Largest baleen whale mass mortality during strong El Niño event is likely related to harmful toxic algal bloom

Abstract

While large mass mortality events (MMEs) are well known for toothed whales, they have been rare in baleen whales due to their less gregarious behaviour. Although in most cases the cause of mortality has not been conclusively identified, some baleen whale mortality events have been linked to bio-oceanographic conditions, such as harmful algal blooms (HABs).In southern Chile, HABs can be triggered by the ocean-atmosphere phenomenon El Niño. The frequency of the strongest El Niño events is increasing due to climate change. In March 2015, by far the largest reported mass mortality of baleen whales took place in a gulf in southern Chile. Here we show that the synchronous death of at least 343, primarily sei, whales can be attributed to HABs during a building El Niño. Although considered an oceanic species, the sei whales died while feeding near to shore in previously unknown large aggregations. This provides evidence of new feeding grounds for the species. The combination of older and newer remains of whales in the same area indicate that MMEs have occurred more than once in recent years.Large HABs and reports of marine mammal MMEs along the north-east Pacific coast may indicate similar processes in both hemispheres. Increasing MMEs through HABs may become a serious concern in the conservation of endangered whale species.

Full text

Largest baleen whale mass mortality
during strong El Nin
˜o event is likely
related to harmful toxic algal bloom
Verena Ha
¨ussermann
1,2,3
, Carolina S. Gutstein
4,5,6
, Michael
Beddington
7
, David Cassis
8
, Carlos Olavarria
9,10
, Andrew C. Dale
7
,
Ana M. Valenzuela-Toro
6,11
, Maria Jose Perez-Alvarez
9,12
,
Hector H. Sepu
´lveda
13
, Kaitlin M. McConnell
3
, Fanny E. Horwitz
14
and
Gu
¨nter Fo
¨rsterra
1,3,15
1Facultad de Ciencias Naturales, Escuela de Ciencias del Mar, Pontificia Universidad Cato
´lica de
Valparaı
´so, Valparaı
´so, Chile
2GeoBio-Center, Munich, Germany
3Huinay Scientific Field Station, Puerto Montt, Region de los Lagos, Chile
4Area de Patrimonio Natural, Consejo de Monumentos Nacionales, Santiago, Regio
´n
Metropolitana, Chile
5Red Paleontolo
´gica U-Chile, Laboratorio de Ontogenia y Filogenia, Departamento de Biologı
´a,
Facultad de Ciencias, Universidad de Chile, Santiago, Regio
´n Metropolitana, Chile
6Department of Paleobiology, National Museum of Natural History, Smithsonian Institution,
Washington, DC, USA
7Scottish Association for Marine Science, Oban, Scotland, UK
8Centro de Investigacio
´n e Innovacio
´n para el Cambio Clima
´tico, Universidad Santo To
´mas,
Santiago, Chile
9Centro de Investigacio
´n Eutropia, Santiago, Regio
´n Metropolitana, Chile
10 Centro de Estudios Avanzados en Zonas Aridas, La Serena, Chile
11 Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, USA
12 Instituto de Ecologı
´a y Biodiversidad, Facultad de Ciencias, Universidad de Chile, Santiago,
Chile
13 Departamento de Geofı
´sica, Universidad de Concepcio
´n, Concepcio
´n, Chile
14 Facultad de Ciencias Naturales y Oceanogra
´ficas, Universidad de Concepcio
´n, Concepcio
´n,
Chile
15 Department of Zoology, Ludwig-Maximilians-University, Munich, Germany
ABSTRACT
While large mass mortality events (MMEs) are well known for toothed whales,
they have been rare in baleen whales due to their less gregarious behavior.
Although in most cases the cause of mortality has not been conclusively identified,
some baleen whale mortality events have been linked to bio-oceanographic
conditions, such as harmful algal blooms (HABs). In Southern Chile, HABs can be
triggered by the ocean–atmosphere phenomenon El Nin
˜o. The frequency of the
strongest El Nin
˜o events is increasing due to climate change. In March 2015, by
far the largest reported mass mortality of baleen whales took place in a gulf
in Southern Chile. Here, we show that the synchronous death of at least 343,
primarily sei whales can be attributed to HABs during a building El Nin
˜o.
Although considered an oceanic species, the sei whales died while feeding near to
shore in previously unknown large aggregations. This provides evidence of new
feeding grounds for the species. The combination of older and newer remains of
whales in the same area indicate that MMEs have occurred more than once in
recent years. Large HABs and reports of marine mammal MMEs along the
How to cite this article Ha
¨ussermann et al. (2017), Largest baleen whale mass mortality during strong El Nin
˜o event is likely related to
harmful toxic algal bloom. PeerJ 5:e3123; DOI 10.7717/peerj.3123
Submitted 12 February 2016
Accepted 26 February 2017
Published 31 May 2017
Corresponding author
Carolina S. Gutstein,
sgcarolina@gmail.com
Academic editor
Mark Costello
Additional Information and
Declarations can be found on
page 44
DOI 10.7717/peerj.3123
Copyright
2017 Häussermann et al.
Distributed under
Creative Commons CC-BY 4.0

Northeast Pacific coast may indicate similar processes in both hemispheres.
Increasing MMEs through HABs may become a serious concern in the
conservation of endangered whale species.
Subjects Conservation Biology, Ecosystem Science, Marine Biology, Paleontology, Zoology
Keywords Chilean Patagonia, Red tide, El Nin
˜o, Sei whales, Drift models, Balaenoptera borealis,
Paralytic shellfish poison, Balaenopteridae, Taphonomy, Climate Change
INTRODUCTION
Although most populations of whales have been fully protected from industrial hunting
for half a century, some were reduced to such low levels that recovery is still very slow
(Baker & Clapham, 2004). Today, whales face additional threats, such as ship strikes,
entanglement and by-catch, underwater noise, pollution and habitat loss (Clapham,
Young & Brownell, 1999). Moreover, since ocean conditions directly influence quality
and availability of the prey species of baleen whales, the effects of climate change will
become a concern (Simmonds & Isaac, 2007).
Mass mortality events (MMEs) of marine mammals generally involve social species
such as dolphins or sea lions, but are rare in baleen whales due to their less gregarious
behavior (Perrin, Wu
¨rsig & Thewissen, 2009). When MMEs have occurred in baleen
whales, they have often extended over several months and large areas, involving mostly
coastal whales (Table 1). In the Northeast Pacific, seven to eight times more gray whales
(Eschrichtius robustus) washed ashore during the years 1999 and 2000 than is usual in
such a time span. Of these, 106 died within a three-month period in Mexico (Gulland
et al., 2005). In the course of 2012, 116 southern right whales (Eubalaena australis),
mostly calves, washed ashore at their breeding ground in Valde
´s Peninsula, Argentina
(Anonymous, 2015). During 2009, 46 humpback whales (Megaptera novaeangliae)
stranded in Australia (Coughran, Gales & Smith, 2013) and 96 in Brazil during 2010, most
of them calves and juveniles (Rowntree et al., 2013). Less frequent and much smaller
in magnitude are sudden and locally restricted baleen whale mortalities. The largest of
those involved 14 humpback whales, which died around Cape Cod during five weeks in
Nov 1987 (Geraci et al., 1989)(Table 1). The causes of most MMEs have not been
conclusively identified (Anonymous, 2015;Coughran, Gales & Smith, 2013;Gulland et al.,
2005); however, paralytic shellfish poisoning (PSP) during harmful algal blooms
(HABs) has been argued as one of the main likely causes (and this is also the case for
other marine vertebrate mass mortalities; Geraci et al., 1989;Durbin et al., 2002;Doucette
et al., 2006;Rowntree et al., 2013;Cook et al., 2015;D’Agostino et al., 2015;Wilson et al.,
2015;Lefebvre et al., 2016).
Harmful algal blooms have an extended record in Southern Chile (particularly the
genus Alexandrium with production of paralytic shellfish toxins (PSTs)). HABs have been
of concern to fishermen and Patagonian communities since at least 1972, when the first
mass intoxication was recorded (Sua
´rez & Guzma
´n, 2005). Since then, the geographic
region in which blooms have been detected has increased to over 1,000 km north–south
extent (Molinet et al., 2003). HABs have also become more frequent, becoming annual
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 2/51

events with blooms normally occurring in large areas during the summer and fall
(Guzma
´n et al., 2002). Due to the danger posed by these toxins, the Chilean government
funds a monitoring program with over 200 sampling stations throughout the Southern
part of Chile, where phytoplankton and shellfish samples are obtained and later analyzed
for the presence of microalgae and their toxins (PST, amnesic shellfish toxin (AST),
diarrheic shellfish toxin (DST)) (Sua
´rez & Guzma
´n, 2005). Unfortunately, mainly due to
the difficulty accessing many sites, these biotoxin data are only available for a limited
coastal area of Southern Chile.
Table 1 Recorded mass mortality events of baleen whales (updated from Table 1 in Rowntree et al. (2013)).
Region/site Time span Species Number Age classes Cause of death Source
Caleta Buena/slight
inlet, Southern Chile
Nov/Dec 1977 Rorqual Four fresh,
numerous
skeletons
Unknown M. Salas, 2015, personal
communication
Cape Cod (USA) Five weeks (11/1987) Humpback 14 HAB (saxitoxin) Geraci et al. (1989)
Upper Gulf of
California (Mexico)
? (1995) Fin, minke
and bryde
1
Eight Unknown Vidal & Gallo Reynoso
(1996)
Eastern North East
Pacific
Throughout 1999 Gray 283
2
Mostly adults Malnutrition? Gulland et al. (2005)
Eastern North East
Pacific
Throughout 2000 Gray 368 Mostly adults Malnutrition? Gulland et al. (2005)
Upper Gulf of
California (Mexico)
? (2009) Unknown 10 Unknown Rowntree et al. (2013)
Australia Throughout 2009 Humpback 46 Mostly calves
and juveniles
Unknown Coughran, Gales & Smith
(2013)
Brazil Throughout 2010 Humpback 96 Mostly calves
and juveniles
Unknown Rowntree et al. (2013)
Peninsula Valde
´s
(Argentina)
2005–2011
3
Southern
right
420 Mostly calves Unknown
(HAB-related?
Starvation?
Kelp gull
harassment?)
D’Agostino et al. (2015);
Wilson et al. (2015)
Puerto Ede
´n area
(Chile)
Mar 2011 Sei and/or
minke
Three Unknown This paper
Estero Cono (Chile) Mar 2012 Sei and/or
minke
15 Unknown R.M. Fischer, 2015,
personal
communication
Puerto Ede
´n area
(Chile)
Jan 2014 Sei and/or
minke
Five Unknown C. Cristie, 2015, personal
communication
Between 46 and 51S,
mainly Golfo de
Penas (Chile)
Feb to early Apr 2015
4
Probably all
sei
343 All HAB This paper
Alaska/British
Columbia (USA/
Canada)
May/Jun 2015 Fin,
humpback,
gray
38 Unknown
(HAB?)
NOAA (2015b)
Notes:
1
In total, 400 cetaceans died, including eight baleen whales.
2
A total of 106 in Mexico during three months.
3
A total of 116 died during 2012.
4
A total of 271 died within one month.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 3/51

Chilean Patagonia is a complex environment that hosts one of the largest and
most extensive fjord regions, with a north–south extent of approximately 1,500 km
(42S–55S), covering an area of over 240,000 km
2
and with a coastline of more than
80,000 km, made up of numerous fjords, channels and islands. At the same time, this is
one of the least scientifically understood marine regions of the world (Fo
¨rsterra, 2009;
Fo
¨rsterra, Ha
¨ussermann & Laudien, 2017). Precipitation can locally exceed 6,000 mm per
year and the tidal range can exceed 7 m. The prevailing strong westerly winds make its
exposed shores amongst the most wave-impacted in the world (Fo
¨rsterra, 2009). These
factors are responsible for the inaccessibility of a large part of this region. Chilean
Patagonia is subdivided into the North, Central and South Patagonian zone (for a
summary of biogeography of the region see Ha
¨ussermann & Fo
¨rsterra, 2005 and Fo
¨rsterra,
Ha
¨ussermann & Laudien, 2017). The remote area around Golfo de Penas and Taitao
Peninsula (Fig. 1) is situated in the Central Patagonian Zone between 47S and 48S.
Except for two Chilean Navy lighthouses at Cabo Raper and San Pedro, the closest human
settlements are more than 200 km away (Tortel, Puerto Ayse
´n and Puerto Ede
´n).
In general, Chilean Patagonia is influenced by the West Wind Drift, a large-scale
eastward (onshore) flow which diverges at the coast to form the northward Humboldt
Current and the southward Cape Horn Current (Thiel et al., 2007). The fjordic nature of
the coastline produces significant local complexity, with many inlets and dispersed
freshwater sources. High productivity in these coastal waters (Fig. 2) is driven by the
availability of both terrestrial nutrients, carried by large rivers originating at the Northern
and Southern Patagonian Ice Fields, and marine nutrients (Gonza
´lez et al., 2010;Torres
et al., 2014). While this region experiences coastal winds that favor net coastal
downwelling, intermittent and/or localized upwelling, in particular in summer and North
of Taitao Peninsula (47S), is expected to enhance the supply of marine nutrients to
coastal waters, and the relative balance between upwelling and downwelling varies from
year to year.
During a vessel-based scuba diving expedition, “Huinay Fiordos 24” (HF24), focused
on benthic fauna between Golfo Tres Montes (Northern Golfo de Penas, 4630′W) and
Puerto Eden (49S), dead baleen whales and skeletal remains were discovered south of
Golfo de Penas and at Golfo Tres Montes. Here, we describe by far the largest ever-
recorded MME of baleen whales at one time and place. Our analyses focus on the location
and cause of the mortality.
MATERIALS AND METHODS
Field surveys
The vessel-based HF24 scuba diving expedition, from Apr 15 to May 8, 2015, aimed to
inventory the benthic fauna of the area between Golfo Tres Montes (Northern Golfo de
Penas, 4630′W) and Puerto Ede
´n (49S). By chance, VH and her team discovered recently
dead baleen whales and skeletal remains in and close to the entrance of the 14 km
long Estero Slight and in the Canal Castillo situated 235 km to the south (Figs. 1 and 3;
Table 2). Georeferences and photographs of different views were taken, whales measured,
and species and sex identified whenever possible. Between May 25 and 31, the Chilean
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 4/51

Fisheries Service (SERNAPESCA), with the support of the Chilean Navy (Armada)
and the Criminal Investigation Department of the Civil Police (PDI), organized a vessel-
based trip to the location of the dead whales in Estero Slight to investigate possible
anthropogenic reasons behind the mortality. During this trip, genetic samples for species
Figure 1 Location of dead whales and skulls found in Chilean Patagonian. Boat track: green (HF24),
flight track: blue (HF25). (A) Golfo de Penas, (B) Golfo Tres Montes and (C) Seno Escondido.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 5/51

identification were taken, one ear bone was extracted and stomach and intestine contents
of two whales were tested for presence of PSTand AST (Fiscalı
´a de Ayse
´n, 2015). During a
subsequent aerial survey, on-board a high wing airplane Cessna 206, between Jun 23
and 27, 2015, three of us (CG, VH and FH) surveyed the coasts along the shores
of Golfo de Penas. This aerial survey covered the coastal area between the Jungfrauen
Islands (48S) and Seno Newman (4639′S) from altitudes between 100 and 850 m and at
speeds between 100 and 200 km/h (Figs. 1 and 4;Table 2). Due to limited flying time
Figure 2 Satellite image (MODIS Aqua) showing the concentration of chlorophyll a on Mar 23, 2015.
Areas where most whales were found are circled.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 6/51

(unstable weather conditions and the inability to refuel in the area), data collection was
focused on counting whale carcasses, recording GPS positions and taking photographs.
A GoPro camera filmed continuously until reaching Seno Newman. The researchers on
the flight counted carcasses and marked their coordinates while an audio recorder
captured the carcass number, position, orientation, photo number, photographer and
geomorphology of the beach. Whale counts were repeated in all areas except Seno
Newman due to adverse weather conditions. Since there are no landing opportunities in
this remote and unpopulated area, it was not possible to take samples or close-up photos,
or to search for additional whale bones.
In addition to the whale carcasses and skeletons from the two surveys, some whale
carcasses and skulls were reported between Feb and Jun 2015 by boat crews navigating the
west coast of Taitao Peninsula and the coast between 4915′and 51S(Table 2). Between
Jan 23 and Mar 1, 2016 (Expedition Huinay Fiordos 27) and between Apr 27 and May 30,
2016 (Expedition Huinay Fiordos 29), two additional vessel-based expeditions were
Figure 3 Documented whale carcasses and skeletal remains during a vessel survey in Apr 21, 2015 in
Caleta Buena, Estero Slight. (A and B) Skeletal remains. (C) Recently dead sei whale. Photos: Keri-Lee
Pashuk, all rights reserved.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 7/51

Table 2 List of whale carcasses, their degree of decomposition/disarticulation, location and date of finding.
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
HF24 expedition
Apr 21, 2015 West of Isla Centro 1 4643.158′S75
22.09′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 21, 2015 West of Isla Centro 2 4643.069′S75
22.553′W 1 Lateral-up Rocky Balaenoptera
borealis
Male
Apr 21, 2015 West of Isla Centro 3 4643.095′S75
22.759′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 21, 2015 West of Isla Centro 4 4643.561′S75
26.079′W 1 Rocky Balaenopteridae
Apr 21, 2015 Caleta Buena 5 4646.92′S75
30.057′W 1 Ventral-up Floating Balaenoptera
borealis
Female
Apr 21, 2015 Caleta Buena 6 4647.25′S75
29.872′W 1 Lateral-up Floating Balaenoptera
borealis
Male
Apr 21, 2015 Caleta Buena 7 4647.248′S75
29.876′W 1 Ventral-up Floating
Apr 21, 2015 Caleta Buena 8 4647.275′S75
29.837′W 1 Lateral-up Rocky Balaenoptera
borealis
Male
Apr 21, 2015 Caleta Buena 9 4647.268′S75
29.82′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 21, 2015 Caleta Buena 10 4647.264′S75
29.807′W 1 Lateral-up Rocky Balaenoptera
borealis
Female
Apr 21, 2015 Caleta Buena 11 4647.261′S75
29.798′W 1 Lateral-up Rocky Balaenoptera
borealis
Female
Apr 21, 2015 Caleta Buena 12 4647.253′S75
29.789′W 1 Lateral-up Rocky Balaenoptera
borealis
Male
Apr 21, 2015 Caleta Buena 13 4647.249′S75
29.787′W 3 Ventral-up Rocky
Apr 21, 2015 Caleta Buena 14 4647.258′S75
29.8′W 3 Ventral-up Floating
Apr 21, 2015 Caleta Buena 15 4647.261′S75
29.812′W 3 Ventral-up Floating
Apr 22, 2015 Estero Slight 16 4647.135′S75
32.269′W 2 Lateral-up Rocky Balaenoptera
borealis
Apr 22, 2015 Estero Slight 17 4647.214′S75
34.332′W 3 Ventral-up Rocky
Apr 22, 2015 Estero Slight 18 4647.817′S75
32.788′W 1 Lateral-up Rocky Balaenoptera
borealis
Female
Apr 22, 2015 Estero Slight 19 4647.951′S75
32.973′W 2 Floating Balaenoptera
borealis
Apr 22, 2015 Estero Slight 20 4648.023′S75
33.055′W 2 Rocky Balaenoptera
borealis
Apr 22, 2015 Estero Slight 21 4648.264′S75
33.425′W 2 Ventral-up Rocky Balaenoptera
borealis
Female
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 8/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Apr 22, 2015 Estero Slight 22 4648.51′S75
33.909′W 1 Lateral-up Rocky Balaenoptera
borealis
Female
Apr 22, 2015 Estero Slight 23 4648.508′S75
33.914′W 1 Lateral-up Rocky Balaenoptera
borealis
Male
Apr 22, 2015 Estero Slight 24 4648.515′S75
34.668′W 1 Lateral-up Sandy Balaenopteridae
Apr 22, 2015 Estero Slight 25 4648.511′S75
34.684′W 3 Dorsal up Sandy Balaenoptera
borealis
Female
Apr 22, 2015 Estero Slight 26 4648.206′S75
34.905′W 3 Ventral-up Rocky
Apr 22, 2015 Estero Slight 27 4648.204′S75
34.909′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 22, 2015 Estero Slight 28 4648.09′S75
34.9′W 3 Ventral-up Rocky
Apr 22, 2015 Estero Slight 29 4648.01′S75
34.909′W 3 Lateral-up Rocky
Apr 22, 2015 Estero Slight 30 4648.008′S75
34.902′W 3 Lateral-up Rocky
Apr 22, 2015 Estero Slight 31 4647.919′S75
34.86′W 1 Lateral-up Floating Balaenoptera
borealis
Female
Apr 22, 2015 Estero Slight 32 4647.642′S75
34.753′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 22, 2015 Estero Slight 33 4647.538′S75
34.651′W 1 Lateral-up Rocky Balaenopteridae
Apr 22, 2015 Estero Slight 34 4647.442′S75
34.463′W 3 Lateral-up Rocky
Apr 22, 2015 Estero Slight 35 4646.173′S75
33.247′W 1 Ventral-up Rocky Balaenoptera
borealis
Male
Apr 22, 2015 Estero Slight 36 4846.002′S75
33.066′W 3 Ventral-up Rocky
Apr 22, 2015 Estero Slight/Baja Julio 37 4845.626′S75
31.102′W 2 Floating
Apr 22, 2015 Estero Slight/Baja Julio 38 4845.530′S75
30.962′W 1 Lateral-up Rocky Balaenopteridae
Apr 22, 2015 Estero Slight/Baja Julio 39 4645.205′S75
30.75′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 22, 2015 Estero Slight/Baja Julio 40 4645.008′S75
30.674′W 1 Lateral-up Rocky Balaenoptera
borealis
Apr 22, 2015 Islote Amarillo 41 4640.967′S75
27.983′W 1 Lateral-up Rocky Balaenopteridae
Apr 22, 2015 Islote Amarillo 42 4640.722′S75
27.21′W 1 Lateral-up Rocky Balaenopteridae
Apr 22, 2015 Isla Esmeralda 43 4848.08′S75
24.29′W
Apr 22, 2015 Isla Hyatt 44 4847.95′S75
26.45′W
Apr 22, 2015 Isla Hyatt 45 4847.3′S75
26.13′W
Apr 22, 2015 Isla Hyatt 46 4847.26′S75
26.01′W
Apr 22, 2015 Isla Hyatt 47 4847.19′S75
25.91′W
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 9/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
HF25 expedition
Jun 23, 2015 Jungfrauen group 48 4732.29′S74
32.484′W 2 2 Lateral-up Rocky
Jun 23, 2015 Jungfrauen group 49 4736.16′S74
34.997′W Floating
Jun 24, 2015 Jungfrauen group 50 483.874′S75
1.788′W Floating Balaenopteridae
Jun 24, 2015 Jungfrauen group 51 483.875′S75
1.791′W Floating Balaenopteridae
Jun 24, 2015 Jungfrauen group 52 484.209′S75
1.052′W Rocky
Jun 24, 2015 Jungfrauen group 53 483.361′S75
7.514′W Rocky
Jun 24, 2015 Jungfrauen group 54 4759.048′S75
15.302′W 2 2 Lateral-up Rocky
Jun 24, 2015 Jungfrauen group 55 4757.402′S75
15.671′W 2 2 Rocky
Jun 24, 2015 Jungfrauen group 56 4757.554′S75
14.56′W 2 1 Rocky
Jun 24, 2015 Jungfrauen group 57 4756.28′S75
14.706′W 2 1 Rocky
Jun 24, 2015 Jungfrauen group 58 4751.025′S75
13.345′W 1 1 Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 59 4750.923′S75
12.912′W 1 1 Rocky
Jun 24, 2015 Jungfrauen group 60 4750.701′S75
12.218′W 2 1 Lateral-up Rocky
Jun 24, 2015 Jungfrauen group 61 4750.799′S75
13.279′W 2 1 Ventral-up Rocky
Jun 24, 2015 Jungfrauen group 62 4748.885′S75
12.317′W 2 Sandy
Jun 24, 2015 Jungfrauen group 63 4748.598′S75
12.183′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Jungfrauen group 64 4752.994′S75
11.915′W Rocky
Jun 24, 2015 Jungfrauen group 65 4752.766′S75
11.704′W Rocky
Jun 24, 2015 Jungfrauen group 66 4753.019′S75
9.343′W 2 Rocky
Jun 24, 2015 Jungfrauen group 67 4753.004′S75
9.316′W 2 1 Rocky
Jun 24, 2015 Jungfrauen group 68 4752.409′S75
8.578′W Sandy Balaenopteridae
Jun 24, 2015 Jungfrauen group 69 4751.775′S75
4.472′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 70 4751.527′S75
3.374′W Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 71 4749.123′S75
3.696′W 2 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 72 4749.698′S75
59.956′W Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 73 4747.558′S74
58.11′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 74 4747.474′S74
58.107′W 2 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Jungfrauen group 75 4747.089′S74
58.445′W Rocky
Jun 24, 2015 Jungfrauen group 76 4717.614′S74
22.75′W Sandy
Jun 24, 2015 Jungfrauen group 77 4717.454′S74
22.494′W Sandy
Jun 24, 2015 San Quintin bay I 78 4650.51′S74
37.41′W Sandy
Jun 24, 2015 San Quintin bay I 79 4649.324′S74
35.952′W Sandy
Jun 24, 2015 San Quintin bay I 80 4649.905′S74
36.359′W Lateral-up Sandy Balaenoptera
borealis
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 10/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 San Quintin bay I 81 4649.973′S74
36.381′W Lateral-up Sandy Balaenoptera
borealis
Jun 24, 2015 San Quintin bay I 82 4650.495′S74
36.442′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 83 4650.488′S74
36.428′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 84 4650.476′S74
36.304′W Ventral-up Sandy–rocky
Jun 24, 2015 San Quintin bay I 85 4650.474′S74
36.288′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 86 4650.476′S74
36.262′W 1 1 Ventral-up Sandy–rocky
Jun 24, 2015 San Quintin bay I 87 4650.47′S74
36.128′W 2 Lateral-up rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 88 4650.467′S74
36.104′W 1 1 Lateral-up rocky
Jun 24, 2015 San Quintin bay I 89 4650.444′S74
36.02′W 2 1 Lateral-up Sandy–rocky
Jun 24, 2015 San Quintin bay I 90 4650.437′S74
35.943′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 91 4650.431′S74
35.931′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 92 4650.428′S74
35.925′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 93 4650.422′S74
35.926′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 94 4650.405′S74
35.924′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 95 4650.404′S74
35.921′W 1 1 Lateral-up Sandy
Jun 24, 2015 San Quintin bay I 96 4650.371′S74
35.951′W 2 1 Lateral-up Sandy
Jun 24, 2015 San Quintin bay I 97 4650.357′S74
35.96′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 98 4650.355′S74
35.957′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 99 4650.353′S74
35.96′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 100 4650.326′S74
36.22′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 101 4650.322′S74
36.024′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 102 4650.285′S74
36.188′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay I 103 4650.256′S74
36.102′W 1 1 Rocky
Jun 24, 2015 San Quintin bay I 104 4650.254′S74
36.094′W 2 1 Rocky
Jun 24, 2015 San Quintin bay I 105 4650.23′S74
36.073′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 106 4650.1′S74
36.194′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 107 4650.243′S74
35.836′W 2 1 Ventral-up Sandy
Jun 24, 2015 San Quintin bay I 108 4650.247′S74
35.834′W 2 1 Ventral-up Sandy
Jun 24, 2015 San Quintin bay I 109 4650.251′S74
35.652′W 3 1 Ventral-up Sandy
Jun 24, 2015 San Quintin bay I 110 4650.258′S74
35.639′W 2 1 Ventral-up Sandy
Jun 24, 2015 San Quintin bay I 111 4650.212′S74
35.585′W 1 1 Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 112 4650.229′S74
35.513′W 2 1 Lateral-up Sandy–rocky
Jun 24, 2015 San Quintin bay I 113 4650.222′S74
35.483′W 2 Rocky
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 11/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 San Quintin bay I 114 4650.214′S74
35.429′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 115 4650.195′S74
35.315′W 1 1 Ventral-up Rocky
Jun 24, 2015 San Quintin bay I 116 4650.184′S74
35.18′W Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 San Quintin bay I 117 4650.172′S74
35.1′W 2 1 Ventral-up Rocky
Jun 24, 2015 San Quintin bay I 118 4650.126′S74
34.995′W 2 1 Sandy–rocky
Jun 24, 2015 San Quintin bay I 119 4650.122′S74
34.894′W Sandy–rocky
Jun 24, 2015 San Quintin bay I 120 4649.958′S74
34.433′W Rocky
Jun 24, 2015 San Quintin bay I 121 4649.928′S74
34.459′W 2 1 Rocky
Jun 24, 2015 San Quintin bay I 122 4649.902′S74
34.385′W 2 Rocky
Jun 24, 2015 San Quintin bay I 123 4649.879′S74
34.158′W Ventral-up Sandy–rocky
Jun 24, 2015 San Quintin bay I 124 4650.482′S74
38.058′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 125 4648.956′S74
39.394′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 126 4649.207′S74
39.756′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 127 4649.145′S74
40.03′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 128 4649.299′S74
40.244′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 129 4649.136′S74
40.346′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 130 4649.134′S74
40.346′W Ventral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 131 4649.117′S74
40.317′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 132 4649.12′S74
40.324′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 133 4648.872′S74
40.634′W Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 134 4649.026′S74
40.594′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 135 4649.017′S74
40.617′W 1 1 Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 136 4649.111′S74
40.713′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 137 4649.109′S74
40.727′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 138 4649.243′S74
40.792′W 1 1 Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 139 4649.218′S74
40.821′W Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 140 4649.182′S74
40.863′W 1 Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 141 4649.185′S74
40.893′W 1 1 Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 142 4649.155′S74
41.014′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 143 4649.146′S74
41.118′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 144 4648.985′S74
41.307′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 145 4649.003′S74
41.312′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 146 4649.008′S74
41.313′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 147 4649.028′S74
41.327′W Lateral-up Rocky Balaenopteridae
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 12/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 San Quintin bay II 148 4649.061′S74
41.359′W Rocky
Jun 24, 2015 San Quintin bay II 149 4649.104′S74
41.404′W Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 150 4649.027′S74
41.441′W Rocky Balaenopteridae
Jun 24, 2015 San Quintin bay II 151 4648.909′S74
41.55′W Floating
Jun 24, 2015 San Quintin bay II 152 4648.87′S74
41.539′W Floating Balaenopteridae
Jun 24, 2015 San Quintin bay II 153 4648.645′S74
41.697′W Sandy
Jun 24, 2015 San Quintin bay II 154 4648.691′S74
41.584′W Sandy
Jun 24, 2015 San Quintin bay II 155 4646.879′S74
46.086′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 San Quintin bay II 156 4649.78′S74
32.109′W Rocky
Jun 24, 2015 Seno Newman 157 4643.813′S74
57.964′W 2 2 Sandy
Jun 24, 2015 Seno Newman 158 4641.327′S75
0.753′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 159 4637.458′S75
2.434′W 2 Sandy–rocky
Jun 24, 2015 Seno Newman 160 4637.415′S75
2.637′W 1 1 Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 161 4637.415′S75
2.635′W 1 1 Sandy–rocky
Jun 24, 2015 Seno Newman 162 4636.941′S75
2.113′W 2 1 Sandy
Jun 24, 2015 Seno Newman 163 4636.918′S75
2.082′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 164 4636.854′S75
2.004′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 165 4636.756′S75
1.976′W Rocky
Jun 24, 2015 Seno Newman 166 4636.539′S75
1.71′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 167 4636.441′S75
2.075′W 1 1 Ventral-up Sandy
Jun 24, 2015 Seno Newman 168 4636.369′S75
1.672′W Floating
Jun 24, 2015 Seno Newman 169 4635.82′S75
1.375′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 170 4635.377′S75
1.041′W 1 1 Ventral-up Rocky
Jun 24, 2015 Seno Newman 171 4635.161′S75
0.66′W Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 172 4635.087′S75
0.513′W 1 Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 173 4635.089′S75
0.49′W 1 Sandy
Jun 24, 2015 Seno Newman 174 4635.083′S75
0.42′W 1 1 Floating Balaenopteridae
Jun 24, 2015 Seno Newman 175 4635.085′S74
59.71′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 176 4634.88′S74
59.475′W Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 177 4634.794′S74
59.426′W Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 178 4634.449′S74
59.313′W Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 179 4633.721′S74
59.271′W 2 Ventral-up Sandy
Jun 24, 2015 Seno Newman 180 4633.501′S74
59.192′W 2 1 Sandy–rocky
Jun 24, 2015 Seno Newman 181 4633.125′S74
58.681′W 2 Rocky
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 13/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 Seno Newman 182 4633.12′S74
58.674′W 1 1 Rocky
Jun 24, 2015 Seno Newman 183 4632.939′S74
58.52′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 184 4632.521′S74
57.707′W 2 Rocky
Jun 24, 2015 Seno Newman 185 4632.473′S74
57.635′W 2 1 Rocky
Jun 24, 2015 Seno Newman 186 4632.424′S74
57.582′W 2 1 Rocky
Jun 24, 2015 Seno Newman 187 4632.388′S74
57.532′W 2 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 188 4632.346′S74
57.469′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 189 4632.348′S74
57.469′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 190 4632.267′S74
57.188′W 2 1 Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 191 4632.096′S74
57.303′W 1 1 Sandy
Jun 24, 2015 Seno Newman 192 4632.07′S74
57.254′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 193 4632.068′S74
57.247′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 194 4632.027′S74
57.153′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 195 4631.998′S74
57.106′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 196 4631.919′S74
57.006′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 197 4631.852′S74
56.936′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 198 4631.829′S74
56.922′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 199 4631.721′S74
56.839′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 200 4631.592′S74
56.733′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 201 4631.461′S74
56.568′W 2 1 Lateral-up Sandy
Jun 24, 2015 Seno Newman 202 4631.311′S74
56.537′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 203 4631.304′S74
56.525′W 2 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 204 4631.265′S74
56.489′W 2 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 205 4631.055′S74
56.197′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 206 4630.974′S74
56.093′W 2 1 Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 207 4630.948′S74
56.065′W 2 1 Lateral-up Sandy–rocky
Jun 24, 2015 Seno Newman 208 4630.866′S74
55.959′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 209 4630.859′S74
55.953′W 2 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 210 4630.824′S74
55.907′W 2 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 211 4630.757′S74
55.817′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 212 4630.702′S74
55.734′W 1 1 Ventral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 213 4630.709′S74
55.689′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 214 4630.707′S74
55.674′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 215 4630.662′S74
55.593′W 3 Ventral-up Rocky Balaenopteridae
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 14/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 Seno Newman 216 4630.624′S74
55.439′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 217 4630.627′S74
55.432′W 2 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 218 4630.629′S74
55.425′W 2 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 219 4630.632′S74
55.419′W 2 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 220 4630.63′S74
55.411′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 221 4630.627′S74
55.368′W Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 222 4630.618′S74
55.338′W Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 223 4630.191′S74
55.327′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 224 4630.093′S74
55.297′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 225 4630.054′S74
55.243′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 226 4629.992′S74
55.167′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 227 4629.984′S74
55.165′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 228 4629.975′S74
55.164′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 229 4629.925′S74
55.167′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 230 4629.895′S74
55.166′W 2 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 231 4629.742′S74
55.164′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 232 4629.329′S74
55.094′W 1 1 Lateral-up Floating
Jun 24, 2015 Seno Newman 233 4629.385′S74
54.993′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 234 4629.32′S74
54.924′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 235 4629.218′S74
54.888′W 1 1 Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 236 4629.137′S74
54.821′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 237 4629.131′S74
54.818′W 2 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 238 4629.124′S74
54.813′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 239 4629.106′S74
54.809′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 240 4629.086′S74
54.803′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 241 4629.066′S74
54.813′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 242 4628.991′S74
54.825′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 243 4628.911′S74
54.822′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 244 4628.887′S74
54.826′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 245 4628.812′S74
54.831′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 246 4628.761′S74
54.83′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 247 4628.705′S74
54.828′W 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 248 4628.658′S74
54.828′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 249 4628.654′S74
54.831′W 1 Lateral-up Rocky Balaenopteridae
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 15/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 Seno Newman 250 4628.645′S74
54.83′W Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 251 4628.637′S74
54.831′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 252 4628.521′S74
54.913′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 253 4627.411′S74
54.979′W 1 1 Ventral-up Rocky
Jun 24, 2015 Seno Newman 254 4627.365′S74
54.984′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 255 4627.314′S74
54.988′W 1 1 Lateral-up Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 256 4627.214′S74
54.829′W Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 257 4626.271′S74
53.366′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 258 4626.119′S74
53.609′W Sandy
Jun 24, 2015 Seno Newman 259 4626.111′S74
53.714′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 260 4626.123′S74
53.747′W Lateral-up Floating Balaenopteridae
Jun 24, 2015 Seno Newman 261 4626.116′S74
53.771′W Lateral-up Floating Balaenopteridae
Jun 24, 2015 Seno Newman 262 4626.264′S74
54.143′W Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 263 4626.336′S74
54.127′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 264 4626.352′S74
54.148′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 265 4626.34′S74
54.321′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 266 4626.335′S74
54.394′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 267 4626.656′S74
55.481′W 2 1 Rocky
Jun 24, 2015 Seno Newman 268 4626.797′S74
55.902′W Rocky
Jun 24, 2015 Seno Newman 269 4627.022′S74
56.047′W 1 1 Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 270 4627.248′S74
56.114′W Rocky
Jun 24, 2015 Seno Newman 271 4627.959′S74
56.175′W Sandy–rocky
Jun 24, 2015 Seno Newman 272 4628.193′S74
56.104′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 273 4628.253′S74
56.094′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 274 4628.385′S74
56.166′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 275 4628.405′S74
56.161′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 276 4628.461′S74
56.144′W Sandy–rocky
Jun 24, 2015 Seno Newman 277 4629.752′S74
57.068′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 278 4630.896′S74
58.426′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 279 4630.918′S74
58.439′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 280 4631.016′S74
58.904′W Rocky
Jun 24, 2015 Seno Newman 281 4631.284′S74
59.402′W 1 1 Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 282 4631.967′S74
59.824′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 283 4631.979′S74
59.845′W 1 1 Lateral-up Sandy–rocky Balaenopteridae
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 16/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Jun 24, 2015 Seno Newman 284 4632.007′S74
59.867′W 1 1 Ventral-up Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 285 4631.638′S75
0.132′W Rocky
Jun 24, 2015 Seno Newman 286 4631.532′S75
0.959′W Rocky
Jun 24, 2015 Seno Newman 287 4631.767′S75
0.989′W Rocky
Jun 24, 2015 Seno Newman 288 4631.798′S75
1.062′W Rocky
Jun 24, 2015 Seno Newman 289 4632.125′S75
0.925′W 1 1 Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 290 4632.493′S75
1.119′W 1 1 Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 291 4632.689′S75
1.12′W 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 292 4633.363′S75
1.351′W 2 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 293 4633.372′S75
1.344′W 1 1 Lateral-up Sandy Balaenopteridae
Jun 24, 2015 Seno Newman 294 4633.428′S75
1.334′W 1 Rocky Balaenopteridae
Jun 24, 2015 Seno Newman 295 4633.958′S75
1.688′W Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 296 4633.966′S75
1.732′W 1 1 Sandy–rocky
Jun 24, 2015 Seno Newman 297 4633.977′S75
1.746′W 2 1 Floating
Jun 24, 2015 Seno Newman 298 4634.271′S75
1.855′W 2 1 Rocky
Jun 24, 2015 Seno Newman 299 4634.429′S75
2.047′W 2 Rocky
Jun 24, 2015 Seno Newman 300 4634.463′S75
2.194′W Sandy–rocky
Jun 24, 2015 Seno Newman 301 4638.102′S75
8.96′W 1 1 Sandy
Jun 24, 2015 Seno Newman 302 4638.089′S75
9.632′W 1 Sandy–rocky
Jun 24, 2015 Seno Newman 303 4639.046′S75
12.857′W Sandy–rocky Balaenopteridae
Jun 24, 2015 Seno Newman 304 4639.4′S75
15.631′W Rocky
Jun 24, 2015 Seno Newman 305 4642.092′S75
14.267′W 1 1 Sandy–rocky Balaenopteridae
Other sources
Middle of
March
Bahı
´a Conos 306 4636.2′S75
28.7′W3
Middle of
March
Bahı
´a Conos 307 4636.229′S75
28.664′W3
Feb 21, 2015 Isla Crosslet 308 4643.494′S75
10.521′W3
Feb 22, 2015 Isla Crosslet 309 4645.32′S75
11.175′W 1 Balaenopteridae
End of Feb
2015
Fiordo San Pablo 310 4636.677′S75
9.685′W 1 Balaenopteridae
End of Feb
2015
Fiordo San Pablo 311 4636.271′S75
9.471′W3
End of Feb
2015
Estero Slight 312 4643.26′S75
9.37′W 1 Lateral-up Floating Balaenoptera
borealis
Female
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 17/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
End of
Feb 2015
Estero Slight 313 4643.26′S75
9.37′W 1 Balaenopteridae
End of
Feb 2015
Estero Slight 314 4643.26′S75
9.37′W3
End of
Feb 2015
Estero Slight 315 4647.18′S75
32.417′W3
Middle of
Mar 2015
Bahı
´a Conos 316 4637.007′S75
27.578′W 1 Balaenopteridae
Middle of
Mar 2015
Bahı
´a Conos 317 4637.084′S75
27.664′W 1 Balaenopteridae
Middle of
Mar 2015
Bahı
´a Conos 318 4637.011′S75
27.788′W 1 Balaenopteridae
Middle of
Mar 2015
Bahı
´a Conos 319 4636.918′S75
27.726′W 1 Balaenopteridae
Middle of
Mar 2015
Bahı
´a Conos 320 4636.893′S75
27.881′W 1 Balaenopteridae
Middle of
Mar 2015
Canal Barros Luco 321 509.450′S75
17.317′W 1 Balaenopteridae
Middle of
Mar 2015
Canal Ladrillero 322 498.000′S75
17.000′W 1 Balaenopteridae
Middle of
Mar 2015
South from Isla Solar 323 5058.975′S75
4.276′W 1 Balaenopteridae
Mar 23, 2015 Near Cape Stokes 324 4654.558′S75
14.109′W 1 Rocky Balaenopteridae
Mar 23, 2015 Near Cape Stokes 325 4655.76′S75
16.796′W 1 Sandy Balaenopteridae
Mar 23, 2015 Brazo Oeste–Barroso 326 4650.91′S75
15.332′W 1 Sandy Balaenopteridae
Mar 25, 2015 Brazo Este–Barroso 327 4651.761′S75
15.577′W 1 Balaenopteridae
Mar 5, 2015 Isla Hereford 328 4643.26′S75
9.37′W 1 Balaenopteridae
Mar 5, 2015 Isla Hereford 329 4643.26′S75
9.37′W 1 Balaenopteridae
Mar 5, 2015 Isla Hereford 330 4643.26′S75
9.37′W3
Mar 5, 2015 Isla Hereford 331 4635.925′S75
11.636′W2
May 14, 2015 Paso Isaza 332 5053.983′S74
18.133′W 1 Lateral-up Floating Balaenoptera
borealis
Male
Jul 5, 2015 Near Puerto Natales 333 4935.733′S74
26.083′W 1 Lateral-up Floating Balaenoptera
borealis
Female
Middle of
May 2015
Near Puerto Natales 334 5128.567′S73
44.95′W3
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 18/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
Middle of
May 2015
Near Puerto Natales 335 5128.392′S73
44.941′W3
Middle of
May 2015
Near Puerto Natales 336 5128.399′S73
45.399′W3
Middle of
May 2015
Near Puerto Natales 337 5128.519′S73
45.078′W3
probably
December
2015
Canal Ladrillero 338 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 339 498.000′S75
17.000′W
probably
December 2015
Canal Ladrillero 340 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 341 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 342 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 343 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 345 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 346 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 347 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 348 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 349 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 350 498.000′S75
17.000′W
(Continued)
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 19/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
probably
December
2015
Canal Ladrillero 351 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 352 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 353 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 354 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 355 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 356 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 357 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 358 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 359 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 360 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 361 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 362 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 363 498.000′S75
17.000′W
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 20/51

Table 2 (continued ).
Date Locality Whale
ID
Latitude Longitude State of
decomposition
Time at sea Carcass
position
Beach type Species Sex
probably
December
2015
Canal Ladrillero 364 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 365 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 366 498.000′S75
17.000′W
probably
December
2015
Canal Ladrillero 367 498.000′S75
17.000′W
HF26 expedition
Feb 4, 2016 Bayron 368 4748.102′S74
58.235′W 1 1 Floating Balaenopteridae
Feb 6, 2016 Seno Escondido 369 4650.885′S74
27.675′W 1 1 Sandy–rocky Balaenopteridae
Feb 13, 2016 Seno Slight 370 4642.880′S75
28.803′W 1 1 Sandy–rocky Balaenopteridae
Feb 14, 2016 Seno Slight 371 4648.525′S75
34.157′W 1 1 Sandy–rocky Balaenopteridae
Feb 14, 2016 Seno Slight 372 4647.800′S75
32.773′W 1 1 Sandy–rocky Balaenopteridae
Feb 15, 2016 Seno Slight 373 4647.272′S75
29.853′W 1 1 Sandy–rocky Balaenopteridae
Feb 15, 2016 Seno Slight 374 4646.232′S75
31.137′W 1 1 Sandy–rocky Balaenopteridae
Feb 18, 2016 Newman 375 4629.557′S74
55.182′W 1 1 Sandy–rocky Balaenopteridae
Feb 22, 2016 Newman 376 4630.672′S74
55.607′W 1 1 Sandy–rocky Balaenopteridae
Feb 23, 2016 Caleta Buena 377 4647.072′S75
29.847′W 1 1 Sandy–rocky Balaenopteridae
Feb 23, 2016 Caleta Buena 378 4647.233′S75
29.843′W 1 1 Sandy–rocky Balaenopteridae
Feb 24, 2016 Slight 379 4647.233′S75
29.843′W 1 1 Sandy–rocky Balaenopteridae
Feb 24, 2016 Slight 380 4648.413′S75
34.772′W 1 1 Sandy–rocky Balaenopteridae
May 2016 Seno Escondido 381 4649.963′S74
39.016′W Floating
May 2016 Slight 382 4647.444′S74
34.460′W
May 2016 Newman 383 4630.672′S74
55.607′W
Other sources
Feb 6, 2016 Islas Jungfrauen 384 4755.527′S75
6.832′W
Mar 13, 2016 Ushuaia 385 5453.756′S67
22.571′W 1 1 Floating Megaptera
novaeangliae
Mar 28, 2016 Navarino 386 5455.350′S68
18.555′W2 1 Megaptera
novaeangliae
Jan 2016 Canal Ladrillero 387 498.000′S75
17.000′W Floating
Jan 2016 Canal Ladrillero 388 498.000′S75
17.000′W Floating
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 21/51

carried out, each to Seno Escondido, Seno Newman and Estero Slight, with the aim
of searching for new carcasses, taking samples for genetic and red tide analyses, and
performing oceanographic transects. Data from those surveys are included here, but most
of the analyses of the samples will be published in a separate paper.
Samples of marine invertebrates were collected under permit of Subsecretaria de Pesca
y Acuicultura (R.EX. 1295 del 27.04.2016). Samples of cetacean carcasses were authorized
by SERNAPESCA, Region de Aysen (Acta Numbers 2016-11-10 and 12).
Satellite image
A high-resolution satellite image was taken of Seno Newman on Aug 13, 2015 using the
Pleiades-1 Satellite. The 16-bit ortho-rectified GeoTIFF multispectral (R-G-B-NIR) and
Panchromatic files have been analyzed to count whale carcasses and determine their
geographic positions (Fig. 5). The whales identified in the satellite image were compared
to the photos and GPS locations obtained during the overflight, and cross-matched
with reference to nearby geomorphological features.
Figure 4 Documented whale carcasses and skeletal remains during an overflight on Jun 25, 2015,
Seno Escondido. The numbers correspond to the whale identification numbers in Table 1. Photos:
Verena Ha
¨ussermann, all rights reserved.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 22/51

Taxonomic analysis
Whales were identified in situ during the vessel-based expedition based on morphological
characteristics. The species identification of the specimens from which tissue was
sampled during the SERNAPESCA expedition to Estero Slight was confirmed genetically
(Fiscalı
´a de Ayse
´n, 2015). A 675 bp fragment of mitochondrial DNA control region
was amplified using the primers using the primers M13 Dlp1.5 5′-TGTAAAACGA
CAGCCAGTTCACCCAAAGCTGRARTTCTA-3′and 8G 5′GGAGTACTATGTCCTG
TAACCA (Dalebout et al., 2005) and sequenced in both directions. Amplification
reactions were performed in a total volume of 25 mlwith5ml PCR buffer 10,2ml
MgCl
2
50 mm, 1 ml of each primer, 2 mldNTP200mmand0.3mlTaq DNA polymerase
(Invitrogen Life Technologies, Carlsbad, CA, USA) and 50 ng DNA. The
PCR temperature profile was as follows: a preliminary denaturing period of 2 min at
94 C followed by 30 cycles of denaturation for 30 s at 94 C, primer annealing for 40 s
at 56 C and polymerase extension for 40 s at 72 C. A final extension period for 10 min at
72 C was included.
Taphonomy
Analysis was carried out, following biostratinomic criteria, on different subsets of
the whale remains recorded during the overflight and the vessel-based surveys.
Characterization of the depositional state of the carcasses was based on a post hoc analysis
of the assemblage, exclusively through photographs, classifying the carcasses into three
taphonomic classes according to previous studies of biostratinomic processes in marine
Figure 5 (A) Satellite image on Aug 13, 2015, used to count the carcasses along Seno Newman. (B–D)
Detail of the carcasses highlighted in (A).
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 23/51

mammals (Pyenson et al., 2014,Liebig, Taylor & Flessa, 2003;Liebig, Flessa & Taylor, 2007;
Scha
¨fer, 1972). The aspects considered were anatomic position of the carcasses (ventral,
dorsal or lateral side-up, n= 201), deposition site (rocky or sandy, n= 295), and the
disarticulation and degree of decay of the carcasses. These final two aspects were sorted
into classes to estimate the sequence of disarticulation/decay addressing two aspects: time
since death (n= 245) and drift time/distance of the carcass (as a proxy to estimate the
relative location of death, n= 151).
To assess the time since death, three categories were defined, reflecting a
straightforward order from the least decomposed to the most disarticulated carcass/
skeleton. “Class 1” refers to carcasses in the lowest to relatively medium state of
decomposition for these assemblages. Included in this category are complete carcasses
with skin, complete carcasses without skin, and complete carcasses with partially
exposed bones (see Fig. 6A). “Class 2” includes carcasses in a relatively greater state of
decomposition but still maintaining their longitudinal axis, although some bones may be
scattered (see Fig. 6B). Finally, “Class 3” refers to isolated skeletal remains with no soft
tissue, such as skulls, dentaries or postcranial remains (see Fig. 6C). Thus, the sequence of
“time since death” should reflect ranges from less than three months (Class 1), several
months, but probably less than six months (Class 2), to a year or more (Class 3).
The analysis of the location of death, namely whether the carcasses are para-
autochthonous or allochthonous was addressed by evaluation of the time that the
carcasses had remained floating in the water column and at the surface (see Scha
¨fer,
1972). For this, we defined two classes, depending of the presence or absence of the
skull, as a proxy for the time floating and the potential distance between the site of
mortality and the observed site of deposition (Fig. 7)(Toots , 196 5 ;Voorhies, 1969;
Behrensmeyer, 1973;Holz & Simo
˜es, 2002;Liebig, Taylor & Flessa, 2003;Simo
˜es &
Holz, 2004). Thus, “Class A” includes carcasses that preserve the skull and “Class B”
includes those without a skull. For this analysis, we excluded skeletons, which were
considered older than a year (minimum age, based on field observations of AVT from
2016 expedition to the site of the mortality).
A geomorphological analysis was made using photographs and Google Earth
(Terrametrics, 2015). We classified the type of depositional locality (i.e., sand/pebble
dominated beach or rocky outcrop) (Table 2) in order to assess the relationship between
these aspects and the taphonomic categories mentioned above; for instance, whether
carcasses that had been transported further and disarticulated (allochthonous) were more
prevalent at high energy sites (i.e., rocky outcrops) and articulated (para-autochthonous)
carcasses more prevalent in low energy environments (i.e., sandy beaches).
To compare the density of the death assemblages at Golfo de Penas with known extinct
and extant death assemblages recorded in the literature, we measured linear dimensions of
the geomorphological units (i.e., length and width of the beach), through the measure
tool in Google Earth, using the highest resolution satellite images available, at sites
where assemblages were found. In this manner, the geographic areas corresponding to
the death assemblages were calculated and the density determined by dividing the number
of specimens in each assemblage by its area.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 24/51

Analysis of the petrotympanic complex (ear bone)
We studied the bones of the middle and inner ear of one whale, collected during the
SERNAPESCA expedition. A volumetric computed tomography in the Morita
tomography (box of 60 mm, 500 cuts) was carried out. The images were visualized
with Osirix Dicom viewer v 5.6 32-bit in search for fractures or micro-fractures, which
would appear as black gaps in the bony tissue.
Analysis for toxins (PST/AST)
Bivalve tissue was sampled in Estero Slight on Apr 22 and on May 25, 2015 (two samples
in total), and in Estero Slight, Seno Newman and Seno Escondido between Jan 23 and
Figure 6 Biostratinomic classification addressing the decomposition/disarticulation of carcasses/
skeletal remains assessing to the time since death. (A and B) Class 1, carcasses in the lowest to rela-
tively medium state of decomposition. (C and D) Class 2, carcasses in a relatively greater state
of decomposition, but still maintaining their longitudinal axis, although some bones may be scattered.
(E and F) Class 3, isolated skeletal remains with no soft tissue. Photos: Verena Ha
¨ussermann (A–D),
Photos: Ana Valenzuela-Toro (E, F), all rights reserved.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 25/51

Mar 1, and Apr 27 and May 30, 2016 (22 samples in total). The stomach content
and intestine content of two whales from Estero Slight were sampled on May 25, 2015.
On Feb 2016, one sample of duodenum content was obtained from a freshly dead whale
observed in Estero Slight. At the same period, one sample of surface-swimming Munida
spp. was collected at 4629.730′S, 7455.722′W. All samples were analyzed in situ for
presence of PST using the protocol already described for the shellfish tissue and stomach
Figure 7 Biostratonomic classification of the location of death of carcasses/skeletal remains.
(A) Carcasses preserving the skull. (B) Carcasses lacking the skull. Photos: Verena Ha
¨ussermann (A),
Fanny Horwitz (B), all rights reserved.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 26/51

content samples. The tissue was homogenized using a blender and mixed in a 1:1 ratio
with a field extraction fluid composed of 2.5 parts of rubbing alcohol (70%) to one
part white vinegar. The mixture was then homogenized manually and filtered through a
paper filter (paper filter #4). The extract obtained after filtration was then used to detect
the presence of toxins through rapid field test kits from scotia rapid testing for PST
and AST. For this, 100 ml of the extract was placed in a test tube containing running
buffer, mixed and then 100 ml of this mixture was placed in a lateral flow enzyme-linked
immunosorbent assay (ELISA) test strip with antibodies specific for PST (saxitoxin
and its derivative toxins) and AST (domoic acid). These tests were left to develop for
1 h before the results were read.
Twenty-two phytoplankton samples were collected in Estero Slight, Seno Newman and
Seno Escondido between Jan 23 and Mar 1, and Apr 27 and May 30, 2016, using a 20 mm
mesh size plankton net in a vertical tow from 15 m depth. The phytoplankton present
in these samples was concentrated using the net, and a 100 ml subsample was placed
in a tube with 0.1M acetic acid and mixed. About 100 ml of this mixture were then added
to a test tube-containing running buffer and an aliquot of this mixture of the same
volume was placed in an ELISA test strip for PSTand left to develop for 1 h before results
were read.
These qualitative PST test strips are extremely sensitive due to the local toxin profile,
which is high in GTX2/3, resulting in detection limits below 32 mg STX Eq/100 g of
tissue. The detection limit for the AST tests was reduced to 2 ppm of domoic acid by
modifying the standard sample preparation protocol by eliminating the dilution of the
sample before mixing it with the buffer.
A graphical analysis of the geographic and temporal distribution of PSP events,
presence of harmful microalgae and environmental variables in the affected region
(43S–51S) from 2007 to Jul 2015 and from Mar 2016 was performed with
the data obtained from the red tide monitoring program conducted by the
SERNAPESCA (R.S. Galdames, 2015, personal communication), in which mytilid
samples are analyzed at several stations throughout Chilean Patagonia approximately
once a month by the “Laboratorios SEREMI Salud,” from Ayse
´n and Magallanes
regions at Southern Chile.
Drift model
Floating objects are directly affected by surface currents, wind and waves. Wind both
drives the Ekman drift of surface water (Ardhuin et al., 2009) and exerts a direct drag
on the emerged surface of an object (Breivik et al., 2012). Stokes drift, the net forward
transport due to non-closed particle trajectories resulting from passing waves, also
contributes to the transport of floating objects. The drift of whale carcasses was simulated
by parameterizing the contribution of these components, based on objects of a similar
size from search and rescue models (Breivik et al., 2012;Peltier et al., 2012). Due to the
large uncertainty in carcass drift characteristics, parameters were varied stochastically
within a wide range of possible values.
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Use was made of existing current and wave products, the HYCOM daily 1/12
simulation (Wallcraft, Metzger & Carroll, 2009), and waves from ECMWF ERA-Interim
reanalysis (Dee et al., 2011). Winds were taken from a custom downscaling of NCEP NFL
boundary conditions using the WRF model (Skamarock & Klemp, 2008) to a sub-4 km
grid size. Drift scenarios were run by stepping forward in time from hypothetical sites
and times of mortality. All of these sites were in shallow water, since carcasses resulting
from mortality in deep water have a tendency to sink and not resurface (Smith et al.,
2015). A horizontal diffusion coefficient of 10 m
2
s
-1
was included in drift tracks to
represent unresolved physical processes. While the resolution of the current and wave
datasets is inadequate to represent detailed coastline or seabed geometry, or the interior
of the fjords, the drift model does clarify the expected distribution and spread of carcasses
from localized sources.
Large-scale wind stress
The large-scale tendency toward upwelling or downwelling provides a key driver of coastal
ecosystems. This was assessed using ECMWF ERA-Interim reanalysis data (Dee et al.,
2011). It is the alongshore component of wind stress that drives Ekman transport normal
to the coast and consequent upwelling or downwelling. Since upwelling and downwelling
are cumulative processes, a time-integrated wind stress was calculated (Pierce et al., 2006)
from a base time of the vernal equinox (September 21). Stress was estimated from
reanalysis winds at 10 m elevation according to Large & Pond (1981). The large-scale
change in coastal orientation was taken into account in extracting the alongshore wind
component, although localized inlets, bays (including the Golfo de Penas) and islands
were not considered.
RESULTS
Field surveys and toxicity tests
Of the total of dead whales observed in all expeditions and reports in 2015 (367), 35
recently dead whales and 12 skeletal remains were discovered during the HF24 expedition:
31 carcasses and 12 skeletal remains were found in and close to the entrance of the 14 km
long Estero Slight and four carcasses in Canal Castillo, situated 235 km to the south, as
well as many whale bones on different beaches (Fig. 3;Table 2). Three hundred and
five carcasses were mapped during the overflight between the Jungfrauen Islands (∼48S)
and Seno Newman (4639′S). In addition to this total of 284 whale carcasses and 21
skeletons from the two surveys, 51 whale carcasses and 11 whale skulls were reported
between Feb and Jun 2015 by boat crews navigating the west coast of Taitao Peninsula and
the coast between 4915′and 51S(Table 2;Fig. 4).
On some photos what could have been carcasses of smaller animals (possibly dolphins
and/or sea lions) were seen, but due to the flying altitude, speed and weather conditions,
the photo quality and resolution did not allow their conclusive identification as
actual carcasses. In Estero Slight, one dead pinniped was found on the shore from the
vessel. During the SERNAPESCA expedition, one Otariidae skull was found and
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 28/51

photographed in the same channel but the correspondence of the carcass and the
skull could not be established.
The 28 whale carcasses that could be identified unambiguously to species level were all
sei whales (Balaenoptera borealis); 15 of these identifications were confirmed genetically.
Seven specimens could be identified as males and ten as females. One hundred and
twenty-nine carcasses were identified as baleen whales of the Balaenopteridae family or
rorquals. The 30 whales examined in detail in Estero Slight during the vessel-based
expedition were between 6 and 15 m long, hence included both juvenile and fully grown
specimens.
None of the examined whales showed any evidence of disease or traumatic damage.
The anatomic structures of the ear bone were in good condition showing no damage;
the stapes were articulated in place, and the bony tissue showed no fractures (Fig. 8).
The analysis of locally collected mytilids in Apr and May 2015 and of the stomach and
intestine content of two whales in May 2015 showed presence of PST and AST.
In 2016, 16 fresh carcasses were observed during the HF27 and HF29 vessel-based
expeditions to Golfo Tres Montes; five further were reported by boat crews navigating the
Southern part of Chilean Patagonia. None of the examined whales showed any evidence
of disease or traumatic damage. Thirty-six rapid tests on PST were run using mussels
(12 tests), Munida (two tests), and phytoplankton (22 tests) in Seno Escondido, Seno
Newman and Estero Slight. Most of the samples collected during the 2016 expeditions
proved to be negative for the presence of PST, nevertheless, both expeditions detected the
presence of PSP in the phytoplankton collected at the entrance of Seno Newman.
A sample collected at the head of Seno Newman was negative for PST, indicating that
the toxic phytoplankton was preferentially located at the mouth of this inlet and nearby
areas of the Canal Chaicaya
´n.
Biostratinomic analysis
Of the 367 dead whales observed in 2015, 305 carcasses were mapped between Seno
Newman (4639′S) and Jungfrauen Islands (∼48S). Those carcasses could be grouped
into five assemblages (Figs. 1 and 9;Table 2), defined as a group of carcasses in close
proximity. The assemblages were called Golfo de Penas, Jungfrauen Islands, Seno
Escondido, Seno Newman and Estero Slight.
Some carcasses were floating (11), but most (284) were deposited ashore (Figs. 3–5).
The greater proportion of carcasses were deposited in a lateral position and to a lesser
extent in the ventral-up position reflecting the hydrodynamics of the body in the sea as
determined by the inflation of the abdominal region and mainly of their tongues, as
observed in a recently dead individual and in some decayed carcasses at Golfo de Penas
(Fig. 10). In general, they were tide-oriented (parallel to the coastline) and all of the
classified carcasses from the overflight were lying on their back or side (ventral-up,
44.3%; lateral-up, 55.7%) (Ta b l e 3 ;Fig. 11C), while only one specimen (from HF24) was
found in a dorsal-up position (data not included in analysis due to different time of
observation).
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 29/51

With respect to the classification of “time since death,” 68.8% of the carcasses were
classified in Class 1 (less than three months), 24.9% in Class 2 (less than six months) and
6.3% in Class 3 (more than a year) (Figs. 11A and 11B;Table 4). With respect to “time
at sea,” 147 (87%) of the carcasses were classified in Class A (short time/distance of drift),
while only four (13%) were identified as Class B (long time/distance of drift) (Fig. 11C;
Figure 8 Digital images obtained through computed volumetric tomography (CVT) scanned at
Morita tomography (box of 60 mm, 500 slices). All acoustic anatomical structures of the middle ear
(ossicles: stapes), internal ear (cochlea: spiral lamina), and the semicircular canals are seen in perfect
condition. Transversal sections of the pars cochlearis of the periotic: (A) midline, (B) more anterior;
sagittal sections of the pars cochlearis of the periotic, (C) anterior, (D) midline and (E) posterior;
Lateromedial sections of the pars cochlearis of the periotic: (F) lateral, (G) half-length and (H) medial.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 30/51

Table 4). There was no pattern relating the geomorphological unit (sandy: 34%,
pebble: 27%, rocky beach: 34%) to the taphonomic classes.
The carcasses found in April in Estero Slight were classified in stage 2 of Geraci &
Lounsbury (2005) indicating a few days to weeks since death; this would be classified as
Class 1 in the taphonomic classes of the present study.
The density of whale carcasses was in average 1,050/km
2
, considering all assemblages
recognized (Table 5).
Carcass drift and potential source locations
The distribution of beached carcasses was simulated from four illustrative source locations
(Figs. 12A–12D). In each case, calculations tracked 13,000 hypothetical carcasses,
reflecting source times spanning a two-month period from mid-February to mid-April
2015 and a range of drift model parameters. The spread of stranding locations therefore
represents variability of the current, wind and wave environment during this period as
well as the uncertainty in model parameters and a diffusive component to the drift tracks.
While each of the illustrated source locations leads to strandings distributed over several
Figure 9 Maps showing the five assemblages of whale carcasses. (A) Golfo de Penas, (B) Seno
Escondido, (C) Seno Newman, (D) Estero Slight and (E) Jungfrauen Islands. State of decomposition
color-coded: yellow (state 1; least decomposed, all articulated), orange (state 2; intermediate decom-
posed), and red (state 3; isolated remains).
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 31/51

hundred kilometers of coastline, there are important differences in these distributions.
A simulated source in Golfo Tres Montes (Northern Golfo de Penas) leads to strandings
throughout the Golfo de Penas (Fig. 12A), including in the Golfo Tres Montes itself. No
other source location (Figs. 12B–12D) leads to strandings in Golfo Tres Montes due to the
direction of prevailing currents and the sheltering effect of Peninsula Taitao. Similarly,
only a source to the north of Peninsula Taitao leads to strandings in that region (Fig. 12B).
Carcasses originating in the Golfo de Penas have a tendency to be transported to the
south by prevailing currents (Figs. 12A,12C and 12D).
Inter-annual variation in upwelling or downwelling
Comparison between the cumulative alongshore wind stress for the year in question and
the previous 20 years (Fig. 13) reveals that the months immediately prior to the mortality
event were anomalous. North of the study area, at 45S, there was an anomalously strong
tendency toward upwelling (an upward trend in Fig. 13), making this one of the most
upwelled years of the period. At the latitude of Golfo de Penas and further south there was
a net tendency to downwelling (a downward trend in Fig. 13), but punctuated by
upwelling events, making this one of the least downwelled years of the period.
DISCUSSION
Possible causes of death (Table 6) need to be analyzed for a mechanism that is capable of
synchronous killing of hundreds of whales, apparently all or most of the same species
(with a few exceptions, i.e., one confirmed pinniped). Baleen whales, in contrast to
Figure 10 Inflation of the tongue and its implication for whale carcass deposition. (A) Inflated tongue in a very recently dead sei whale (weeks)
indicated by the arrowhead. (B) Close-up of the mouth with dislocate mandibles due to the previous inflation of the tongue (arrowhead), which is
decayed and removed by scavengers. (C) Whale carcass seen from the overflight deposited in lateral position and its protuberant inflated tongue
(arrowhead). Photos: Brice Mone
´gier (A), Verena Ha
¨ussermann (B, C), all rights reserved.
Table 3 Anatomical position. Proportion of carcasses in each anatomical position as recorded from the
overflight survey and posterior photographic analysis.
Anatomical position of Carcass Unknown Dorsal-up Ventral-up Lateral-up Total
Count 187 0 43 54 97
Proportion (%) 65.84 0 15.14 19.01 100
Proportion (%) based on classified
individuals only
– 0 44 56 100
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 32/51

odontocetes, are less social and do not use echolocation to navigate (Perrin, Mead &
Brownell, 2009). The latter characteristics are key aspects used to explain mass mortalities
in odontocetes.
Possible causes for the death of hundreds of baleen whales include a lethal and highly
contagious unknown virus or infection, noise-related mechanisms at sea, and intoxication
by biotoxins (domic acid, saxitocin, etc.; Geraci et al., 1989;Fire et al., 2010;Lefebvre
et al., 2016;Pyenson et al., 2014;Table 6). In this assemblage, the individuals could not
be tested for viruses or bacteria, due to their advanced state of decomposition. There was
no evidence of pathological modifications that could be attributed to such a cause;
however, it is not possible to completely discard this hypothesis.
The only potentially lethal noise-related mechanism for a baleen whale are very intense
noises associated with blasting in close proximity (Ketten, 1992). This could injure the
animal and cause hemorrhage or provoke panic, disorientation and favor entrapment
Figure 11 Graphs showing the proportion of the total classified carcasses in the biostratonomic
analysis. (A) Time since death. (B) Time since death, combining Class 1 and 2. (C) Location of
death and (D) Anatomical positions of carcasses (lateral, ventral and dorsal-up).
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 33/51

(not yet described for baleen whales, Goldbogen et al., 2013). Although there was no
evidence of bony damage or micro-fracture of the one examined periotic, this cannot be
excluded for the other individuals. Any other noise-related damage could neither be ruled
out due to the decomposition of the soft tissue structures, nevertheless, there is no
evidence that for baleen sonar and ground noise could trigger more than non-lethal
behavioral and temporary effects (Goldbogen et al., 2013). The strongest argument against
this hypothesis is that whales died synchronously along hundreds of kilometers of
shoreline and at least five different sources of carcasses were identified (see discussion on
drift models), which could only be explained by a large number of blastings along the
coast during a very restricted time period. The study carried out by SERNAPESCA
(Fiscalı
´a de Ayse
´n, 2015;Ulloa et al., 2016, available upon request from SERNAPESCA
authorities) based on partial necropsies of two whales in late May 2015, found no evidence
of any trauma or human interaction. The whales were already in decomposition stages
3–4 and Class 1 of taphonomic classes used here.
Paralytic shellfish toxin is known to accumulate in the pelagic stage of the squat lobster
Munida gregaria (MacKenzie & Harwood, 2014), an important prey of sei whales
(Matthews, 1932). Older reports (Tabeta & Kanamura, 1970) and recent observations by
boat crews (K.-L. Pashuk, 2015, personal communication) indicate that squat lobster
abundance fluctuates strongly and can reach extremely high concentrations, especially
in Golfo Tres Montes (Tabeta & Kanamura, 1970). The presence of PST in mytilids
from the area and in the whale carcasses and the absence of evidence for other causes of
Table 4 Minimal number of individuals (MNI). Estimation of minimal number of individuals are
given to each of the classes of decomposition/disarticulation stages recorded at Golfo de Penas.
Classes of decomposition Class MNI Proportion (%)
Time since death 1 141 68.78
2 51 24.88
3 13 6.34
Total 205 100
Time at sea A 147 97.35
B 4 2.64
Total 151 100
Table 5 Density of specimens in assemblages (specimens/km
2
).
Area (km
2
) Number of specimens Density (specimens/km
2
)
Assemblage 1—Jungfrauen group 0.19 30 156
Assemblage 2—Escondido inlet 0.02 47 1,906
Assemblage 3—Escondido inlet 0.01 32 1,987
Assemblage 4—Newman inlet 0.60 149 248
Assemblage 5—Slight inlet 0.04 40 952
Total area of assemblages/specimens 0.87 298 341
Average 0.17 59 1,050
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 34/51

death leaves PSP as the most probable cause of death (Table 6). Although AST was also
detected in one of the stomach content samples, it is not believed to be the cause of
the MME as it was not detected by the toxin monitoring stations. A mixed assemblage of
40 skeletons from the Miocene in the north of Chile, dominated by rorqual whales and
attributed to four recurrent HAB events, shows many similarities to the assemblages
described here (Pyenson et al., 2014). The characteristics of the MME and the
repetition in the same locality are common features for HAB-mediated mortalities
Figure 12 Location of beached carcasses (blue) predicted by the drift model from four possible
mortality locations (A–D, red stars). Mortalities during a two month period are simulated, from
mid-February to mid-April 2015, with multiple carcasses (n= 200) of varying drift properties released
each day to predict the range of resulting carcass locations. Green vectors show time-averaged surface
currents for this period (HYCOM model). Depth contours at 50 and 100 m are indicated (GEBCO),
although nearshore waters and inlets are not resolved.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 35/51

(Brongersma-Sanders, 1957) (see Tables 6 and 7). MMEs through PSP in rorquals are thus
not a recent phenomenon in the Southeast Pacific. Nevertheless, whalebone
accumulations and reports of mortalities in Chilean Patagonia of up to 15 rorquals going
back to at least 1977 suggest an increase in the frequency of mortalities (Table 8). Since the
early 1990s, HABs have been recorded every year in spring and autumn along the entire
Patagonian coast, patterns are patchy and generally restricted to bays and fjords. The same
is true the coast of the Northeast Pacific where HAB events have been increasing in
strength and extension (Cook et al., 2015). This MME coincided with increased mortality
of baleen whales along the west coast of North America in 2015 (NOAA, 2015b), and
with the most extended and longest lasting HAB event registered there (NOAA, 2015c).
A positive correlation between the occurrence of PST blooms and the ENSO indices in
northern and central Patagonia has been shown (Cassis, Mun
˜oz & Avaria, 2002;Guzma
´n
& Pizarro, 2014). A similar correlation between the abundance of toxic harmful algae and
surface temperatures, which in turn are affected by ENSO, was observed in Ayse
´nby
Cassis, Mun
˜oz & Avaria (2002).ElNin
˜o events have increased in frequency and strength
due to global warming (Cai et al., 2014). A strong El Nin
˜o event began to build in
Figure 13 Cumulative alongshore component of nearshore wind stress (red) from ECMWF
ERAInterim reanalysis winds at latitudes (A) 49S, (B) 47S, (C) 45S, with an origin time of the
vernal equinox, Sep 21, 2014. Gray shading shows the envelope of variability experienced during
1995–2014, with darker shading indicating one standard deviation from the mean for this period.
Vertical lines show the timing of vessel (green) and aerial (blue) observations of whale carcasse.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 36/51

Table 6 Comparison of the usual causes of death with the evidence encountered at Golfo the Penas.
Cause of death
for marine
mammals
Main feature Type of
evidence
(confirm–
discard)
Observation
at Golfo de
Penas
Expected in
rorqual event
Oceanographic
conditions near
time of death
Rorqual species
recorded
References Oceanographic
conditions
observed at GP
Starvation by
abundance
surpassing
carrying
capacity
Thin blubber
layer, or
empty
stomach, or
numbers
around
5% of
population
Measurements,
necropsy and
population
numbers
nearby
carrying
capacity
Not likely, sei
whales are
still
recovering
from
whaling, last
species to be
hunted
Reported
in one species
Low productivity
event
Reported
in gray whales
(Eschrichthius
robustus)
Gulland et al.
(2005)
High
productivity
event
Epidemic
disease
Morbillivirus:
contagious-
epidemic,
emaciated,
external
and internal
parasites,
lesions and
inflammatory
reactions
Histology,
parasitology–
virology test
No signs of
external or
internal
lesions in
the whales of
Estero Slight
Stomach
content
present
No test
available
Low numbers,
young individuals
Shift in
temperature,
anthropogenic
contamination,
mutation of
virus
Juveniles and
calves fin
whales,
Balaenoptera
physalus
Brongersma-Sanders
(1957),Jauniaux et al.
(2000),Shimizu et al.
(2013),Van Bressem
et al. (2014),Mazzariol
et al. (2016)
Unknown
Military
exercise with
sonar
Only confirmed
in dolphins
Ear damage
and—or
hemorrhage
nearby the ears
Unknown Unknown No military
exercises
public
programed,
Chilean law for
the protection
of whales
Unknown Goldbogen et al.
(2013),Nowacek
et al. (2007),
Southall et al.
(2009)
Not reported
Poisoning by
toxins of
harmful algal
bloom
Massive,
multispecific,
recurrent in
time
HAB reported,
shift in
oceanographic
conditions, El
Nin
˜o event
Yes Yes High
productivity
event, El Nin
˜o
influence
Balaenoptera
physalus,
Megaptera
novaeangliae,
Balaenoptera
acutorostrata
Geraci et al. (1989),
Fire et al. (2010),
Pyenson et al. (2014),
Brongersma-Sanders
(1957) (present work)
Yes, at the
closest station
of red tide
monitoring
Trauma: ship
collision/
entanglement
Evidence of
trauma, small
number (i.e.,
eight deaths in
19 years in
USA)
Lesions,
hematoma
No sign of
internal or
external
lesion
Yes (small number
of individuals at a
time)
Not related Eubalaena
glacialis
Kraus (1990),Moore et al.
(2004),Vanderlann &
Taggart (2007)
Not related
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Sep 2014, which became the strongest El Nin
˜o of all time (NOAA, 2015a). The calculated
cumulative windstress (Fig. 13) suggests that during this period there was an anomalous
tendency toward coastal upwelling and associated nutrient delivery. Exceptionally high
levels of PST, 10 times higher than usual peaks were reported in Mar 2015 from the closest
monitoring site 120 km north of the mortality area (Isla Canquenes, Fig. 14).
The presence of PST during Feb 2016 was accompanied by deep red/brown surface
water discoloration due to the high abundance of Alexandrium catenella. This HAB
was coincidental with an unusually large bloom of the same toxic species in the waters
around Chiloe
´island (42S) (Herna
´ndez et al., 2016). The May 2016 expedition did not
observe water discoloration at this location, nevertheless the phytoplankton samples
obtained at the mouth of Seno Newman were also positive for PST, indicating that this
toxic species can be present in the area for long periods of time during the summer. The
PST levels at Isla Canquenes were not elevated in 2016; however, at two sites in the Messier
Channel levels four and seven times higher than usual peaks, were measured (Fig. 15).
Rorqual whales sink shortly after death (Smith et al., 2015). Once carcasses have
sunk below a depth of 50–100 m, they tend not to re-float since hydrostatic pressure
compresses decomposition gases (Smith et al., 2015). The bathymetry in the Golfo de
Penas area and off the steeply sloping Taitao Peninsula (Fig. 12) requires that the whales
that washed ashore all died near the shore. Thus, we conclude that despite common
belief (Perrin, Wu
¨rsig & Thewissen, 2009) sei whales opportunistically feed close to shore
and may even follow their prey into narrow and shallow inlets and channels. This
hypothesis is supported by the fact that live sei whales were observed near shore in Golfo
de Penas and Estero Slight on several occasions (Table 8).
The drift model suggests that the observed carcasses originated from multiple sites.
The carcasses found in the two fjordic inlets of Seno Newman and Estero Slight (62%
of the total) probably died not far from where they stranded, either in the Golfo Tres
Table 7 Main biostratinomic pathways and their significance in understanding the thanatocenosis.
Time since
death
Condition of the
carcasses
Age proportions Sex proportions Geographic
position
Observed
Catastrophic—
single event
Highly homogenous
Majority within one
to a few classes (42)
Same as population rate Same as population rate Homogenous Homogenous;
see Table S2
Time averaged Highly heterogeneous
Several classes present
Same as proportion of annual
mortality of the population
No pattern, different from
ratio of population
Heterogeneous Homogenous;
see Table S2
Location of
death
Condition of the carcasses Anatomic position expected Anatomic
position expected
Orientation Anatomic
position
observed
Autochthonous Very well preserved, low
disarticulation
Position of life: dorsal-up (5) Dorsal-up No trend Dorsal-up:
1.00%
Allochthonous Disarticulation and
scattering present,
depending on time
and distance to final
deposit
Heterogeneous depending on
time since death or time of drift
Majority ventral to lateral up
(5, see Fig. S5)
Ventral-up—
lateral-up
One main direction
(current-wind) and/or
two main directions
(tide)
Ventral-up:
20.40%
Lateral-up:
78.61%
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 38/51

Montes or within the inlets themselves (Figs. 1 and 9), since source locations elsewhere in
Golfo de Penas or north of Taitao Peninsula do not lead to carcasses in this region (Figs.
12B–12D). Although the inlets themselves are not resolved in the drift model, the net
seaward surface outflow of a fjord would only allow carcasses to collect toward its head (as
observed) if wind and waves in that direction dominated their drift, or if they died close
to the site where they were found. Modeled winds were occasionally toward the head
of Seno Newman, on Mar 20 and during Apr 14–18, but almost never in the case of Estero
Slight (Fig. 16), so it is highly likely that the carcasses found within these inlets were
the result of mortality within the inlets themselves. Carcasses from within these inlets
could, however, be exported to nearby coastal waters and then distributed around Golfo
de Penas as seen in the drift simulations for a source in Golfo Tres Montes (Fig. 12A),
so mortality within the inlets of Seno Newman and Estero Slight could have been the
source for carcasses found elsewhere in Golfo Tres Montes or Golfo de Penas.
The accumulation of carcasses in the convoluted and extremely shallow Estero
Escondido is similarly unresolvable by the drift model, but it also appears highly likely
that these carcasses resulted from mortality within the inlet itself. It is, however, unclear
Figure 14 Spatial distribution of PST (STX. Eq./100 g tissue) as measured in mytilids and the
relative abundance of Alexandrium catenella between 43S and 51S in Mar 2015. Inset shows the
toxin level at the closest site to the Golfo de Penas, Isla Canquenes (4543′31″S; 7406′51″W) measured
between Mar 2010 and Mar 2015. Shellfish consumption is unsafe for humans if values rise above 80 mg
STX. Eq./100 g tissue.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 39/51

why dozens of large whales would swim into a narrow inlet which in most parts is
only between 2 and 7 m deep (maximum depth 15 m just inside extremely shallow
entrance) (Fig. 17).
Drift predictions from sources within Golfo de Penas, or to the south (Figs. 12A,12C
and 12D), never led to carcasses on or to the north of Taitao Peninsula, therefore the
observed carcasses on the exposed shoreline in that region (Estero Cono) likely originated
close to shore, either locally or to the north. The carcasses found between the Southern
end of Golfo de Penas and 49S either died very close to where they washed ashore or
were transported from the large concentrations in Golfo de Penas by clockwise flow within
the gulf. The five whales between 49S and 51S probably died locally.
Surveys in the Golfo de Penas area have sighted sei whales in all seasons, with up to 600
individuals, some even near to the shore of Golfo de Penas and Estero Slight (Table 8).
Therefore, the number of whales that have been exposed to toxins could be considerable.
It has been calculated that less than 10% of the gray whales that are estimated to die
each year in the eastern North Pacific are washed ashore, while most sink and do not
Figure 15 Spatial distribution of PST (STX. Eq./100 g tissue) as measured in mytilids between 43S
and 51S in Mar 2016. In 2016, the PST levels in the Golfo Tres Montes region were not elevated.
However, values four to seven times higher than usual peaks were measured in the channels of Central
Patagonia. Shellfish consumption is unsafe for humans if values rise above 80 mg STX. Eq./100 g tissue.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 40/51

resurface (Rugh et al., 1999). Assuming a similar ratio, our observations may greatly
underestimate the actual magnitude of this mortality event. Many whales may have sunk
and never re-surfaced, and a significant number of carcasses may have been washed ashore
on the many remote beaches that could not be surveyed due to adverse weather
conditions. Others may have been destroyed by wave action from winter storms on the
high-energy rocky shores that dominate the area.
In other reported MMEs, the period of the time of a massive mortality was
determined by considering the number of carcasses, and their temporal and spatial
extent. This ranged from two years (gray whales; Gulland et al., 2005) to a few weeks
(humpback whales; Geraci et al., 1989). To determine the time span of this MME, the
classification of carcasses was carried out following the disarticulation sequence
proposed by Scha
¨fer (1972).
Table 8 Sei whales observed in Chilean Patagonia (whaling ended in 1976).
Region/site Number of whales Time span Distance to shore (mi) Source
43–45S 286 Mar 25–Apr 03, 1966 60–70 Aguayo-Lobo (1974)
39–41S 345 Oct 09–20, 1966 60–120 Aguayo-Lobo (1974)
46–48S 114 Dec 13–23, 1966 20–60 Aguayo-Lobo (1974)
Golfo de Penas (∼4630′–48S) 600 Mar 1966 11–24 L. Pastene, 2015, personal communication
Golfo de Penas (∼4630′–48S) Small number May 25–28, 1971 Inshore Gilmore (1971)
53–55S Large concentrations Feb 1994 Not mentioned Pastene & Shimada (1999)
Slight inlet (∼4645′S) Two Jul 2015 Near to shore J. Cabezas, 2015, personal communication
Figure 16 Wind roses at the entrance to two inlets, Seno Newman (A) and Estero Slight (B), derived
from a local high-resolution implementation of the WRF model. Spoke lengths indicate the frequency
of occurrence of winds from each direction. Colors represent speed. Seno Newman has a significant up-
inlet component (winds from SSW) but Estero Slight does not (winds from NNE).
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 41/51

Time since death and time of transportation at sea of the carcass are slightly different in
terms of articulation and state of decomposition. Following Scha
¨fer (1972),thefirstbreakage
of the outer tissue of a carcass at sea should occur within a week to a month, although in
Chilean Patagonia the time span could be a little greater due to the low temperature. In
addition, some carcasses could have drifted for some weeks, arrived intact on shore, and
then decayed more rapidly exposing the bones, while other carcasses could have floated
longer until skull, tail and limbs were disarticulated, but decayed more slowly due to
the colder water temperatures. This was in agreement with the comparisons of the
disarticulation of carcasses in the field assessed through the photographs of the different
expeditions to the same area (Estero Slight, in Apr and May 2015). Nevertheless, at the
present assemblage, the time until the bones were exposed was extended from one to around
Figure 17 Nautical maps of Escondido and Slight Inlet. (A) Section of the Bahia San Quintin showing
Escondido Inlet (maximum depth 15 m). (B) Section of Hoppner Bay showing Estero Slight (maximum
depth 152 m). Sources: Map nr 8820 and 8810 from armada de Chile. Newman Inlet is poorly charted
with only five depths indicated along the inlet, the largest being 82 m.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 42/51

three months (Class 1) and time of disarticulation was shifted from three to six months
(Class 2), due to the low average temperature in the study area.
Considering available information on MMEs time scales, it is reasonable to suppose this
event occurred over a time span of approximately three to maximum six months
(Nov 2014–Apr 2015). Nevertheless, the record of other crews (Tab l e 2)andmodeled
oceanographic conditions (see “Carcass drift and potential source locations,” above) point
to the beginning of the die off around February at Golfo de Penas. Thus, the Class 2 carcasses
would indicate another pulse of corpses arriving at the same area in a different taphonomic
condition, which could suggest: (a) longer drift time/distance transport; (b) equal arrival but
different time of death; or (c) higher energy environment. The classification of “time at sea”
analysis suggested that drift time was in its majority the same with a similar proportion
of Class A (short drift time/distance). The analysis of the anatomic positions suggests
the allochthonous nature of the deposits in all assemblages (see Pyenson et al., 2014).
Only two carcasses were found in a dorsal up position, which suggests live stranding.
The average density of Golfo Tres Montes assemblages is equivalent to one third of the
density calculated for Cerro Ballena, a Late Miocene (∼9 Mya) fossil red tide linked
assemblage of northern Chile (3,000/km
2
,Pyenson et al., 2014)(Table 5). However, this
difference is likely to have a sampling bias since in Golfo Tres Montes and Golfo de Penas
we could only could the carcasses along the coastline, but not on the seafloor.
CONCLUSION
1. The whales died at sea, close to where they beached. About 90% of the whales died during
one MME (94.7% for time since death and 87% for time at sea analysis), most probably
between Feb and Apr 2015. No major mortality has occurred in the same area in 2016,
but mortalities in other areas cannot be excluded (see Fig. 15 for 2016 toxin levels).
2. Since it is likely that all or most of the affected whales were sei whales, the documented
mortality may represent a significant increase over the usual death rate of Southern
Hemisphere sei whales (Reilly et al., 2008). If the frequency and magnitude of MMEs
increase due to climate change this would have a significant impact on the local
population and threaten the recovery of this endangered species, which in the Southern
Hemisphere was reduced by whaling from about 100,000 to 24,000 individuals by 1980
(Perrin, Wu
¨rsig & Thewissen, 2009).
3. This MME and historical data suggest that, at least during years with abundant squat
lobsters, the Golfo de Penas is one of the most important feeding grounds for sei whales,
hosting the largest and densest known sei whale aggregations outside the polar regions.
4. The MME reported herein and its probable connection to El Nino-caused red tide
events throughout the Eastern Pacific could indicate that marine mammals are among
the first oceanic megafauna victims of global warming.
5. Discoveries of dead whales in this remote area are chance finds. To clarify the extent,
frequency and magnitude of MMEs, an assessment and systematic monitoring of
whale populations in Central Chilean Patagonia is necessary. We suggest to do this
through regular satellite images.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 43/51

ACKNOWLEDGEMENTS
We particularly thank the organizers and participants of the expedition organized
by the Chilean Fisheries Service (SERNAPESCA), especially B. Caceres, G. Garrido,
M. Ulloa, F. Viddi, J. Acevedo, T. Garcı
´a, C. Caldero
´n and L. Bedrin
˜ana. Thanks also to
R. Brownell, N. Pyenson, L. Pastene, E. Poulin, F. Beaujot, U. Po
¨rschmann, P. Pascoe,
S. Kraft, K.-L. Pashuk and V. Beasley. Thanks to Bidema PDI, Fiscalı
´a de Ayse
´n and
Armada de Chile for field support. We thank Percy Ramirez, Romulo Melo Cuevas, Brice
Mone
´gier, Sven Nielsen, and Regina Maria Fischer for reports of whale carcasses. We are
thankful to many more people for assisting with fieldwork, technical support and
logistics, for sharing or facilitating data and information, and for discussions. This is
publication number 134 of Huinay Scientific Field Station.
ADDITIONAL INFORMATION AND DECLARATIONS
Funding
The expedition during which Verena Ha
¨ussermann discovered the initial whales was
funded by Fondecyt Project Nos. 1131039, 1161699 to VH and 1150843 to GF, the
overflight by National Geographic Society/Waitt Grants Program #W380-15 to Carolina S.
Gutstein, Verena Ha
¨ussermann and Maria Jose Perez-Alvarez and the satellite image by a
Pew fellowship for marine conservation to Verena Ha
¨ussermann. Taphonomic analyses
were funded by U-REDES (Domeyko II UR-C12/1, Universidad de Chile) to A. Vargas and
Consultora Paleosuchus LTDA. Maria Jose Perez-Alvarez was funded by CONICYT
Postdoctoral FONDECYT Program 3140513, Projects ICM P05-002 and PFB 023.
Carolina S. Gutstein was founded by CONICYT Postdoctoral FONDECYT Program
3160710. 2016 expedition was funded by Blue Marine Foundation and Paulsen Editions
Foundation to Keri Lee Pashuk (Saoirse) and Consejo de Monumentos Nacionales.
The funders had no role in study design, data collection and analysis, decision to publish
or preparation of the manuscript.
Grant Disclosures
The following grant information was disclosed by the authors:
Fondecyt Projects: 1131039, 1161699 and 1150843.
National Geographic Society/Waitt Grants Program: #W380-15.
U-REDES (Domeyko II UR-C12/1, Universidad de Chile).
CONICYT Postdoctoral FONDECYT Program: 3140513.
CONICYT Postdoctoral FONDECYT Program: 3160710.
Competing Interests
The authors declare that they have no competing interests.
Author Contributions
Verena Ha
¨ussermann conceived and designed the experiments, performed the
experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 44/51

paper, prepared figures and/or tables and reviewed drafts of the paper, literature review,
summarizing data, carried out field work in April 2015 and June 2015.
Carolina S. Gutstein conceived and designed the experiments, performed the
experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote
the paper, prepared figures and/or tables and reviewed drafts of the paper, literature
review, summarizing data, carried out field work in June 2015, did taphonomic analysis,
examined ear bone.
Michael Beddington conceived and designed the experiments, performed the
experiments, analyzed the data, wrote the paper, prepared figures and/or tables,
reviewed drafts of the paper and drift models, construction and running of drift models.
David Cassis conceived and designed the experiments, performed the experiments,
analyzed the data, contributed reagents/materials/analysis tools, wrote the paper,
prepared figures and/or tables, reviewed drafts of the paper and literature review on
red tides, analyzed mytilid, plankton and stomach and intestine samples for PST and
AST in 2015.
Carlos Olavarria conceived and designed the experiments, analyzed the data, wrote the
paper, reviewed drafts of the paper and literature review.
Andrew C. Dale conceived and designed the experiments, performed the experiments,
analyzed the data, wrote the paper, prepared figures and/or tables, reviewed drafts of
the paper, literature review and collection of oceanography data, support in
methodology and interpretation of drift models.
Ana M. Valenzuela-Toro conceived and designed the experiments, performed the
experiments, analyzed the data, wrote the paper, prepared figures and/or tables,
reviewed drafts of the paper and literature review on taphonomy, carried out field work
in January to March 2016, helped with taphonomic analysis.
Maria Jose Perez-Alvarez conceived and designed the experiments, analyzed the data,
wrote the paper and reviewed drafts of the paper.
Hector H. Sepu
´lveda conceived and designed the experiments, performed the
experiments, analyzed the data and collection of oceanographic data.
Kaitlin M. McConnell performed the experiments, analyzed the data, carried out field
work in April 2015, January to March and April to May 2016, analyzed mytilid,
plankton and stomach and intestine samples in 2016.
Fanny E. Horwitz analyzed the data and prepared figures and/or tables, carried out field
work in June 2015, helped with taphonomic analysis.
Gu
¨nter Fo
¨rsterra conceived and designed the experiments, analyzed the data, wrote the
paper and reviewed drafts of the paper, writing of article.
Animal Ethics
The following information was supplied relating to ethical approvals (i.e., approving body
and any reference numbers):
The samples (genetics, ear bone, stomach/intestine content and mussels) were taken
during the cruise of the National Fisheries Service. The report from the cruise is supplied
as a Supplemental File.
Häussermann et al. (2017), PeerJ, DOI 10.7717/peerj.3123 45/51

Field Study Permissions
The following information was supplied relating to field study approvals (i.e., approving
body and any reference numbers):
Samples of marine invertebrates were collected under permit of Subsecretarı
´a de Pesca
y Acuicultura (R.EX. 1295 del 27.04.2016). Samples of cetaceans were authorized by
SERNAPESCA, Region de Aysen (Acta Numbers 2016-11-10 and 12).
Data Deposition
The following information was supplied regarding data availability:
The research in this article did not generate any raw data.
Supplemental Information
Supplemental information for this article can be found online at http://dx.doi.org/
10.7717/peerj.3123#supplemental-information.
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