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Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)
Migratory destinations of endangered humpback whales,
Megaptera novaeangliae (Cetartiodactyla: Balaenopteridae), from El Salvador
Nicola Ransome1, 2, 3*; https://orcid.org/0000-0002-3130-3966
Melvin G. Castaneda1, 2; https://orcid.org/0000-0001-7559-1042
Ted Cheeseman4, 5; https://orcid.org/0000-0002-5805-2431
John Calambokidis6; https://orcid.org/0000-0002-5028-7172
Fred Sharpe7; https://orcid.org/0000-0002-6256-5547
1. Proyecto Megaptera El Salvador, Los Cóbanos, Sonsonate, El Salvador; melvingiocastaneda@gmail.com
2. Fundación Naturaleza El Salvador, San Salvador, El Salvador; fundanaturaleza@gmail.com
3. Harry Butler Institute, Environmental and Conservation Sciences, College of Science, Health, Engineering and
Education, Murdoch University, Western Australia, Australia; nicola.ransome@murdoch.edu.au (*Correspondence).
4. Marine Ecology Research Centre, Southern Cross University, Lismore, New South Wales, Australia
5. Happywhale, Santa Cruz, California, US; ted@happywhale.com
6. Cascadia Research Collective, Olympia, Washington, US; calambokidis@cascadiaresearch.org
7. Alaska Whale Foundation, Petersburg, Alaska, US; fsharpe@alaskawhalefoundation.org
Received 31-VII-2022. Corrected 21-III-2023. Accepted 10-IV-2023.
ABSTRACT
Introduction: The study of many aspects of cetacean ecology is made possible by identifying individuals through
space and time. Humpback whales (Megaptera novaeangliae) can be easily identified by photographing their
ventral tail flukes’ unique shape and pigmentation patterns. The small and endangered distinct population seg-
ment (DPS) of Central America humpback whales visit El Salvador seasonally each winter; however, dedicated
research has been extremely limited there. Before 2018, only 11 individual whales had been photo-identified, and
the migratory destinations of Salvadoran humpback whales were unknown. In recent years, photo-identification
efforts have increased, and today there are 92 individually identified humpback whales from El Salvador.
Objective: To identify the main high-latitude feeding areas of Salvadoran humpback whales.
Methods: Using the online matching platform Happywhale, Salvadoran whales were matched via automated
image recognition to a global humpback whale fluke photo-identification catalog of 66 043 individuals.
Results: In total, 80 (87.0 %) of the whales photographed in El Salvador were matched to individuals seen in
North Pacific feeding areas. Sighting histories of Salvadoran whales resighted in feeding areas ranged from two
to 29 years (average = 12.1, SD = 5.8). While we note that survey effort was likely very different between regions,
the main feeding area of Salvadoran humpback whales on Happywhale was Central California (n = 70, 76.1 %).
Of these whales, 21 (22.8 %) had also been sighted in Southern California, while just three (3.3 %) individual
whales were registered only in Southern California. Additionally, two whales (2.2 %) were sighted in Southern
British Columbia, Canada, and one whale was matched to a humpback whale from Southeast Alaska. This whale
(of unknown sex) has a sighting history of 27 years but no prior documentation in a breeding area and is the
first published sighting of a Southeast Alaskan humpback whale in the breeding area of the endangered Central
America DPS.
Conclusions: Our study shows that while Salvadoran humpback whales were matched to various feeding areas in
the Eastern North Pacific, their primary migratory destinations are in Southern and Central California.
https://doi.org/10.15517/rev.biol.trop..v71iS4.57283
SUPPLEMENT • WHALES
2Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)
INTRODUCTION
The humpback whale, Megaptera novae-
angliae (Borowski, 1781) is a large migratory
baleen whale with a cosmopolitan distribution,
that typically migrates long distances between
high-latitude summer feeding areas and low-
latitude winter breeding areas (Dawbin, 1966).
Their extensive annual migrations can be over
16 000 km round trips (Rasmussen et al., 2007;
Stone et al., 1990), and therefore humpback
whales of many worldwide populations will
travel through the territorial waters of multiple
countries each year. This creates challenges for
developing management strategies for endan-
gered and recovering populations and means
understanding migratory patterns and connec-
tions is critical for conservation. To aid with
management, in 2016 the National Oceanic
and Atmospheric Administration (NOAA) of
the US government identified 14 main breeding
regions of humpback whales for a worldwide
status review, which they defined as having
distinct population segments (DPSs) that visit
to breed and calve each year; nine of these were
classified as “Not at Risk”, one as “Threatened”,
and only four as “Endangered” (Bettridge,
2015). The list of endangered DPSs included
the Central America DPS of the North Pacific
humpback whale, which was described as small
and genetically distinct, and considered to be at
moderate risk of extinction (Bettridge, 2015).
Key words: large whale conservation; endangered populations; migratory species; critical habitat protection;
Central America distinct population segment.
RESUMEN
Destinos migratorios de ballenas jorobadas en peligro de extinción, Megaptera novaeangliae
(Cetartiodactyla: Balaenopteridae), del El Salvador
Introducción: El estudio de muchos aspectos de la ecología de los cetáceos es posible gracias a la identificación de
individuos a través del espacio y el tiempo. Las ballenas jorobadas (Megaptera novaeangliae) se pueden identificar
fácilmente al fotografiar la forma única de la aleta caudal y el patrón de pigmentación de su lado ventral. Una parte
del segmento de población distinta (DPS), pequeña y en peligro de extinción de las ballenas jorobadas de América
Central visita estacionalmente cada invierno El Salvador, sin embargo, la investigación ha sido extremadamente
limitada. Antes del 2018, solo existían imágenes de identificación de 11 ballenas individuales, y se desconocía el
destino migratorio de las ballenas jorobadas salvadoreñas. En los últimos años, los esfuerzos de foto-identifica-
ción han aumentado, y hoy en día hay 92 ballenas jorobadas identificadas individualmente en El Salvador.
Objetivo: Identificar las principales áreas de alimentación en latitudes altas de las ballenas jorobadas salvadoreñas.
Métodos: Utilizando la plataforma en línea Happywhale, las aletas caudales de las ballenas de El Salvador fueron
comparadas a través del reconocimiento automático de imágenes con un catálogo global de foto-identificación
de 66 043 individuos.
Resultados: En total, 80 (87.0 %) de las ballenas fotografiadas en El Salvador se compararon con individuos vistos
en las áreas de alimentación del Pacífico Norte. El historial de re-avistamientos de ballenas salvadoreñas en áreas
de alimentación fluctó de dos a 29 años (promedio = 12.1, d.e. = 5.8). La principal zona de alimentación para las
ballenas jorobadas salvadoreñas fue el centro de California (n = 70, 76.1 %). De estas ballenas, 21 (22.8 %) tam-
bién se habían avistado en el sur de California. Solo tres ballenas se habían visto (3.3 %) únicamente en el sur de
California. Dos ballenas jorobadas (2.2 %) fueron avistadas en el sur de la Columbia Británica, Canadá, y lo más
importante, una fue identificada como una ballena jorobada del sureste de Alaska. Esta ballena de sexo descono-
cido tiene un historial de avistamientos de 27 años, pero sin documentación previa en un área de reproducción.
Este es el primer avistamiento publicado de una ballena jorobada del sudeste de Alaska en el DPS en peligro de
extinción de América Central, y tal vez sea particularmente importante por razones de manejo.
Conclusiones: Este estudio encuentra que aunque las ballenas jorobadas que llegan a El Salvador se observan
en varias localidades del Pacifico norte, su migración tiene como destino principal las aguas del Pacifico sur y
central de California.
Palabras clave: conservación de ballenas; poblaciones en peligro; especies migratorias; protección de hábitat
crítico; Segmento Poblacional Distinto de Central America.
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Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)
The study of many aspects of cetacean
ecology is made possible by identifying indi-
viduals through space and time. Humpback
whales can be easily identified by their ventral
tail flukes’ unique shape and pigmentation pat-
terns (Katona & Whitehead, 1981). For the last
five decades, photographic identification (e.g.
photo-identification) of humpback whales and
collaboration between international researchers
has allowed for a growing understanding of the
movements and migrations of humpback whale
populations globally (Calambokidis et al., 2000,
Calambokidis et al., 2001, Calambokidis et
al., 2008; Cheeseman et al., 2021) However,
worldwide there remain a few areas of seasonal
habitat of the species where research has not
been initiated. One such place was the Central
American country of El Salvador, considered
part of the breeding area of the Central Amer-
ica DPS. Whilst cetacean research was growing
worldwide, El Salvador was in the midst of civil
war, and dedicated cetacean surveying was
extremely limited. Prior to 2018, only 11 indi-
vidual humpback whales’ fluke identification
images existed, and therefore the migratory
destinations of Salvadoran humpback whales
were unknown. Increased photo-identification
efforts began in the Pacific waters in 2018, and
dedicated cetacean surveying was initiated in
2020. Here we present, for the first time, migra-
tory connections of a significant number of
Salvadoran humpback whales to North Pacific
feeding areas, to aid in international manage-
ment decisions and planning for the endan-
gered Central America DPS.
Between 1999 and 2006, 11 photo-iden-
tification images of humpback whales were
collected in the Pacific waters of El Salvador as
part of Cascadia Research Collective research
efforts throughout Central America (Calam-
bokidis et al., 2008, Rasmussen et al., 2012). In
2006, a small whale-watching industry began
in Los Cóbanos, Sonsonate, El Salvador (Cas-
taneda et al., 2021). In 2018, these tourism trips
were then used as a research platform. Data
collected included photo-identification images
of humpback whales, Global Positioning Sys-
tem (GPS) tracks, and basic environmental
data (sea state, water temperature, cloud cover
and visibility). In total, over 33 whale watch
trips were conducted which resulted in over
109 hours of surveying, and 10 new photo-
identification images. In 2020, 10 dedicated
cetacean surveys were completed, involving 64
hours of surveying, encountering five groups
of humpback whales and identifying seven
individuals. In 2021, 41 research surveys were
completed, of a total of 129 hours of surveys, 54
humpback whale groups were encountered, and
49 unique photo-identification images were
collected. Since 2019, an additional 15 photo-
identification images have also been collected
on whale watch trips in the region.
All unique photo-identification images of
individual humpback whales were uploaded
to the research collaboration and citizen sci-
ence web platform Happywhale (www.happy-
whale.com). Individual whales were matched
via automated image recognition to a global
humpback whale fluke photo-identification
catalog of 66 043 individuals, of which 27 536
were identified in the North Pacific Ocean
(Cheeseman et al., 2021). Images were matched
with an expected accuracy of 97–99 % of
potential matches found, match results were
manually confirmed, and unmatched individu-
als with fluke identification photos of sufficient
quality were considered new to the dataset and
given an ID number. Great-circle distances
between sighting locations of matched whales
were then calculated using the methodology of
Bowditch (1994).
Overall, 92 individual humpback whales
have been identified in El Salvador between
1999–2021 during the boreal winter months,
December through March. Via Happywhale, 80
(87.0 %) of the humpback whales photographed
in El Salvador were matched to individuals seen
in North Pacific feeding areas. No matches
were made to areas outside of the North Pacif-
ic. Sighting histories of Salvadoran humpback
whales resighted in feeding areas ranged from
two to 29 years (average = 12.1, sd = 5.8).
The main feeding area where whales
were resighted was Central California (n = 70,
76.1 %). Of these whales, 21 (22.8 %) had also