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.

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

4Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)

been sighted in Southern California. While only

three (3.3 %) individually identified humpback

whales were documented in just Southern Cali-

fornia, and in no other feeding area. In total, 16

whales (17.4 %) had been sighted in Northern

California, of which seven (8.8 %) had also

been sighted in the centre of the state and five

(6.3 %) in both Central California and South-

ern California. Two humpback whales (2.2 %)

were sighted in Southern British Columbia,

Canada, and most significantly, one individual

photographed in El Salvador in 2021, was iden-

tified as a humpback whale that has been docu-

mented feeding in Southeast Alaska (SEAK)

in multiple years (Fig. 1). In fact, this whale of

unknown sex and named SEAK-5011, has been

sighted five times over 27 years in SEAK, span-

ning four decades, being photographed in 1994,

2004 and 2021. Prior to 2021, SEAK–5011 had

not been documented in a breeding area. On

5 February 2021, SEAK–5011 was seen in a

group of two adult whales, near Los Cóbanos,

Sonsonate, El Salvador. That same year but

after 196 days, SEAK– 5011 was photographed

in SEAK on the 20 August 2021, followed by

another nearby sighting on 26 August 2021.

Both feeding area observations were made in

Frederick Sound, SEAK, and a minimum great-

circle distance between the sightings from El

Salvador and SEAK was calculated as approxi-

mately 6 100 km.

Previous studies have shown that hump-

back whales from the Central America DPS

predominantly feed in the coastal waters of

California (Calambokidis et al., 2000, Calam-

bokidis et al., 2008; Rasmussen et al., 2012;

Steiger et al., 1991). Our results support this

finding with 83.7 % (77/92 whales) of whales

photographed in El Salvador being matched to

images taken in the waters of California, and

Fig. 1. Migratory connections of humpback whales from El Salvador. Numbers in arrows represent the number of individual

whales matched between locations. Photo inset is of humpback whale SEAK–5011. CA= California, WA= Washington state

(US), BC= British Columbia (Canada), SEAK = Southeast Alaska.

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)

suggest that Southern and Central California

are likely the most important feeding areas of

humpback whales that winter in El Salvador.

Our analysis found that nearly all Salvadorian

humpback whales registered in Southern Cali-

fornia (87.5 %, 21/24 whales) were also seen

feeding in Central California. These results

could be interpreted as implying the Southern

California region is a transitory area to pre-

ferred feeding areas further north, rather than

the terminal end of migration. However, we

note that Happywhale effort is far greater in

Central California (Author, Ted Cheeseman,

Unpublished data), and also the possible source

of these results.

The presence of humpback whales of the

Central America DPS throughout the Califor-

nia feeding areas has particular significance to

regional fishing regulations and management.

Entanglement of humpback whales in gear of

the California Dungeness crab pot fishery has

increased at an alarming rate since 2014 (Lebon

& Kelly, 2019), and has been demonstrated to

reduce survivorship, particularly for juvenile

humpback whales (Tackaberry et al., 2022).

Large whales may travel thousands of kilome-

ters carrying fishing gear and be entangled for

many months, even years (Cassoff et al., 2011),

and mulitple entangled humpback whales have

been encountered in El Salvador (Castaneda et

al., 2022). In the US, the species is protected

under the Marine Mammal Protection Act

(MMPA) and Endangered Species Act (ESA).

The continued documentation of the seasonal

presence of the endangered Central America

DPS in coastal California, an area where entan-

glement rates are high and increasing (Lebon &

Kelly, 2019), should be a critical consideration

for the future management of regional fisheries.

Our results also support previous findings

(Calambokidis et al., 2000, Calambokidis et

al., 2008), that a small number of humpback

whales from the Central America DPS may

be present in the more northern North Pacific

feeding areas of Washington State (US) and

British Columbia (Canada). Although match-

ing attempts of humpback whale catalogs

between North Pacific feeding areas and the

Central America DPS has been occurring since

the 1990s (Calambokidis et al., 2000, Calam-

bokidis et al., 2008; Rasmussen et al., 2012; Stei-

ger et al., 1991), this is the first published report

of a humpback whale photographed between

Central America and SEAK. This has relevance

for the management and protection of the

SEAK feeding region of humpback whales. As

part of the final rule of the Endangered Species

Act published in April 2021, the United States’

National Marine Fisheries Service (NMFS)

recently delisted SEAK for humpback whales,

stating that it was not ‘Critical Habitat’ for any

of the endangered or threatened North Pacific

DPSs. SEAK humpback whales are most com-

monly matched to the Hawaiian Archipelago

(Calambokidis et al., 2008), a breeding region

of a DPS classified as “Not at Risk” (Bet-

tridge et al., 2015). The recapture of just one

whale between SEAK to the endangered Cen-

tral America DPS does not negate NMFS’s “Not

Critical” designation. However, the documen-

tation of a whale in SEAK from a previously

unsurveyed breeding region, combined with

the fact that ~38 % of humpback whales that

feed in SEAK are yet to be matched to breeding

areas (Happywhale, unpublished data), lends

to the possibility of more, as-of-yet undiscov-

ered migratory connections between the two

regions. If more matches are found between

Central America and SEAK, it could have

repercussions for future regional conservation

and management planning in Alaska.

Lastly, our study shows the importance of

initiating research efforts in unsurveyed areas

of humpback whale habitat. This is especially

true in breeding areas of the at risk (threatened

and endangered) DPSs. Although SEAK–5011

has a sighting history of 27 years in the SEAK

feeding areas, this adult whale had never before

been documented in a breeding area. This

is despite several decades of intensive pho-

to-identification and matching efforts in the

neighbouring Mexico DPS (Calambokidis et

al., 2008, Cheeseman et al., 2021, Urbán et al.,

2000) and predominantly the southern region

of the Central America DPS (Steiger et al.,

1991; Calambokidis et al., 2000, Calambokidis

6Revista de Biología Tropical, ISSN: 2215-2075 Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)

et al., 2008; Rasmussen et al. 2012). Humpback

whales have been shown to exhibit strong

site-fidelity to seasonal breeding habitat in the

North Pacific (Acebes et al., 2021; Herman et

al., 2011). Therefore, this sighting of a SEAK

humpback whale in a previously unsurveyed

region of the breeding area of the endangered

Central America DPS, highlights the need for

expansion of research efforts to include all

known humpback whale habitat. It also exem-

plifies the merit of the new research efforts that

have been initiated in El Salvador, and the value

of continued surveying and cetacean studies in

the Pacific waters of this country.

Ethical statement: the authors declare that

they all agree with this publication and made

significant contributions; that there is no con-

flict of interest of any kind; and that we fol-

lowed all pertinent ethical and legal procedures

and requirements. All financial sources are fully

and clearly stated in the acknowledgments sec-

tion. A signed document has been filed in the

journal archives.

Author Contribution: NR conceptualized

this study, collected field data, analyzed the

data, and drafted early and revised versions

of this manuscript. MGC collected field data

and edited the manuscript, TC curated photo-

graphic data and edited the manuscript, JC and

FS collected and curated photographic data,

and edited various versions of this manuscript.

ACKNOWLEDGMENTS

Firstly, we would like to honor the work

of the late Marlenne Vázquez Cuevas for her

contribution to initiating humpback whale

research in El Salvador, and for her dedication

and enthusiasm in the field in 2020. Marlenne

worked tirelessly for countless hours, plan-

ning and organizing this research initiative in

El Salvador, and without her this study would

not have been possible. We would also like to

thank volunteers, students and fishermen of

the community of Los Cóbanos for all the effort

and support that made this study possible. We

would like to express our gratitude for the sup-

port of the Ministerio de Medio Ambiente y

Recursos Naturales (MARN) de EL Salvador

and the Programa Nacional de Conservación

de Cetáceos. We also thank Dr. Jeff Moore for

his work in ensuring funding for research in

Central America in 2021, and Dr. Joshua Smith

of Murdoch University for his advice and sup-

port. We would like to also thank Happywhale

and all who collaborate with them, especially

Alaska Sea Adventure for a sighting of SEAK–

5011 in 2004, and David Alfaro and Jose Baires

for sightings in El Salvador in 2018 and 2019.

Research in El Salvador was conducted under

permission GVS–AIMA–041–2020. Research

in SE Alaska was conducted under NOAA/

NMFS Research Permit No. 19703.

Funding in El Salvador was kindly gifted

by the Society of Marine Mammalogy, the Ruf-

ford Foundation, NOAA, MARN, and Cascadia

Research Collective. Equipment was also gifted

by Idea Wild. We would like to take this oppor-

tunity to thank you all for supporting this new

research initiative in El Salvador. The planning,

research and completion of this paper was

supported by the Post-graduate Internation-

al Scholarship of Murdoch University, Perth,

Western Australia granted to Nicola Ransome.

REFERENCES

Acebes, J. M. V., Okabe, H., Kobayashi, N., Nakagun,

S., Sakamoto, T., Hirney, B., & Uchida, S. (2021).

Interchange and movements of humpback whales

(Megaptera novaeangliae) between western North

pacific winter breeding grounds in Northern Luzon,

Philippines and Okinawa, Japan. Journal of Cetacean

Research and Management, 22, 39–53. https://doi.

org/10.47536/JCRM.V22I1.201

Bettridge, S., Olivia, M., Baker, C. S., Barlow, J.,Clapham,

P., Ford, M. J., Gouveia, D., Mattila, D. K., Pace, R.

M., Rosel, P. E., Silber, G. K., & Wade, P. R. (2015).

NOAA Technical Memorandum NMFS Status Review

of the Humpback Whale (Megaptera novaeangliae)

Under the Endangered Species Act. NOAA technical

memorandum NMFS; NOAA–TM–NMFS–SWFSC.

National Oceanic and Atmospheric Administration.

https://repository.library.noaa.gov/view/noaa/4883

Bowditch, N. (1994). American practical navigator: an epi-

tome of navigation. Defense Mapping Agency Hydro-

graphic Center. Defense Mapping Agency, Office of

Revista de Biología Tropical, ISSN: 2215-2075, Vol. 71(S4): e57283, diciembre 2023 (Publicado Nov. 01, 2023)

Distribution Services. https://msi.nga.mil/api/publi-

cations/download?key=16693975/SFH00000/Bow-

ditch_Vol_2_LoRes.pdf&type=view

Calambokidis, J., Steiger, G. H., Rasmussen, K., Urbán, J.

R., Balcomb, K. C., Ladrón De Guevara, P. P., Sali-

nas Z., M., Jacobsen, J. K., Baker, C. S., Herman, L.

M., Cerchio, S., & Darling, J. D. (2000). Migratory

destinations of humpback whales that feed off Cali-

fornia, Oregon and Washington. Marine Ecology

Progress Series, 192, 295–304. https://doi.org/10.3354/

meps192295

Calambokidis, J., Steiger, G. H., Straley, J. M., Herman, L.

M., Cerchio, S., Salden, D. R., Urban R., J., Jacobsen,

J. K., Von Ziegesar, O., Balcomb, K. C., Gabriele, C.

M., Dahlheim, M. E., Uchida, S., Ellis, G., Mlyamura,

Y., de guevara Paloma Ladrón, P., Yamaguchi, M.,

Sato, F., Mizroch, ... Quinn, T. J. (2001). Movements

and population structure of humpback whales in the

North Pacific. Marine Mammal Science, 17, 769–794.

https://doi.org/10.1111/j.1748-7692.2001.tb01298.x

Calambokidis, J., Falcone, E. A., Quinn, T. J., Burdin, A. M.,

Clapham, P. J., Ford, J. K. B., Gabriele, C. M., LeDuc,

R., Matilla, D., Rojas-Bracho, L., Straley, J. M., Taylor,

B. L., Urbán R, J., Weller, D., Witteveen, B., Yamagu-

chi, M., Bendlin, A., Camacho, D., Flynn, K., … Wade,

P. R. (2008). SPLASH: Structure of populations, levels

of abundance and status of humpback whales in the

North Pacific. Final report for Contract AB133F–03–

RP–00078. https://hawaiihumpbackwhale.noaa.gov/

science/archive.html

Cassoff, R. M., Moore, K. M., McLellan, W. A., Barco, S. G.,

Rotstein, D. S., & Moore, M. J. (2011). Lethal entan-

glement in baleen whales. Diseases of Aquatic Orga-

nisms, 96, 175–185. https://doi.org/10.3354/dao02385

Castaneda, M. G., Cuevas, M. V., Escalante, Á. H. F., &

López, J. D. S. (2021). Turismo de avistamiento de

cetáceos en Los Cóbanos, El Salvador: un primer

acercamiento a la actividad. Realidad y Reflexión,

54, 123–139. https://doi.org/10.5377/ryr.v54i54.12071

Castaneda, M. G., Martínez de Navas, E., Ransome, N. L.,

Benito, P. C., Pineda, L., & Aguilar Villalta, L. M.,

(2022). Eventos de cetáceos enmallados en El Salva-

dor. Revista Minerva, 5. https://minerva.sic.ues.edu.

sv/index.php/Minerva/issue/view/11/14

Cheeseman, T., Southerland, K., Park, J., Olio, M., Flynn, K.,

Calambokidis, J., Jones, L., Garrigue, C., Frish-Jordán,

A., Howards, A., Reade, W., Neilsen, J., Gabriele, C.,

& Clapham, P. (2021). Advanced image recognition: a

fully automated, high-accuracy photo-identification

matching system for humpback whales. Mammalian

Biology, 102, 915–929. https://doi.org/10.1007/

s42991-021-00180-9

Dawbin, W. H. (1966). The seasonal migratory cycle of

humpback whales. In Whales, dolphins and porpoises

(pp. 145-169). University of California Press.

Herman, L. M., Pack, A. A., Rose, K., Craig, A., Her-

man, E. Y. K., Hakala, S., & Milette, A. (2011).

Resightings of humpback whales in Hawaiian waters

over spans of 10-32 years: Site fidelity, sex ratios,

calving rates, female demographics, and the dyna-

mics of social and behavioral roles of individuals.

Marine Mammal Science, 27, 736–768. https://doi.

org/10.1111/j.1748-7692.2010.00441.x

Katona, S. K., & Whitehead, H. P. (1981). Identifying

humpback whales using their natural markings.

Polar Record, 20, 439–444. https://doi.org/10.1017/

S003224740000365X

Lebon, K. M., & Kelly, R. P. (2019). Evaluating alternati-

ves to reduce whale entanglements in commercial

Dungeness Crab fishing gear. Global Ecology and

Conservation, 18, e00608. https://doi.org/10.1016/j.

gecco.2019.e00608

Rasmussen, K., J. Calambokidis, & Steiger, G. (2012).

Distribution and migratory destinations of hum-

pback whales off the Pacific coast of Central

America during the boreal winters of 1996–2003.

Marine Mammal Science, 28, 267–279. https://

doi/10.1111/j.1748-7692.2011.00529.x

Stone, G. S., Florez-Gonzalez, L., Katona, S. (1990). Whale

migration record. Nature, 346, 705. https://doi.

org/10.1038/346705a0

Steiger, G. H., Calambokidis, J., Sears, R., Balcomb, K.

C., & Cubbage, J. C. (1991). Movement of hum-

pback whales between California and Costa Rica.

Marine Mammal Science, 7, 306–310. https://doi.

org/10.1111/j.1748-7692.1991.tb00105.x

Urbán R., J., Jaramillo L., A., Aguayo L., A., Ladrón de

Guevara P., P., Salinas Z., M., Alvarez F., C., Medrano

G., L., Jacobsen, J. K., Balcomb, K. C., Claridge, D.

E., Calambokidis, J., Steiger, G. H., Straley, J. M., von

Ziegesar, O., Waite, J. M., Mizroch, S., Dahlheim, M.

E., Darling, J. D., & Baker, C. S. (2000). Migratory

destinations of humpback whales wintering in the

Mexican Pacific (Megaptera novaeangliae). Journal

of Cetacean Research and Management, 2, 100–110.

https://doi.org/10.47536/jcrm.v2i2.493