149 dBRMS re: 1μPa (U. S. Navy, 3rd Fleet, 2006) which would have been 

audible to people in the water at the time (Brandt and Hollien, 1969), despite the fact that the 

vessels were some tens of kilometers away from the Bay. Many people reported hearing 

sounds in the water but the majority of what was reported were vocalizations and whistles 

from the animals themselves. One person indicated to the stranding network that loud sonar 

sounds were detectable in the water for over an hour, but this was not reported by other 

individuals involved in the event. 

These results strongly suggest that sounds associated with the operations of July 3, 2004 could 

have been audible to some or all of the animals as they were milling within the embayment. If 

the U. S. Navy propagation modeling is correct, the active sonar transmissions on July 3 from 

vessels located on PMRF were likely a dominant acoustic event in at least some of Hanalei 

Bay while the animals were milling over a period of many hours. The significance of the 

estimated level of sonar exposure, or the cumulative exposure dose, over the period of several 

hours while the operations at PMRF were ongoing and the whales were within Hanalei Bay is 

not clear. 

42
Conclusion 

Mass stranding events of melon-headed whales have not previously been reported in Hawai‘i 

except for the 1841 report of animals in Hilo Bay being driven to shore. It must be noted that 

the exact circumstances surrounding that event will never be known. The first confirmed 

single stranding of a melon-headed whale in Hawaii was in 1964 and since that time Hawaii 

has had more confirmed reports than any other state in the U.S. There has only been one 

confirmed mass stranding of melon-headed whales in the U.S., an event involving 5 whales 

which stranded in Florida in March 2006 following several days in which a larger group was 

observed close to shore and in shallow waters prior to the stranding. Melon-headed whales 

may occur in large group sizes in the wild, and therefore may strand in large numbers when 

such events occur (range is 4 to >250). Melon-headed whales are not normally considered an 

island-associated species, although there may be some exceptions to this, e.g., Palmyra Atoll 

(Barlow, pers. comm.) and Marquesas Islands (Perrin 1976; Reeves et al., 1999) which is 

approximately 2000 miles to the southeast. They may be more common around some of the 

Pacific Islands that have deep water areas close to shore; however, they are more typically 

seen far from any land and are so classified as a pelagic species. 

Only three groups of melon-headed whales were detected within 25 nmi of the main Hawaiian 

Islands by Mobley et al. (2000), and a single group was detected over 500 miles from the main 

Hawaiian Islands by Barlow (2006) during a survey of the Hawaiian waters. The best estimate 

of abundance near the main Hawaiian Islands (within 25 nmi) is 154 based on the Mobley et 

al. (2000) analysis. Considering that Baird et al. (pers.com) determined, using boat-based 

observations involving 18 sightings, a mean group size of 147 for melon-headed whales in 

Hawai‘i, the entire abundance near the main Islands could be found in a single group. 

However, Mobley et al. (2000) found a much smaller mean group size (13.5), perhaps 

indicating that animals may also be more dispersed at times. The median group size 

determined during the surveys around the Hawaiian Islands and in the eastern tropical Pacific 

over the past 2 decades (24 sightings) is approximately 90 (Barlow, pers. comm. Baird et al.

(pers. comm.) have sighted a group with sufficient frequency off the lee side of the Big Island 

to indicate that there may be island-associated individuals around Hawai‘i. However, that 

does not mean unequivocally that the individuals that entered Hanalei Bay were Hawai‘i 

residents. These whales could have been a pelagic group that just happened to be around the 

islands at the time of the event. It is uncommon for these deep dwelling animals to be found 

in such shallow waters in Hawai‛i, as these animals prefer water that is > 2000 meters. Also, 

despite records of melon –headed whale mass strandings elsewhere in large groups, mass 

strandings of melon-headed whales are rare in U.S. waters, including in those of Hawaii. 

During the time the melon-headed whales were in Hanalei Bay, the animals were “milling 

about”—sometimes in tightly packed subgroups with individuals exhibiting spy hopping and 

tail slapping. Most investigators agree that tail slaps convey a threat or accompany frustration 

in addition to establishing contact with other school members (Dudzinski et al., 2002). 

Unusually high frequencies of spy hopping and “milling behavior” may be abnormal 

behaviors possibly related to normally pelagic animals being in a shallow embayment. Mass 

stranding of beached whales are often preceded by “milling” events, where a group of 

normally pelagic dolphins enters shallow water and begins to circle continuously or move 

43
about haphazardly in a tightly packed group, with an occasional member breaking away and 

swimming toward the beach (Geraci and Lounsbury 1993). Milling behavior may last only a 

short time or up to several days before stranding occurs (or does not occur in some cases), so 

prompt and appropriate intervention by humans maximizes the changes of preventing beach 

strandings or rescuing animals that strand (Geraci and Lounsbury, 1993, 2005). It is well 

known from many acoustic drive fisheries targeting small cetaceans that boat operators can 

use sound produced by various means to provide an acoustic barrier that can be used to drive 

animals to shore until a mass stranding results (Brownell et al., 2005). The combination of 

herding with small vessels and acoustic deterrents has been successful in preventing several 

milling events from becoming mass strandings of Atlantic white-sided dolphins 

(Lagenorhynchus acutus) in the Cape Cod region of Massachusetts (Touhey, 2003). 

A single male calf was found dead after the stranding, but MRI and CT images as well as 

necropsy findings showed no signs of acoustic or blunt trauma. The combination of post 

mortem findings suggests that this was a calf that died in poor nutritional status with evidence 

of stranding-related stress common among cetaceans. There were several changes detected by 

imaging and histology (fluid in the right Eustachian tube, congestion of the right lung) that 

suggest this animal was lying on its right side for a significant period post mortem. The cause 

of this mortality is unknown but it is likely a result of lack of nutrition, dehydration, and 

maternal separation. The reason for the lack of nursing is unknown. The animal was known 

to be separated from the herd on afternoon of July 4, 2004 at which time it was seen alone. 

Although it is possible that the female and calf separated during the milling in the Bay or upon 

exit from it, we do not know whether the female was in the Bay, had previously died, or was 

separated prior to entrance into the Bay. We do know that the animal was obtaining marginal 

nutrition at best and had not nursed for longer than the 28 hours; however, lack of nursing is 

not always indicative of maternal separation. 

Environmental analyses did not indicate any compelling reason that the animals entered the 

Bay on the morning of July 3, 2004 nor remained in the Bay through the morning of July 4, 

2004. There were no obvious significant weather or oceanographic events, harmful algal 

blooms, or known unusual biological predator or prey events that could explain the animals’ 

behavior moving into the Bay nor the groups continued presence in the Bay. However, we 

emphasize that there is a considerable dearth of information about these latter two variables 

before and during the event given our limited capacity to observe the surrounding 

environment. Strandings have been reported to occur due to other biological factors such as 

infectious diseases, toxic exposures, and others, but most commonly with unknown causes. 

Mass strandings more often involve highly social species where the strong cohesive social 

structure causes a group of animals to follow one lead animal into shallow waters or 

embayments and the animals maintain a highly cohesive group. In some cases in which the 

lead animal was sick or injured, once that animal is removed the rest of the group could be 

herded out to sea. We are unable to determine whether there was an ill or injured lead animal 

in this event; however no freshly injured or other stranded animals were observed during or 

following this event. Additionally, there may be other potential causative factors not 

considered in this report for which there is absolutely no information. Assessing causation of 

such an anomalous event involving a large group of apparently healthy animals thus remains 

limited by available information regarding potentially significant biological and other factors. 

44
The only known, large-scale, anthropogenic activities occurring in the vicinity of this 

stranding event were the active sonar transmissions covering much of the area between the 

islands of Oahu and Kaua‘i on July 2 and those occurring at PMRF on July 3. This 

investigation considered the possibility that military, mid-frequency sonar transmissions on 

the afternoon and evening of July 2 caused the group of whales to move from areas to the 

south and east of Kaua‘i into Hanalei Bay on the morning of July 3 and that transmissions on 

July 3 played some role in their refusal to depart. The results of this analysis indicate that 

such an association was possible based on the estimated sound transmission conditions and 

reasonable animal movement speeds over the time period. The analysis is limited in that the 

location of the animals prior to their arrival in Hanalei Bay is unknown and omnidirectional 

(rather than focused) propagation of the sonar is presumed. 

Sound propagation models of the RIMPAC sonar exercises conducted by NMFS on July 3, 

2004 at Pacific Missile Range Facility (PMRF) off the NW coast of Kaua‘i suggest that sonar 

transmissions could have been detectable near or within Hanalei Bay; analyses by U. S. Navy, 

3rd Fleet (2006) support and in fact considerably strengthen this conclusion. If sonar 

transmissions were audible at Hanalei Bay during the exercises, they could have contributed to 

the animals remaining there on July 3, 2004. The decision by the Navy to cease operations of 

active sonar as requested by NMFS may have provided an opportunity for the stranding 

network to herd the milling animals out of the Bay. Sonar transmissions were not present for 

~18 hours prior to the animals being herded from the Bay and it is unclear why the animals 

failed to leave during this timeframe. The presence of large numbers of people in the Bay 

interacting with the milling animals on July 3 (prior to the concerted effort to move the 

animals on July 4) could have interfered with their ability to move cohesively out of the Bay. 

Since the most sustained effort to move the animals out of the Bay did not occur until after the 

sonar and chaotic human interaction was terminated, it is difficult to determine whether their 

positive response to the concerted herding effort was due to the absence of sonar exposure, the 

absence of intermittent and random human interactions, or a combination of these or other 

factors. Based on previous experience with small cetaceans in near shore stranding events, 

timely, coordinated, and appropriate intervention with the melon-headed whales on July 4 may 

have prevented this milling event from resulting in additional mortality. 

While causation of this stranding event may never be unequivocally determined, we consider 

the active sonar transmissions of July 2-3, 2004, a plausible, if not likely, contributing factor 

in what may have been a confluence of events. This conclusion is based on: (1) the evidently 

anomalous nature of the stranding; (2) its close spatiotemporal correlation with wide-scale, 

sustained use of sonar systems previously associated with stranding of deep-diving marine 

mammals; (3) the directed movement of transmitting vessels toward the southwest and 

southeast coast of Kaua‘i; (4) the results of acoustic propagation modeling and an analysis of 

possible animal transit times to the Bay; and (5) the absence of any other compelling causative 

explanation. The initiation and persistence of this event may have resulted from an interaction 

of biological and physical factors. The biological factors may have included the presence of 

an apparently uncommon, deep-diving cetacean species (and possibly an offshore, nonresident group), social interactions among the animals before or after they entered the Bay, 

and/or unknown predator or prey conditions. The physical factors may have included the 

45
presence of nearby deep water, multiple vessels transiting in a directed manner while 

transmitting active sonar over a sustained period, the presence of surface sound ducting 

conditions, and/or intermittent and random human interactions while the animals were in the 

Bay. 

The absence of information on a number of key points is significantly restrictive. The 

limitations of available information regarding where animals were prior to entering the Bay, 

their previous potential exposure history to tactical mid-frequency sonar or other human sound 

sources, and key biological information such as the presence of anomalous predator or prey 

distributions preclude a single unequivocal conclusion. Key questions regarding the 

possibility that sonar transmissions were responsible for the stranding event remain 

unanswered. For instance, why would a single cetacean species exclusively respond in such a 

dramatic and coherent manner when, based on the analyses conducted here and by U. S. Navy, 

3rd Fleet (2006) and knowledge of Hawaiian cetacean abundance, many other marine 

mammals in the areas surrounding Kaua‘i were also exposed to sonar signals on July 2-3 

2004? Another pressing question is why, given the apparent historical frequency of active, 

military sonar use in and around the Hawaiian Islands, such exposures have apparently not 

triggered similar events previously? There are hypothetical explanations for these and other 

lingering questions (e.g., lack of previous concerted observational effort and the physical 

nature of the coastline and strong current patterns in the Hawaiian Islands that may limit the 

likelihood of detecting stranding events), but they too are strongly limited by the lack of 

information about both nominal behavior of this species and their reaction to natural and 

human sound sources. However, the limitations of the conclusions in this report demonstrates 

the need for concerted research on the distribution, life history, ecology, and behavior of deepdiving whales, including behavioral and physiological responses to both natural and 

anthropogenic acoustic stimuli. Complete and thorough response to and investigation of 

marine mammal stranding events are essential in understanding physical and biological 

contributing factors. 

46
Acknowledgements 

We are extremely grateful to the many people who assisted both on scene and off scene in this 

event, to the necropsy team, and to the reviewers of this document. 

The on scene responders worked tirelessly to assess the situation, develop a plan to move the 

animals out of the Bay, and reduce the human interactions while the animals were in the Bay. 

They include: the Hanalei Canoe Club, particularly Hanalei Hermosura and Kainoa Forrest; 

the County of Kauai Water Safety Officers, particularly Chad Listman and Jody Simpson; the 

County of Kauai Police Department; NOAA Fisheries Service’s Office for Law Enforcement 

special agents Paul Newman and Tommy Friel; the State of Hawaii’s Department of Land and 

Natural Resources, Division of Conservation and Resources Enforcement, particularly Milton 

Ching; NOAA Fisheries Service’s Pacific Islands Fishery Science Center, particularly Jennifer 

Bethel; NOAA Hawaiian Islands Humpback Whale National Marine Sanctuary, particularly 

Jean Souza; and the Hawaiian Islands Stranding Response Group, particularly Dr. Gregg 

Levine and Marlee Breese. U.S. Navy personnel with whom NOAA communicated during the 

event include LCDR Dan Dusek (3rd Fleet Battle Watch), LCDR Greg Geisen (Navy Public 

Affairs at PacFleet for RIMPAC ops), and CDR Dean Leach (PacFleet Environmental 

Counsel’s Office). 

In addition, we would like to thank those people who took the excellent photographs and 

provided copies to NOAA for documentation of the event, the animal behaviors, and the 

people involved. These include: Dennis Fujimoto, photographer for The Garden Island 

Newspaper; David Boynton; Brenda Zaun, wildlife biologist Kilauea Point National Wildlife 

Refuge; Jean Souza and Gretchen Johnson, NOAA Hawaiian Humpback Whale National 

Marine Sanctuary. Personal accounts of the events were provided by Gretchen Johnson and 

Dr. Bob Braun and these were invaluable in providing timelines and outlining events as they 

occurred. Joan Souza, Marlee Breese, and Dr. Bob Braun conducted additional interviews of 

eye witnesses for the report. Several NOAA Fisheries Service staff in Hawaii and at 

Headquarters provided additional support during and after the event including Brad Ryon, 

Tamra Farris, Dr. Janet Whaley, Trevor Spradlin and Connie Barclay. 

There has been considerable input for the report from numerous colleagues. The 

environmental analyses would not have been possible without the use of data and maps from 

Joshua Watson, Techniques Development Meteorologist of the National Weather Service; 

Andrew Nash, Director of Operations, National Weather Service, Honolulu; Mike Peccini, 

I.M. Systems Group, Inc.; and Huaichen Yang, RS Information Systems. Angela CollinsPayne, Mary Jacobs-Spaulding and Trevor Spradlin from NOAA Fisheries Office of Protected 

Resources provided additional assistance with the report preparation. 

Partial support for this stranding response came from the NOAA Fisheries John H. Prescott 

Marine Mammal Rescue Assistance Grant Program award to the Hawaiian Islands Stranding 

Response Group (NA03NMF4390037). 

47
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55
Appendices 

Appendix 1: Level A data sheet for the melon-headed whale calf stranded on July 5, 

2004 and necropsied on July 7, 2004. 

Appendix 2: Necropsy report for the melon-headed whale calf 

Appendix 3: List of contributors to the report 

Appendix 4: List of reviewers of the report

56
Appendix 1. 

Level A Data sheet for the melon-headed whale calf 

57


Appendix 2. 

Necropsy Report for the melon-headed whale calf

60
Necropsy Report on Melon-headed Whale (Peponocephala electra) 

Frances Gulland Vet.MB, PhD1

; Dorian Houser PhD2; Linda Lowenstine DVM, PhD, Dip. 

ACVP3; Kathleen Colegrove DVM1 & 3; Martin Haulena DVM1; J. A. Barakos MD4; 

1. The Marine Mammal Center, 1065 Fort Cronkhite, Sausalito, CA 94965 

2. Biomimetica, 9751 Shantung Drive, Santee, CA 92071 

3. Pathology Service, Veterinary Medical Teaching Hospital, University of California, Davis, 

CA 95616 

4. Department of Radiology, Neuroradiology Section, California Pacific Medical Center, San 

Francisco, CA 94147-5432 

This carcass is a neonate, male, code 2 (fresh, organs intact, dead 48 hours minimum) whale calf 

that was collected in Hanalei Bay, Kauai, Hawaii, on 7/5/04. It was shipped Federal Express 

7/6/04 on ice to The Marine Mammal Center (TMMC), Sausalito, California, from where it was 

taken to Raytel Imaging, San Francisco, for magnetic resonance imaging (MRI) and computer 

tomography (CT) scans prior to gross necropsy and collection of tissues for histopathology, 

bacteriology and banking at TMMC on 7/7/04. 

Imaging

Magnetic resonance imaging prior to dissection was performed using a GE Genesis Signa 1.5T 

MRI using GE XL 9.0 software. T1-weighted scans of in the sagittal and axial planes were 

collected for the head. In addition, the following pulse sequences were performed: T2* gradient 

echo (GRE) in the coronal and axial planes, T2 fast spin echo (FSE) in the coronal plane, and T2

fluid attenuation inversion recovery (FLAIR) in the coronal and axial planes. T1-weighted axial 

and T2 FSE coronal scans were collected for the thoracic region. (Parameters for the scans can 

be found at the end of this section.) 

Righ

Le

t

ft

Dorsal

Ventral

A B

Figure 1. Images demonstrating normally developed brain without indication of

hemorrhage, lesion or subdural hematomata. (A) CT scan through the brain, auditory

bullae, and associated air spaces. (B) T2* GRE of the same region. 
Computed tomography was performed with a GE Lightspeed CT. Images collected of the chest 

region (source of 140 kV at 120 mA) were contiguous and collimated to 5 mm. Images of the 

temporal bone (source of 120 kV at 100 mA) were also contiguous but collimated to 1 mm. 

Incomplete cerebral myelination was consistent with neonatal developmental stage. No localized

hemorrhages were observed within the parenchyma. No localized subarachnoid or 

intraventricular hemorrhages were observed and there was no indication of subdural hematomata 

(Fig. 1). No hemorrhage was apparent in any of the acoustic fats (i.e., melon and fats associated 

with the lower jaw). 

Right

Left

Anterior

Posterior

Figure 2. Coronal MRI image collected with the T2 FLAIR pulse sequence. The red 

arrow indicates the position of the cochlea. Some localized fluid accumulation 

appears in the Eustachian tube and associated sinus. 

Right

Righ

Le

t

ft

Left

Dorsal

Ventral

Anterior

Posterior

A B

Figure 3. (A) CT demonstrating consolidative changes of the right lung, and to a

lesser degree, in the left lung. (B) MRI collected with T2 FSE pulse sequence. The 

red arrow denotes the pronounced consolidative changes of the right lung. 

The auditory bullae appeared grossly normal and the persistence of cochlear fluid permitted the 

cochlea to be visualized via the FLAIR pulse sequence (Fig.2). Associated sinuses and 
Eustachian tubes appeared clear except for a localized region of hyperintensity involving the 

Eustachian tube and associated air spaces of the right auditory bulla, potentially corresponding to 

localized fluid accumulation. This collection measures approximately 7 x 9 x 10 mm. Although 

partially located within the pneumatized bone, it is not contiguous with the cochlea. 

Airspace consolidative changes were observed in approximately 75% of the right lung (Fig. 3) 

and to a lesser extent in the ventral (caudal) portion of the left lung lobe. The main bronchi 

appeared clear and free of debris. The skeletal system was free of fractures and no structural or 

congenital deformities of either the soft tissue or skeletal system were detected. 

MRI scan parameters – Head: 

Plane and Scan Type TR / TE Slice Thickness / Skip Matrix 

Sagittal T1 500/17 4 mm / 1 mm 256 x 224 

Axial T1 600/9 4 mm / 1 mm 320 x 224 

Axial/Coronal GRE T2* 517/15 5 mm / 1 mm 256 x 256 

(20 degree flip) 

Axial/Coronal FLAIR 9000/133 4 mm / 1 mm 256 x 224 

(TI = 2200) 

Coronal FSE T2 4000/110 4 mm / 1 mm 384 x 224 

MRI scan parameters – Chest: 

Plane and Scan Type TR / TE Slice Thickness / Skip Matrix 

Axial T1 567/14 8 mm / 2 mm 256 x 192 

Coronal FSE T2 3000/62 8 mm / 2 mm 256 x 192 

Measurements taken at the time of necropsy

Weight: 17.5 kg 

1. Total length: 115 cm 

2. Snout to anus: 78 cm 

3. Snout to genital slit: 67 cm 

4. Snout to umbilicus: 56 cm 

5. Snout to throat grooves: N/A 

6. Snout to dorsal fin tip: 70 cm 

7. Snout to anterior dorsal fin: 53 cm 

8. Snout to flipper: 28 cm 

9. Snout to ear: 23.5 cm 

10. Snout to eye: 17.5 cm 

11. Snout to gape: 15 cm 

12. Snout to blowhole: 15 cm 

13. Snout to melon apex: N/A (atrophied/non-developed melon) 

14. Eye to ear: 6 cm 

15. Eye to gape: 3 cm 

16. Eye to blowhole edge, left: 11.3 cm 

17: Eye to blowhole edge, right: 12.7 cm 
18. Blowhole length: 1.3 cm Blowhole width: 3 cm 

19. Diameter of ear opening: N/A (ear opening not distinguishable) 

20. Head diameter at eyes: 15 cm

21: Length of eye opening: 3 cm

22. Rostral width, melon apex: N/A 

23. Projection up/lower jaw: 0 cm

24. Number of throat grooves: N/A 

25. Length of throat grooves: N/A 

26. Flipper length, anterior: 23.8 cm

27. Flipper length, posterior: 17.4 cm 

28: Flipper width, maximum: 6.5 cm 

29: Length at mammary slits: N/A 

30: Number of mammary slits: N/A 

31: Length of genital slit: 9 cm; length of anal slit: 4.5 cm

32: Perineal length: 1.5 cm 

33. Fluke width: 25 cm

34. Fluke depth: lobe = 9 cm, notch = 8.5 cm

35. Fluke notch depth: 1.9 cm

36. Dorsal fin height: 10 cm

37. Dorsal fin base length: 15 cm

38: Girth at eye: 57.5 cm 

39. Girth at axilla: 56.5 cm

40. Girth, maximum: 57.5 cm

41. Girth at anus: 33.3 cm 

42. Girth midway anus to notch: 23.6 cm

43. Height same place: 10.5 cm

44. Thickness same place: 4.4 cm

45. Blubber thickness, dorsal: 11 mm 

46. Blubber thickness lateral: 11 mm 

47. Blubber thickness ventral: 10 mm 

Post mortem findings: 

Figure 4. Left lateral view of whale carcass 

Examined is the carcass of a 17. 5 kg, male melon headed whale (Peponocephala electra; Fig.4). 
 

In several areas the skin is flaking off the underlying tissue (interpreted to be post mortem

change). Approximately 6-8 circumferential fetal folds are present along the body (Fig. 5). The 

flukes are folded under at the tips (possible post mortem artifact). The umbilicus is absent (Fig. 

6) and the umbilical slit is partially closed. Along the inner body wall the umbilical slit is 

surrounded by a small amount of fibrous tissue (Fig. 7). Several vibrissae are present along the 

rostrum. The melon is poorly developed and the body is thin, with concavity caudal to the skull. 

Figure 5. Fetal folds on right side of

carcass 

Figure 6. Umbilical scar on ventrum of 

carcass 

Figure 7. Internal view of healing umbilical

scar. 
There are several, 1.0 - 5.0 cm long, linear, depressed areas of skin along the chin and ventral 

mandible that have slightly raised, dark grey edges. Several, shallow, gray linear depressions are 

present along the ventrum, at midline and adjacent to the umbilicus and genital slits. Rake marks 

are present on the right side of the head lateral and anterior to the right eye and over the body. A 

single circumferential, 2.0 mm wide linear depression extends circumferentially around the head 

at the level of the eye (Figs. 8A and B). There is no evidence of hemorrhage associated with this 

linear depression. 

A B

Figures 8 (A and B). Circumferential linear lesion in skin. 

There is scant adipose tissue in the abdominal cavity, around the kidneys, and in the coronary 

groove. The umbilical vein is partially patent. The urachus and umbilical arteries are partially 

patent. 

There is a small amount of light tan, foamy fluid in the distal trachea and main stem bronchi. The 

right lung lobes are slightly collapsed, diffusely mottled dark red and purple, rubbery and exude 

foamy fluid and a large amount of blood on cut section (Fig. 9). The anterioventral, medial 

dorsal and margins of the left lung lobes are markedly collapsed, and approximately 50-60 % of 

the left lung is dark purple and rubbery. The remaining areas of left lung are dark pink and 

aerated. All sections of lung float in formalin. The heart weighs 141.2 g (0.8 % of body weight), 

the right ventricle is 0.8 cm thick, the left ventricle is 1.0 cm thick, and the interventricular 

septum is 1.0 cm thick. The ductus arteriosus is closed and the foramen ovale is slightly 

fenestrated. The thymus extends partially up the trachea and several lobes are present just distal 

to the larynx. 

There is an approximately 4.0 cm diameter area of muscle over the distal left jaw that is pale 

pink to tan. There is no evidence of hemorrhage along the mandibular adipose tissue or skeletal 

muscle. 

The esophagus and all chambers of stomach are empty. Minimal, light yellow to tan thick fluid is 

present throughout the small and large intestine. There is no evidence of meconium within the 

colon. Approximately 25 ml of golden urine is present in the bladder. The testes are immature. 

 

The head was sectioned transversely at 1 to 2 cm increments using a band saw and the sections 

were examined grossly. Selected sections were fixed in formalin for preservation. No 

hemorrhages were detected in sinuses or inner ear cavities (Fig.10). The remainder of the head 

was refrozen. 
Figure 9. Dorsal view of lungs removed from

thorax. 

Figure 10. Sagital section of the frozen, formalin-fixed head at the level of the ears,

showing absence of hemorrhage. The scale on the right side indicates 1 cm. 
Microbiology: Aerobic and anaerobic bacterial culture of lung and liver grew Enterococcus sp., 

and two strains of Photobacterium damsela from each tissue. 

Tissues banked for toxicology at –400

 C: Blubber (ventral midline and dorsum), liver, kidney, 

urine. 

Tissues collected in DMSO for genetics: Skin (shipped to NOAA Southwest Fisheries Science 

Center, Chivers lab.) 

Tissues frozen at –700 C: lung, liver, spleen, kidney, serum (clotted blood from heart), urine, 

skeletal muscle, blubber. 

Tissues sampled for histopathology: lungs, heart, trachea, aorta, thymus, salivary gland, 

thyroid glands, tongue, esophagus, stomach, duodenum, jejunum, ileum, colon, pancreas, spleen, 

liver, kidney, ureter, urinary bladder, blubber, adrenal glands, skin (multiple sites), eye, blubber, 

muscle (multiple sites), testes, brain, and the mediastinal, sternal, axillary, and mesenteric lymph 

nodes. 

Histopathology

1) Lungs: Mild, multifocal, acute neutrophilic bronchopneumonia 

2) Lungs: Moderate circulating leukocytosis and mild neutrophilic interstitial pneumonia 

3) Lungs: Mild (right lung lobes) to moderate (left lung lobes) regional atelectasis, and 

moderate multifocal edema with aspirated squames and mild alveolar histiocytosis (Fig. 

11) 

4) Lungs: Acute passive congestion (moderate, right side and mild left) 

5) Jejunum: Mild multifocal acute superficial neutrophilic enteritis 

6) Skin, chin: Moderate multifocal, acute ulcerative and necrotizing dermatitis with 

epidermal hydropic degeneration 

7) Cranial mediastinal, sternal, cervical and axillary lymph nodes: Moderate sinusoidal 

congestion, histiocytosis and erythrophagocytosis 

8) Cervical and axillary lymph nodes: Mild sinusoidal neutrophila and minimal multifocal 

neutrophilic lymphadenitis 

9) Cranial mediastinal, sternal, cervical, and axillary lymph nodes: Multiple mineralized 

concretions (see comment) 

10) Spleen: Marked lymphoid depletion, circulating histiocytosis, and moderate 

extramedullary hematopoiesis (see comment) 

11) Heart: Mild, multifocal, acute myofiber necrosis 

12) Body as a whole: Emaciation 

13) Liver: Moderate diffuse congestion, mild hepatic lipidosis, and mild hepatocellular 

anisokaryosis with intracytoplasmic protein droplets 

14) Mesenteric lymph node: Moderate lymphoid hyperplasia and sinusoidal histiocytosis 

15) Kidneys: Moderate segmental congestion 

16) Pancreas: Mild zymogen depletion 

17) Brain: Mild meningeal congestion 

18) Tongue: Moderate segmental epithelial ballooning degeneration 
19) Skin, head (circumferential depression): Thinning of stratum spinosum (intermediativum) 

and mild, multifocal, keratinocyte hydropic degeneration 

20) Umbilicus: Superficial bacterial colonization and necrosis of distal umbilical vein and

artery with fibroplasia (interpreted as normal regression) 

21) Testes: Infantile 

Figure 11. Hemotoxylin and Eosin stained 

section of right lung showing congestion and

atelectasis. 

Comments: 

Based on the presence of fetal skin folds, degree of umbilical regression, standard length 

(reported normal birth length for Peponocephala electra is one meter), and histological 

appearance of the organs, this calf was most likely about a week old. All tissues examined were 

appropriately developed for a newborn cetacean and sections of lung were either fully or 

partially aerated. The meconium had been completely excreted, which occurs within the first 

few days of life in most species. The umbilicus had begun to regress and the ductus arteriosus 

was completely closed. 

All of the inflammatory changes noted in the tissues examined were regarded to be mild, acute 

(6-12 hours old), and could have been secondary to injuries acquired during stranding or from

being trapped in shallow water. There was no evidence of hemorrhage in the brain or in the 

cervical, cranial, or mandibular tissues and blubber. There was no evidence of viral disease in the 

tissues examined. Although cause of death could not be definitively determined, it is highly 

likely that maternal separation and poor nutritional condition were related to this calf’s stranding. 

 

This calf was emaciated and there was poor development of the melon. The stomach and 

intestines were empty. Therefore, this young whale likely had not nursed in sometime prior to 

stranding. Given the circumstances of the stranding, it is possible that this young animal was 

separated from the dam prior to stranding. It is not possible to determine whether this animal had 

ever nursed after being born. The thymus was well developed and there was no evidence of 

atrophy or depletion that can occur if there is poor nutrition or stress early in neonatal life. 

Hepatic lipidosis in young animals is often related to inanition or poor in utero nutrition. 
Bronchopneumonia is a common finding in stranded cetaceans and in mild cases is often related 

to the act of stranding or being trapped in shallow water. There was a circulating leukocytosis in 

the lungs and in a few areas a very mild acute interstitial pneumonia. These interstitial changes 

were interpreted to be secondary to acute systemic inflammation. The left lung lobes were 

partially atelectic, which could be consistent with partial failure of alveolar expansion after birth 

(atelectasis neonatorum). The right lung lobes were diffusely congested and edematous 

consistent with stranding in right lateral recumbency. Small numbers of aspirated squames are 

normally found in the lungs of neonatal animals and can be present in the lungs weeks after birth. 

Acute myofiber degeneration and necrosis in the heart is thought to be related to stress induced 

endogenous catecholamine release. In this case the lesions were mild in the sections examined. 

The skin lesions on the ventral mandible were acute and suggestive of external trauma. 

Interestingly, there was epithelial necrosis and adjacent intracellular edema in addition to the 

abrasions and ulcerations. These lesions can be associated with toxic injury to keratinocytes. 

Given the underwater topography of the area in which this animal stranded, we considered 

whether this change could have been related to contact or abrasions with coral. Similar lesions 

have been reported in humans following contact with coelenterates (Letot, B., PierardFranchimond, C. & Pierard, G.E. Acute reactions to coelenterates, Dermatologica 1990, 180: 

224-227). There was a moderate drainage reaction in several of the lymph nodes examined and 

in the axillary and cervical lymph nodes there was sinusoidal neutrophilia and lymphadenitis. 

Again, these changes were very mild and, given the location of the lymph nodes, the 

inflammation may be related to the acute skin lesions. There was marked lymphoid depletion in 

the spleen. The lymphoid atrophy may be related to the mild inflammation in the skin, lungs, or 

small intestine, or could be reflective of the animal’s poor nutritional condition and debilitation, 

though the thymus was not similarly depleted. Extramedullary hematopoiesis in the spleen is a 

normal finding in neonatal cetaceans. 

 

The thin linear indention that extended circumferentially around the head was not associated 

with inflammation histologically. The indention was associated with sub-lethal cellular changes 

indicating that the changes probably occurred ante-mortem. The exact etiology of this skin lesion 

is not known, however, similar facial clefts due to constriction by amniotic bands have been 

described in humans infants, and can be induced experimentally in lambs and mice (Rowsell, 

A.R. 1989. The amniotic band disruption complex. The pathogenesis of oblique facial clefts; an 

experimental study in the foetal rat. Br. J. Plast. Surg. 42:291-5; and Lockwood, C., Ghidini, 

A., Romero, R., Hobbins, J.C. 1989. Amniotic band syndrome: reevaluation of its pathogenesis. 

J. Obstet. Gynecol. 160:1030-3). This indention was regarded to be a separate entity from the 

fetal folds common in neonatal cetaceans which were also present in this young whale. There 

was no inflammation associated with the rake marks examined histologically, suggesting that at 

least some of the rake marks occurred after death. 

 

In several of the peripheral and thoracic lymph nodes examined there were small, mineralized 

concretions in the capsule and fibrous tissue septa of the node. In some areas these concretions 

were associated with the capillary endothelial cell lining. The significance of this finding is not 

known. Similarly, the adrenal cortex was much thinner than expected and from what has been 

noted in other cetacean species. Again, the significance of this change is unknown, and it may be 

an anatomic variation of this species or related to age. 
 

Conclusions: 

The combination of imaging, necropsy and histological findings suggest this calf was a neonate 

that died in poor nutritional status. There are several changes detected by imaging and histology 

(fluid in the right Eustachian tube, congestion of the right lung) that suggest this animal was 

lying on its right side for a significant period post-mortem. No evidence of trauma was detected. 

 
Appendix 3. 

Report Contributors 

Bernadette Allen, M.S. 

National Museum of Natural History 

Smithsonian Institution 

MRC 108 

P.O. Box 37012 

Washington, D.C. 20013 

Jay Barlow, Ph.D. 

Southwest Fisheries Science Center 

NOAA National Marine Fisheries Service 

8604 La Jolla Shores Drive 

La Jolla, CA 92037 

Jerome Barakos, M.D. 

Department of Radiology 

California Pacific Medical Center 

San Francisco, CA 94147 

Robert L. Brownell, Ph.D. 

Southwest Fisheries Science Center 

NOAA National Marine Fisheries Service 

1352 Lighthouse Avenue 

Pacific Grove, CA 93950 

Dorian Houser, Ph.D. 

BIOMIMETICA 

7951 Shantung Drive 

Santee, CA 92071 

Linda J. Lowenstine, D.V.M., Ph.D., Dip. A.C.V.P. 

School of Veterinary Medicine 

University of California Davis 

One Shields Avenue 

Davis, CA 95616 

James Mead, Ph.D. 

National Museum of Natural History 

Smithsonian Institution 

MRC 108 

P.O. Box 37012 

Washington, D.C. 20013 

Jean Souza 

Hawaiian Islands Humpback Whale National Marine Sanctuary 

NOAA National Ocean Service 

4370 Kukui Grove Street 

Lihue, HI 96766 

72
Appendix 4. 

Report Reviewers 

Jay Barlow, Ph.D. 

Southwest Fisheries Science Center David Rotstein, D.V.M., MPVM, Dipl. ACVP 

NOAA National Marine Fisheries Service College of Veterinary Medicine 

8604 La Jolla Shores Drive University of Tennessee 

La Jolla, CA 92037 2407 River Drive, Room A201 

Knoxville, TN 37996 

Robert L. Brownell, Ph.D. 

Southwest Fisheries Science Center Lori Schwacke, Ph.D. 

NOAA National Marine Fisheries Service CEBER 

1352 Lighthouse Avenue NOAA National Ocean Service 

Pacific Grove, CA 93950 219 Ft. Johnson Road 

Charleston, SC 29412 

Ailsa Hall, Ph.D. 

Senior Scientist Sofie Van Parijs, Ph.D. 

Sea Mammal Research Unit Northeast Fisheries Science Center 

Gatty Marine Laboratory NOAA National Marine Fisheries Service 

University of St. Andrews 166 Water Street 

St. Andrews Woods Hole, MA 02543 

Fife, Scotland KY16 8LB 

United Kingdom Randall Wells, Ph.D. 

Chicago Zoological Society 

Leila Hatch, Ph.D. c/o Mote Marine Laboratory 

Gerry E. Studds-Stellwagen Bank National 1600 Ken Thompson Parkway 

Marine Sanctuary Sarasota, FL 34236 

NOAA National Ocean Service 

175 Edward Foster Road 

Scituate, MA 02066 

Aleta Hohn, Ph.D. 

Southeast Fisheries Science Center 

NOAA National Marine Fisheries Service 

101 Pivers Island Road 

Beaufort, NC 28516 

Dorian Houser, Ph.D. 

BIOMIMETICA 

7951 Shantung Drive 

Santee, CA 92071 

Sue Moore, Ph.D. 

National Marine Mammal Laboratory 

Alaska Fisheries Science Center 

NOAA National Marine Fisheries Service 

7600 Sand Point Way, NE 

Seattle, WA 98115 

73