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Rediscovery of a humpback whale (Megaptera novaeangliae)
feeding ground in the Straits of Magellan, Chile
Jorge Gibbons
*
, Juan J. Capella
+
and Carlos Valladares
#
Contact e-mail: yubarta@emcali.net.co
ABSTRACT
New information is presented on the summer distribution of southeastern Pacific humpback whales along the Southern Chilean fjords.
Sightings of 128 humpback whales observed between December and June from 1997-2001 were analysed. Sightings occurred between
48°50AS to 54°18AS and were concentrated in the waters surrounding Isla Carlos III in the Straits of Magellen (53°37AS, 72°21AW) and in
the Canal Wide (49°36AS–5°S). To date, 23 individual whales have been identified from photographs of the ventral surface of the flukes.
Throughout the austral summer, seven individuals were resighted near Isla Carlos III over periods between 2-5 months. Two individuals
were observed in 1999 and 2000, and two individuals were previously recorded in 1997 in Canal Wide, about 365km north of Isla Carlos
III. Historical records show the occurrence of whales in the area from the 16
th
to the 20
th
Century. From historic records, scattered whaling
data, the small amount of scientific literature available, and the results of this study, it is suggested that the southwestern part of the Straits
of Magellan, especially the waters surrounding Isla Carlos III, is the first known feeding ground for humpback whales along the Pacific
coast of South America.
KEYWORDS: HUMPBACK WHALE; SOUTH AMERICA; PACIFIC OCEAN; SIGHTINGS SURVEY; PHOTO-IDENTIFICATION;
FEEDING GROUNDS
INTRODUCTION
Humpback whales (Megaptera novaeangliae) are widely
distributed throughout the oceans of the Southern
Hemisphere. The question of stock identity has recently been
reviewed by the IWC Scientific Committee (e.g. IWC,
1998b; 2001). Seven distinct Southern Hemisphere breeding
stocks have been identified, including Group G – the West
South America stock (see Fig. 1, IWC, 1998a, p.27). The
general distribution and migratory destinations of humpback
whales in the West South America stock (Group G) are
known from studies based on whaling data (Townsend,
1935; Clarke, 1962; Aguayo, 1974; Ramírez, 1988),
occasional sightings (Oporto, 1986; Guerra et al., 1987;
Aguayo et al., 1998; Gibbons et al., 1998; Capella et al.,
1999) and from the identification of individual animals
(Stone et al., 1990; Flórez, 1991; Flórez et al., 1998;
Scheidat et al., 2000; Félix and Haase, 2001).
The known summer feeding grounds of the southeastern
Pacific humpback whale stock extend along the western
coast of the Antarctic Peninsula (Omura, 1953; Mackintosh,
1965; Olavarría et al., 2000), south to the Antarctic
Convergence. The cold inshore waters of the southern
Chilean fjords, including the Straits of Magellan, have not
been considered part of the summer range of humpback
whales in the Eastern South Pacific.
In recent years, however, there has been an apparent
increase in the frequency of sightings of humpback whales
off the coast of Chile (Aguayo, et al., 1998; Capella et al.,
1999), especially during summer and autumn in the
Patagonian fjords between 49°S to 53°S (Gibbons et al.,
1998). This paper considers sightings and photo-
identification data that have been collected since 1997 in the
Southern Chilean fjords, as well as a compilation of historic
records and opportunistic observations. These data are used
to examine local distribution, seasonality and the possible
existence of feeding grounds in the Straits of Magellan.
METHODS
Study area (Fig. 1)
The study was carried out along inner waters in the Southern
Chilean fjords, from south of the Golfo de Penas (47°40AS)
and the Beagle channel (55°S). The region exhibits a varied
physiography, with more than 37,000km of coastline, great
environmental heterogeneity and extreme oceanographic
conditions.
Due to its large geographical extent, the area has been
divided into the three regions described below.
Region (1). Patagonian fjords, from the south of Golfo de
Penas (47°22°S, 74°50W) to the western area of the Straits
of Magellan (52°40AS).
The area under study included the main channels that
connect this area with the Pacific Ocean (Canal Messier,
Canal Wide and Canal Concepción), interior channels and
fjords that are adjacent to the Southern Ice fields (a 300km 3
40km wide field of ice). This area is characterised by cold
waters with low salinity due to the high rainfall, fresh water
influx from rivers and glacial melting.
Region (2). The Straits of Magellan.
This is a 570km long V-shaped channel that connects the
Pacific and the Atlantic Oceans and separates the southern
part of the continent from Tierra del Fuego. Linked with the
Straits are the sounds, Seno Almirantazgo, Seno Otway and
Seno Skyring; due to their characteristics these last two
sounds are considered true inner seas (Magazzú et al., 1996).
This region has rich habitat diversity as a result of the
different influences of the water masses coming from the
Pacific and the Atlantic Oceans, the east-west gradient in
precipitation, the freshwater contribution of rivers and
glaciers, and major differences in coastal morphology, tides
and water depths (Panella et al., 1991).
*
Instituto de la Patagonia, Universidad de Magallanes, Punta Arenas, Chile, Casilla 113-D.
+
Fundación Yubarta, Apartado Aéreo 33141, Cali, Colombia.
#
España 666, Punta Arenas.
J. CETACEAN RES. MANAGE. 5(2):203–208, 2003 203
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Region (3). Fuegian fjords located to the south of the Straits
of Magellan.
These are similar to the Patagonian fjords in extent,
environmental heterogeneity and varied physical geography,
although glacial influence from the Darwin mountains is less
important than from the Southern Ice fields. They are
influenced in the east by Atlantic waters.
Survey methods and effort
Region 1
A total of 16 trips were made in different boats (14-16m in
length, similar in height and speed) for a total of 126 days of
work: 52 days in 1997, 47 in 1998, 25 in 2000 and 2 in 2001
(Table 1). The surveys followed a predetermined track of
approximately 1,172km (Fig. 1), with minor variations in
five excursions. Iceberg Fjord, Peel Fjord, Golfo de Trinidad
and Seno Ladrones were occasionally visited in addition to
the predetermined track.
Region 2
Both systematic and non-systematic sampling occurred. In
the Primera Angostura of the Straits of Magellan, 227
crossings were made on commercial ferries between Punta
Delgada (52°29AS, 69°30AW) and Bahía Azul (52°029A,
69°31AW) for a total of 22 days between May 2000 and June
2001, on a twice-monthly basis (Fig. 1).
Fig. 1. Humpback whale survey track in the Patagonian and Fuegian fjords and the Straits of Magellan.
GIBBONS et al.: HUMPBACK FEEDING GROUND IN STRAITS OF MAGELLAN204
In the central area (Paso Ancho) of the Straits of Magellan,
48 trips were made between Punta Arenas (53°07AS,
70°55AW) and Bahía Chilota, Tierra del Fuego (53°18AS,
70°26AW) onboard commercial ferries (Fig. 1), for a total of
24 days between June 2000 and June 2001, on a
twice-monthly basis.
Between Seno Otway and the southern portion of the
Straits of Magellan (Fig. 1), surveys were conducted along a
259km predetermined (entire or partial) track. A total of 57
days over 21 months from 1999 to 2001 were dedicated to
surveys (Table 1). Two main vessels were used: a 10m rigid
inflatable boat with an inboard diesel engine and a Zodiac
MK5 equipped with a 40Hp outboard engine. Shore based
surveys around Isla Carlos III and vessel surveys along the
Straits of Magellan from Punta Arenas to the western mouth
of the Straits were occasionally conducted.
Seno Skyring was surveyed opportunistically on 3 and 21
February 2000 and 30 March 2001, as was Seno
Almirantazgo on 1 September 2000 and 8 February 2001.
Region 3
A total of seven trips was made in December 1999, April,
August, October and November 2000 and February 2001, for
a total of 63 days (Table 1). These trips were made using
different boats (14-16m in length, similar in height and
speed), along a predetermined 497km track between Paso
Shag (Bárbara Channel) and the east of Isla Navarino (Fig.
1). Other surveyed sections, where the effort was more
irregular, have not been considered in this analysis.
Data collection
For each sighting of a whale or a group of whales, the
following information was recorded: date, time, GPS
position, group size and feeding behaviour. Whenever
possible, pictures of flukes or dorsal fins were taken.
Humpback whales were usually individually identified by
their unique patterns of ventral fluke pigmentation (Katona
and Whitehead, 1981). Whales were photographed with a
35mm camera using a 70-210mm zoom lens, black and
white or colour print film (ISO 100 and 200) and colour slide
film (ISO 100 and 400). Photo-identification effort was low
for Region 1 section and minimal for Region 3. Search effort
does not include fieldwork carried out in rain or seastate >4
Beaufort.
For the literature survey to determine the historic presence
of whales in the study area, shipping reports, historic
chronicles written since the European discovery of the
Straits of Magellan in the 16
th
century, other non-referenced
sources of information on whales, as well as available
scientific literature were reviewed. Opportunistic records of
humpback whales in recent years, obtained from
photographs or detailed observations provided by qualified
observers that included date and location, were also
collected.
Data management and analysis
Sightings data were analysed by month in order to examine
the temporal and geographic distribution of humpback
whales.
Relative abundance (defined as the number of whales
surveyed per hour during systematic sampling) was
estimated by region and month. Analysis units of a constant
length of 86.5km were established in the Fuegian and
Patagonian fjords and in Seno Otway 2 Straits of Magellan.
Relative abundance was compared among all the units with
whale records in order to identify concentration areas of
humpback whales.
High-quality fluke photographs (60% or more of the fluke
surface and a vertical angle sufficient to distinguish the
shape of the trailing edge of the fluke) were used to identify
individual animals and create a catalogue. Poor-quality
photographs were not considered in the dataset. Photographs
were used to assess annual returns and within-season
‘residency’. The term ‘residency’ means here the interval
from the first to the last sighting of an individual whale in a
season. Photo-identification data collected along the
Patagonian fjords (two whales) north to 51°S between 1997
and 1998 (Gibbons et al., 1998) were also included for
regional comparison between Regions and verification of
local movements.
RESULTS
Distribution, abundance and seasonality of whales
An overall summary of effort and whales observed in the
three regions is given in Table 1. A total of 128 groups were
observed. These groups were distributed from Canal Messier
(48°50AS) in the north to the Fuegian fjords (54°18AS) in the
south. Whales were not evenly distributed, with a number of
concentrations being observed. The highest relative
abundance in the period December to May, was observed in
the units that included the Straits of Magellan between Canal
Jerónimo and Isla Charles, with 1 animal/hour, increasing to
1.51 animals/hour in the specific area of Isla Carlos III but
decreasing to 0.21 animals/hour in Canal Wide in the
Patagonian fjords region (Fig. 2). Humpback whales were
not seen in Seno del Almirantazgo, Seno Skyring or in the
western Primera Angostura and the central areas (Punta
Arenas – Porvenir) of the Straits of Magellan. They were
only occasionally seen in the northernmost part of Fuegian
fjords (2 sightings) with just one sighting on a systematic
track in good conditions (Figs 1 and 2).
Humpback whales were observed from late spring to late
autumn. The first sighting was made on 1 December (1998)
and the last on 8 June (1997). No whales were directly
observed between July and November although there is
evidence from other observers of the presence of humpback
whales in the months of August, October and November (see
below). The greatest frequency of sightings (98%) occurred
between January and May (Fig. 3).
Group size
Humpback whales formed small groups, with a maximum of
five, a mean of 1.9 (SD=0.73) and a mode of two. Group
size distribution is given in Fig. 4.
Resighting, local movements and residency of
individuals
Twenty-seven individual whales have been identified from
fluke photographs. A total of six different animals have been
resighted between years, indicating that at least some
individuals return to the area. The observed ‘residence’ time
of individuals throughout the summer season ranged from 1
to 5 months, with three different whales being seen more
than once in a year. The individual with the longest
‘residence’ was identified in January, February and May
1999. Short-range movements were recorded in different
years for two individuals photographed in Canal Wide
(50°03’S, 74°33’W) in February and June 1997 respectively,
and again in the proximity of Isla Carlos III in February and
April 1999, respectively. These sites are separated by
approximately 365km.
J. CETACEAN RES. MANAGE. 5(2):203–208, 2003 205
Fig. 2. Humpback whales sighting distribution on the Patagonian and Fuegian Fjords and the Straits of Magellan.
Fig. 3. Seasonal changes in abundance of humpback whales throughout
the study period (1997-2001) in the Southern Chilean fjords
region.
Fig. 4. Frequency histogram of group size in the Patagonian fjords and
the Straits of Magellan during the study period.
GIBBONS et al.: HUMPBACK FEEDING GROUND IN STRAITS OF MAGELLAN206
Foraging activities
Common humpback whale feeding behaviour was observed
throughout the summer and autumn, including surface
feeding (both vertical and horizontal lunge feeding; Jurasz
and Jurasz, 1979) and ‘flick’ feeding. However, other typical
feeding behaviour described for the species in the Northern
Hemisphere, bubble net and bubble cloud feeding (Jurasz
and Jurasz, 1979; Hain et al., 1982), was not recorded.
Defecation was not observed during the study.
Other behaviour, presumed to be subsurface feeding, was
also observed. This included observations of regular diving
in the same location for 7-15 minutes whilst simultaneous
surface feeding by South American fur seals (Arctocephalus
australis) and sea birds (skuas, Catharacta chilensis; South
American stern, Sterna hirundinacea; black-browed
albatross, Diomedea melanophris; and Southern fulmar,
Fulmarus glacialoides) occurred. These events were
observed for several hours on 12 different days in 1999 and
2000. The prey species recorded, based on surface
observations during these events, were Galatheid crab
(Munida subrugosa) and schooling fish such as herring
(Sprattus fueguensis).
Historic and present time records
There is evidence of the presence of whales in the Straits of
Magellan, mainly near Isla Carlos III, for six consecutive
centuries. Up to the middle of the 19
th
century, these reports
referred in a general way to ‘whales’. Pedro Sarmiento de
Gamboa, a 16th century explorer, charted numerous
sightings around Isla Carlos III (53°37AS, 72°21AW) and the
western branch of the Straits of Magellan during the summer
(February) in 1583 (Sarmiento de Gamboa, 1954). Less than
one hundred years later, John Narborough observed whales
in the same area in November 1670 (Mantellero, 2000) and
L.A. Bougainville one century later, on 27 December 1767
(Bougainville, 1946)
1
. In the 19th century, Phillip Parker
King (Adventure and Beagle Expedition) sighted large
numbers of whales near Caleta Bradley, 20km south of Isla
Carlos III in April 1828 (King and Fitz Roy, 1839). The first
explicit mention of humpback whales was made by C.
Skogman in 1841. He stated that the frigate Eugenia
encountered ‘many humpbacks and finbacks’ around Isla
Carlos III (south of the English Narrows) in February, 1841
(Skogman, 1942)
2
. B. Phillipi mentioned humpback whales
in the Straits of Magellan in 1843 (Martinic, 2001). A shore
whaling station was established to the southeast of Punta
Arenas (see Fig. 2) in Bahía El Aguila (70°58AS, 53°48AW),
on the northern coast of the Straits of Magellan in 1905.
Hunting operations from this shore station were
concentrated on the coastal waters of the southern tip of
western South America (Martinic, 1977), although the
species hunted were not clearly documented. The first
confirmed report of humpback whales in the Patagonian
fjords during the 20
th
century concerns whales taken in 1914
and 1915 by Chilean whalers (Martinic, 1977).
Since the 1970s, several confirmed records of humpback
whales have been collected. In 1972 and 1973, photographs
of the same individual were taken in the Patagonian channels
and the Straits of Magellan (Orlando Dollenz, pers. comm.);
two whales were sighted in the Canal Wide in the Patagonian
fjords in January, 1984 (Oporto, 1986); a picture of two
humpback whales from Mussel Bay, Isla Carlos III in April,
1984 (Alfonso Martinez, pers. comm.); two sightings from
the Canal Abra Channel, 40km north of Isla Carlos III in
March, 1997 (Francisco Garrido, pers. comm.); two
individuals near Isla Carlos III in January, 1998 (Rodrigo
Hucke, pers. comm.); one individual in Mussel Bay, Isla
Carlos III in October, 1999 (Porter, pers. comm.); pictures of
one individual from Primera Angostura, in the eastern
portion of the Straits of Magellan in August 1999 and near
Punta Arenas in June, 2000 respectively (Carlos Leal, pers.
comm.); pictures of one individual from the Fuegian fjords
in March, 2000 (Alejo Contreras, pers. comm.); and a
videotape of two individuals from Seno Unión (52°10AS) in
the Patagonian fjords in November 2000 (Gonzalez, pers.
comm.). Gibbons et al. (1998) detailed 32 sightings obtained
in surveys along the Patagonian fjords (48°S-52°40AS); these
are included in this paper.
DISCUSSION
Distribution and seasonality
The information shows that Isla Carlos III, in the
southwestern section of the Straits of Magellan, appears to
be a suitable feeding habitat for humpback whales. However,
the sample size and effort is still too small to determine the
limits of this feeding ground or to eliminate the possibility of
others in the southern Chilean fjords.
The occasional sightings of humpback whales in the
Straits of Magellan (Leal, pers. comm.) and the Patagonian
channels during winter suggest that not all animals undertake
the migration to low latitudes each year, (c.f. Brown et al.,
1995). Some whales may remain in this feeding ground
through the austral winter.
Residence
The sightings of the same animal over a 5-month period in
the study area, is similar to the upper range reported for some
summer areas from the Northern Hemisphere (e.g. Baker et
al., 1985; Clapham and Mayo, 1987; Katona and Beard,
1990; Clapham et al., 1993). The annual return reported here
(two whales) provides some evidence for the existence of
foraging area philopatry. Studies conducted elsewhere have
suggested that this is the case for humpbacks on other
high-latitude feeding grounds in the North Atlantic and
North Pacific (Baker et al., 1985; Katona and Beard, 1990;
Clapham et al., 1993; IWC, 2002). It is probable that the data
presented here under-represent the true rates of residence
and annual returns given the low level of observations and
effort.
Despite the inevitable uncertainty surrounding the species
identity of early historical records, the probable residence of
humpback whales in the area is reinforced by historical
information that constitutes a complementary line of
evidence. The existence of reports of ‘whales’ from each
century after the 16th century, confirmed in conjunction with
the presence of humpback whales from early 20th century,
has led us to suggest that humpback whales have
traditionally occupied this region as a summer habitat. A
possible recolonisation by whales to their historic feeding
area might reflect a recovery of the Group G stock from
relatively recent commercial exploitation. However, there
are no reliable estimates of the population size in their
summer grounds and the extent to which humpback whales
return to a specific location has not been fully
documented.
1
Bougainville De, L.A. Viaje alrededor del mundo por la fragata del
rey la ‘Boudeuse’ y la fusta la Estrella en 1767, 1768 y 1769. Segunda
Edición. Espasa – Calpe Argentina, S.A. Buenos Aires 1946. Colección
Austral.
2
Skogman, C. Viaje de la fragata Eugenia. 1851-1853. Brasil,
Uruguay, Argentina, Chile, Peru. Ediciones Argentinas Solar, Buenos
Aires.
J. CETACEAN RES. MANAGE. 5(2):203–208, 2003 207
CONCLUSION
Although the data collected during the three years remains
limited, it does show that feeding behaviour is observed.
Together with the inference information about residence, it
suggests that the area of Isla Carlos III is a feeding ground,
the first identified for humpback whales in South America. It
is located about 2,000km closer to the tropical areas than the
principal feeding area near the Western Antarctic Peninsula
(Stone et al., 1990).
The relationship between the humpback whales of the
Straits of Magellan with animals from Colombia and the
Western Antarctic Peninsula is being investigated through
analysis of genetic and photo-id evidence.
ACKNOWLEDGMENTS
We thank the Universidad de Magallanes and Instituto de
Fomento Pesquero (IFOP) for helping to fund this research.
We are grateful to Conrado Alvarez, Ricardo Matus, Olivia
Blank, Stefan Bräger, Alejandro Kush, Jaime Gibbons,
Alfonso Martínez, Jaime Cárcamo and Carlos Seguel for
their field assistance and to Antonio Larrea, Isabel C. Avila
and Alexander Tobón for helping in photographic laboratory
work. We also thank Alejo Contreras, Patricio Contreras,
Orlando Dollenz, Rodrigo Hucke, Carlos Leal, Francisco
Garrido, Jorge Ramírez, Mariano Riveros and Tim Scoones
for providing us with records and numerous photographs:
Alfredo Prieto and Mateo Martinic helped us generously in
assembling historical data.
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Date received: November 2001.
Date accepted: July 2003.
GIBBONS et al.: HUMPBACK FEEDING GROUND IN STRAITS OF MAGELLAN208
