STRUCTURE OF A LONG-FINNED PILOT
WHALE SCHOOLSTRANDED IN PATAGONIAENRIQUE A. CRESPO*, GUSTAVO PAGNONI** ANDSUSANA N. PEDRAZA***ABSTRACT

A herd of 17 southern long-finned pilot whales, Globicephala melaena
edwardii (Smith, 1834) was found in November 1982 stranded near Punta
Tombo, Argentina, at the beach above the high tide line. The herd wascomposed of nine females, seven males, and an individual of indeterminated sex (5 years, the youngest individual). Using age criteria obtained for
the North Atlantic population of the species (Sergeant, 1962) all thefemales (9-16 years) were estimated as sexually mature, three males (7-11years) as probably immature, and two males ( 14 and 16 years) having
attained breeding maturity. The reliable estimate of remaining two males,(12 years) was not possible from their ages. Due to the advanced decomposition, no further information on the growth or reproductive status wasavailable.
INTRODUCTION

The mass stranding of Cetaceans attracted the interest of many biologists, anda considerable number of papers dealing with it were published (Geraci,1978; Sergeant, 1983). The long-finned pilot whale Globicephala melaena(Trail, 1809) mass strands like other highly social members of the Orcininae(Sergeant, 1983). Sergeant suggested that the frequency of mass stranding inCetaceans might be a density dependent event of highly social Cetaceanspeoes.
Mass stranding of Cetaceans in Argentine coasts has been reported forthe sperm whale (Castello and Pinero, 1974) and the southern long-finned
pilot whale (Pinero and Castello, 1975). Goodall (1978) has described individual and mass strandings of Cetaceans in Tierra del Fuego.

* Centro Nacional Patag6nico-28 de Julio 28-9120 Puerto Madryn-Provincia de Chubut-Republica
Argentina** Direcci6n de Conservaci6n de! Patrimonio Turistico de la Provincia de Chubut-Sarmiento 386-9120
Puerto Madryn-Provincia de Chubut-Republica Argentina*** Departamento de Ciencias Biol6gicas-Facultad de Ciencias Exactas y Naturales Universidad deBuenos Aires-Ciudad Universitaria-1428 Buenos Aires-Republica Argentina

Sci. Rep. Whales Res. Inst.,
No. 36, 1985, 97-106

98

CRESPO, PAGNONI AND PEDRAZA
10'55ow

44°10'Fig. 1. Location of the stranding. The isobaths are indicated in meter.

The present paper describes the age and body length compositions of agroup of southern long-finned pilot whale Globicephala melaena edwardii(Smith, 1834), stranded at Punta Tombo, in the Patagonian coast.
MATERIALS AND METHODS

Features of the stranding
The mass stranding took place 2 km south of Punta Tombo (44°02'S,65°0l'W), the Chubut Province Penguin Reserve (Fig. 1). The whales were
found stranded on a rocky platform, above sandy and stony beaches, about 3
to 8 m inland side of the normal high tides line.
Nothing is known about the instance of the mass stranding, even if the17 individuals represent an entire school or part of a lager one. The date ofSci. Rep. Whales Res. Inst.,
No. 36, 1985

ILOTWHALESCHOOLSTRUCTUREOFA P

99ub‑os
hetw
ngt
itar
a
ep
els
hannhecett
acidn.Arrowsi
gni
andrtesh. Viewoft.2
giF
hem.
ente)foundbetw
imen No.9cepSe(tmalludtaesgrahel,andtspu
org,sehewhalompositionoftceofde
er
hedeg
om tr
dfetamits
andingwase
rt
es
ht
s
y
tda
sr
i
hef
ohaveoccurredaroundth,thebeacnt
nofthemi
oi
ti
soep
handt
dse
peris
ed
swer
e.Thewhal
stewashighediethofNovember, 1982,whent
n.2mostofthemwereiginF
sshownich,butaebea
hlong103metersofta).9o
Ne(dmallrgeo
a.A ltrap),whichwere30m ah
c
ase
lami
n
8a
twogroups(2mhannel1oac
etti
sopp,andospuor
hetwogeoft
emiddlhtt
trandeda
wass
ementswere
sura
lme
anr
etxreeht
handsomeotng
e.Bodylpeewideand3m de.
vresePenguinReheperoft
heGameke
sbyt
lau
di
iv
dnli
l
nfroma
e
kat

se
ice
p
fs
η ooi
taci
fi
t
ne
dI
ength
sandl
r
e
t
car
ahlc
ai
na
sofcr
si
eba
hdont
ei
fit
den
swasi
eicep
Thes‑er
eph,andt)
e1bl.3andTagiF)(
1791e(dbyBreebircse
sdraeppilef
hoft,
seDavich (te patihlw
artne
rk and v
le ma
dda
sheye mark,siti
he ofwencshati
neachjaww
2io1hrangedfrom9t
tee.Themeannumberoft)06
91‑nateshs20% oftswa
reppilefh
engthoft.Themeanl)65=n2(3.
0meanof1e,er
Bs(eicepisshrtodfetrope7% r2‑8erangeof1hnt
niiag,aht
gnedl
dar
r
et
f
veoneweeka
er
seRe
h
heGamekeeperoft
nbyt
eka.Photographst)9711)and.4gi
Fk(remayeehtoneanimalhadt
asetltaah,showedt
g
ni
dnar
t
hes
t
o
sduet
lranimaeht
Theywerenotconfirmedono
h.
ct
a
lp
ar
t
ne
ev
h
hert
anot
srk
hema
tt
ah
sknownt
ti.I
noitairalv
audividnionoritaroirete
dvancedd
eahtohtsitihom wr
sf
laudivdintdeadi
su
gorj
nivi
ualyevenonl
div
idnyiyvarma.
)
,1960
s
eiv
aDy(ardarkg,.
tsn.I
ssReealp.Wh
i Rec
S,1985
6No.3

100

CRESPO, PAGNONI AND PEDRAZATABLE 1,
Specimen
No.
1
2
3
4
5
6
7
89
10
11
12
13
14
15
1617mean(1) UR: upper right jaw,

LR: lower right jaw,

NUMBER OF TEETH OF THE PUNTA TOMBO SPECIMEN
No. of teeth (1)URUL

10101191010111110911111010910101010II11IIIIIILR
1210101010109910

LL

10109119910IIII

121011121010II

1091112111012

10.40

10.40

10.25

10.23

UL: upper left jaw
LL: lower left jaw

Skull of Specimen No. 11 was deposited in the mastozoological collectionof the Facultad de Ciencias Exactas y Naturales, Universidad de Buenos
Aires, (Specimen number 3855) (Fig. 3).
Age determination
Two large teeth were taken from a jaw of each individual. The teeth
were sectioned longitudinally (sagitally) with a hand saw, and ground withsand paper to a thickness of about 100 µ,m. Then the teeth were examined for
dentinal growth layers under a dissecting microscope (X8 to X40). Fig. 5
shows the sagital section of Specimen No. 1 and No. 16, and Fig. 6, cemen·tum layers in Specimen No. 2 and No. 8.
The pattern of the dentinal growth layers was the same as described bySergeant ( 1962). The outermost dentinal layer was the prenatal dentine, ending in a traslucent neonatal line. The 2nd layer was generally opaque andended in a clear zone. The opaque layer, sometimes contained a fine clearzone (accesory layer). The 3rd was less than half of the width of the 2nd layer
anq the thickness of the subsequent layers declined with increasing order.
The deposition rate of these layers was assumed as annual without further
confirmation (Sergeant, 1962). A double-layer effect was observed in some ofSci. Rep. Whales Res. Inst.,
No. 36, 1985

目Fig.3.Lateral and dorsalview of t
he skull ofSpecim
en No.1
1(F.C.E.N・.U.
B.
AMast.Coll.No.3
855).Scaleindi
cates10cm.

Fig.4.P
i
gen
ta
t
i
o
nofs
omei
ndiv
idualsinthemassstrandi
ng.Arrowindicatesthewhitishmarkbehi
ndt
heeye.

hhN
EehEh
2・河内︑ ＝sch
・之︒同色 u ﹄百句切日目﹄

司−0ー4 ヱ﹀﹁問的︵UZOOF﹃刃旬︒吋己閉山間 O 司 ﹀ ヱ ﹁ ︒︑H 4︿印︑CRE
SPO,PAGNONIANDPEDRAZA

102−

EE ︷UU凶・E
叫d＝guEuuE Cuh司二 回ZEE司g弓z−u一回・uhJ 油亡 ︶∞ E・︵白黒兵一℃一士石− m ︵回﹄開︼一CZEUECua∞ ﹄OE2zuEUU DコO﹄国55ト ．0 ・出店
O﹄ Eコuguc

乙別的UE＝z UE EU QJFEdcuEUU υい時一周﹄＝ dus．
−PE
U 町c
・E S同E 出U
向 一uUEZE
ω＝＝℃
5 2 5的 U
EO− 52uh同一 E− EE司 2− 5uEzu一−
U一ど一υ dzuh 制︻一L −コEU℃−周回国EU﹄aHOu
EU 一凶︵同﹂司L メdτ8 弘吉 弘 U− E司J59﹄︶ − ℃E国︵ご同uh肘て du乙 由 − 凶OZEUECU色的﹄0203UU同 − −凶何回・凶岡田弘Sci.Rep.WhalesRes.Ins.
t,

No.36,1985

103

STRUCTURE OF A PILOT WHALE SCHOOLTABLE 2,

LIST OF INDIVIDUALS MASS STRANDED AT PUNTA TOMBO IN NOVEMBER 1982

Specimen
No.
I

2
34
56
7
89101112
13
14
15
1617Sex

Body lengthAge (1)

malefemale
femalefemalemalefemale
malemalemalefemale4.46
4.204.68
4.83
3.35
4.00
3.93
5.00
5.38
4.40
3.28
4.10
4.10
4.60
4.28
4.50
4.72

1211
13
12
79814
16
13
5911

femalemalefemale
femalemalefemale

II101216

Estimated sexual
maturity (2)maturematurematurematureimmature
matureimmature
maturematurematureimmature
matureimmature
maturematurematuremature(I) Age in number of dentinal growth layers (presumably years).
(2) Sexual maturity is estimated using criteria of Sergeant (1962), i.e. sexually mature at 11 years (male) or
6 years (female).

the teeth, therefore an overestimation of the age of the whale could result.
Nearly same number of layers were observed in dentine and cementumof the same tooth, which suggests a same deposition rate in both tissues.
RESULTS

Sex, standard length and age of the specimens are shown in Table 2. Ages
ranged from 9 to 16 years in females and 7 to 16 years in males. The oldest
individuals were much younger than what is known for the northern long-finned pilot whale (50 years, Sergeant, 1962) or the short-finned pilot whale (62years, Kasuya and Matsui, 1984).
The body length ranged from 400 to 4 72 cm in females and 335 to 538
cm in males. The upper limit of the range was smaller in both sexes than themaximum reported by Sergeant (1962) (females: 536 cm, males: 622 cm).
On the northern long-finned pilot whale, Sergeant (1962) estimated thefemale age and body length at the attainment of sexual maturity as 4-8 years(mean 6) and 341-386 cm (mean 356), respectively. The ages of males at theattainment of sexual maturity and breeding maturity was 11-16 years (mean11) and over 12 years, respectively. If these criteria are used tentatively all thenine females (9-16 years and 400-483 cm) are considered as mature, fourmales (12-16 years and 446-538 cm) as probably have attained sexual maturSci. Rep. Whales Res. Inst.,
No. 36, 1985

CRESPO, PAGNONI AND PEDRAZA

104

Ec6-.c50 )4c(1)-3'E2+~·;:::JtV(ii'tJ

c1(ijtVQ)

enE:Jx"'o+Fig. 7. Scatter plot of body length on age of the mass stranding ofGlobicephala melaena edwardii. Ages and body lengths at sexual maturity are mean values estimated by Sergeant (1962) for the northernlong-finned pilot whale.

ity, and three males (7-11 years and 335-410 cm) as immature. An individualof unknown sex (5 years and 328 cm) is estimated as immature (Fig 7 andTable 2). However, this clasification has to be considered as tentative, because
there is no base to believe that the growth in the present population is thesame as that in the North Atlantic population studied by Sergeant (1962), andbecause the individual variation of growth is wide in the species. There were
no juveniles below 5 years of age.
Of the 16 sexed individuals 9 (56%) were females and 7 (44%) weremales. The female/male ratio was 1.28 and the mature female/mature maleratio was probably 2.50 (9/4). This suggests a polygynous school structure as
indicated for the North Atlantic long-finned pilot whale (sergeant, 1962) and.the short-finned pilot whale in the North Pacific (Kasuya and Marsh, 1984).
DISCUSSION

The southern long-finned pilot whales have been sighted or stranded in theArgentine coast (Pinero and Castello, 1975; Goodall, 1978), although little
knowledge is available about the composition of the herds. No explotation ofthis species exists at least in recent years in the Argentine waters.
According to Sergeant (1962), the sizes of herd of long-finned pilot
whale ranged from a few individuals up to 200 or more. The mean herd sizeof the species driven ashore in Newfoundland and those stranded naturally
all over the world was about 85 individuals, with the highest frequency beSci. Rep. Whales Res. Inst.,
No. 36, 1985

STRUCTURE OF A PILOT WHALE SCHOOL

105

tween 21-50 individuals, though the most frequent herd size in sightings in
the Labrador Sea made by the U.S. Coast Guard was 11-20 individuals wit_h amean of 20. This suggest that the pelagic herds tended to be smaller thanthose stranded or driven ashore (Sergeant, 1962, 1983). He also concludes
that the herd size was variable under different circumstances like feeding,stress, migrations, etc, and smaller units may occasionally agregate to form
larger ones or viceversa.
The present herd was composed of 17 individuals. Another herd
stranded at Punta Norte (Peninsula Valdes - Chubut) on August 30th, 1976,
was composed of 25 animals, but except for 2 males and 3 females the remaining 20 individuals were returned to sea (J. C. Lopez, pers. comm.).
Castello (1975) reported a stranding of 56 individuals at Isla Trinidad, butthere was left no information on the sex ratio. Goodall (1978) recorded agroup of 9 animals stranded in Isla d!=' los Estados. These herd sizes are notdifferent from those reported by Sergeant (1962).
Although the pilot whales are known to be sexually dimorphic (Sergeant,1962; Kasuya and Matsui, 1984), this is not detected in the present materials.
This may be related to one or two of these possibilities: (1) small sample size,(2) skewed school composition and (3) that sexual maturity is attained muchlater in the population (dimorphism appears at later age).

ACKNOWLEDGEMENTS
The authors are indebted to Carlos Passera, Gamekeeper of the Penguin
Reserve of Punta Tombo, who provided measurements and photographs of
the whales, to Juan Carlos Lopez who provided valuable information, to Lie.
Claudio J. Bidau, Depto. de Ciencias Biloogicas (F.C.E.N.-U.B.A.) who corrected the English manuscript, and to Lie. Hugo P. Castello, Museo Argentino de Ciencias Natuirales and Dr Toshio Kasuya, Far Seas Fish. Res. Lab.,for their valuable suggestions and critical reading of the manuscript.

REFERENCES
BREE, P.H.]. VAN, 1971. On Globicephala sieboldii Gray, 1846, and other species of Pilot Whales. (Notes on
Cetacea, Delphinoidea III. Beaufortia, 19 (249): 79-87.
CASTELLO, H.P. and M.E. PINERO, 1974. Varamientos de cachalotes, Physeter catodon, en las costas <lei Atlantico del Brasil y la Argentina (Cetacea, Physeteridae). Physis,'secci6n A, 33 (86): 371-374.
DAVIES, J.L., 1960. The southern form of the pilot whale.]. MAMM., 41 (1): 29-34.
GERACI, J.R., 1978. The enigma of marine mammals strandings. Oceanus, 21: 38--47.
GooDAL, R.N.P., 1978. Report on the small Cetaceans stranded on the coasts of Tierra <lei Fuego. Sci. Rep.
Whales Res. Inst., 30: 197-230.
KASUYA, T. and MARSH, H. 1984. Life history and reproductive bilogy of the short-dinned pilot whale,
Globicephla macrorhynchus, off the Pacific coast of Ja pan. Rep. int. Whal. Commn (Special Issue 6): 259310.
KASUYA, T. and S. MATSUI, 1984. Age determination and growth of the short-finned pilot whale off thePacific coast of Japan. Sci. Rep. Whales Res. Inst., 35: 57-91.
Sci. Rep. Whales Res. Inst.,
No. 36, 1985

106

CRESPO, PAGNONI AND PEDRAZAPINERO, M.E. and H.P. CASTELLO, 1975. Sobre ballenas piloto, Globicephala melaena edwardi (Cetacea, Delphinidae), varadas en Isla Trinidad, Provincia de Buenos Aires. Rev. Mus. Arg. Cien. Nat., 12 (2): 1324.
SERGEANT, D.E., 1962. The bilogy of the pilot or pothead whale Globicephala melaena (Traill) kin Newfoundland waters. Bull. Fish. Res. Board Can., 132: 84.
SERGEANT, D.E., 1983. Mass strandings of toothed whales. Sci. Rep. Whales Res. Inst., 34: 1-47.
TORANZOS, F.I. 1962. Teoria estadistica y aplicaciones. Ed. Kapelusz., Pg. 128.

Sci. Rep. Whales Res. Inst.,
No. 36, 1985