U. S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Southwest Fisheries Science Center

NOAA-TM-NMFS-SWFSC-540

MARCH 2015

NOAA Technical Memorandum NMFS

STATUS REVIEW OF THE HUMPBACK WHALE (MEGAPTERA

NOVAEANGLIAE) UNDER THE ENDANGERED SPECIES ACT

Shannon Bettridge, C. Scott Baker, Jay Barlow, Phillip J. Clapham, Michael Ford, David Gouveia, 

David K. Mattila, Richard M. Pace, III, Patricia E. Rosel, Gregory K. Silber, Paul R. Wade
The National Oceanic and Atmospheric Administration (NOAA), organized in 

1970, has evolved into an agency that establishes national policies and manages 

and conserves our oceanic, coastal, and atmospheric resources. An 

organizational element within NOAA, the Office of Fisheries, is responsible for 

fisheries policy and the direction of the National Marine Fisheries Service (NMFS).

In addition to its formal publications, the NMFS uses the NOAA Technical 

Memorandum series to issue informal scientific and technical publications when 

complete formal review and editorial processing are not appropriate or feasible. 

Documents within this series, however, reflect sound professional work and may 

be referenced in the formal scientific and technical literature.
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NOAA Technical Memorandum NMFS

This TM series is used for documentation and timely communication of preliminary results, interim reports, or special

purpose information. The TMs have not received complete formal review, editorial control, or detailed editing.

NOAA Technical Memorandum NMFS

This TM series is used for documentation and timely communication of preliminary results, interim reports, or special

purpose information. The TMs have not received complete formal review, editorial control, or detailed editing.

NOAA-TM-NMFS-SWFSC-540

National Oceanic and Atmospheric Administration

U.S. DEPARTMENT OF COMMERCE

Penny S. Pritzker, Secretary of Commerce

Dr. Kathryn D. Sullivan, Administrator

National Marine Fisheries Service

Eileen Sobeck, Assistant Administrator for Fisheries

MARCH 2015

STATUS REVIEW OF THE HUMPBACK WHALE 

(MEGAPTERA NOVAEANGLIAE) UNDER THE 

ENDANGERED SPECIES ACT

Shannon Bettridge, C. Scott Baker, Jay Barlow, Phillip J. Clapham, 

Michael Ford, David Gouveia, David K. Mattila, Richard M. Pace, III, 

Patricia E. Rosel, Gregory K. Silber, Paul R. Wade

Affiliation of Authors:

NMFS O/PR, Oregon State U., SWFSC, AFSC, NWFSC, NERO, 

HIHWNMS, NEFSC, SEFSC, O/PR, & AFSC (respectively)
DISCLAIMER

This document is a compilation of the best available scientific and commercial data and a 

description of threats to humpback whales (Megaptera novaeangliae). It does not represent a 

decision by the National Marine Fisheries Service (NMFS) on whether this taxon or any subset 

thereof should be proposed for listing as threatened or endangered under the Federal Endangered 

Species Act or whether the current listing status should be changed. That decision will be made 

by NMFS after reviewing this document, other relevant biological and threat information not 

included herein, efforts being made to protect the species, and all relevant laws, regulations, and 

policies. The result of the decision will be posted on the NMFS web site (refer to: 

http://www.nmfs.noaa.gov/pr/) and announced in the Federal Register.

Cover photograph by Cornelia Oedekoven; Southwest Fisheries Science Center, Marine 

Mammal and Turtle Division.
HUMPBACK WHALE BIOLOGICAL REVIEW TEAM

C. Scott Baker

Marine Mammal Institute

Oregon State University

Jay Barlow

National Marine Fisheries Service

Southwest Fisheries Science Center

Shannon Bettridge

National Marine Fisheries Service

Office of Protected Resources

Phillip Clapham

National Marine Fisheries Service

Alaska Fisheries Science Center

Michael Ford

National Marine Fisheries Service

Northwest Fisheries Science Center

David Gouveia

National Marine Fisheries Service

Northeast Regional Office

David Mattila

National Ocean Service

Hawaiian Islands Humpback Whale

National Marine Sanctuary

Richard M. Pace, III

National Marine Fisheries Service

Northeast Fisheries Science Center

Patricia E. Rosel

National Marine Fisheries Service

Southeast Fisheries Science Center

Gregory K. Silber

National Marine Fisheries Service

Office of Protected Resources

Paul R. Wade

National Marine Fisheries Service

Alaska Fisheries Science Center

iii
ACKNOWLEDGEMENTS

The Humpback Biological Review Team would like to thank Alyson Fleming and Jennifer 

Jackson for their invaluable work on the NOAA Technical Memorandum that provided 

significant contributions to this status review. Alyson Fleming also served as rapporteur for the 

Biological Review Team’s meetings. The Society for Marine Mammalogy’s Taxonomic 

Committee provided their collective expertise and advice on genetics and classification of this 

cosmopolitan species. Sonja Kromann provided great assistance locating background literature 

for this review. Layne Bolen researched and provided background information on existing 

regulatory mechanisms, and Jeff Adams created several of the maps contained in this report. We 

also thank Alex Zerbini, peer reviewers, and other individuals who provided information and 

guidance in support of this document. 

iv
EXECUTIVE SUMMARY

Humpback whales (Megaptera novaeangliae) were listed as endangered in 1970 under the 

Endangered Species Conservation Act of 1969, the precursor to the Endangered Species Act 

(ESA). When the ESA was enacted in 1973, humpback whales were included in the List of 

Endangered and Threatened Wildlife and Plants (the List) as endangered and were considered as 

“depleted” under the Marine Mammal Protection Act (MMPA).

In May 2010, the National Marine Fisheries Service (NMFS) convened the Humpback Whale 

Biological Review Team (BRT) to conduct a comprehensive review of the status of humpback 

whales as the basis for considering revisions to this species’ listing status. The ESA, as amended 

in 1978, defines a species to be “any subspecies of fish or wildlife or plants, and any distinct 

population segment of any species of vertebrate fish or wildlife which interbreeds when mature” 

(Section 3(16)). Guidance on what constitutes a “distinct population segment” (DPS) is provided 

by the joint NMFS-Fish and Wildlife Service (FWS) interagency policy on vertebrate 

populations (61 FR 4722, 7 February 1996). To be considered a DPS, a population, or group of 

populations, must be “discrete” from the remainder of the taxon to which it belongs; and 

“significant” to the taxon to which it belongs. Information on distribution, ecological situation, 

genetics, and other factors is used to evaluate a population’s discreteness and significance. 

Conducting an ESA status review therefore involves two key tasks: identifying the taxonomic 

units (species, subspecies or DPS) to be evaluated, and assessing the risk of extinction for each 

of these units.

Identification of Distinct Population Segments

Humpback whales are found in all oceans of the world with a broad geographical range from 

tropical to temperate waters in the Northern Hemisphere and from tropical to near-ice-edge 

waters in the Southern Hemisphere. Nearly all populations undertake seasonal migrations 

between their tropical and sub-tropical winter calving and breeding grounds1 and high-latitude 

summer feeding grounds. 

Humpback whales are currently considered to be a monotypic species, but whales from the 

Northern and Southern Hemispheres differ from each other substantially in a number of traits, 

including coloration, timing of reproduction and migratory behavior, diet, and molecular genetic 

characteristics. Within the Northern Hemisphere, populations from the Atlantic and Pacific also 

differ markedly in molecular genetic traits and coloration patterns, with no evidence of exchange 

of individuals between these ocean basins. In the Northern Indian Ocean, a population 

inhabiting the Arabian Sea is also markedly divergent in molecular and behavioral characteristics

from all other populations globally. Whales from these four areas (North Pacific, North Atlantic, 

Southern Hemisphere, and Arabian Sea) were so divergent that the BRT considered the 

possibility that they might reasonably be considered different sub-species, and enlisted the aid of 

the Committee on Taxonomy of the Society for Marine Mammalogy to help address this 

question. The committee concluded that if a taxonomic revision of humpback whales were to be 

undertaken, it is likely that the North Atlantic, North Pacific and Southern Hemisphere groups 

1 In this document, the term “breeding ground” refers to areas in tropical or subtropical waters where humpback 

whales migrate in winter to mate and give birth to calves. 

v

 
would be recognized as sub-species. The BRT therefore largely focused on the question of 

whether any DPS could be identified within each of these major ocean basins, although we also 

evaluated whether any DPS so identified would also be discrete and significant if evaluated with 

reference to the entire global species. 

Population structure in humpback whales has been previously evaluated both for breeding areas 

and feeding areas. In applying the discreteness and significance criteria, the BRT focused on 

breeding populations as the units that could be identified as DPSs, consistent with the language 

in the ESA that species (including DPS) “interbreed when mature.” Information on where a 

breeding population feeds, however, was considered in evaluating both the significance and 

discreteness of that population. 

The BRT evaluated genetic data, tagging and photographic-ID data, demographic information, 

geographic barriers, and stranding data, and determined that there are at least 15 DPS of 

humpback whales. Significant differences in patterns of genetic variation and information on the 

rates of exchange of individuals among breeding areas were particularly important for evaluating 

population discreteness, and patterns of geographic occurrence, differences in ecology among 

feeding and in some cases breeding areas, and degree of genetic differentiation were most 

important for determining significance. 

Based on this information, the BRT identified the following humpback whale distinct population 

segments, named after their primary breeding locations (Figure 1):

1. West Indies

2. Cape Verde Islands/Northwest Africa

3. Hawaii

4. Central America

5. Mexico

6. Okinawa/Philippines

7. Second West Pacific (exact location unknown)

8. West Australia

9. East Australia

10. Oceania

11. Southeastern Pacific

12. Brazil

13. Gabon/Southwest Africa

14. Southeast Africa/ Madagascar

15. Arabian Sea

vi
Figure 1. Approximate locations of breeding/wintering areas for the 15 DPSs. 

A brief description of each DPS is provided below. 

North Atlantic Distinct Population Segments

1. West Indies – The West Indies DPS consists of the humpback whales whose breeding range 

includes the Atlantic margin of the Antilles from Cuba to northern Venezuela, and whose 

feeding range primarily includes the Gulf of Maine, eastern Canada, and western Greenland. 

While many West Indies whales also use feeding grounds in the central (Iceland) and eastern 

(Norway) North Atlantic, many whales from these feeding areas appear to winter in another 

location. The West Indies DPS was determined to be discrete based upon genetic evidence and 

on a lack of evidence for exchange with the eastern Atlantic breeding population (or any other 

population) based on re-sighting data. This DPS was determined to be significant with respect to 

other North Atlantic DPS due to the significant gap in the breeding range that would occur if it 

went extinct. Loss of the West Indies population would result in the loss of humpback whales 

from all the Northwest Atlantic breeding (Caribbean/West Indies) and feeding grounds (United 

States, Canada, Greenland) and would also result in the loss of a significant portion of whales 

occupying feeding grounds in the Northeast Atlantic.

2. Cape Verde Islands plus Northwest Africa – This DPS consists of the humpback whales 

whose breeding range includes waters surrounding the Cape Verde Islands as well as an 

undetermined breeding area in the eastern tropical Atlantic which may be more geographically 

diffuse than the West Indies breeding ground. The population of whales breeding in Cape Verde 

Islands plus this unknown area likely represent the remnants of a historically larger population 

breeding around Cape Verde Islands and northwestern Africa (Reeves et al. 2002). There is no 

known overlap in breeding range with North Atlantic humpback whales that breed in the West 

Indies, although overlap occurs among feeding aggregations from different breeding populations. 

vii
The DPS was determined to be discrete based upon genetic evidence that suggests a second 

breeding ground occupied by whales that feed primarily off Norway and Iceland, as well as the 

gap that would exist in the breeding range if it became extinct. Loss of this unit would result in a 

loss of this unique breeding ground as well as a significant number of whales that feed in Iceland 

and Norway.

North Pacific Distinct Population Segments

3. Hawaii – The Hawaii DPS consists of humpback whales that breed within the main Hawaiian 

Islands. Whales from this breeding population have been observed in most known feeding 

grounds in the North Pacific, but about half of the whales from population migrate to Southeast 

Alaska and Northern British Columbia. They also commonly utilize northern British Columbia, 

northern Gulf of Alaska and Bering Sea feeding grounds. This DPS was determined to be 

discrete based on significant genetic differentiation from other North Pacific breeding areas and

evidence for low rates of movement among breeding areas in the North Pacific based on sighting 

data. The Hawaii DPS was determined to be significant due to the gap that would result in 

breeding and feeding ranges if it were to go extinct, ecological differences in feeding areas 

compared to other populations, and marked levels of genetic divergence to other populations. 

4. Central America – The Central American DPS is composed of whales that breed along the 

Pacific coast of Costa Rica, Panama, Guatemala, El Salvador, Honduras and Nicaragua. Whales 

from this breeding ground feed almost exclusively offshore of California and Oregon in the 

eastern Pacific, with only a few individuals identified at the northern Washington –southern 

British Columbia feeding grounds. This DPS was determined to be discrete based on re-sight 

data as well as findings of significant genetic differentiation between it and other populations in 

the North Pacific. The genetic composition of the DPS is also unique in that it shares 

mitochondrial DNA (mtDNA) haplotypes with some Southern Hemisphere DPSs, suggesting it 

may serve as a conduit for gene flow between the North Pacific and Southern Hemisphere. The 

breeding ground of this DPS occupies a unique ecological setting, and its primary feeding 

ground is in a different marine ecosystem from most other populations. Loss of this population

would also result in a significant gap in the range the species.

5. Mexico – The Mexican DPS consists of whales that breed along the Pacific coast of mainland 

Mexico, the Baja California Peninsula and the Revillagigedos Islands. The Mexican DPS feeds 

across a broad geographic range from California to the Aleutian Islands, with concentrations in 

California-Oregon, northern Washington – southern British Columbia, northern and western Gulf 

of Alaska and Bering Sea feeding grounds. This DPS was determined to be discrete based on 

significant genetic differentiation as well as evidence for low rates of movements among 

breeding areas in the North Pacific based on sighting data. It was determined to be significant 

due to the gap in breeding grounds that would occur if this DPS were to go extinct and the 

marked degree of genetic divergence to other populations. It also differs from some other North 

Pacific populations in the ecological characteristics of its feeding areas. 

6. Okinawa/Philippines – The Okinawa/Philippines DPS consists of the whales’ 

breeding/wintering in the area of Okinawa and the Philippines. Animals transiting the 

Ogasawara area are believed to be a mixture of whales from this DPS and the second West 

Pacific DPS (# 7, below). The Okinawa/Philippines DPS migrates to feeding grounds in the 

northern Pacific, primarily off the Russian coast. The population was determined to be discrete 

viii
based upon both significant genetic differentiation from other North Pacific populations and 

apparently limited exchange with other breeding populations in the North Pacific based on resighting data. The population was determined to be significant due to the gap in both the 

breeding and feeding ranges that would arise if the population were to go extinct, marked levels 

of genetic differentiation from other populations, and a primary feeding area that differs in its 

ecological characteristics from other populations. The relationship between this DPS and the 

Second West Pacific DPS is somewhat uncertain, however, due to the latter’s unknown breeding 

location. 

7. Second West Pacific DPS – The existence of this breeding population is inferred from 

sightings of whales in Aleutian Islands area feeding grounds that cannot be linked to any known 

breeding population and by the significant genetic differences that were found between 

Ogasawara and the Okinawa/Philippines DPS. Some of these whales may transit the Ogasawara 

area in route to unknown breeding grounds further south. This inferred breeding population was 

considered to be discrete based primarily upon the apparent low exchange with other breeding 

populations in the North Pacific. Its significance was hard to assess, but it appears to feed 

primarily in a marine ecosystem (the Aleutian Islands) that is rarely used by whales from other 

populations. Loss of this population was also considered likely to result in a gap in the range, 

based on a discrete feeding area and an unknown breeding area. 

Southern Hemisphere Distinct Population Segments

8. West Australia – The West Australia DPS consists of the whales whose breeding/wintering 

range includes the West Australia coast, primarily in the Kimberly Region. Individuals in this 

population migrate to feeding areas in the Antarctic, primarily between 80°E and 110°E based on 

tagging data. The population was considered discrete based upon lack of evidence for exchange 

with other breeding populations as well as significant genetic differentiation from other 

populations in the Southern Hemisphere. It was considered significant due to the gap in both the 

breeding and feeding range that would be created should the population go extinct. 

9. East Australia – The East Australia DPS consists of the whales’ breeding/wintering along the 

eastern and northeastern Australian coast. Based upon tagging, telemetry, and re-sighting data, 

individuals in this population migrate to Antarctic feeding areas ranging from 100°E to 180°E, 

but concentrated mostly between 120°E and 180°E. The population was considered discrete 

based upon its distribution and level of genetic differentiation from other populations. It was 

considered significant due to the gap in the range that would occur should the population go 

extinct. 

10. Oceania – The Oceania DPS consists of whales that breed/winter in the South Pacific Islands 

between ~160°E (west of New Caledonia) to ~120°W (east of French Polynesia), including 

American Samoa, the Cook Islands, Fiji, French Polynesia, Republic of Kiribati, Nauru, New 

Caledonia, Norfolk Island, New Zealand, Niue, the Independent State of Samoa, Solomon 

Islands, Tokelau, Kingdom of Tonga, Tuvalu, Vanuatu, Wallis and Futuna. Individuals in this 

population are believed to migrate to a largely undescribed Antarctic feeding area. The 

population was considered discrete based on its breeding distribution and level of genetic 

differentiation from other populations. It was considered significant based upon the gap in the 

range that would occur should the population go extinct. 

ix
11. Southeastern Pacific – The Southeastern Pacific DPS consists of whales that breed/winter 

along the Pacific coasts of Panama to northern Peru (9°N-6°S), with the main wintering areas 

concentrated in Colombia. Feeding grounds for this DPS are thought to be concentrated in the 

Chilean Magellan Straits and the western Antarctic Peninsula. These cross-equatorial breeders 

feed in the Southern Ocean during much of the austral summer. The population was considered 

discrete based on its breeding distribution and level of genetic differentiation from other 

populations. It was considered significant based on the gap in the range that would occur should 

it go extinct, the marked level of genetic divergence from other populations, and the unique 

ecological setting of its breeding area. 

12. Brazil – This DPS consists of whales that breed between 3°S and 23°S in the southwestern 

Atlantic along the coast of Brazil with a prominent concentration around the Abrolhos Bank 

(15°-18°S) and feed off South Georgia and the South Sandwich Islands. The population was 

considered discrete based on its breeding distribution and level of genetic differentiation from 

other populations. It was considered significant based upon the gap in range that would occur 

should the population go extinct and its feeding location in a distinct marine ecosystem. 

13. Southwest Africa – The Southwest Africa DPS consists of whales that breed and calve off 

central western Africa between ~6°S and ~6°N in the eastern Atlantic, including the coastal 

regions of northern Angola, Congo, Togo, Gabon, Benin, other coastal countries within the Gulf 

of Guinea and possibly further north. This DPS is thought to feed offshore of west South Africa 

and Namibia south of 18°S and in the Southern Ocean beneath west South Africa (20°W –

10°E). The population was considered discrete based on its breeding distribution, which is 

geographically separated from other breeding distributions, and level of genetic differentiation 

from other populations. It was considered significant based upon the gap in the range that would 

occur should the population go extinct.

14. Southeast Africa/ Madagascar– The Southeast Africa/ Madagascar DPS includes whales 

breeding in at least three different areas in the western Indian Ocean: one associated with 

mainland coastal waters of southeastern Africa, extending from Mozambique to as far north as 

Tanzania and southern Kenya, a second found in the coastal waters of the northern Mozambique 

Channel Islands and the southern Seychelles and the third found in the coastal waters of eastern 

Madagascar. The feeding grounds of this DPS in the Southern Ocean are not well defined but 

are believed to include multiple localities to the west and east of the region bounded by 5°W –

60°E. The population was considered discrete based on its breeding distribution, which is 

geographically separated other breeding grounds and level of genetic differentiation from other 

populations. It was considered significant based upon the gap in the range that would occur 

should the population go extinct.

Northern Indian Ocean Distinct Population Segments

15. Arabian Sea – The Arabian Sea DPS includes those whales that are currently known to breed 

and feed along the coast of Oman. However, historical records from the eastern Arabian Sea 

along the coasts of Pakistan and India indicate its range may also include these areas. The 

population was considered discrete based upon its unique breeding and feeding distribution 

which is geographically separated other breeding distributions, and level of genetic 

differentiation from other populations. It was considered significant based upon the gap in both 

x
the range that would occur should the population become extinct, its unique ecological setting, 

and marked degree of genetic differentiation from other populations. 

Threats Assessment and Evaluation of Extinction Risk

The BRT then assessed the extinction risk of each DPS. Assessment of extinction risk includes 

the evaluation of demographic information and threats experienced by each DPS. The BRT 

qualitatively assessed the severity, geographic scope, and level of certainty of potential 

individual threats to humpback whales, and assessed abundance and trend data (where available) 

for each DPS. Because the severity and scope of these threats may change through time, each 

threat was evaluated based on its current impact. 

Overall, no humpback whale DPSs are known to be declining, although seven DPSs do not have 

trend information available. Eight of the DPSs are thought to be increasing or stable. Twelve of 

the DPSs are estimated to number more than 2,000 total individuals (some much more). Three 

DPSs have an estimated abundance between 100 and 2,000 total individuals. There is much 

uncertainty about the population size of two DPSs, the Cape Verde Islands/Northwest Africa and

the Second Western Pacific. The Arabian Sea DPS is the only DPS likely to number fewer than 

100 individuals. 

In the North Atlantic Ocean, the threats of harmful algal blooms (HABs), vessel collisions, and 

fishing gear entanglements are likely to moderately reduce the population size or the growth rate 

of the West Indies DPS. All other threats, with the exception of climate change (uncertain

severity), are considered likely to have no or minor impact on population size or the growth rate 

of this DPS. For the Cape Verde Islands plus Northwest Africa DPS, the threats of HABs, 

disease, parasites, vessel collisions, fishing gear entanglements and climate change were 

identified but the effects remain uncertain. All other threats to this DPS are considered likely to 

have no or minor impact on the current population size or growth rate. The population of whales 

in this DPS likely represent the remnants of a historically larger population.

In the North Pacific Ocean, energy development, directed or incidental takes (bycatch), whaling, 

and competition with fisheries are each considered likely to moderately reduce the population 

size or the growth rate of the Okinawa/Philippines DPS. Vessel collisions are considered likely 

to moderately reduce the population size or the growth rate of the Central America and 

Okinawa/Philippines DPSs. Fishing gear entanglements are considered likely to moderately 

reduce the population size or the growth rate of the Hawaii, Central America, and Mexico DPSs 

and likely to seriously reduce the population size or growth rate of the Okinawa/Philippines 

DPS. In general, there is great uncertainty about the threats facing the Second West Pacific DPS. 

All other threats are considered likely to have no or minor impact on population size or the 

growth rate or are unknown.

In the Southern Hemisphere, all threats are considered likely to have no or minor impact on 

population size or the growth rate or are unknown, with the exception of energy exploration 

posing a moderate threat in western Australia and in various locations on the western coast of 

Africa (because of the substantial number of oil rigs and proposals for many more in these

regions) and fishing gear entanglements posing a moderate threat to the Colombia, Southeast 

Africa/ Madagascar, and Oceania DPSs. 

xi
The Arabian Sea DPS faces unique threats in part because these whales do not extensively 

migrate and therefore feed and breed in the same, relatively constrained, geographic location. 

Energy exploration and fishing gear entanglements are considered likely to seriously reduce the 

population’s size or growth rate, and disease, vessel collisions and climate change are likely to 

moderately reduce the population’s size or growth rate.

Considering the demographics of existing (or imminent) threats facing each DPS, the BRT 

evaluated the risk of extinction for each DPS. The BRT used a structured decision-making 

process to account for uncertainty in risk assessment. In this approach, each BRT member 

distributed 100 likelihood points among the defined scenarios or options, reflecting their opinion 

of the relative likelihood that the status of a specific DPS falls into each of three risk categories: 

high, moderate, and not at risk. For example, if a BRT member concluded that the available 

information indicated a very high certainty that a DPS was at high risk of extinction, that 

member would put all or most points into the “high risk” category. On the other hand, if a BRT 

member concluded that information was inconclusive, she or he might split his or her points into 

two or even all three categories. High risk of extinction was defined by the BRT as: a species or 

DPS that has productivity, spatial structure, genetic diversity, and/or a level of abundance that 

place its near term persistence in question. Moderate risk of extinction was defined by the BRT 

as: a species or DPS is at moderate risk of extinction if it exhibits characteristics indicating that it 

is likely to be at a “high risk of extinction” in the future. The third risk category was “not at risk 

of extinction”. The BRT decided to evaluate extinction risk over a time frame of the next 3 

generations (~60 years). 

Conclusions of the Status Review

The BRT conducted its analysis using the best available science and concluded:

• Nine DPSs are not at risk of extinction with high certainty (>80% of votes): the West 

Indies, Hawaii, Mexico, west Australia, east Australia, Colombia, Brazil, 

Gabon/Southwest Africa, and Southeast Africa/Madagascar;

• The Oceania DPS is not at risk of extinction with moderate certainty (68% of votes),

with some support for moderate risk of extinction (29% of votes); 

• Both the Okinawa/Philippines and Central America DPSs were most likely at moderate

risk of extinction (44% and 56% of votes, respectively), with some support for high risk

(36% and 28% of votes, respectively) and minor support for not at risk (21% and 16% of 

votes, respectively);

• The Arabian Sea DPS is at high risk of extinction (87% of votes); and

• There was considerable uncertainty regarding the risks of extinction of two of the DPSs 

due to a general lack of data: the Cape Verde Islands plus Northwest Africa and the 

Second West Pacific.

xii
TABLE OF CONTENTS

EXECUTIVE SUMMARY ............................................................................................................ v

LIST OF TABLES..................................................................................................................... xviii

LIST OF FIGURES ................................................................................................................... xviii

LIST OF ACRONYMS AND TERMS ....................................................................................... xix

I. INTRODUCTION.................................................................................................... 1

A. ESA Overview.......................................................................................................... 1

A.1 Purpose ..................................................................................................................... 1

A.2 Listing....................................................................................................................... 1

B. Scope and Intent of the Status Review..................................................................... 2

C. Key Questions in ESA Evaluations.......................................................................... 3

C.1 The “species” question ............................................................................................. 3

C.2 The “extinction risk” question.................................................................................. 3

C.3 Decision making process.......................................................................................... 4

II. The Species Question ............................................................................................... 5

A. Humpback whale life history and ecology............................................................... 6

A.1 Taxonomy................................................................................................................. 6

A.2 Physical Description................................................................................................. 7

A.3 Behavior ................................................................................................................... 7

A.4 Feeding ..................................................................................................................... 8

A.5 Reproduction ............................................................................................................ 9

A.6 Natural Mortality...................................................................................................... 9

B. Differentiation among ocean basins and sub-specific taxonomy........................... 10

C. North Atlantic Populations Overview .................................................................... 13

C.1 Distribution and Migratory Patterns....................................................................... 13

C.2 Patterns of genetic variation among the North Atlantic breeding areas................. 14

D. North Pacific Populations Overview...................................................................... 14

D.1 Distribution and Migratory Patterns....................................................................... 14

D.2 Patterns of genetic variation among the North Pacific breeding areas................... 15

E. Southern Hemisphere Populations Overview......................................................... 15

xiii
E.1 Distribution and Migratory Patterns....................................................................... 15

E.2 Patterns of genetic variation among the Southern Hemisphere breeding areas..... 18

F. Arabian Sea Population .......................................................................................... 18

F.1 Distribution and Migratory Patterns....................................................................... 18

F.2 Patterns of genetic variation between the Arabian Sea population and other 

populations ............................................................................................................. 19

G. Evaluation of Discreteness..................................................................................... 19

G.1 North Atlantic Ocean.............................................................................................. 20

G.2 North Pacific Ocean ............................................................................................... 22

G.3 Southern Hemisphere and Arabian Sea.................................................................. 24

H. Determining Significance....................................................................................... 26

H.1 Ecological setting ................................................................................................... 27

H.2 Gap in the range ..................................................................................................... 28

H.3 Genetic differentiation............................................................................................ 29

H.4 Descriptions of the identified humpback whale Distinct Population Segments .... 32

H.4.1 North Atlantic Distinct Population Segments..................................................... 33

H.4.2 North Pacific Distinct Population Segments....................................................... 34

H.4.3 Southern Hemisphere Distinct Population Segments.......................................... 36

III. Assessment of Extinction Risk............................................................................... 39

A. Overview of Threats Analysis................................................................................ 40

B. General Description of Threats .............................................................................. 40

B.1 Present or threatened destruction, modification, or curtailment of its habitat or 

range ....................................................................................................................... 40

B.2 Overutilization for commercial, recreational, scientific, or educational purposes. 43

B.3 Disease or predation ............................................................................................... 46

B.4 Adequacy of Existing Regulatory Mechanisms..................................................... 47

B.4.1 International agreements..................................................................................... 48

B.4.2 Domestic Regulatory Mechanisms...................................................................... 51

B.4.3 Regional or National Regulations other than United States................................ 55

B.5 Other natural or manmade factors affecting its continued existence ..................... 55

C. Overview of Assessment of Extinction Risk.......................................................... 63

xiv
C.1 Relationship between population size and trend and extinction risk ..................... 63

C.2 Applicability of Population Viability Analysis...................................................... 67

C.3 Evaluation of Extinction Risk ................................................................................ 67

C.4 Assessment of a significant portion of its range..................................................... 68

C.5 Humpback whale recovery plan ............................................................................. 69

D. Threats and Extinction Risk Analysis Results, by DPS ......................................... 70

D.1 West Indies............................................................................................................. 70

D.1.1 Abundance........................................................................................................... 70

D.1.2 Trends.................................................................................................................. 73

D.1.3 Threats Analysis.................................................................................................. 77

D.1.4 Extinction Risk.................................................................................................... 79

D.1.5 Significant portion of its range............................................................................ 80

D.2 Cape Verde Islands/Northwest Africa.................................................................... 80

D.2.1 Threats Analysis.................................................................................................. 80

D.2.2 Extinction Risk.................................................................................................... 81

D.2.3 Significant portion of its range............................................................................ 81

D.3 North Pacific DPSs................................................................................................. 82

D.3.1 Abundance........................................................................................................... 82

D.3.2 Trends.................................................................................................................. 82

D.4 Hawaii .................................................................................................................... 83

D.4.1 Threats Analysis.................................................................................................. 83

D.4.2 Extinction Risk.................................................................................................... 85

D.4.3 Significant portion of its range............................................................................ 86

D.5 Central America ..................................................................................................... 86

D.5.1 Threats Analysis.................................................................................................. 86

D.5.2 Extinction Risk.................................................................................................... 89

D.5.3 Significant portion of its range............................................................................ 89

D.6 Mexico.................................................................................................................... 89

D.6.1 Threats Analysis.................................................................................................. 90

D.6.2 Extinction Risk.................................................................................................... 92

D.6.3 Significant portion of its range............................................................................ 92

xv
D.7 Okinawa/Philippines DPS and Second West Pacific DPS..................................... 92

D.7.1 Threat Analysis ................................................................................................... 93

D.7.2 Extinction Risk.................................................................................................... 94

D.7.3 Significant portion of its range............................................................................ 95

D.8 West Australia ........................................................................................................ 95

D.8.1 Threats Analysis.................................................................................................. 95

D.8.2 Extinction Risk.................................................................................................... 96

D.8.3 Significant portion of its range............................................................................ 97

D.9 East Australia ......................................................................................................... 97

D.9.1 Threats Analysis.................................................................................................. 97

D.9.2 Extinction Risk.................................................................................................... 99

D.9.3 Significant portion of its range............................................................................ 99

D.10 Oceania................................................................................................................. 100

D.10.1 Threats Analysis................................................................................................ 100

D.10.2 Extinction Risk.................................................................................................. 102

D.10.3 Significant portion of its range.......................................................................... 102

D.11 Southeastern Pacific ............................................................................................. 102

D.11.1 Threats Analysis................................................................................................ 102

D.11.2 Extinction Risk.................................................................................................. 105

D.11.3 Significant portion of its range.......................................................................... 105

D.12 Brazil .................................................................................................................... 105

D.12.1 Threats Analysis................................................................................................ 105

D.12.2 Extinction Risk.................................................................................................. 108

D.12.3 Significant portion of its range.......................................................................... 109

D.13 Gabon/Southwest Africa ...................................................................................... 109

D.13.1 Threats Analysis................................................................................................ 109

D.13.2 Extinction Risk.................................................................................................. 111

D.13.3 Significant portion of its range.......................................................................... 111

D.14 Southeast Africa/ Madagascar.............................................................................. 111

D.14.1 Threats Analysis................................................................................................ 112

D.14.2 Extinction Risk.................................................................................................. 114

xvi
D.14.3 Significant portion of its range.......................................................................... 114

D.15 Arabian Sea .......................................................................................................... 114

D.15.1 Extinction Risk.................................................................................................. 117

D.15.2 Significant portion of its range.......................................................................... 117

IV. Summary of risk assessment ................................................................................ 119

A. Evaluation of Abundance and Trends.................................................................. 119

B. Evaluation of Threats ........................................................................................... 121

C. Summary of Extinction Risk Conclusions........................................................... 125

V. Literature Cited..................................................................................................... 126

Appendix A: Question posed to the ad-hoc committee on taxonomy within the Society for 

Marine Mammalogy............................................................................................. 157

Appendix B: List of national laws related to conservation of marine mammals....................... 161

Appendix C: Response to Peer Review Comments................................................................... 192

xvii
LIST OF TABLES

Table 1. Humpback Whale Subspecies Scenarios Voting........................................................... 12

Table 2. Major known humpback whale breeding areas by major ocean basin. ......................... 20

Table 3. North Atlantic Discreteness Scenarios Voting. ............................................................. 22

Table 4. Western North Pacific Discreteness Scenarios Voting.................................................. 23

Table 5. Large Marine Ecosystems inhabited by humpback whale populations......................... 27

Table 6. Summary of information used to evaluate the significance criteria of the DPS policy. 31

Table 7. Summary of abundance for each DPS. ........................................................................ 120

Table 8. Summary of what is known about the trends in abundance for each DPS. ................. 121

Table 9. Severity of current or imminent threats to humpback whales, by DPS....................... 123

Table 10. Summary of extinction risk assessments. .................................................................. 125

LIST OF FIGURES

Figure 1. Approximate locations of breeding/wintering areas for the 15 DPSs. ......................... vii

Figure 2. Frequency of major mtDNA clades among humpback whale populations.................. 13

Figure 3. Southern hemisphere humpback whale stock structure hypothesized by the IWC...... 25

Figure 4. Approximate breeding locations of humpback whale distinct population segments 

worldwide..................................................................................................................... 32

Figure 5. North Atlantic Ocean Distinct Population Segments. .................................................. 34

Figure 6. North Pacific Ocean Distinct Population Segments..................................................... 36

Figure 7. Southern Hemisphere and Arabian Sea Distinct Population Segments. ...................... 38

Figure 8. Revised trend analysis for NA humpback West Indies breeding population, based on 

feeding-breeding ground mark-recapture abundance estimates (Stevick et al. 2003; 

NMFS unpublished data).............................................................................................. 74

Figure 9. A comparison of the fit of a linear model and a simple logistic model to the abundance 

data from Figure 8. ....................................................................................................... 75

xviii
LIST OF ACRONYMS AND TERMS

The following are standard abbreviations for acronyms and terms found throughout this 

document:

ATBA Area to be Avoided

BRT Biological Review Team

CH Chlordane (insecticide)

CITES The Convention on International Trade in Endangered Species of Wild Fauna 

and Flora

CMS Convention on the Conservation of Migratory Species of Wild Animals or 

Bonn Convention

DDT Dichloro-diphenyl-trichloroethane

DOY Day of year

DPS Distinct population segment

ESA Endangered Species Act of 1973, as Amended

EU European Union

FEMAT Forest Ecosystem Management Assessment Team

FWS U.S. Fish and Wildlife Service

HAB Harmful algal bloom

HCH Hexachlorocyclohexane

IMO International Maritime Organization

IUCN International Union for the Conservation of Nature and Natural Resources or 

“the World Conservation Union”

IUU Illegal, unreported or unregulated

IWC International Whaling Commission

JARPA Japanese Whale Research Program under Special Permit in the Antarctic

JARPN Japanese Whale Research Program under Special Permit in the North Pacific

LFA Low-frequency active (sonar)

LNG Liquefied Natural Gas

The List List of Endangered and Threatened Wildlife and Plants

MARPOL International Convention for the Protection of Pollution from Ships

MMPA Marine Mammal Protection Act of 1972, as Amended

MONAH More of North Atlantic Humpbacks

MOU Memorandum of Understanding

MPA Marine protected area

mtDNA Mitochondrial deoxyribonucleic acid

nDNA Nuclear deoxyribonucleic acid

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric Administration

NWHI Northwest Hawaiian Islands

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

PAH Polycyclic aromatic hydrocarbons

PARS Port Access Route Study

PBDE Polybrominated diphenyl ether

xix
PCB Polychlorinated biphenyl

PSSA Particularly Sensitive Sea Areas

PVA Population viability analysis

SMM Society for Marine Mammalogy

SPLASH Structure of Populations, Levels of Abundance and Status of Humpback 

Whales in the North Pacific

TSS Traffic Separation Scheme

UME Unusual mortality event

USCG United States Coast Guard

WNP Western North Pacific

YONAH Years of North Atlantic Humpbacks

xx
I. INTRODUCTION

This review assesses the status of humpback whales (Megaptera novaeangliae), listed globally as 

an endangered species under the U.S. Endangered Species Act (ESA). The National Marine 

Fisheries Service (NMFS) recognized that significant new information was available since the 

original listing of humpback whales under the ESA, warranting an in-depth analysis of the 

species’ classification and status under the ESA. The agency convened a Biological Review 

Team (BRT) to conduct a comprehensive evaluation of humpback whales worldwide to 

determine 1) whether Distinct Population Segments (DPS) could be identified within this 

species’ global distribution, and 2) to evaluate the extinction risk of each identified DPS. This 

report describes the BRT’s deliberations and conclusions. A companion report (Fleming and 

Jackson 2011) summarizing the available information on the biology and threats facing

humpback whales globally was prepared for the BRT’s review, and provides more detailed 

information on these topics. 

A. ESA Overview

A.1 Purpose

The purpose of the Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.), is to 

provide a means to conserve the ecosystems upon which endangered species and threatened 

species depend, to provide a program for the conservation of endangered and threatened species, 

and to provide a means toward taking appropriate steps to recover endangered and threatened 

species. NMFS and U.S. Fish and Wildlife Service (FWS) jointly administer the ESA, and are 

responsible for determining whether species, subspecies, or distinct population segments of 

vertebrate species (DPS) are endangered or threatened. NMFS has jurisdiction over most species 

of marine mammals, including humpback whales. 

A.2 Listing

Humpback whales were listed as endangered in 1970 under the Endangered Species 

Conservation Act of 1969, the precursor to the ESA. When the ESA was enacted in 1973, 

humpback whales were included in the List of Endangered and Threatened Wildlife and Plants 

(the List) as endangered and were also considered as “depleted” under the Marine Mammal 

Protection Act (MMPA).

Under section 4(a) of the ESA and 50 CFR part 424 of NMFS’ listing regulations, NMFS makes 

determinations as to whether a marine mammal species should be listed as endangered or 

threatened, or whether it should be reclassified or removed from the List. Section 4(c)(2)(A) 

requires that NMFS conduct a review of listed species at least once every five years. On the 

basis of such reviews, under section 4(c)(2)(B) NMFS determines whether a particular species 

should be removed from the List (delisted), or reclassified from endangered to threatened, or 

from threatened to endangered. Accordingly, in 2010 NMFS began a comprehensive evaluation 

of the status of humpback whales, currently classified globally as an endangered species, as the 

basis for considering revisions to this species’ listing status. This report is intended to form the 

basis for that review. 

1
B. Scope and Intent of the Status Review

The purpose of this status review is to evaluate the extinction risk of the humpback whale. The 

ESA, as amended in 1978, defines a species to be “any subspecies of fish or wildlife or plants, 

and any distinct population segment of any species or vertebrate fish or wildlife which 

interbreeds when mature” (Section 3(16)). Therefore, this status review evaluates whether any 

subspecies or DPSs can be identified, and then evaluates the risk of extinction of each identified 

DPS. The report provides reviews and summaries of published and unpublished literature, 

reports, plans, and data, coupled with numerous communications and consultation with 

appropriate experts for obtaining updated information. NMFS formally announced initiation of a 

humpback whale Status Review on 12 August 2009 (74 FR 40568), and solicited new 

information concerning the status of humpback whales worldwide from the public, relevant 

governmental agencies, tribes, the scientific community, industry, environmental entities, and 

any other interested parties. NMFS requested information pertaining to species’ biology 

including population trends, distribution, abundance, demographics, and genetics; habitat 

conditions; conservation measures that have been implemented that benefit the species; status 

and trends of threats; and other new information, data, or corrections. 

In addition to soliciting new information from the public, NMFS contracted with two researchers 

to prepare a Background Report on humpback whale biology, population status, and threats. The 

researchers conducted numerous interviews and an extensive literature review, and the 

information they compiled is synthesized in a report (Fleming and Jackson (2011). The 

document underwent scientific peer review and was then made available for use in the Status 

Review. This Status Review report contains a summary of general information on humpback 

whale biology, population status, and threats, but we refer readers to the Background Report for 

a more thorough discussion of many of these topics. 

In May 2010, NMFS convened the Humpback Whale Biological Review Team (BRT), 

comprised of experts in the fields of humpback whale biology and ecology, conservation 

biology, taxonomy, population dynamics and modeling, and marine policy and management to 

conduct a comprehensive review of the status of humpback whales and develop a Humpback 

Whale Status Review Report (Status Review). The BRT’s charge was to: 

(a) Synthesize and analyze available information on the species; 

(b) Evaluate best available scientific information on population structure and analyze 

these data for potential identification of DPSs; 

(c) If DPSs are identified, analyze the status of each; and

(d) Review the five factors listed under Section 4(a)(1) of the ESA that describe the 

reasons for a species’ or DPS’ status and potential threats.

In April 2013, NMFS received a petition from the Hawai’i Fishermen’s Alliance for 

Conservation and Tradition to delineate a Distinct Population Segment of humpback whales in 

the North Pacific and to de-list this DPS under the ESA. In August 2013, NMFS issued its 90-

day finding in response to this petition and determined that the petitioned action may be 

warranted (78 FR 53391, August 29, 2013). A status review was initiated in response to the 

2
petition and that review was included under the BRT’s on-going global review of humpback 

whale status. On February 26, 2014, the State of Alaska submitted a petition to delineate the 

Central North Pacific stock of the humpback whale as a DPS and remove the DPS from the List 

of Endangered and Threatened Species under the ESA. NMFS issued its 90-day finding in 

response to this petition and determined that the petitioned action may be warranted (79 FR 

36281, June 26, 2014). Both petitioned actions were incorporated into this global status review.

This Status Review and the accompanying Background Report are a compilation of the best 

available scientific and commercial information on humpback whales and a description of threats 

to the species, as well as an evaluation of whether any populations meet the DPS Policy criteria 

and an analysis of extinction risk to any identified DPSs. It does not represent a decision by 

NMFS on whether this species, or any subdivision thereof, should be proposed for listing as 

threatened or endangered under the ESA or a change in status with regard to the List. That 

decision will be made by NMFS after reviewing this document, efforts being made to conserve 

the species, and relevant laws, regulations, and policies. The determinations in this regard will 

be posted on the NMFS Office of Protected Resources web site (http://www.nmfs.noaa.gov/pr) and 

published in the Federal Register. 

C. Key Questions in ESA Evaluations

Conducting an ESA status review involves two key tasks: delineating the taxonomic group(s) 

under consideration and assessing the risk of extinction for the identified taxonomic group(s) (or 

DPSs). Such a review may also consider the extent to which existing and emerging threats, 

while not necessarily posing an immediate extinction risk, may hamper the recovery of a species.

C.1 The “species” question

For the purpose of the ESA, a species is defined as “any subspecies of fish or wildlife or plants, 

and any distinct population segment of vertebrate fish or wildlife which interbreeds when 

mature” (16 U.S.C. 1532). As amended in 1978, the ESA allows listing of DPSs of vertebrates, 

as well as named species and subspecies. The BRT applied the joint U.S. NMFS-FWS “Policy 

Regarding the Recognition of Distinct Population Segments Under the Endangered Species Act” 

(61 FR 4722, 7 February 1996) to determine whether the globally-listed humpback whale could 

be delineated into DPSs. This analysis is described in detail in Chapter II of this Review. 

C.2 The “extinction risk” question

The term “endangered species” is defined in section 3 of the ESA as “any species which is in 

danger of extinction throughout all or a significant portion of its range.” A “threatened species” 

is “any species which is likely to become an endangered species within the foreseeable future 

throughout all or a significant portion of its range.”

The ESA directs that when evaluating a species’ extinction risk, a variety of information shall be 

considered, including the following factors (section 4(a)(1)(A)-(E)): 

A. The present or threatened destruction, modification, or curtailment of its habitat or 

range;

3
B. Overuse for commercial, recreational, scientific or educational purposes;

C. Disease or predation;

D. The inadequacy of existing regulatory mechanisms; or

E. Other natural or man-made factors affecting its continued existence.

The BRT assessed the extinction risk for each identified DPS based on a variety of factors, 

including abundance, trends in abundance, risks to diversity and spatial structure, and the risk 

factors A-E above. Based on this information, each DPS was placed in one of three extinction 

risk categories: high, moderate, or not at risk. This process and the conclusions of the BRT are 

described in Chapter III of this review. 

C.3 Decision making process

In reaching its conclusions, the BRT considered all available information, both qualitative and 

quantitative. To allow for expressions of the level of uncertainty in identifying DPSs or in 

assessing extinction risk, the BRT adopted a likelihood point method, often referred to as the 

FEMAT method, because it is a variation of a method used by scientific teams evaluating options 

under the Forest Plan (Forest Ecosystem Management: An Ecological, Economic, and Social 

Assessment Report of the Forest Ecosystem Management Assessment Team, or FEMAT) 

(FEMAT 1993). This method has been previously used in numerous ESA status reviews (e.g., 

Krahn et al. 2004b; Gustafson et al. 2006; Gustafson et al. 2010). In this approach, each BRT 

member distributes 10 “likelihood” points among a number of proposed options (e.g., DPS 

configurations or extinction risk categories), reflecting their opinion of how likely each option 

correctly reflects the true situation. 

4
II. The Species Question

The ESA, as amended in 1978, defines a species to be “any subspecies of fish or wildlife or 

plants, and any DPS of any species or vertebrate fish or wildlife which interbreeds when mature” 

(Section 3(16)). Guidance on what constitutes a DPS is provided by the joint NMFS-FWS 

interagency policy on vertebrate populations (61 FR 4722, 7 February 1996). To be considered 

“distinct”, a population, or group of populations, must be “discrete” from the remainder of the 

taxon to which it belongs; and “significant” to the taxon to which it belongs as a whole. 

Discreteness and significance are further defined by the Services in the following Policy 

language:

Discreteness: A population segment of a vertebrate species may be considered 

discrete if it satisfies either one of the following conditions:

1. It is markedly separated from other populations of the same taxon as a 

consequence of physical, physiological, ecological, or behavioral factors. 

Quantitative measures of genetic or morphological discontinuity may provide 

evidence of this separation.

2. It is delimited by international governmental boundaries within which 

differences in control of exploitation, management of habitat, conservation status, 

or regulatory mechanisms exist that are significant in light of section 4(a)(1)(D) of 

the [Endangered Species] Act.

Significance: If a population segment is considered discrete under one or more of 

the above conditions, its biological and ecological significance will then be 

considered in light of congressional guidance (see Senate Report 151, 96th 

Congress, 1st Session) that the authority to list DPSs be used “sparingly” while 

encouraging the conservation of genetic diversity. In carrying out this 

examination, the Services will consider available scientific evidence of the 

discrete population segment's importance to the taxon to which it belongs. This 

consideration may include, but is not limited to, the following:

1. Persistence of the discrete population segment in an ecological setting unusual 

or unique for the taxon,

2. Evidence that loss of the discrete population segment would result in a 

significant gap in the range of a taxon, 

3. Evidence that the discrete population segment represents the only surviving 

natural occurrence of a taxon that may be more abundant elsewhere as an 

introduced population outside its historic range, or 

4. Evidence that the discrete population segment differs markedly from other 

populations of the species in its genetic characteristics.

The joint policy states that international boundaries within the geographical range of the species 

may be used to delimit a discrete population segment in the United States. This criterion is 

applicable if differences in the control of exploitation of the species, the management of the 

5
species’ habitat, the conservation status of the species, or regulatory mechanisms differ between 

countries that would influence the conservation status of the population segment in the United 

States. However, as this report focuses on the biological status of the species, the BRT focused 

only on biological information in identifying humpback whale DPSs, understanding that factors 

associated with international boundaries could be considered elsewhere.

Most populations of humpback whales migrate seasonally between low latitude breeding areas 

and high latitude feeding areas. In applying the significance and discreteness criteria, the BRT 

focused on breeding populations as the units that could potentially be identified as DPSs, 

consistent with the language in the ESA that species “interbreed when mature.” The BRT was 

also interested in identifying demographically cohesive populations, and some feeding areas 

contain whales from multiple breeding populations. Information related to a population’s 

feeding area(s) was clearly important for evaluating the population’s ecological setting, however, 

which is an important factor for evaluating both discreteness and significance. Information on 

genetic differences among breeding populations, rates of observed intra- or inter-seasonal 

movement of individuals among breeding areas, and the physical locations of breeding areas 

were particularly useful for evaluating discreteness. Information on a population’s distribution 

and ecological setting, including both the breeding and feeding areas, along with the degree of 

genetic, behavioral or morphological differentiation from other populations, was important for 

evaluating significance. 

A. Humpback whale life history and ecology

Humpback whales (Megaptera novaeangliae; Borowski, 1781) are baleen whales of the family 

Balaenopteridae. They are found in all oceans. This chapter presents a general overview of the 

biology of the humpback whale species, excerpted largely from Fleming and Jackson (2011).

A.1 Taxonomy

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Cetacea

Family: Balaenopteridae

Genus: Megaptera

Species:Megaptera novaeangliae

Common name: Humpback whale

Historically, numerous subspecies of humpback whales have been named, although they are not 

widely recognized today and Megaptera novaeangliae remains the accepted taxonomic 

classification for the species. A thorough review of known taxonomic listings for humpback 

whales is presented in Clapham and Mead (1999) and Rice (1998). Recently, Jackson et al.

(2014) proposed that humpback whales in three major ocean basins (North Pacific, North 

Atlantic, and Southern hemisphere) be considered separate subspecies, a possibility discussed in 

more detail in section II B below. 

6
A.2 Physical Description

Humpback whales are large baleen whales with long pectoral flippers, distinct ventral fluke 

patterning, dark dorsal coloration, a highly varied acoustic call (termed ‘song’) and a diverse 

repertoire of surface behaviors. Their body coloration is primarily dark grey, but individuals 

have a variable amount of white on their pectoral fins, flukes, and belly. This variation is so 

distinctive that the pigmentation pattern on the undersides of their flukes is used to identify 

individual whales. Coloring of the ventral surface varies from white to marbled to fully black. 

Dorsal surfaces of humpback whale pectoral flippers are typically white in the North Atlantic 

and black in the North Pacific (Perrin et al. 2002), and are one-third of the total body length. 

Similar to all baleen whales, body lengths differ between the sexes, with adult females being 

approximately 1-1.5m longer than males. Humpback whales reach a maximum of 16-17 m, 

although lengths of 14-15 m are more typical. Adult body weights in excess of 40 tons make 

them one of the largest mammals on earth (Ohsumi 1966).

A.3 Behavior

Humpback whales are globally distributed and generally are highly migratory, spending spring, 

summer, and fall feeding in temperate or high-latitude areas of the North Atlantic, North Pacific 

and Southern Ocean and migrating to the tropics in winter to breed and calve. The Arabian Sea 

humpback whale population does not migrate extensively, remaining in tropical waters yearround (Baldwin 2000; Minton et al. 2010b).

Humpback whales travel great distances during migration, the farthest migration of any mammal. 

The longest recorded migration between a breeding and feeding area was 5,160 miles 

(8,300 km). This trek, from Costa Rica to Antarctica, was completed by seven individuals, 

including a calf (Rasmussen et al. 2007). One of the more closely studied routes has shown 

whales making the 3,000-mile (4,830 km) trip between Alaska and Hawaii in as little as 36 days

(Gabriele et al. 1996).

During summer and fall, humpback whales spend much of their time feeding and building fat 

stores for winter. In their low-latitude wintering grounds, humpback whales congregate and are 

believed to engage in mating and other social activities. Humpback whales are generally 

polygynous, with males exhibiting competitive behavior on wintering grounds (Tyack 1981; 

Baker and Herman 1984; Clapham 1996). A complex behavioral repertoire exhibited in these 

areas can include aggressive and antagonistic behavior, such as chasing, vocal and bubble 

displays, horizontal tail thrashing, and rear body thrashing. Males within these groups also make 

physical contact, striking or surfacing on top of one another. Also on wintering grounds, males 

sing complex songs that can last up to 20 minutes and may be heard up to 20 miles (30 km) away 

(Clapham and Mattila 1990; Cato 1991). A male may sing for hours, repeating the song 

numerous times. All males in a population sing the same song, but that song continually evolves 

over time (Darling and Sousa-Lima 2005). Humpback whale singing has been studied for 

decades, but its function remains uncertain.

Humpback whales are a favorite of whale watchers, as the species frequently performs aerial 

displays, including breaching, lobtailing, and flipper slapping, the purposes of which are not well 

understood. Diving behavior varies by season, with average lengths of dives ranging from <5 

7
minutes in summer to 10-15 minutes (and sometimes more than 30 minutes) in winter months 

(Clapham and Mead 1999). Typically, humpback whale groups are small (e.g., <10 individuals 

but can vary depending on social context and season), and associations between individuals do 

not last long, with the exception of the mother/calf pairs (Clapham and Mead 1999).

A.4 Feeding

Humpback whales have a diverse diet that slightly varies across feeding aggregation areas. The 

species is known to feed on both small schooling fish and on euphausiids (krill). Known prey 

organisms include species representing Clupea (herring), Scomber (mackerel), Ammodytes (sand 

lance), Sardinops (sardine), Engraulis (anchovy), Mallotus (capelin), and krills such as 

Euphausia, Thysanoessa, and Meganyctiphanes (Baker 1985; Geraci et al. 1989; Clapham et al.

1997). Humpback whales also exhibit flexible feeding strategies, sometimes foraging alone and 

sometimes cooperatively (Clapham 1993). During the winter, humpback whales subsist on 

stored fat and likely feed little or not at all. 

In the Northern Hemisphere, feeding behavior is varied and frequently features novel capture 

methods involving the creation of bubble structures to trap and corral fish; bubble nets, clouds, 

and curtains can be observed when humpback whales are feeding on schooling fish (Hain et al.

1982). Lobtailing and repeated underwater ‘looping’ movements (referred to as kick feeding) 

have also been observed during surface feeding events and it may be that certain feeding 

behaviors are spread through the population by cultural transmission (Weinrich et al. 1992; 

Friedlaender et al. 2006). On Stellwagen Bank, in the Gulf of Maine, repeated side rolls have 

been recorded when whales were near the bottom, which likely serves to startle prey out of the 

substrate for better foraging access (Friedlaender et al. 2009). In many locations, feeding in the 

water column can vary with time of day, with whales bottom feeding at night and surface feeding 

near dawn (Friedlaender et al. 2009). 

Humpback whales are ‘gulp’ or ‘lunge’ feeders, capturing large mouthfuls of prey during feeding 

rather than continuously filtering food, as may be observed in some other large baleen whales 

(Ingebrigtsen 1929). In the Southern Hemisphere, only one style of foraging (‘lunge’ feeding) 

has been reported. When lunge feeding, whales advance on prey with their mouths wide open, 

then close their mouths around the prey and trap them by forcing engulfed water out past the 

baleen plates. Southern Hemisphere humpback whales forage in the Antarctic circumpolar 

current, feeding almost exclusively on Antarctic krill (Euphausia superba) (Matthews 1937; 

Mackintosh 1965; Kawamura 1994). Stomach content analysis from hunted whales taken in subtropical waters and on migratory routes indicated that stomachs were nearly always empty 

(Chittleborough 1965). Infrequent sightings of feeding activity and stomach content data suggest 

that some individuals may feed opportunistically during the southward migration toward 

Antarctic waters (Matthews 1932; Dawbin 1956; Kawamura 1980).

In the Southern Ocean, Antarctic krill tend to be most highly concentrated around marginal sea 

ice zones, where they feed on sea ice algae. As a result, Southern Hemisphere humpback whale 

distribution is linked to regions of marginal sea ice (Friedlaender et al. 2006) and zones of high 

euphausiid density (Murase et al. 2002), with foraging mainly concentrated in the upper 100m of 

the water column (Dolphin 1987; Friedlaender et al. 2006). There is evidence of a positive 

relationship between prey density and humpback whale abundance (Friedlaender et al. 2006).

8
A.5 Reproduction

The mating system of humpback whales is generally thought to be male-dominance polygyny, 

also described as a ‘floating lek’(Clapham 1996). In this system, multiple males compete for 

individual females and exhibit competitive behavior. Humpback song is a long, complex 

vocalization (Payne and McVay 1971) produced by males on the winter breeding grounds, and 

also less commonly during migration (Clapham and Mattila 1990; Cato 1991) and on feeding 

grounds (Clark and Clapham 2004). The exact function has not been determined, but behavioral 

studies suggest that song is used to advertise for females, and/or to establish dominance among 

males (Tyack 1981; Darling and Bérubé 2001; Darling et al. 2006). It is widely believed that, 

while occasional mating may occur on feeding grounds or on migration, the great majority of 

mating and conceptions take place in winter breeding areas (Clapham 1996; Clark and Clapham 

2004). Breeding in the Northern and Southern Hemisphere populations is out of phase by 

approximately six months, corresponding to their respective winter periods.

Sexual maturity of humpback whales in the Northern Hemisphere occurs at approximately 5-11 

years of age, and appears to vary both within and among populations (Clapham 1992; Gabriele et 

al. 2007; Robbins 2007). Average age of sexual maturity in the Southern Hemisphere is 

estimated to be 9-11 years. In the Northern Hemisphere, calving intervals are between one and 

five years, though 2-3 years appears to be most common (Wiley and Clapham 1993; Steiger and 

Calambokidis 2000). Estimated mean calving rates are between 0.38 and 0.50 calves per mature 

female per year (Clapham and Mayo 1990; Straley et al. 1994; Steiger and Calambokidis 2000)

and reproduction is annually variable (Robbins 2007). In the Southern Hemisphere, most 

information on humpback population characteristics and life history was obtained during the 

whaling period. Post-partum ovulation is reasonably common (Chittleborough 1965) and interbirth intervals of a single year have occasionally been recorded. This may be a consequence of 

early calf mortality; the associated survival rates for annually born calves are unknown in the 

Southern Hemisphere.

Humpback whale gestation is 11-12 months and calves are born in tropical waters (Matthews 

1937). Lactation lasts from 10.5-11 months (Chittleborough 1965), and weaning begins to occur 

at about age six months and calves attain maternal independence around the end of their first 

year (Clapham and Mayo 1990). Humpback whales exhibit maternally directed fidelity to 

specific feeding regions (Martin et al. 1984; Baker et al. 1990).

The average generation time for humpback whales (the average age of all reproductively active 

females at carrying capacity) is estimated at 21.5 years (Taylor et al. 2007). Empirically 

estimated annual rates of population increase range from a low of 0 to 4% to a maximum of 

12.5% for different times and areas throughout the range (Baker et al. 1992; Barlow and 

Clapham 1997; Steiger and Calambokidis 2000; Clapham et al. 2003a); however, Zerbini et al.

(2010) recently concluded that any rate above 11.8% per year is biologically implausible for this 

species.

A.6 Natural Mortality

Annual adult mortality rates have been estimated to be 0.040 (SE = 0.008) (Barlow and Clapham 

1997) in the Gulf of Maine, and 0.037 (95% CI 0.022-0.056) (Mizroch et al. 2004) in the North 

9
Pacific Hawaiian Islands populations. In the Southern Hemisphere, estimates of annual adult 

survival rates have been made using photo-identification studies in Hervey Bay, east Australia 

(1987-2006) and range between 0.87 and 1.00 (Chaloupka et al. 1999).

Robbins (2007) estimated calf (0-1 year old) survival for humpback whales in the Gulf of Maine 

at 0.664 (95% CI: 0.517-0.784) which is low compared to other areas and annually variable. 

Barlow and Clapham (1997) estimated a theoretical calf mortality rate of 0.125 on the Gulf of 

Maine feeding ground. Using associations of calves with identified mothers on North Pacific 

breeding and feeding grounds, Gabriele (2001) estimated mortality of juveniles at 6 months of 

age to be 0.182 (95% CI: 0.023-0.518). Survival of calves (6-12 months) and juveniles (1-5 

years) has not been described in detail for the Southern Hemisphere. Killer whales are likely the 

most common natural predators of humpback whales.

B. Differentiation among ocean basins and sub-specific taxonomy

Humpback whales routinely make extensive migrations between breeding and feeding areas 

within an ocean basin. Despite this potential for long distance dispersal, there is considerable 

evidence that dispersal or interbreeding of individuals from different major ocean basins is 

extremely rare and that whales from the major ocean basins are differentiated in a number of 

characteristics that are summarized below. 

Reproductive Seasonality: Humpback whales breed and calf in July-November in the Southern 

Hemisphere and in Jan-May in the Northern Hemisphere (including the Arabian Sea). It is not 

known if reproductive seasonality in baleen whales is determined genetically or whether it 

results from a learned behavior (migration to a particular feeding destination) combined with a 

physiological response to day length. 

Behavior: The most obvious behavioral difference is that migrations to and from high latitudes 

are in opposite times of the calendar year for Southern Hemisphere and most Northern 

Hemisphere populations, following the difference in reproductive seasonality. A Northern 

Hemisphere exception to this migration pattern is found in the Arabian Sea where a nonmigratory population is found. Although these behavioral differences could be learned, they 

could also be innate, genetically determined traits. Seasonality in singing and other mating 

behaviors also follows the differences in reproductive seasonality.

Color patterns: Humpback whales in the Southern Hemisphere tend to have a much more white 

pigmentation on their bodies which is especially noticeable laterally (Matthews 1937; 

Chittleborough 1965). This has been noted in eastern and western Australia, the Coral Sea, and 

Oceania, but might not be characteristic of all Southern Hemisphere populations. Rosenbaum et 

al. (1995) ranked ventral fluke coloration patterns from one (nearly all white) to five (nearly all 

black) and compared whales from several breeding areas. He found that over 80% of humpback 

whales in eastern and western Australia were in Category 1, and that less than 10% of whales in 

three breeding areas in the North Pacific were ranked in that category. Only 36% of Southern 

Hemisphere whales in Colombia were classified in Category 1, but Colombian whales were still, 

on average, whiter than North Pacific whales. A higher frequency of pectoral fins with white 

dorsal pigmentations is found in the North Atlantic compared to the North Pacific (Clapham 

2009). 

10
Genetics: Baker and Medrano-Gonzalez (2002) reviewed the worldwide distribution of mtDNA 

haplotypes. They found three major clades with significant differences among major ocean 

basins (Figure 2), although there were no completely fixed differences among these areas. The 

North Pacific included only the AE and CD clades, the North Atlantic included only the CD and 

IJ clades, and the Southern Oceans included all three. In a more recent comparison, Jackson et 

al. (2014) found no shared haplotypes between the North Pacific and North Atlantic. Based on

patterns of mtDNA variation, Rosenbaum et al. (2009) estimated an average migration rate of 

less than one per generation between the Arabian Sea and neighboring populations in the 

southern Indian Ocean, and Jackson et al. (2014) also estimated generally <1 migrant per 

generation among the North Pacific, North Atlantic and Southern Hemisphere populations. 

Ruegg et al. (2013) also found a high degree of genetic differentiation between samples from the 

North Atlantic and the Southern Hemisphere. 

The BRT considered the possibility that humpback whales from different ocean basins might 

reasonably be considered to belong to different subspecies. Subspecific taxonomy has some 

potential relevance to the identification of DPSs, because under the 1996 DPS policy the 

discreteness and significance of a potential DPS is evaluated with reference to the taxon (species 

or subspecies) of which it is a part. In some cases previous BRTs concluded that subspecific 

taxonomy has a large influence on DPS structure (e.g. southern resident killer whales; Krahn et 

al. 2004b), while in others subspecific taxonomy has not been relevant (e.g. steelhead trout DPS 

– (Busby et al. 1996). 

Rice (1998) reviewed previous subspecies designations for humpback whales. Tomilin (1946)

named a Southern Hemisphere subspecies (M. n. lalandii) based on body length, but this length 

difference was not substantiated in subsequent studies. The populations around Australia and 

New Zealand were described as another subspecies (M. n. novazelandiae) based on color 

patterns and length (Ivashin 1958). Rice (1998) noted that the statistical ability to classify these

proposed subspecies is “not quite as high as is customarily required for division into subspecies” 

and that genetic analyses using restriction-fragment length polymorphisms is not congruent with 

the proposed regional division. Rice (1998) therefore recommended that Megaptera 

novaeangliae be considered monotypic. As was summarized above, however, since 1998

additional information has accumulated on the genetic distinctiveness of different geographic 

populations of humpback whales, and some new subspecies have been proposed (Jackson et al.

2014).

One criterion for separation of subspecies is the ability to differentiate 75% of individuals found 

in different geographic regions (Reeves et al. 2004b). Based on this criterion, differences in the 

calendar timing of mating and reproduction could be used to distinguish close to 100% of 

Northern Hemisphere from Southern Hemisphere individuals, but it is not known if this 

genetically determined. Based on mtDNA haplotypes that have been identified to date, 

haplotype could be used to distinguish 100% of North Pacific from North Atlantic individuals, 

but some haplotypes from both ocean basins are shared with the Southern Ocean. Ventral fluke 

color patterns can be used to correctly differentiate >80% of whales in eastern and western 

Australia from the whales in the North Pacific (Rosenbaum et al. 1995).

Given this uncertainty, the BRT asked the Committee on Taxonomy of the Society for Marine 

Mammalogy (SMM) to examine the evidence for the recognition of subspecies of humpback 

whale and to determine whether subspecies are likely to be recognized. Specifically, the 

11
following question was asked of the Committee: “Are humpback whales (Megaptera 

novaeangliae) that feed in the North Atlantic, North Pacific, Southern Oceans and Arabian Sea 

likely to belong to different sub-species?” A questionnaire (Appendix A) with related 

background information was provided to the chairman of the SMM Committee on Taxonomy

(Dr. William Perrin, SWFSC), and he distributed the questionnaire to the Committee (which also 

included two members of the humpback whale BRT)2. The Committee was asked only for their 

scientific opinion on the likelihood of the existence of humpback whale subspecies and was not 

asked to comment on the relevance of their opinion on the designation of DPSs for humpback 

whales. The responses from members of the Committee were summarized by their chairman:

"The balance of opinion in the SMM Committee on Taxonomy is that given the evidence 

on genetics, morphology, distribution and behavior, if a taxonomic revision of the 

humpback whale were undertaken, it is likely that the North Atlantic, North Pacific and 

Southern Hemisphere populations would be accorded subspecific status. Whether the 

Arabian Sea population would merit recognition as a subspecies separate from the 

Southern Hemisphere whales, with which it is most closely related genetically, is less 

certain. However, it is clearly geographically isolated and genetically differentiated."

Using its structured decision making process, the BRT evaluated the following question: Based 

on the discussions and collective knowledge of the BRT, the Background Report (Fleming and 

Jackson 2011), and the response from the SMM Committee on Taxonomy, is there enough 

scientific information to suggest that humpback whales from different major ocean basins could 

reasonably be considered different subspecies? BRT members were given 100 probability units, 

which they distributed into following three scenarios based on their assessment of the available 

information.

Table 1. Humpback Whale Subspecies Scenarios Voting.

Scenario Description Proportion of 

Votes

1. Single Species • Single global species 22%

2. Three subspecies

• North Atlantic

• North Pacific

• Southern Hemisphere (including Arabian Sea)

55%

3. Four subspecies

• North Atlantic

• North Pacific

• Southern Hemisphere

• Arabian Sea

23%

2 William F. Perrin, Chair (Southwest Fisheries Science Center, USA), C. Scott Baker (Oregon State University, 

USA), Annalisa Berta (San Diego State University, USA), J. Boness (University of Maine, USA), Robert L.

Brownell, Jr. (NOAA Fisheries, USA), Merel L. Dalebout (University of New South Wales, Australia), Daryl P. 

Domning (Howard University, USA), Rebecca M. Hamner (student member, Oregon State University, USA), 

Thomas A. Jefferson (NOAA Fisheries, USA), James G. Mead (National Museum of Natural History, USA 

(emeritus)), Dale W. Rice (National Marine Mammal Laboratory, USA (retired)), Patricia E. Rosel (Southeast 

Fisheries Science Center, USA), John Y. Wang (FormosaCetus Research and Conservation Group, Canada/Taiwan), 

Tadasu Yamada (National Museum of Nature and Science, Japan)

12

 
Overall, the three subspecies scenario had 55% support while both the single global species 

scenario and the four subspecies scenario had ~22% support. The BRT therefore felt reasonably 

certain (78% support) that the available information suggested that multiple subspecies of 

humpback whale could be identified3. 

Figure 2. Frequency of major mtDNA clades among humpback whale populations. 

Reproduced from Baker and Medrano-Gonzalez (Baker and Medrano-Gonzalez 2002). 

C. North Atlantic Populations Overview

C.1 Distribution and Migratory Patterns

In the Northern Hemisphere, humpback whales summer in the biologically productive, northern 

latitudes and travel south to warmer waters in winter to mate and calve. Migratory routes and 

migratory behavior are likely to be maternally directed (Martin et al. 1984; Baker et al. 1990). 

Feeding areas are often near or over the continental shelf, and are associated with cooler 

temperatures and oceanographic or topographic features that serve to aggregate prey (Moore et 

al. 2002; Zerbini et al. 2006b). 

Primary humpback whale feeding areas in the North Atlantic Ocean range from 42° to 78°N and 

include waters around Iceland, Norway and the Barents Sea in the central and eastern North 

3 In October 2014, subsequent to the Team’s deliberations, the SMM Committee on Taxonomy revised their official 

list of recognized species and subspecies to include three named subspecies of humpback whale: M. n. australis

(Lesson, 1828) − southern humpback whale, M. n. kuzira (Gray, 1850) − North Pacific Humpback whale, and M. n. 

novaeangliae (Borowski, 1781) − North Atlantic humpback whale.

13

 
Atlantic Ocean, and western Greenland, Newfoundland, Labrador, the Gulf of St Lawrence and 

the Gulf of Maine in the western North Atlantic Ocean. Known breeding areas occur in the West 

Indies and (to a much lesser extent) around the Cape Verde Islands (Katona and Beard 1990; 

Clapham 1993; Palsbøll et al. 1997). In contrast to humpbacks in the North Pacific, a relatively 

small proportion of whales in the North Atlantic Ocean feed in U.S. waters; in addition, the 

predominant breeding and calving area lies in the territorial sea of the Dominican Republic, 

although whales are also found scattered throughout the rest of the Antilles and coastal waters of 

Venezuela.

Recently, a few humpback whales have also been found in the Mediterranean Sea but little is 

known about humpback whale use of this region and there is no evidence for a large humpback 

whale presence there, either currently or in historical times (Frantzis et al. 2004). There are also 

sporadic sightings of humpback whales in a wide range of places including waters offshore from 

of the Southeast U.S. and mid-Atlantic States, in the Gulf of Mexico and in the waters around 

Ireland. Bermuda is a known mid-ocean stopover point for humpback whales on their 

northbound migration (Stone et al. 1987).

C.2 Patterns of genetic variation among the North Atlantic breeding areas

Genetic studies have identified 25 humpback whale haplotypes in the western North Atlantic, 12 

haplotypes in eastern North Atlantic samples, and 19 haplotypes in the Gulf of Maine population 

(Palsbøll et al. 1995; Larsen 1996; Rosenbaum et al. 2002). Humpback whales in the North 

Atlantic Ocean appear to have higher haplotype diversity than humpback whales in the North 

Pacific Ocean (Baker and Medrano-González 2002). Haplotype diversity is lowest in 

populations around Norway and Iceland and higher around the northwestern feeding areas off 

Greenland, Gulf of St. Lawrence and Gulf of Maine (Baker and Medrano-González 2002). 

Observed nucleotide diversity is also higher in the North Atlantic than the North Pacific (Baker 

and Medrano-González 2002).

There are no published studies of genetic variation between breeding areas in the western and 

eastern North Atlantic. Palsboll et al. (Palsbøll et al. 1995) and Valsecchi et al. (1997) found 

significant (FST= ~0.04) levels of mtDNA and nuclear genetic variation among North Atlantic 

feeding areas, however, suggesting the possibility that there may also be genetically distinct 

breeding areas. Photo-ID and genetic matching data suggest no evidence for substructure within 

the West Indies breeding population (reviewed by Fleming and Jackson 2011), so this 

differentiation likely is due to genetic divergence between the West Indies and a second North 

Atlantic breeding population likely associated with the Cape Verde Islands or other areas in the 

North Eastern Atlantic. 

D. North Pacific Populations Overview

D.1 Distribution and Migratory Patterns

Humpback whales in the North Pacific migrate seasonally from northern latitude feeding areas in 

summer to low-latitude breeding areas in winter. Feeding areas are dispersed across the Pacific 

Rim from California, USA to Hokkaido, Japan. Within these regions, humpback whales have 

14
been observed to spend the majority of their time feeding in coastal waters. Breeding areas in 

the North Pacific are more geographically separated than the feeding areas and include regions 

offshore of mainland Central America; mainland, Baja Peninsula and the Revillagigedos Islands, 

Mexico; Hawaii; and Asia including Ogasawara and Okinawa Islands and the Philippines. 

About half of the humpback whales in the North Pacific Ocean breed and calve in the U.S. 

waters off Hawaii; greater than half of North Pacific Ocean humpback whales feed in U.S. 

waters. 

Humpback whales in the North Pacific rarely move between these breeding regions. Strong 

fidelity to both feeding and breeding sites has been observed but movements between feeding 

and breeding areas are complex and varied (Calambokidis et al. 2008; Barlow et al. 2011). An 

overall pattern of migration has recently emerged. Asia and Mexico/Central America are the 

dominant breeding areas for humpback whales that migrate to feeding areas in lower latitudes 

and more coastal areas on each side of the Pacific Ocean, such as California and Russia. The 

Revillagigedo Archipelago and Hawaiian Islands are the primary winter migratory destinations 

for humpback whales that feed in the more central and higher latitude areas (Calambokidis et al.

2008). However, there are exceptions to this pattern and it seems that complex population 

structure and strong site fidelity coexist with lesser known, but potentially high, levels of 

plasticity in the movements of humpback whales (Salden et al. 1999).

D.2 Patterns of genetic variation among the North Pacific breeding areas

Baker et al. (2013) recently analyzed genetic variation in a large (n = 2,193) sample of whales 

from 8 breeding and 10 feeding regions within the North Pacific. The 8 possible breeding 

regions included the Philippines, Okinawa, Ogasawara, Hawaii, Revillagigedo, Baja California, 

the Mexican mainland coast, and Central America. Overall, the level of genetic divergence 

among breeding areas at the mtDNA control region was substantial (FST = 0.093). Pairwise 

estimates of divergence among breeding areas ranged from none (FST = ~0.000; Philippines vs 

Okinawa) to very high (FST>0.2 for Hawaii vs Okinawa and Philippines, and Hawaii vs Central 

America). In addition to little divergence between Okinawa and the Philippines, the three 

Mexican areas (mainland coast, Baja California, and Revillagigedos Islands) were also not 

significantly differentiated. The breeding areas were less strongly (but still significantly) 

differentiated at 10 nuclear microsatellite loci (FST = 0.006), suggesting the possibility of male 

mediated gene flow among breeding areas.

E. Southern Hemisphere Populations Overview

Current Southern hemisphere humpback whale population abundance based on circumpolar 

surveys of the Antarctic is estimated to be over 50,000 (Branch 2007) with at least twelve 

breeding grounds identified at temperate latitudes: Brazil, Gabon and central West Africa, 

Mozambique, the Comoros Archipelago, Madagascar, the Arabian Sea, West Australia, East 

Australia, New Caledonia, Tonga, French Polynesia, and the southeastern Pacific (Stevick et al.

2006; Zerbini et al. 2006b; Engel and Martin 2009; IWC 2011).

E.1 Distribution and Migratory Patterns

15
Southwestern Atlantic Ocean (Brazil)

The primary mating/calving ground of humpback whales in the western South Atlantic Ocean is 

the coast of Brazil. Whales are regularly found over the continental shelf (up to about 500m in 

depth) from 5-24oS between April and December with peaks in August and September (Martins

et al. 2001; Zerbini et al. 2004; Rossi-Santos et al. 2008; Andriolo et al. 2010). Occasional 

sightings have been made in coastal waters north of 5oS and south of 24oS as well as in various 

oceanic islands (e.g. near the Fernando de Noronha, São Pedro and São Paulo and TrindadeMartinz Vaz Archipelagos, Pretto et al. 2009), but it is not yet clear whether these regions 

correspond to the typical range of the species. This population migrates to feeding grounds 

located east of the Scotia Sea near South Georgia and the South Sandwich Archipelagos (Stevick

et al. 2006; Zerbini et al. 2006b; Engel et al. 2008; Engel and Martin 2009; Zerbini et al. 2011).

The winter breeding distribution of humpback whales in the southwestern Atlantic (June to 

December) is concentrated around the Abrolhos Bank region in Brazil (15-18°S) and 500 km 

north, along the north coast of Bahia State and Espirito Santo State (Rossi-Santos et al. 2008)

and near Salvador and Recife. In a line transect survey of the coastal waters between 5° and 

12°S, the majority of humpback whales (>90%) were found to be concentrated within 300m of 

the shoreline, with all whales distributed within 800m of the shore (Zerbini et al. 2004). 

Humpback whales migrate seasonally past coastal waters off the South American coast, the 

majority travelling offshore towards feeding grounds between 20° and 25°S (Andriolo et al.

2006; Zerbini et al. 2006c), via a narrow (∼600km wide) migratory corridor (Zerbini et al.

2006c). Satellite telemetry, photo-identification and genetic studies indicate that most whales 

frequent offshore summer feeding grounds in the South Atlantic, near South Georgia and the 

South Sandwich Islands (Stevick et al. 2006; Zerbini et al. 2006b; Engel and Martin 2009).

Southeastern and Central eastern Atlantic (Gabon)

A humpback whale winter breeding and calving ground is located off central western Africa 

between ~6°S and ~6°N in the eastern Atlantic. This includes the coastal regions of northern 

Angola (Best et al. 1999; Weir 2007), Congo, Togo, Gabon (Walsh et al. 2000; Rosenbaum and 

Collins 2006), Benin (Van Waerebeek 2003), offshore islands (Príncipe and São Tomé, Carvalho

et al. 2011), Pagalu (Aguilar 1985) and other coastal countries within the Gulf of Guinea

(Rosenbaum and Mate 2006), with a northerly extent that includes occasional sightings and 

strandings off the coast of Ghana (Van Waerebeek et al. 2009). Periods of peak abundance are 

found between July and September, with some whales still present as late as December and 

January in Angola, Gabon and São Tomé (Weir 2007). Ongoing investigations are studying 

migratory patterns to summer feeding grounds (Rosenbaum and Mate 2006; Zerbini et al. 2011). 

The Gabon/Southwest Africa region appears to serve a variety of purposes with some individual 

whales remaining in the area through the year while some utilize the area for feeding and others 

for mating.

Southwestern Indian Ocean (Madagascar, Comoros Archipelago, Mozambique)

At least three winter breeding aggregations of humpback whales have been suggested in the 

southwestern Indian Ocean from historical whaling records and contemporary surveys (Wray 

and Martin 1983; Best et al. 1998). One is associated with the mainland coastal waters of 

southeastern Africa, extending from Mozambique (24°S, Findlay et al. 1994), to as far north as 

Tanzania and southern Kenya (Wamukoya et al. 1996; Berggren et al. 2001; O'Connor et al.

2009). The second is found in the coastal waters of the northern Mozambique Channel Islands 

16
(Comoros Archipelago) (Ersts et al. 2006; Kiszka et al. 2007; Kiszka et al. 2010) and the 

southern Seychelles (Reeves et al. 1991; Hermans and Pistorius 2008). The third is associated 

with the coastal waters of Madagascar (15-25°S), best described in Antongil Bay on the east 

coast (Rosenbaum et al. 1997).

At least three migratory pathways to Antarctic summer feeding grounds in this region have been 

proposed using a compilation of data from surveys, whaling and acoustic records and sightings 

(Best et al. 1998). The first pathway (and the one for which the greatest evidence is available) 

occurs off the coast of east South Africa, where humpback whales arrive at the coast from 

Knysna (33°S 23°E, April onwards) during the northward migration and depart the coast at a 

similar longitude on the southward migration through December. Other potential migratory 

paths have been suggested in the central Mozambique Channel and offshore along the 

Madagascar Ridge (which runs between Madagascar and ~40°S). The Madagascar Ridge has 

been identified as a potential migratory route based on whaling and sightings data from Walter’s 

Shoal, a location on the Madagascar Ridge, south of Madagascar (Best et al. 1998). The 

Mozambique Channel route was proposed based on acoustic surveys in 1994, which recorded a 

few singing whales in the center of the channel. That the same surveys did not detect singers

away from the middle of the channel might suggest (on rather weak evidence) that the Channel is 

not commonly bisected but instead serves primarily as a thoroughfare for whales on the east 

African migratory route (Best et al. 1998). The migratory path for whales wintering in La 

Réunion and Mauritius has not yet been identified. 

Southeastern Indian Ocean (West Australia)

Humpback whale wintering grounds and coastal migratory routes in the eastern Indian Ocean are 

located between 15-35°S along the west coast of Australia, with major calving grounds occurring 

in the Kimberley Region (15-18°S) and resting areas on the southern migration at Exmouth Gulf 

(21°S) and at Shark Bay (25°S) (Bannister and Hedley 2001; Jenner et al. 2001). 

During the southward migration to their Antarctic feeding grounds, whales are found close to 

shore along much of the coast, mostly occurring within the 200m isobath. During the northward 

migration, whales tend to be distributed farther from shore, out to the continental shelf boundary 

(Jenner et al. 2001; Jenner et al. 2006), with whales observed as far out as the 1400m isobath in 

some places e.g. Northwest Cape (Jenner et al. 2006).

Southwestern Pacific (East Australia)

Humpback whales along the east coast of Australia are thought to breed primarily in waters 

inside the Great Barrier Reef (16-21°S) (Chittleborough 1965; Simmons and Marsh 1986) and 

are seen as far north as Murray Island at ~10°S (Simmons and Marsh 1986). Northward 

migration of humpbacks to the breeding ground occurs (i) along the Australian mainland coast 

(and sometimes eastwards through Bass Strait, Paterson 1991), (ii) through New Zealand’s Cook 

Strait, and (iii) past Foveaux Strait off the New Zealand southwest coast (Dawbin 1964; Franklin

et al. 2011), as suggested by photo-identification studies and Discovery- mark returns. 

Discovery marks and satellite telemetry suggest east Australian whales feed in a broad swath of 

the Antarctic between 100°E-175°W, or that they frequent at least two feeding regions, one due 

south of eastern Australia stretching to the east beneath New Zealand, and one south of west 

Australia at ~100°E and accessed via migration through Bass Strait.

17
Oceania

The longitudinal distribution boundaries of humpback whales wintering in Oceania lie between 

~160°E (west of New Caledonia) and ~120°W (east of French Polynesia) and latitudinally 

between 0° and 30°S (Reeves et al. 1999), a range that includes American Samoa (United States 

of America), the Cook Islands, Fiji, French Polynesia (France), Republic of Kiribati, Nauru, New 

Caledonia (France), Norfolk Island, New Zealand, Niue, the Independent State of Samoa, 

Solomon Islands, Tokelau, Kingdom of Tonga, Tuvalu, Vanuatu, Wallis and Futuna (France). 

Southeastern Pacific (Colombia, Panama, Ecuador)

The wintertime breeding distribution of humpback whales in the southeastern Pacific (May to 

November) includes the coastal waters between Panama and northern Peru, with the main 

wintering areas concentrated in Colombia (Gorgona Island, Málaga Bay and Tribugá Gulf), 

Panama and Ecuador. Low densities of whales are also found around the Galápagos Islands 

(Félix et al. 2006b) and coastal sightings have been made as far north as Costa Rica (Coco Island 

and Golfo Dulce, 8°N) (Acevedo and Smultea 1995; May-Collado et al. 2005). In the summer 

months, these whales migrate to feeding grounds located in waters off of southern Chile, the 

Magellan Strait, and the Antarctic Peninsula (May-Collado et al. 2005; Félix et al. 2006b; 

Acevedo et al. 2008).

E.2 Patterns of genetic variation among the Southern Hemisphere breeding areas

Olavarría et al. (2007) analyzed patterns of mtDNA control region variation obtained from 1,112 

samples from 6 breeding grounds in the South Pacific: New Caledonia, Tonga, Cook Islands, 

eastern Polynesia, Colombia, and Western Australia. Of these areas, the samples from Colombia 

were most differentiated (FST = 0.06 – 0.08 in pairwise comparison to other areas). Pairwise 

divergence among the other areas was lower (FST = 0.01 – 0.05). All pairwise comparisons were 

statistically >0, however, and indicated a lack of free exchange among these breeding areas. 

Levels of haplotype diversity were generally very high (0.90 – 0.97). Rosenbaum et al. (2009)

conducted a similar study of breeding areas in the Southern Atlantic and Western Indian Oceans, 

including the coastal areas of Brazil, Southwestern Africa, and Southeastern Africa. Levels of 

differentiation among these are statistically significant but relatively low, with FST ranging from 

0.003 (among two Southwestern African locations) to 0.017 (between Brazil and Southeastern 

Africa). Although there was some detectable differentiation among samples from Southwestern 

and Southeastern African coastal locations (B1/B2 and C1/C2/C3 IWC stocks, respectively), the 

levels of divergence within these areas were very low (FST = 0.003-0.009 within the “B” stock 

and 0.002-0.005 within the “C” stock). The estimated number of migrants per generation was 26 

between Brazil and Southwestern Africa, and 33 between Southwestern and Southeastern Africa. 

F. Arabian Sea Population

F.1 Distribution and Migratory Patterns

Sightings and survey data suggest that humpback whales in the Arabian Sea are primarily 

concentrated in the shallow near-shore areas off the coast of Oman, particularly in the Gulf of 

Masirah and Kuria Muria Islands regions (Minton 2004); sightings and strandings suggest a 

population range that encompasses the northern Gulf of Aden, the Balochistan coast of Pakistan, 

18
and western India and Sri Lanka, with occasional sightings on the Sistan and Baluchistan coasts 

of Iran, and also Iraq (Al Robaae 1974; Braulik et al. 2010). Photo-identification re-sightings 

suggest humpback whales move seasonally between the Dhofar region (Kuria Muria Islands) in 

winter and the Gulf of Masirah to the north in summer, with similar re-sighting rates between 

and within regions (Minton et al. 2010b).

Despite extensive comparisons of photo-identification catalogues and genotyped individuals 

between Oman and the other Indian Ocean catalogues and genetic datasets, no matches have 

been detected between regions (Pomilla et al. 2006; Minton et al. 2010a). Humpback whales 

from this region carry fewer and smaller barnacles than Southern Hemisphere whales, and do not 

exhibit the white oval scars indicative of cookie cutter shark (Isistius brasiliensis) bites, a feature 

commonly seen on some Southern Hemisphere humpback whales (Mikhalev 1997). 

Connections with the Northern Hemisphere populations are highly unlikely as there is no 

accessible northward passage from the Arabian Sea. Furthermore, there are no mitochondrial 

haplotypes or song patterns shared with North Pacific humpback whales (Whitehead 1985; 

Rosenbaum et al. 2009); thus, on current evidence, and in the absence of comparisons with far 

western North Pacific humpbacks, it appears that whales from these populations have no recent 

biological connectivity. Analysis of fetal lengths in pregnant females killed by Soviet whalers 

clearly indicate that this population exhibits a Northern Hemisphere reproductive cycle, with 

births occurring in the boreal winter (Mikhalev 1997).

F.2 Patterns of genetic variation between the Arabian Sea population and other populations

Nuclear and mitochondrial genetic diversity of humpback whales from Oman (up to 47 

individuals sampled) is the lowest among all breeding grounds (Pomilla et al. 2006; Olavarría et 

al. 2007; Rosenbaum et al. 2009). Mitochondrial DNA analysis revealed only eight distinct 

haplotypes, half of which are exclusive to Oman (not detected on other breeding grounds, 

Pomilla et al. 2006). Haplotype diversity at the mtDNA control region is markedly lower than in 

other populations (0.69 vs 0.90-0.98 for Southern Hemisphere populations and 0.84 for North 

Pacific populations (Olavarría et al. 2007; Rosenbaum et al. 2009; Baker et al. 2013). 

Genetic data (nuclear microsatellites and mitochondrial control region) and fluke pigmentation 

markings indicate that this breeding population is significantly differentiated from Southern 

Indian Ocean breeding grounds (Rosenbaum et al. 2009). Nuclear genetic analysis suggests that 

this population is the most strongly and significantly differentiated in all comparisons among 

other Indian Ocean and South Atlantic breeding populations (pair-wise FST range between Oman 

and Southern Indian Ocean breeding populations = 0.38-0.48; (Pomilla et al. 2006). Levels of 

mitochondrial differentiation between Oman and other Indian Ocean breeding grounds are 

around ten times higher than among the other breeding grounds (pair-wise FST range between 

Oman and other Indian Ocean breeding populations 0.11-0.15; (Rosenbaum et al. 2009).

G. Evaluation of Discreteness

The BRT initially evaluated the discreteness of known major humpback whale breeding 

populations (Table 2). Quantitative measures of genetic differentiation; direct estimates of 

dispersal among breeding populations from tagging, photo-identification, or genetic recapture; 

19
and geographic discontinuities in distribution were used as the primary information sources for 

determining population discreteness. This information is summarized in the previous sections of 

this report and is reviewed in greater detail by Fleming and Jackson (2011). The BRT concluded 

that populations from different ocean basins were clearly distinct on the basis of geographic 

isolation, substantial levels of genetic divergence, coloration differences between northern and 

Southern Hemisphere populations, behavioral differences in migration and breeding timing, and 

lack of observed dispersal (see Chapter II B). The discussion below therefore focuses largely on 

the information related to the existence of discrete populations within major ocean basins. 

Table 2. Major known humpback whale breeding areas by major ocean basin.

Ocean Basin Major known breeding area

North Atlantic West Indies, along the Atlantic margins of the 

Antilles from Cuba to Northern Venezuela

Cape Verde Islands

North Pacific Hawaii Islands

West coast of Central America

West coast of Mexico

Revillagigedos Islands

Baja California

Okinawa

Philippines

Ogasawara

Southern Hemisphere Western Australian coastal areas

Eastern Australia coastal area

Oceania, from New Caledonia to French 

Polynesia

Coastal areas of Colombia, Panama and 

Ecuador

Coastal areas of Brazil

Southwest African coastal areas

Southeast African coastal areas, including the 

Comoros and the Seychelles and Madagascar

Arabian Sea Oman coastal areas

G.1 North Atlantic Ocean

There is one very well studied breeding ground in the North Atlantic Ocean: the West Indies. 

Most of the humpback whales on the western North Atlantic feeding grounds (Gulf of Maine, 

Gulf of St Lawrence, West Greenland, and eastern Canada) go to the West Indies to breed 

(approximately 90%; (Clapham et al. 1993; Mattila et al. 2001). Some of the Iceland and 

Norway feeding ground whales also go to the West Indies, but genetic evidence suggests that 

most whales that feed off Iceland and Norway migrate to some other breeding ground possibly in 

the eastern tropical Atlantic (Clapham et al. 1993). However, the location of the northeastern 

20
Atlantic breeding ground is still not well understood. The only candidate from historical whaling 

records is the Cape Verde Islands, but current studies show only a small number of whales there 

(far fewer than are known to exist in the northeastern Atlantic) and sighting histories of these 

whales link them to waters off Iceland or Norway (Katona and Beard 1990; Jann et al. 2003). 

The Cape Verde Islands may be part of a larger breeding area or there may be a third separate 

breeding area that is as yet undiscovered (Charif et al. 2001; Reeves et al. 2002). There is a 

significant degree of heterogeneity in nuclear DNA between the western, central (Iceland) and 

eastern (Norway) North Atlantic feeding grounds further supporting the possibility of a third 

breeding area (Larsen 1996). 

The BRT decided upon four plausible discreteness scenarios among which they would vote: 

1. One unit

2. Two units: West Indies and Cape Verde Islands

3. Two units: West Indies and Cape Verde Islands plus an associated breeding area

4. Three units: West Indies and Cape Verde Islands and another unknown breeding area

The group evaluated the proposed scenarios, distributing 100 points across the range of four 

scenarios to reflect their levels of confidence in each option. After initial votes were cast and 

shared with the group, a discussion of the results followed and some members modified their 

votes. Final voting results showed approximately 70% support for two distinct populations 

based on a two breeding area scenario and 27% support for three distinct populations (Table 3). 

The BRT noted that the distinction between scenarios 2 and 3 was relatively unimportant (in that 

they both designate 2 discrete populations), and it is clear that gaining a better understanding of 

where the whales that do not go to the West Indies are migrating is a major priority. Scenario 3 

was viewed as the most likely scenario, and the BRT concluded that two populations of 

humpback whales in the North Atlantic Ocean meet the established criteria for being discrete 

under the DPS policy guidelines: West Indies and Cape Verde Islands plus another associated 

breeding area off northwest Africa. 

The BRT concluded that the humpback whales found breeding around the Cape Verdes Islands, 

which include at least some of the whales that feed in the eastern and perhaps central North 

Atlantic, constitute a discrete population from humpback whales that breed in the West Indies. 

In particular, the West Indies and Cape Verde Islands are separate breeding grounds based on: 1) 

no photographic matches between individuals using the West Indies and Cape Verde Islands 

areas (acknowledging that there is a large discrepancy in sample size between the two areas), 2) 

occupation of both breeding grounds at the same time, 3) evidence from 19th century whaling 

data of a historically larger population at the Cape Verde Islands than exists today, and 4) 

evidence from genetic heterogeneity that the West Indies is not the only breeding ground. In 

addition, the Cape Verde Islands cannot account for the abundance of whales estimated from the 

eastern North Atlantic feeding grounds that are apparently not using the West Indies, so there 

must be an additional breeding area somewhere, likely near Northwest Africa.

21
Table 3. North Atlantic Discreteness Scenarios Voting.

Scenario Description Proportion of 

Votes

1. One unit All of North Atlantic Ocean 2%

2. Two discrete units West Indies 

Cape Verde Islands 18%

3. Two discrete units

West Indies 

Cape Verde Islands plus other associated 

breeding area

53%

4. Three discrete units

West Indies

Cape Verde Islands

Unknown breeding area

27%

G.2 North Pacific Ocean

North Pacific humpback whales are known to aggregate in at least eight geographically separate 

areas during their breeding season: Central America; mainland Mexico; Baja California, 

Mexico; the Revillagigedos Archipelago, Mexico; the Hawaiian Islands, USA; Ogasawara 

Islands, Japan; Okinawa Islands, Japan; and the northern Philippine Islands. In addition, results 

from the Structure of Populations, Levels of Abundance and Status of Humpback Whales in the 

North Pacific (SPLASH) study (Calambokidis et al. 2008) indicate the existence of at least one 

additional breeding area whose location has not been identified. 

Two of these nine areas were identified as likely migratory routes to other locations and might 

therefore not be primary migratory destinations: the waters off Baja California and the 

Ogasawara Islands. Available genetic and demographic studies indicate that humpback whales 

migrating to mainland Mexico and to the Revillagigedos Islands pass by the tip of Baja 

California. The BRT therefore concluded that humpback whales off Baja California should not 

be considered a discrete population. Similarly, some humpback whales migrating to the 

Okinawa Islands pass by the Ogasawara Islands, and the Ogasawara Islands are thought likely to 

be along the migration route to the yet-unidentified breeding area that was described by the 

SPLASH program. The BRT was not certain, however, on how to classify the Ogasawara area 

and therefore used the structured decision making process to evaluate relative certainty of 

whether whales in this area formed a discrete population (see below).

In the eastern North Pacific, humpback whales in Central America have a unique mtDNA 

signature, as reflected in the frequencies of haplotypes (Baker et al. 2008a; Baker et al. 2008b). 

This frequency composition is significantly different from that found in all other breeding 

grounds in the North Pacific. The BRT concluded that humpback whales in Central America are 

a discrete population. In Mexico, the mainland population does not differ significantly from the 

Revillagigedos population in its mtDNA haplotype frequencies (Baker et al. 2013). Photoidentification studies also indicate considerable movement of individuals between mainland and 

offshore island breeding areas in Mexico (Calambokidis et al. 2008). The BRT also therefore 

concluded that mainland Mexico and the Revillagigedos populations are not discrete from each 

other but considered together as a single Mexico population are discrete from all other 

22
populations. The Hawaii population of humpback whales is separated by the greatest geographic 

distance from neighboring populations and was significantly different from other populations in 

both frequencies of mtDNA haplotypes and nDNA (microsatellite) alleles (Baker et al. 2013). 

The BRT therefore concluded that whales wintering in Hawaii constitute a discrete population. 

Humpback whales in Okinawa were not significantly different in either mtDNA or nDNA from 

whales in the Philippines (Baker et al. 2013), so those two areas were pooled for all subsequent 

analyses of population structure. The genetic data from the pooled populations from Okinawa 

and the Philippines populations differ significantly in both mtDNA and nDNA markers from 

humpback whale in the Ogasawara Islands and all other populations (Baker et al. 2013);

however, given the likelihood that Ogasawara whales are only passing through en route to two or 

more migratory destinations, the BRT could not reach consensus in delineating discrete 

populations in the western North Pacific.

The diversity of opinion in the BRT regarding population discreteness in the western North 

Pacific was expressed in the voting process. BRT members were given 100 probability units, 

which they voted according to the strength of their belief in the following three scenarios given 

the available information (Error! Reference source not found.).

Table 4. Western North Pacific Discreteness Scenarios Voting.

Scenario Description Proportion of 

Votes

1. One discrete unit • Okinawa/Philippines/Ogasawara pooled 13%

2. Two discrete units • Okinawa/Philippines pooled

• Ogasawara 25%

3. Two discrete units

• Okinawa/Philippines pooled and 2nd

unidentified breeding area; 

• Ogasawara as migratory route

62%

The percentage distribution of votes strongly favored the delineation of two distinct populations 

(with a combined 87% of votes). Scenario 3 (which included the Ogasawara area as a migratory 

route for both discrete populations) was viewed as the most likely scenario.

The BRT concluded that five breeding populations of humpback whales in the North Pacific 

meet the established criteria for being discrete under the DPS policy guidelines: (1) Central 

America, (2) Mexico (mainland Mexico and the Revillagigedos Islands), (3) the Main Hawaiian 

Islands, (4) the Okinawa and Philippine Islands pooled, and (5) an unidentified breeding area in 

the western North Pacific. 

Recently, Lammers et al. (2011) used acoustic recorders to document the presence of humpback 

whales wintering in the Northwest Hawaiian Islands (NWHI) and suggested this area as a 

possibility for the unidentified breeding location. Johnston et al. (2007) also reported whales in 

the NWHI area, and using habitat modeling suggested that it was well suited to being a 

humpback whale wintering area. However, the theory that the NWHI is the unidentified western 

North Pacific breeding area, and its status relative to adjacent breeding areas, cannot be 

23
evaluated until individual identification data (photo-id and genetic) from the NWHI are 

compared to other areas of the North Pacific, including Hawai’i and to the feeding grounds to 

which animals from the unidentified western Pacific DPS are believed to migrate. Furthermore, 

the BRT noted that the presence of humpback whales in the NWHI is also consistent with an 

alternative explanation, namely expansion of the range of the population of the main Hawaiian 

Islands. Further research is required to determine which of these hypotheses is correct.

G.3 Southern Hemisphere and Arabian Sea

The International Whaling Commission (IWC) has been involved in the comprehensive 

assessment of humpback whales in the Southern Hemisphere since 1991, bringing together 

available information on distribution, migration, abundance, past exploitation and population 

(stock) structure. A report on an IWC workshop devoted to Southern Hemisphere stock structure 

issues has recently been published (IWC 2011). On the basis of these ongoing assessments, the 

IWC recognizes at least seven “breeding stocks” associated with low-latitude, winter breeding 

grounds and, in some cases, migratory corridors. These seven breeding stocks are referred to 

alphabetically, from A to G, to distinguish them from the six management areas on feeding 

grounds of the Antarctic, referred to as Areas I-VI. The current breeding stock designations are 

southwestern Atlantic (A), southeastern Atlantic (B), southwestern Indian Ocean (C), 

southeastern Indian Ocean (D), southwestern Pacific (E), Oceania (E and F) and southeastern 

Pacific (G). These designations have been subdivided to reflect improved understanding of 

substructure within some of these regions: Gabon (B1) and Southwest Africa (B2) in the 

southeastern Atlantic; Mozambique (C1), the Comoros Archipelago (C2), Madagascar (C3) and 

the Mascarene Islands (C4) in the southwestern Indian Ocean, east Australia (E1), New 

Caledonia (E2), Tonga (E3), the Cook Islands (F1) and French Polynesia (F2) in the 

southwestern Pacific and Oceania (illustrated in Figure 3). The IWC has also chosen to include in 

this assessment, a year-round population of humpback whales found in the Arabian Sea, north of 

the equator in the northern Indian Ocean (formerly referred to as breeding stock X).

The BRT noted that the magnitude of genetic differentiation (as measured by FST) was generally 

lower among Southern Hemisphere breeding areas than it is in the Northern Hemisphere, 

indicating greater demographic connectivity among these areas. Even so, significant 

differentiation was present among major breeding areas, and the estimated number of 

migrants/generation among areas was small compared to the estimated sizes of the populations. 

The BRT also discussed the potential for using photo-ID matching to evaluate isolation or 

interchange among breeding stocks, but variability in effort and availability of these data 

prevented a systematic comparison across all areas (IWC 2011). In contrast, analysis of several 

large and comparable datasets of mtDNA haplotype diversity and differentiation have been 

published or made available in reports to the IWC. These allow a standardized comparison of 

overall and stock-by-stock (pair-wise) differentiation.

24
Figure 3. Southern hemisphere humpback whale stock structure hypothesized by the IWC. 

All boundaries are approximate. Dotted lines represent hypothetical connections between breeding and feeding areas, 

thin lines represent a small number of documented connections, and thick lines represent a large number of documented

connections. Lines illustrate connections only, and are not necessarily indicative of actual migratory routes. Reproduced 

from IWC (2011) – see that document for details.

The BRT concluded that the seven breeding stocks of humpback whales currently recognized by 

the IWC meet the criteria for being discrete populations under the DPS policy guidelines, with 

the following modification. The BRT agreed that breeding stocks E and F represented at least 

two discrete populations, but that the primary division was between eastern Australia and 

Oceania (defined here to include New Caledonia, Tonga, Samoa, American Samoa, and French 

Polynesia), as there are large differences in the rates of recovery between these two regions 

indicating separation. Breeding population in New Caledonia and east Australia are separate but 

some overlap between the populations occurs: some whales bound for New Caledonia use the 

same migratory pathways as some whales headed past east Australia. There was consensus to 

divide the Southern Hemisphere into seven discrete units, listed below, and to remove the 

Arabian Sea from the Southern Hemisphere group, making it a separate category.

Following review of documents and discussion, the BRT agreed that the Arabian Sea population 

was clearly discrete from all other populations. Genetic samples (nuclear microsatellites and 

mitochondrial control region), fluke pigmentation markings, and data on the reproductive cycle 

indicate that this breeding population is significantly differentiated from all other Indian Ocean 

breeding populations. Levels of mitochondrial differentiation between Arabian Sea and 

Southern Hemisphere breeding populations are around ten times greater than among these other 

breeding populations (Rosenbaum et al. 2009). Despite extensive comparisons of photoidentification catalogues and individual genotypes, no matches have been detected between the 

Arabian Sea and the ‘neighboring’ Southern Hemisphere breeding populations (e.g., IWC 

breeding stock C; Rosenbaum et al. 2009). As stated elsewhere, connections with the Northern 

Hemisphere are highly unlikely as there is no northward passage through the Arabian Sea, the 

Indian Ocean population shares no mitochondrial haplotypes in common with the North Pacific, 

suggesting that whales from these populations have no recent biological connectivity. The 

25
Philippines population has the highest likelihood of interchange with the Arabian Sea; however, 

the number of samples from this population is small.

Southern Hemisphere Discrete Units:

A. Brazil

B. Gabon/Southwest Africa

C. Southeast Africa/ Madagascar

D. West Australia

E. East Australia 

F. Oceania*, including New Caledonia, Tonga, Cook Islands, Samoa, American Samoa and 

French Polynesia

G. Southeastern Pacific (Colombia and Ecuador)

* Differs from International Union for the Conservation of Nature and Natural Resources 

(IUCN) definition of Oceania in recognizing the distinction between East Australia and breeding 

population(s) to the east. 

In summary, the BRT examined global humpback whale population structure and identified at 

least 15 discrete breeding units: 2 in the North Atlantic, 5 in the North Pacific, 7 in the Southern 

Hemisphere, and 1 in the Arabian Sea.

H. Determining Significance

Under the joint FWS/NMFS DPS policy, a population qualifies as a DPS if it is both discrete and 

significant relative to the taxon to which it belongs based on the criteria described in the 

introduction to this chapter. The BRT examined global humpback whale population structure

and identified 15 discrete breeding units (two in the North Atlantic, five in the North Pacific, 

seven in the Southern Hemisphere and one in the Arabian Sea). These 15 discrete populations 

were then analyzed to determine if any or all of them met the significance criteria of the joint 

DPS policy based on their ecological characteristics, geographic range, genetics, or other factors

as defined by the DPS policy. 

The BRT concluded (see Section II B) that whales from the North Pacific, North Atlantic, 

Southern Hemisphere and Arabian Sea were markedly differentiated from each other at genetic, 

behavioral, morphological, and geographic factors to the degree that they could arguably be 

considered different subspecies. In evaluating the significance criterion, the BRT therefore 

largely focused on differentiation within major ocean basins and whether any of the 15 discrete 

units described above are “significant” with respect the other populations collectively within 

their respective ocean basin (i.e., the potential oceanic subspecies). Recognizing that formal 

subspecies of the humpback whale are not currently recognized, however, and that there was 

some uncertainty within the BRT about likely subspecies designations, the BRT also discussed 

whether the identified populations within ocean basins would be considered ‘significant’ with 

respect to the entire global species. 

26
H.1 Ecological setting

Many of the 15 discrete humpback whale populations the BRT identified occupy different large 

marine ecosystems as defined by the National Oceanic and Atmospheric Administration

(NOAA) (http://www.lme.noaa.gov), either in their breeding range, feeding range or both (Table 

5). The BRT weighted ecological differences among feeding areas more heavily than among 

breeding areas, since the team concluded that the ecological characteristics of humpback whales 

in their breeding ranges were largely similar among populations. In contrast, the BRT concluded 

whales largely foraging in different large marine ecosystems inhabit different ecological settings 

and that this is relevant in evaluating the significance of these populations. 

Table 5. Large Marine Ecosystems inhabited by humpback whale populations

Large Marine Ecosystem

Discrete Unit Breeding range Primary Feeding range

West Indies Caribbean Sea Scotian Shelf, NewfoundlandLabrador Shelf, Canadian Eastern

Arctic-West Greenland, Iceland 

Shelf and Sea, Norwegian Sea

Cape Verde Islands + plus Northwest Africa Eastern Atlantic/Canary Current? Iceland Shelf and Sea, Norwegian 

Sea

Hawaii Insular Pacific-Hawaiian East Bering Sea, Gulf of Alaska

Central America Pacific Central-America California Current

Mainland Mexico Pacific Central-American California Current, Gulf of Alaska, 

East Bering Sea

Revillagigedos Islands Revillagigedos Islands Gulf of Alaska, East Bering Sea

Mexico – Baja California Current Gulf of Alaska, East Bering Sea

Okinawa/Philippines Kuroshio Current West Bering Sea

Second West Pacific ? Aleutian Islands

West Australia Northwest Australian Shelf Antarctic

East Australia Northeast Australian Shelf Antarctic

Oceania Oceania Antarctic

Southeastern Pacific Pacific Central-America Antarctic

Brazil East Brazil Shelf Sub-Antarctic areas around the 

South Georgia and South Sandwich 

Islands

Gabon/Southwest Africa Guinea Current, Benguela Current Antarctic

Southeast Africa/ Madagascar Agulhas Current Antarctic

Arabian Sea Arabian Sea Arabian Sea

27
Within the North Atlantic, the West Indies and Cape Verde/Northwest Africa breeding 

populations both are believed to feed in largely overlapping areas, so BRT concluded that these 

two groups did not occupy unique ecological settings within the North Atlantic, although 

together they differ ecologically from other populations worldwide. Within the North Pacific, 

the Okinawa/Philippines, Hawaii, Mexican, and Central American populations tended to feed in 

different marine ecosystems, although there was some overlap. The Central American 

population’s breeding habitat is also ecologically unique for the species as it is the only area 

where documented geographic overlap of populations that feed in different hemispheres occurs, 

potentially creating a conduit for genetic exchange between the two hemispheres. A minority of 

members believed that this was an example of temporal and geographic overlap, not a unique 

ecological setting, however. 

The Arabian Sea population persists year-round in a monsoon driven tropical ecosystem with 

highly contrasting seasonal wind and resulting upwelling patterns. The BRT therefore concluded 

that this population persists in a unique ecological setting. 

Within the Southern Hemisphere, most breeding populations feed in the same Antarctic marine 

ecosystem. One exception is the Brazil population, which feeds north of 60 degrees in the South 

Georgia and South Sandwich Islands area (IWC 2011). In addition to feeding in the Antarctic 

system, the Gabon/Southwest Africa population may also feed along the west the coast of South 

Africa in the Benguela Current, but this is uncertain (IWC 2011). Like the Central America 

population, the South Eastern Pacific breeding population may also be ecologically unique as it 

is the only population in the Southern Hemisphere to occupy an area also used by a Northern 

Hemisphere population. 

H.2 Gap in the range

Most of the discrete breeding populations occupy non-overlapping areas during the winter 

months that, if lost, would arguable result in a significant gap in the range, certainly within an 

ocean basin and likely within the global distribution of the species. Possible exceptions are the 

Southeast Pacific and Central America breeding populations, which occupy a partially 

overlapping breeding range. The breeding range of the unidentified Western Pacific population 

is not known, so it is not clear if its loss would result in a significant gap. 

The feeding areas of the discrete populations overlap more than the breeding areas do, but in 

many cases if lost would, in combination with the lost breeding area, contribute to a significant 

gap in the species’ range. In the North Atlantic Ocean, the West Indies and Cape Verde 

Islands/Northwest Africa populations have a largely overlapping feeding range, so loss of either 

population would not necessarily create a significant gap in the feeding range as long as the other 

population remained. The BRT noted, however, that most of the whales feeding throughout the 

North Atlantic are from the West Indies population. If all North Atlantic humpback whales were 

extinct, this would also clearly create a gap within the range of the global species. 

In the North Pacific Ocean, loss of the Hawaii breeding population would result not only in loss 

of humpbacks from the Hawaiian Islands but also from SE Alaska and Northern British 

Columbia. Similarly, loss of the Okinawa/Philippines population would likely result in a 

significant gap in Pacific feeding range as these individuals are the only breeding population to 

migrate primarily to Russia and loss of this population would therefore result in a loss of feeding 

28
range along the Russian coast. Loss of the Mexican and Central American populations would 

result in the loss of humpback whales in the California current along the coasts of California, 

Oregon and Washington. 

For the Southern Hemisphere, determination of feeding range is more difficult since Antarctic 

feeding areas are less well studied and fewer connections between breeding and feeding 

populations have been made. However, some populations such as Brazil, Southwest Africa, 

Southeast Africa, and the Southeast Pacific are believed to have fairly discrete and nonoverlapping feeding areas (Figure 3), suggesting that if any of these feeding areas were lost it 

would, in combination with the lost breeding area, result in a significant gap in the range. 

Finally, the Arabian Sea population segment does not migrate extensively, but instead feeds and 

breeds in the same geographic location. No other humpback whale populations occupy this area 

and hence, a loss of the Arabian Sea population would result in a significant gap in the range of 

the species.

H.3 Genetic differentiation

The BRT discussed whether there was evidence for marked genetic divergence among any of the 

discrete populations. Although there was not clear agreement on the definition of “marked”, the 

BRT concluded that strong patterns of genetic differentiation in mtDNA sequence among most 

of the North Pacific breeding populations indicated marked genetic divergence, consistent with 

the conclusions in Baker et al. (2013). The overall level of differentiation among breeding 

populations within the North Pacific (FST = 0.09) was similar to the level of divergence among 

ocean basins and is consistent with a relatively high degree of divergence of these populations. 

In the Southern Hemisphere, the Southeastern Pacific population is the only breeding population

that contains a genetic signal from Northern Hemisphere populations, giving it a unique genetic 

signature within the Southern Hemisphere (Baker et al. 1993; Baker and Medrano-González 

2002). It is also the most divergent of any of the Southern Hemisphere populations (Olavarría et 

al. 2007). In addition, individuals in this region are morphologically distinct as they have darker 

pectoral fin coloration than other individuals in the Southern Hemisphere (Chittleborough 1965), 

although the genetic basis for this trait is not known. Nonetheless, a majority of the BRT 

concluded that the Southeastern Pacific population was sufficiently differentiated so as to differ 

‘markedly’ in its genetic characteristics from other Southern Hemisphere populations. In 

contrast, all other Southern Hemisphere populations were characterized by generally low levels 

of differentiation among them, consistent with demographically discrete populations but not 

necessarily with marked genetic divergence associated with long-term isolation (Olavarría et al.

2007; Rosenbaum et al. 2009). 

The BRT also concluded that the Arabian Sea population differed markedly in its genetic 

characteristics from other populations in the Indian Ocean and worldwide. The degree of genetic 

differentiation at multiple genetic markers between this population and other populations was 

similar to or greater than the degree of divergence among the North Pacific, North Atlantic, and 

Southern Hemisphere areas.

29
Summary

The BRT concluded that all 15 discrete populations met at least one and in most cases several of 

the factors for the significance criterion when evaluated with respect to the other populations 

within ocean basins, resulting in identification of 15 DPSs (Table 6).

The BRT also discussed whether any or all of these populations would also be considered 

discrete and significant if they were evaluated with respect to the entire global species, rather 

than to other populations collectively within the three major ocean basins considered by the BRT 

to be possible subspecies. The BRT concluded that most of the identified populations are clearly 

both discrete and significant, whether considered with respect to the potential ocean-basin based 

subspecies or the global species. In particular, the five North Pacific populations are 

characterized by marked genetic divergence both from each other and from all other populations 

within the species (Baker et al. 2013), and they tend to concentrate their feeding in different

large marine ecosystems, although there is some overlap. Similarly, the West Indies population 

is marked by substantial genetic divergence from all populations in the Pacific and Southern 

Hemisphere, feeds in a distinct set of marine ecosystems, and if lost would result in the loss of 

humpback whales from much of the North Atlantic. The BRT was uncertain if the Cape Verde 

Islands/Northwest Africa population would be considered significant if evaluated against the 

global species. Its genetic characteristics and feeding ranges are not well understood and could

overlap considerably with the West Indies population. It is possible, therefore, that if evaluated 

with respect to the global species, the West Indies and Cape Verde Islands/Northwest Africa 

populations might reasonably be combined into a single DPS. Similarly, the BRT was somewhat 

uncertain about whether the unidentified Western Pacific population would be considered a DPS 

with respect to the global species, due to many uncertainties about this population. 

Likewise, the BRT was uncertain if all of the populations identified within the Southern 

Hemisphere would be considered significant if evaluated with respect to the global species. 

With the exception of the Southeast Pacific population, the Southern Hemisphere populations are 

characterized by relatively low levels of genetic divergence from each other and less ecological 

divergence among feeding areas. Nonetheless, loss of any of these populations would arguably 

result in a significant gap in the range of the global species based on breeding locations and 

hypothesized migration routes, and some of these populations also have distinct feeding areas. 

The BRT unanimously concluded that the Arabian Sea population would be considered a DPS 

under any global taxonomic scenario, due to its marked genetic divergence from all other 

populations and unique ecological setting. 

30
Table 6. Summary of information used to evaluate the significance criteria of the DPS policy. 

Discrete populations were compared with respect to ecological differences/gap in range/genetics/coloration/behavior (respectively). A 

“1” indicates a difference between a pair of populations, and “0” indicates that the populations do not differ substantially in that factor, 

and “?” indicates a lack of information. This information was used to evaluate whether a discrete population was significant with 

respect to the taxon to which it belongs. See text for details. 

31
H.4 Descriptions of the identified humpback whale Distinct Population Segments

The BRT examined the global humpback whale population and determined that 15 populations 

met the DPS Policy criteria and, therefore, qualify as DPSs (listed below, and illustrated in 

Figure 4).

1. West Indies

2. Cape Verde Islands plus Northwest Africa

3. Hawaii

4. Central America

5. Mexico

6. Okinawa/Philippines

7. Second West Pacific

8. West Australia

9. East Australia

10. Oceania

11. Southeastern Pacific

12. Brazil

13. Gabon/Southwest Africa

14. Southeast Africa/ Madagascar

15. Arabian Sea

Figure 4. Approximate breeding locations of humpback whale distinct population segments worldwide. 

32
H.4.1 North Atlantic Distinct Population Segments

1. West Indies – The West Indies DPS consists of the humpback whales whose breeding range 

includes the Atlantic margin of the Antilles from Cuba to northern Venezuela, and whose 

feeding range primarily includes the Gulf of Maine, eastern Canada, and western Greenland. 

While many West Indies whales also use feeding grounds in the central (Iceland) and eastern 

(Norway) North Atlantic, many whales from these feeding areas appear to winter in another 

location. The West Indies population was determined to be discrete based upon genetic evidence 

and on a lack of evidence for exchange with the eastern Atlantic breeding population (or any 

other population) based on re-sighting data. This population was determined to be significant 

with respect to other North Atlantic populations due to the significant gap in the breeding range

of the unnamed North Atlantic subspecies that would occur if it went extinct. Loss of the West 

Indies population would result in the loss of humpback whales from the Northwest Atlantic 

breeding (Caribbean/West Indies) and feeding grounds (United States, Canada, Greenland) and 

would also result in the loss of a significant portion of whales occupying feeding grounds in the 

Northeast Atlantic.

2. Cape Verde Islands plus Northwest Africa – This DPS consists of the humpback whales 

whose breeding range includes waters surrounding the Cape Verde Islands as well as an 

undetermined breeding area in the eastern tropical Atlantic which may be more geographically 

diffuse than the West Indies breeding ground. The population of whales breeding in the Cape 

Verde Islands plus this unknown area likely represent the remnants of a historically larger 

population breeding around Cape Verde Islands and northwestern Africa (Reeves et al. 2002). 

There is no known overlap in breeding range with North Atlantic humpback whales that breed in 

the West Indies, although overlap occurs among feeding aggregations from different breeding 

populations. 

The population was determined to be discrete based upon genetic evidence that suggests a 

second breeding ground occupied by whales that feed primarily off Norway and Iceland, as well 

as the gap that would exist in the breeding range of the unnamed North Atlantic subspecies if it 

became extinct. Loss of this unit would result in a loss of this unique breeding ground as well as 

a significant number of whales that feed in Iceland and Norway.

33
Figure 5. North Atlantic Ocean Distinct Population Segments.

H.4.2 North Pacific Distinct Population Segments

3. Hawaii – The Hawaii DPS consists of humpback whales that breed within the main Hawaiian 

Islands. Whales from this breeding population have been observed in most known feeding 

grounds in the North Pacific, but about half of the whales from the population migrate to 

Southeast Alaska and Northern British Columbia. They also commonly utilize northern British 

Columbia, northern Gulf of Alaska and Bering Sea feeding grounds. This population was 

determined to be discrete based on significant genetic differentiation from populations in other 

North Pacific breeding areas and evidence for low rates of movement among breeding areas in 

the North Pacific based on sighting data. The Hawaii population was determined to be 

significant due to the gap that would result in breeding and feeding ranges if it were to go 

extinct, ecological uniqueness of feeding areas, and marked levels of genetic divergence when 

compared to the other North Pacific populations. 

4. Central America – The Central America DPS is composed of whales that breed along the 

Pacific coast of Costa Rica, Panama, Guatemala, El Salvador, Honduras and Nicaragua. Whales 

from this breeding ground feed almost exclusively offshore of California and Oregon in the 

eastern Pacific, with only a few individuals identified at the northern Washington –southern 

British Columbia feeding grounds. This population was determined to be discrete based on resight data as well as findings of significant genetic differentiation between it and other 

populations in the North Pacific. The genetic composition of the DPS is also unique in that it 

shares mtDNA haplotypes with some Southern Hemisphere DPSs, suggesting it may serve as a 

conduit for gene flow between the North Pacific and Southern Hemisphere, although there was 

some disagreement within the BRT on whether this was a strong indicator of significance. The 

breeding ground of this population occupies a unique ecological setting, and its primary feeding 

ground is in a unique marine ecosystem for the North Pacific. Loss of this population would also

result in a significant gap in the range of the species.

34
5. Mexico – The Mexican DPS consists of whales that breed along the Pacific coast of mainland 

Mexico, the Baja California Peninsula and the Revillagigedos Islands. The Mexican DPS feeds 

across a broad geographic range from California to the Aleutian Islands, with concentrations in 

California-Oregon, northern Washington – southern British Columbia, northern and western Gulf 

of Alaska and Bering Sea feeding grounds. This population was determined to be discrete based 

on significant genetic differentiation as well as evidence for low rates of movements among 

breeding areas in the North Pacific based on sighting data. It was determined to be significant 

due to the gap in breeding grounds that would occur if this population were to be extirpated and 

the marked degree of genetic divergence from other populations in the North Pacific.

6. Okinawa/Philippines – The Okinawa/Philippines DPS consists of the whales’ 

breeding/wintering in the area of Okinawa and the Philippines. Animals transiting the 

Ogasawara area are believed to be a mixture of whales from this DPS and the second West 

Pacific DPS (# 7, below). The Okinawa/Philippines DPS migrates to feeding grounds in the 

northern Pacific, primarily off the Russian coast. The population was determined to be discrete 

based upon both significant genetic differentiation from other North Pacific populations and 

apparently limited exchange with other breeding populations in the North Pacific based on resighting data. The population was determined to be significant due to the gap in both the 

breeding and feeding ranges that would arise if the population were to go extinct, marked levels 

of genetic differentiation from other population in the North Pacific, and a primary feeding area 

that is unique in its ecological characteristics compared to other populations in the North Pacific. 

The relationship between this DPS and the Second West Pacific DPS is somewhat uncertain, 

however, due to the latter’s unknown breeding location. 

7. Second West Pacific DPS – The existence of this breeding population is inferred from 

sightings of whales in Aleutian Islands area feeding grounds that cannot be linked to any known 

breeding population and from the significant genetic differences that were found between 

Ogasawara whales and the Okinawa/Philippines DPS. Some of these whales may transit the 

Ogasawara area in route to unknown breeding grounds farther south. This inferred breeding 

population was considered to be discrete based primarily upon the apparent low exchange with 

other breeding populations in the North Pacific. Its significance was hard to assess, but it 

appears to feed primarily in a marine ecosystem (the Aleutian Islands) that is rarely used by 

whales from other populations. Loss of this population was also considered likely to result in a 

gap in the range, based on a discrete feeding area and an unknown breeding area. 

35
Figure 6. North Pacific Ocean Distinct Population Segments. 

Breeding areas are numbered, with linkages to predominant feeding areas (letters) illustrated. Only the general locations 

of areas are shown. Information primarily from Calambokidis et al. (2008) and Barlow et al. (2011).

H.4.3 Southern Hemisphere Distinct Population Segments

8. West Australia – The West Australia DPS consists of the humpback whales whose 

breeding/wintering range includes the West Australia coast, primarily in the Kimberly Region. 

Individuals in this population migrate to feeding areas in the Antarctic, primarily between 80°E 

and 110°E based on tagging data. The population was considered discrete based upon lack of 

evidence for exchange with other breeding populations as well as significant genetic 

differentiation from other populations in the Southern Hemisphere. It was considered significant 

due to the gap in both the breeding and feeding range that would be created should the 

population become extirpated. 

9. East Australia – The East Australia DPS consists of the whales’ breeding/wintering along the 

eastern and northeastern Australian coast. Based upon tagging, telemetry, and re-sighting data, 

individuals in this population migrate to Antarctic feeding areas ranging from 100°E to 180°E, 

but concentrate mostly between 120°E and 180°E. The population was considered discrete 

based upon its distribution and level of genetic differentiation from other populations. It was 

considered significant due to the gap in the range that would occur should the population become 

extirpated. 

10. Oceania – The Oceania DPS consists of whales that breed/winter in the South Pacific Islands 

between ~160°E (west of New Caledonia) to ~120°W (east of French Polynesia), including 

American Samoa, the Cook Islands, Fiji, French Polynesia, Republic of Kiribati, Nauru, New 

Caledonia, Norfolk Island, New Zealand, Niue, the Independent State of Samoa, Solomon 

36
Islands, Tokelau, Kingdom of Tonga, Tuvalu, Vanuatu, Wallis and Futuna. Individuals in this 

population are believed to migrate to a largely undescribed Antarctic feeding area. The 

population was considered discrete based on its breeding distribution and level of genetic 

differentiation from other populations. It was considered significant based upon the gap in the 

range that would occur should the population become extirpated. 

11. Southeastern Pacific – The Southeastern Pacific DPS consists of whales that breed/winter 

along the Pacific coasts of Panama to northern Peru (9°N-6°S), with the main wintering areas 

concentrated in Colombia. Feeding grounds for this DPS are thought to be concentrated in the 

Chilean Magellan Straits and the western Antarctic Peninsula. These cross-equatorial breeders 

feed in the Southern Ocean during much of the austral summer. The population was considered 

discrete based on its breeding distribution and level of genetic differentiation from other 

populations. It was considered significant based on the gap in the range that would occur should 

it become extirpated, the marked level of genetic divergence for the Southern Hemisphere, and 

the unique ecological setting of its breeding area. 

12. Brazil – This DPS consists of whales that breed between approximately 3°S and 23°S in the 

southwestern Atlantic along the coast of Brazil with a prominent concentration around the 

Abrolhos Bank (15°-18°S) and feed off South Georgia and the South Sandwich Islands. The 

population was considered discrete based on its breeding distribution and level of genetic 

differentiation from other populations. It was considered significant based upon the gap in range 

that would occur should the population become extirpated and its feeding location in a distinct 

marine ecosystem. 

13. Southwest Africa – The Southwest Africa DPS consists of whales that breed and calve off 

central western Africa between ~6°S and ~6°N in the eastern Atlantic, including the coastal 

regions of northern Angola, Congo, Togo, Gabon, Benin, other coastal countries within the Gulf 

of Guinea and possibly farther north. This DPS is thought to feed offshore of west South Africa 

and Namibia south of 18°S and in the Southern Ocean beneath west South Africa (20°W –

10°E). The population was considered discrete based on its breeding distribution, which is 

geographically separated from other breeding distributions, and level of genetic differentiation 

from other populations. It was considered significant based upon the gap in the range that would 

occur should the population become extirpated.

14. Southeast Africa/ Madagascar– The Southeast Africa/ Madagascar DPS includes whales 

breeding in at least three different areas in the western Indian Ocean: one associated with 

mainland coastal waters of southeastern Africa, extending from Mozambique to as far north as 

Tanzania and southern Kenya, a second found in the coastal waters of the northern Mozambique 

Channel Islands and the southern Seychelles and the third found in the coastal waters of eastern 

Madagascar. The feeding grounds of this DPS in the Southern Ocean are not well defined but 

are believed to include multiple localities to the west and east of the region bounded by 5°W –

60°E. The population was considered discrete based on its breeding distribution, which is 

geographically separated from other breeding grounds and level of genetic differentiation from 

other populations. It was considered significant based upon the gap in the range that would 

occur should the population become extirpated.

15. Arabian Sea – The Arabian Sea DPS includes those whales that are currently known to breed 

and feed along the coast of Oman. However, historical records from the eastern Arabian Sea 

37
along the coasts of Pakistan and India indicate its range may also include these areas. The 

population was considered discrete based upon its unique breeding and feeding distribution 

which is geographically separated from other breeding distributions, and level of genetic 

differentiation from other populations. It was considered significant based upon the gap in the

range that would occur should the population become extirpated, its unique ecological setting, 

and marked degree of genetic differentiation from other population in the Southern Hemisphere. 

Figure 7. Southern Hemisphere and Arabian Sea Distinct Population Segments.

38
III. Assessment of Extinction Risk

The BRT was charged with assessing the risk of extinction for each DPS identified. The 

information considered in evaluating a DPS’s status can be grouped into two general categories: 

(1) demographic information reflecting the past and present status (e.g., data on population 

abundance or density, population trends and growth rates, exchange rates of individuals among 

populations, and the ecological, life-history, or genetic diversity among populations); and (2) 

information on threats faced by the DPS (e.g., overutilization, disease, climate change). The 

demographic and threats data reviewed by the BRT are thoroughly described in the Background 

Report (Fleming and Jackson 2011) and summarized in this chapter. 

Evaluating extinction risk of a species includes considering the available information concerning 

the abundance, growth rate/productivity, spatial structure/connectivity, and diversity of a species 

and assessing whether these demographic criteria indicate that it is at high risk of extinction; at 

moderate risk; or neither. The demographic risk criteria described above were evaluated based 

on the present species status in the context of historical information, if available, and threats that 

might alter the determination of the species’ overall level of extinction risk. These threats are 

critical considerations in evaluating a species’ extinction risk; forecasting the effects of threats 

into the foreseeable future usually necessitates qualitative evaluations and the application of 

informed professional judgment. This evaluation highlights factors that may exacerbate or 

ameliorate demographic risks so that all relevant information may be integrated into the 

determination of overall extinction risk for the species.

Section A of this chapter describes the process used by the BRT to analyze threats as they relate 

to the current status of the 15 identified humpback whale DPSs. Section B presents a general 

description of the past, current, or potential threats for humpback whales under the relevant 

section 4(a)(1) factor to avoid duplication. 

Section C of this chapter describes the BRT’s approach to analyzing demographic factors and 

extinction risk. Section D evaluates the threats specific to each DPS and, taken in consideration 

with demographic factors, assesses the risk of extinction for each DPS. 

Analysis of Factors Listed Under ESA Section 4(a)(1)

Under Section 4(a)(1) of the ESA, NMFS and FWS are required to determine whether any 

species is an endangered or threatened species because of any of the following factors. These 

factors are:

A. The present or threatened destruction, modification, or curtailment of its habitat or 

range;

B. Overutilization for commercial, recreational, scientific, or educational purposes;

C. Disease or predation;

D. The inadequacy of existing regulatory mechanisms; or

E. Other natural or manmade factors affecting its continued existence.

39
The BRT qualitatively assessed the severity, geographic scope, and level of certainty of 16 

potential threats to humpback whales for each DPS. Because the severity and scope of 

individual threats may change through time, each threat was evaluated based on its current 

and/or future potential for impact.

A. Overview of Threats Analysis

The BRT began its qualitative assessment of threats by defining the following threat severity 

levels: 

4 = Very high: the threat is likely to on its own create a high risk of extinction.

3 = High: the threat is likely to seriously reduce the population size or its growth rate.

2 = Medium: the threat is likely to moderately reduce the population size or its growth 

rate.

1 = Low or none: the threat is likely to have no or minor impact on the population size or 

growth rate. 

U = Unknown: the severity of the threat is unknown.

The BRT focused on threats that are acting currently or that will have predictable impacts in the 

future. For example, in almost all DPSs whaling was considered to be a low threat currently

since present-day whaling is not known to kill more than a few individual whales, despite the 

fact that whaling was clearly a severe threat in the past. 

The BRT collectively evaluated the threats posed to each DPS individually and then examined 

and discussed the results across all DPSs to ensure that the assigned threat level was evaluated 

consistently across each DPS. The BRT noted because the threat levels encompass fairly broad 

categories, not all threats of the same level are necessarily exactly equal in severity.

B. General Description of Threats

B.1 Present or threatened destruction, modification, or curtailment of its habitat or range 

Coastal Development

Substantial coastal development is occurring in many regions, and may include construction of 

ports that can cause increased turbidity of coastal waters, higher volume of ship traffic, and 

physical partitioning or disruption of the marine environment. Noise associated with 

construction (e.g., pile driving, blasting, or explosives) and dredging has the potential to affect 

whales by generating sound levels believed to disturb marine mammals under certain conditions. 

The majority of the sound energy associated with both pile driving and dredging is in the low 

frequency range (<1,000 Hz; Illingworth and Rodkin Inc. 2001; Reyff 2003; Illingworth and 

Rodkin Inc. 2007). Because humpback whales would only be affected when close to shore, the 

BRT believed that these effects on the whales would generally be low. However, if coastal 

development occurred in seasonal areas or migration routes where whales concentrate, 

individuals in the area could be more seriously affected. Scheduling in-water construction 

activities to avoid those times when whales may be present would likely minimize the 

disturbance. 

40
The BRT was unaware of any circumstance of coastal development resulting in humpback whale 

serious injury or mortality and therefore determined that in general coastal development likely 

poses a low level threat to humpback whales.

Contaminants

For purposes of this Status Review, the BRT agreed to consider as contaminants heavy metals, 

persistent organic pollutants, effluent, airborne contaminants, plastics, and other marine debris 

and pollution with the exception of oil spills, which is evaluated under ‘energy exploration and 

development’. Numerous regions were highlighted as having known or hypothesized high 

contaminant levels from run-off, large human populations, and low levels of regulatory control. 

Halogenated organic pollutants (including dichloro-diphenyl-trichloroethane (DDT)), 

hexachlorocyclohexane (HCH) and chlordane (CH) insecticides, polychlorinated biphenyl (PCB) 

coolants and lubricants, and polybrominated diphenyl ether (PBDE - flame retardants) can 

persist in the environment for long periods. Air-borne pollutants are particularly concentrated in 

areas of industrialization, and in some high latitude regions (Aguilar et al. 2002). While the use 

of many pollutants is now either banned or strictly regulated in some countries (e.g., DDTs and 

PCBs), their use is still unregulated in many parts of world, and they can be transported long 

distances via oceanographic processes and atmospheric dispersal (Aguilar et al. 2002).

Humpback whales can accumulate lipophilic compounds (e.g., halogenated hydrocarbons) and 

pesticides (e.g., DDT) in their blubber, as a result of feeding on contaminated prey 

(bioaccumulation) or inhalation in areas of high contaminant concentrations (e.g., regions of 

atmospheric deposition; Barrie et al. 1992; Wania and Mackay 1993). Some contaminants (e.g., 

DDT) are passed on maternally to young during gestation and lactation (e.g., fin whales, Aguilar 

and Borrell 1994).

Elfes et al. (2010) described the range and degree of organic contaminants accumulated in the 

blubber of humpback whales sampled on Northern Hemisphere feeding grounds. Concentrations 

were high in some areas (Southern California and Northern Gulf of Maine), possibly reflecting 

proximity to industrialized areas in the former case, and prey choice in the latter (Elfes et al.

2010). There were also higher levels of PCBs, PBDEs, and CH insecticides in the North Atlantic 

Ocean (Gulf of Maine and Bay of Fundy) than the North Pacific (California, South East Alaska, 

Aleutian Islands). The highest levels of DDT were found in whales feeding off Southern 

California, a highly urbanized region of the coast with substantial discharges (Elfes et al. 2010). 

This same study found a linear increase in PCB, DDT and chlordane concentration with age of 

the whales sampled. Generally, concentrations of these contaminants in humpback whales were 

low relative to levels found in odontocetes (O'Shea and Brownell 1994). Little information on 

levels of contamination is available from humpback whales on Southern Hemisphere feeding 

grounds. 

The health effects of different doses of contaminants are currently unknown for humpback 

whales (Krahn et al. 2004c). There is evidence of detrimental health effects from these 

compounds in other mammals, including disease susceptibility, neurotoxicity, and reproductive 

and immune system impairment (Reijnders 1986; DeSwart et al. 1996; Eriksson et al. 1998). 

Contaminant levels have been proposed as a causative factor in lower reproductive rates found 

41
among humpback whales off Southern California (Steiger and Calambokidis 2000), but at 

present the threshold level for negative effects, and transfer rates to calves, are unknown for 

humpback whales. Metcalfe et al. (2004) found in biopsy sampled humpback young of the year 

in the Gulf of St. Lawrence PCB levels similar to that of their mothers and other adult females, 

indicating that bioaccumulation can be rapid, and that transplacental and lactational partitioning 

did little to reduce contaminant loads.

Although there has been substantial research on the identification and quantification of such 

contaminants on individual whales, no detectable effect from contaminants has been identified in 

baleen whales. There may be chronic, sub-lethal impacts that are currently unknown. The 

difficulty in identifying contaminants as a causative agent in humpback whale mortality and/or 

decreased fecundity led the BRT to conclude the severity of this threat was low in all regions, 

except where lack of data indicated a finding of unknown.

Energy Exploration and Development

The BRT defined identified threats from energy exploration and development to include oil spills 

from pipelines, rigs or ships, increased shipping, and construction surrounding energy 

development (oil, gas, or alternative energy). This category does not include noise from energy 

development, which is considered under ‘anthropogenic noise’. 

Little is known about the effects of oil or petroleum on cetaceans and especially on mysticetes. 

Oil spills that occur while whales are present could result in skin contact with the oil, baleen 

fouling, ingestion of oil, respiratory distress from hydrocarbon vapors, contaminated food 

sources, and displacement from feeding areas (Geraci et al. 1989). Actual impacts would depend 

on the extent and duration of contact, and the characteristics of the oil. Most likely, the effects of 

oil would be irritation to the respiratory membranes and absorption of hydrocarbons into the 

bloodstream (Geraci et al. 1989). Polycyclic aromatic hydrocarbons (PAHs) are components of 

crude oil which are not easily degraded and are insoluble in water, making them quite 

detrimental in the marine environment (Pomilla et al. 2004). PAHs have been associated with 

proliferative lesions and alteration to the immune and reproductive systems (Martineau et al.

2002). Long term ingestion of pollutants, including oil residues, could affect reproduction, but 

data are lacking to determine how oil may fit into this scheme for humpback whales.

Although the risk posed by operational oil rigs is likely low, failures and catastrophic events that 

may result from the presence of rigs pose high risks. Since the BRT had already determined that 

threat assessments would focus on present threats, the mere presence of oil rigs was not 

interpreted to warrant a threat level above low. However, the level of impact that such a 

catastrophic event may have on a population was considered in the evaluations. 

Harmful Algal Blooms (HABs)

Some algal blooms are harmful to marine organisms and have been linked to pollution from 

untreated industrial and domestic wastewater. Toxins produced by different algae can be 

concentrated as they move up the food chain, particularly during algal blooms. Naturally 

occurring toxin poisoning can be the cause of whale mortalities and is particularly implicated 

42
when unusual mortality events4 (UME) occur. The best documented UME for humpback whales 

attributable to disease occurred in 1987-1988 in the North Atlantic, when at least 14 mackerelfeeding humpback whales died of saxitoxin poisoning (a neurotoxin produced by some 

dinoglagellate and cyanobacteria species) in Cape Cod, Massachusetts (Geraci et al. 1989). In 

the Gulf of Maine in 2003, a few sampled individuals among 16 humpback whale carcasses were 

found with saxitoxin and domoic acid (produced by certain species of diatoms, a different type of 

algae) and the situation was declared to be an Unusual Mortality Event (Gulland 2006). 

Despite the UMEs described above, harmful algal blooms (HABs) were determined to represent 

a minor threat to most humpback whale populations. HABs may be increasing in Alaska, but the 

BRT was unaware of records of humpback whale mortality resulting from HABs in this region. 

The BRT discussed the possible levels of unobserved mortality that may be resulting from HABs 

and determined that as the West Indies population had been affected by HABs in the past it is 

likely experiencing a higher level of HAB-related mortality than is detected.

B.2 Overutilization for commercial, recreational, scientific, or educational purposes

Whaling

Direct hunting, although rare today, was the main cause of initial depletion of humpback whales 

and other large whales. An international moratorium on commercial whaling for all large whale 

species was established by the International Whaling Commission (IWC) in 1982, which took 

effect in 1986 and affected all member (signatory) nations (paragraph 10e, IWC 2009a). 

However, the moratorium can be circumvented by any country that lodged an objection to the 

decision, or through special permit whaling (so-called “scientific whaling”). Norway and 

Iceland both maintain objections, while Japan has extensively utilized the scientific whaling. 

Commercial Whaling

Iceland and Norway currently hunt a number of whale species commercially under objection to 

the IWC moratorium, although humpback whales have not been hunted by either nation in recent 

years. The present international moratorium on commercial whaling will remain in place unless 

a 75% majority of IWC signatory members vote to lift the moratorium. Following this, under 

current IWC management procedures, humpback whale stocks considered to have recovered to

over 54% of their pre-whaling levels (based on a detailed “comprehensive assessment” of their 

population status) could be subject to commercial whaling, with a quota that in theory would be 

determined by the Revised Management Procedure. This procedure implements a quasiBayesian Catch Limit Algorithm to calculate allowable catches for each stock (Cooke 1992). 

The effects of these catches on population abundance would be simulated via a series of 

Implementation Simulation Trials prior to agreement of quotas for commercial hunting. Since 

whaling is carried out under objection by Iceland and Norway, they are not subject to this 

management scheme for allocating quotas for any species.

The BRT believed that the likelihood of a resumption of commercial whaling is currently low; 

however, if hunting were to resume (either through objection, scientific research takes or 

commercial quotas), the impact on the DPSs concerned would have to be evaluated at that time.

4 Unusually large numbers of whales stranding in close proximity and in a relatively short time frame, exhibiting 

similar or unusual pathological or clinical states or an abnormal physical condition

43

 
Scientific Whaling

Since implementation of the international moratorium of whaling, some nations have continued 

to hunt whales under Article VIII of the International Convention for the Regulation of Whaling 

1946, which allows the killing of whales for scientific research purposes. Three nations 

originally conducted scientific whaling; Iceland, Norway, and Japan. Presently only Japan 

pursues scientific whaling, under the programs JARPAII and JARPNII (‘Japanese Whale 

Research Program under Special Permit in the Antarctic’ and ‘North Pacific’ respectively) while 

Iceland and Norway hunt whales commercially under objection to the moratorium. Scientific 

whaling is presently unregulated, and no quotas are enforced for this activity (Clapham et al.

2003b). In 2012 the Government of Japan issued Special Permits authorizing the 

implementation of a take of Antarctic minke, fin and humpback whales for scientific purposes in 

the Southern Ocean; research take of up to 50 humpbacks is included in the Special 

Permits. However, at the time of this review Japan had informed the Secretariat that it will 

continue to suspend the capture of humpback whales for the 2013 season (IWC 2013).

Subsistence Hunting 

Subsistence hunting in the North Atlantic is conducted on the island of Bequia in St. Vincent and 

the Grenadines in the Lesser Antilles (Reeves 2002). In 1986, St Vincent and the Grenadines 

asked for a humpback quota from the IWC based on their history of artisanal whaling in the 

community and the small number of whales taken (Reeves 2002). Bequia currently retains an 

IWC “block” quota of up to 24 whales over a six-year period (2013-2018) (IWC 2012). 

A small hunt, not regulated by the IWC, is also thought to exist in the Gulf of Guinea at the 

island of Pagalu (Aguilar 1985; Reeves 2002). No information exists on the fishery since 1975, 

but as of 1970 whales were still being taken in the area. 

It does not appear that Tonga hunted whales before Europeans arrived in the region in the 19th

century (Reeves 2002). Tonga was used as a provisioning station for whaling vessels from the 

Northern Hemisphere while they operated in the South Pacific. Tongans then began conducting 

shore-based whaling in the late 1880s or early 1900s and developed a taste for whale meat, 

increasing demand and prompting new boats and whalers to enter the growing industry (Reeves 

2002). Catch rates (whales landed) were estimated at 10-20 whales/year for the 1950s and 1960s 

and at least 3-8 whales/year for the mid 1970s (Reeves 2002). In 1979, the Tonga Whaling Act 

was passed after a Royal Decree in 1978, prohibiting the catch of whales on what was originally 

designated as a temporary basis pending an assessment of the population by the International 

Whaling Commission (Keller 1982; Reeves 2002; Kessler and Harcourt 2012). However, no 

whaling has been carried out in Tonga since then.

Greenland began hunting humpback whales before 1780 (Reeves 2002). As the take of bowhead 

whales decreased from 1750 to 1850, humpback whales became a more frequent target (Reeves 

2002). The hunting of humpback whales by Greenland was banned by the IWC beginning in 

1986, although 14 whales were taken illegally over the period 1988-2006. In 2010, a quota was 

reinstated, and 27 humpbacks were killed between 2010 and 2012.

Other “hunts”

Genetic monitoring of Japanese markets (1993-2009) identified humpback whale as the source of 

17 whale meat products. These are believed to have been killed through direct or indirect 

fisheries entanglement (Steel et al. 2009). In Japan, it is legal to kill and sell any entangled 

44
whale as long as the take is reported; there is suspicion that this provides a cover for intentional 

“entanglements”, although the level of such takes in currently unknown.

In summary, the current impact of whaling activities on global humpback whale populations is 

very low, with only a handful of humpback whales taken annually in two known aboriginal 

fisheries. The BRT discussed the possibility of expanded commercial whaling of humpback 

whales in the Southern Ocean but determined that new whaling action in the near future was 

unlikely. Therefore, the BRT attributed a low level risk of whaling for all but one DPS. 

Poaching is suspected to occur in Korean waters and off Japan, and for this reason the threat of 

whaling to the Okinawa/Philippines DPS was determined to be medium.

Whale-watching

Whale-watch tourism is a global industry with major economic value for many coastal 

communities (O'Connor et al. 2009). The industry has been expanding rapidly since the 1980s 

(estimated 3.7% global increase in whale watchers per year between 1998-2008, O'Connor et al.

2009; Kessler and Harcourt 2012). Whale-watching operations have been documented in 119 

countries worldwide as of 2008, including on many humpback whale feeding grounds, breeding 

grounds and migratory corridors (O'Connor et al. 2009).

The most common reported response of humpback whales to whale-watching boats was 

increased swimming speed during exposure; there was little evidence of significant effects on 

inter-breath intervals and blow rates (Weinrich et al. 2008). Passive acoustic monitoring and 

localization of humpback whale songs in the presence of whale-watching boats on Brazilian 

breeding grounds also found that whales moved away from the boat in the majority of cases 

(68.4% of the time when boats were less than 2.5 miles distant, Sousa-Lima and Clark 2009). 

Only one study has attempted to assess the population-level effects of whale-watching on 

humpback whales, as the relevant parameters are very difficult to measure. Weinrich and 

Corbelli (2009) reported that calving rate and calf survival to age two did not seem to be 

negatively affected by whale-watching on a subset of the Gulf of Maine feeding ground 

(Stellwagen Bank). The authors noted that in areas of heavy ship traffic, isolating the impacts of 

whale-watching on biological parameters is difficult and may not be conclusive (Weinrich and 

Corbelli 2009) and is difficult to determine at either the individual or population level.

Efforts to manage whale-watching operations have included limiting the number of whalewatching vessels, limiting the time vessels spend near whales, specifying the manner of 

operating around whales, and establishing limits to the period of exposure of the whales. In 

some areas, whale-watching industries operate under regulations while others operate under 

guidelines or are still unregulated, and this industry is still growing rapidly in many areas (over 

10% per year in Oceania, Asia, South America, Central America and the Caribbean) (Carlson 

2009; O'Connor et al. 2009).

The BRT discussed the available evidence regarding the impact of whale-watching on humpback 

whale populations. All available evidence supports the negligible impact of these activities, and 

the BRT determined this threat is low for all DPSs. 

45
Scientific Research

Humpback whales have been the subject of field research studies for decades. The primary 

objective of many of these studies has generally been to gather data for behavioral and ecological 

studies. In the U.S., permits authorize investigators to make close approaches to endangered 

whales for photographic identification, biopsy sample collection, behavioral observations, 

passive acoustic recording, aerial photogrammetry, satellite tagging, and underwater 

observations. Research on humpback whales is likely to continue and increase in the future, 

especially for the collection of genetic information, photographic studies, and acoustic studies. 

Research activities could result in disturbance to humpback whales, but are closely monitored 

and evaluated in the U.S. in an attempt to minimize any necessary impacts of research. 

The BRT discussed the available evidence regarding the impact of scientific research on 

humpback whale populations. All available evidence supports the negligible impact of these 

activities, and the BRT determined this threat is low for all DPSs. 

B.3 Disease or predation

Disease and Parasites

Information on disease or parasites is unavailable for many humpback whale populations. Direct 

monitoring of species biochemistry and pathology, used to determine the state of health in 

humans and domestic animals, is very limited for humpback whales as for most marine 

mammals and there is little published on humpback whale disease as a result. Humpback whales 

carry a crustacean ectoparasite (cyamid Cyamus boopis). While the whale is the main source of 

nutrition for this parasite (Schell et al. 2000), there is little evidence that they contribute to whale 

mortality. Humpback whales can also carry the giant nematode Crassicauda boopis (Bayliss 

1920), which is known to cause a serious inflammatory response (leading to vascular occlusion 

and kidney failure) in a few balaenopterid species (Lambertsen 1992). 

Individual humpback whales in Hawaiian waters have a high occurrence of skin lesions but it is 

unclear whether this is due to a parasite or disease. It is estimated that approximately 60% of 

adults in Hawaii and Oceania have these skin lesions. Whether the lesions are entirely benign is 

unknown. The BRT concluded that where some information is available, disease and parasites 

do not pose a substantial threat to humpback whale populations.

Predation

The most common predator of humpback whales is the killer whale (Orcinus orca, Jefferson et 

al. 1991), although predation by large sharks may also occur. Attacks by false killer whales 

(Pseudorca crassidens) have also been reported or inferred on rare occasions. Attacks by killer 

whales on humpback whale calves has been inferred by the presence of distinctive parallel ‘rake’ 

marks from killer whale teeth across the flukes (Shevchenko 1975). While killer whale attacks 

of humpback whales are rarely observed in the field (Ford and Reeves 2008), the proportion of 

photo-identified whales bearing rake scars is between zero and 40%, with the greater proportion 

of whales showing mild scarring (1-3 rake marks) (Wade et al. 2007; Steiger et al. 2008). This 

suggests that attacks by killer whales on humpback whales vary in frequency across regions. It 

also suggests either most killer whale attacks result in mild scarring, or those resulting in severe 

scarring (4 or more rakes, parts of fluke missing) are more often fatal. Most observations of 

humpback whales under attack from killer whales reported vigorous defensive behavior and tight 

grouping when more than one humpback whale was present (Ford and Reeves 2008).

46
Photo-identification data indicate that rake marks are usually acquired in the first year of life, 

although attacks on adults also occur (Wade et al. 2007; Steiger et al. 2008). Killer whale 

predation may influence survival during the first year of life (Wade et al. 2007). There has been 

some debate as to whether killer whale predation (especially on calves) is a motivating factor for 

the migratory behavior of humpback whales (Corkeron and Connor 1999; Clapham 2001). How 

significantly motivating this factor is also depends on the importance of humpback whales in the 

diet of killer whales, another debated topic that remains inconclusive in the published literature 

(Springer et al. 2003; Wade et al. 2007; Kuker and Barrett-Lennard 2010). No analyses of killer 

whale stomach contents have revealed remains of humpback whales (Shevchenko 1975),

suggesting that if humpback whales are taken at all, they comprise at most a small part of the 

diet. However these analyses took place during the height of the whaling period, when 

humpback whales were at a low density, and may therefore have been less available for 

predation. 

There is also evidence of shark predation on calves and entangled whales (Mazzuca et al. 1998). 

Shark bite marks on stranded whales may often represent post-mortem feeding rather than 

predation i.e., scavenging on carcasses (Long and Jones 1996). 

The BRT noted that 44% of all flukes photographed from the humpback whale population off 

Mexico are scarred with killer whale tooth rakes. Even for this population, the BRT determined 

that the actual impact of predation at the population level is likely quite low and noted that 

although scarring is a useful assessment, the level of mortality is unknown but is likely not 

prohibiting population growth. The threat of predation was therefore ranked as low or unknown 

for all DPSs. 

B.4 Adequacy of Existing Regulatory Mechanisms

Most of the threats the BRT evaluated are subject to various national, international and/or local 

regulations, and the BRT determined that the adequacy of these regulations is, at least to a large 

degree, reflected in the overall biological status of the species. The BRT also considered the 

adequacy of the major regulations governing these threats when making predictions about future 

status. For example, the International Convention for the Regulation of Whaling and the Marine 

Mammal Protection Acts provide a regulatory context for evaluating the likelihood that 

overutilization will become a significant threat in the future, assuming these or equivalent laws 

or agreements remain in effect in the future. 

Here, we summarize key regulatory mechanisms identified as potentially affecting the 

conservation of humpback whales. Some additional area-specific information is presented in the 

relevant DPS-specific sections as appropriate. 

47
B.4.1 International agreements

International Convention for the Regulation of Whaling

The International Whaling Commission was set up under the International Convention for the 

Regulation of Whaling, signed in 1946. The organization describes its functions as follows:

The main duty of the IWC is to keep under review and revise as necessary the measures laid 

down in the Schedule to the Convention which govern the conduct of whaling throughout the 

world. These measures, among other things, provide for the complete protection of certain 

species; designate specified areas as whale sanctuaries; set limits on the numbers and size 

of whales which may be taken; prescribe open and closed seasons and areas for whaling; 

and prohibit the capture of suckling calves and female whales accompanied by calves. The 

compilation of catch reports and other statistical and biological records is also required.

In addition, the Commission co-ordinates and funds conservation work on many species of 

cetaceans. This includes work to reduce the frequency of ship strikes, to co-ordinate 

disentanglement events and to establish Conservation Management Plans for key species 

and populations. Recently, the Commission has adopted a Strategic Plan for Whale

Watching so as to facilitate the further development of this activity in a way which is 

responsible and consistent with international best practice. [http://iwc.int/history-andpurpose, accessed February 10, 2014]. 

Part of the IWC’s function is to set catch limits for commercial whaling. These have been set at 

zero since 1985, an action known as the commercial whaling moratorium. Since that time, the 

IWC’s Scientific Committee has developed a stock assessment and catch limit methodology 

called the “revised management procedure”, with the goal of providing information on catch 

limits consistent with maintaining sustainable populations. As of 2014, the IWC has maintained 

the zero catch limit, however, a policy which has engendered considerable debate within the 

organization. The IWC’s regulations provide a process by which countries may object to 

specific provisions, and Norway and Iceland currently allow commercial whaling based on these 

objections. The IWC also develops catch limits for aboriginal whaling, including take of 

humpback whales in coastal areas of Greenland and the West Indies. The ICRW allows for 

signatory nations to harvest whales for scientific purposes through their own national permit 

process, although humpback whales have not been reported to have been taken under this 

process. 

The Convention on International Trade in Endangered Species of Wild Fauna and Flora 

(CITES)

The Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES)

is aimed at protecting species at risk from unregulated international trade. CITES regulates 

international trade in animals and plants by listing species in one of its three appendices. The 

level of monitoring and control to which an animal or plant species is subject depends on which 

appendix the species is listed in. Appendix I includes species threatened with extinction which 

are or may be affected by trade; trade of Appendix I species is only allowed in exceptional 

circumstances. Appendix II includes species not necessarily threatened with extinction 

presently, but for which trade must be regulated in order to avoid utilization incompatible with 

their survival. Appendix III includes species that are subject to regulation in at least one country, 

48
and for which that country has asked other CITES Party countries for assistance in controlling 

and monitoring international trade in that species. Humpback whales are currently listed in 

Appendix I under CITES.

The International Union for the Conservation of Nature and Natural Resources Red List

The IUCN Red List identifies and documents those species most in need of conservation 

attention if global extinction rates are to be reduced. It is widely recognized as the most 

comprehensive, apolitical global approach for evaluating the conservation status of plant and 

animal species. In order to produce Red Lists of threatened species worldwide, the IUCN 

Species Survival Commission draws on a network of scientists and partner organizations, which 

use a scientifically standardized approach to determine species’ risks of extinction. Humpback 

whales are currently classified by the IUCN as “least concern” (IUCN 2013; IUCN Red List of 

Threatened Species. Version 2013.2. <www.iucnredlist.org>. Downloaded on 11 February 

2014). 

International Maritime Organization (IMO) 

The International Maritime Organization (IMO), a branch of the United Nations and the 

recognized international authority on shipping and safety at sea, participates in reducing the 

shipping industry’s impacts to the sea from pollution (oil, garbage, noxious substances). 

Regulations to address pollution from maritime vessels include MARPOL (International 

Convention for the Protection of Pollution from Ships), MARPOL Annexes, International 

Conventions on Oil Pollution Preparedness Response and Co-operation, and Prevention of 

Marine Pollution by Dumping of Wastes and Other Matter. The IMO’s Marine Environment 

Protection Committee designates regions as “Particularly Sensitive Sea Areas” (PSSA) and 

“Areas to be Avoided” for various ecological, economic or scientific reasons. PSSA regions

include The Great Barrier Reef (Australia), the Galapagos Islands (Ecuador), and the 

Papahanaumokuakea Marine National Monument (North Pacific). The IMO was approached 

for the first time regarding conservation of an endangered whale species in 1998 – a protective 

measure for North Atlantic right whales (Silber et al. 2012). Since then, the IMO has been 

approached over a dozen times with nations’ proposals to establish or amend routing measures in 

various locations to reduce the threat of vessel collisions with endangered whales, including

humpback whales (Silber et al. 2012). For example, the IMO has endorsed Areas To Be 

Avoided in U.S. and Canadian waters to reduce the threat of ship strikes of right whales 

(Fleming and Jackson 2011, pp. 28-29), measures that also benefit humpback whales. IMOendorsed modifications to Traffic Separation Schemes (TSS) have been established in areas off 

Boston, San Francisco, near Santa Barbara (the latter two primarily for humpback whales); and a 

new TSS, along with vessel speed advisories, have been proposed for the Pacific side of the 

Panama Canal to protect large whale species from vessel collisions. 

Convention on the Conservation of Migratory Species of Wild Animals (CMS) or Bonn 

Convention 

Convention on the Conservation of Migratory Species of Wild Animals (CMS) is an 

intergovernmental treaty which requires range states to protect migratory species including

humpback whales where they occur, conserve or restore habitats, mitigate obstacles to migration 

and control other endangering factors. The humpback whale is listed in Appendix I of the CMS 

(species in danger of extinction throughout all or a significant portion of their range). Parties to 

CMS are required to prohibit take of Appendix I species. The CMS has developed binding

49
Agreements and nonbinding Memoranda of Understanding (MOU). An MOU for the 

Conservation of Cetaceans and their Habitats in the Pacific Islands Regions became effective in 

2006 and offers a level of protection to the Southern Hemisphere populations of humpback 

whales and their habitats in this region. The CMS Agreements on the Conservation of a) Small 

Cetaceans in the Baltic, North East Atlantic, Irish and North Seas (29.03.1994) and b) Cetaceans 

of the Black Seas, Mediterranean and Contiguous Atlantic Area are not designed specifically for 

the humpback whale but may provide incidental protection to the species. 

Council of Europe’s Bern Convention on the Conservation of European Wildlife and Habitats

The Bern Convention is a regional European treaty on conservation of wild flora and fauna and 

their natural habitats and calls for signatories to provide special protection for fauna species 

listed in Appendix II and III to the convention. The convention is a binding agreement for 

participating parties, and its aim is to ensure conservation by means of cooperation, including 

efforts to protect migratory species. The Parties promote national policies and education for the 

conservation of nature and the integration of conservation into environmental policies. 

The humpback whale is listed in Appendix II - fauna species to be strictly protected – which 

prohibits deliberate capture and killing, damage to or destruction of breeding sites, deliberate 

disturbance of animals during breeding and rearing, and the possession of and internal trade in 

these animals alive or dead (Council of Europe’s Bern Convention 2013).

Council of the European Union (EU) Directive 92/43 on the Conservation of Natural Habitats 

and of Wild Fauna and Flora (EU Habitats Directive)

The provisions of the EU Habitats Directive are intended to promote the conservation of 

biodiversity in EU member countries. EU members meet the habitat conservation requirements 

network known as Natura 2000. Humpback whales are listed in Annex IV of the convention 

which identifies species determined to be in need of strict protection across the European region. 

Twenty-seven member states work with the same legislative framework to protect species. 

Actions originating from the EU Habitats Directive that may provide protection to humpback 

whales in the region include a) coordinated development of a European Red List of species 

threatened at the European level (parallel with the IUCN listings), and b) guidance documents on 

the protection of species listed under the Directive, and on the development of a network of 

conservation areas in the offshore marine environment and c) species assessment reports. While 

not regulatory in nature, these actions are designed to reduce threats and provide a conservation 

benefit to the Atlantic humpback whales. 

Numerous additional international or regional treaties, conventions and agreements offer some 

degree of protection for humpback whales and their habitat (reviewed by Hoyt 2011). 

Commission for the Conservation of Antarctic Marine Living Resources

This commission was established in 1982 with 25 member countries. Its objective is the 

conservation of Antarctic marine life, particularly krill and the Antarctic marine ecosystems that 

depend on krill. The commission manages fisheries for Antarctic krill and several finfish species 

with the goal of ensuring long-term sustainability and existing ecological relationships. 

50
B.4.2 Domestic Regulatory Mechanisms

Marine Mammal Protection Act of 1972, as amended (MMPA)

In U.S. waters, humpback whales are protected by the MMPA (16 U.S.C. 1361 et seq.). The 

MMPA was enacted in response to growing concerns among scientists and the general public 

that certain species and populations of marine mammals were in danger of extinction or 

depletion as a result of human activities. The MMPA set forth a national policy to prevent 

marine mammal species or population stocks from diminishing to the point where they are no 

longer a significant functioning element of the ecosystems. The lead federal agencies for 

implementing the MMPA are FWS and NMFS.

The MMPA places an emphasis on habitat and ecosystem protection. The habitat and ecosystem 

goals set forth in the MMPA include: (1) management of marine mammals to ensure they do not 

cease to be a significant element of the ecosystem to which they are a part; (2) protection of 

essential habitats, including rookeries, mating grounds, and areas of similar significance “from 

the adverse effects of man's action”; (3) recognition that marine mammals “affect the balance of 

marine ecosystems in a manner that is important to other animals and animal products” and that 

marine mammals and their habitats should therefore be protected and conserved; and (4) 

directing that the primary objective of marine mammal management is to maintain “the health 

and stability of the marine ecosystem.” Congressional intent to protect marine mammal habitat is 

also reflected in the definitions section of the MMPA. The terms “conservation” and 

“management” of marine mammals are specifically defined to include habitat acquisition and 

improvement.

The MMPA includes a general moratorium on the taking and importing of marine mammals, 

which is subject to a number of exceptions. Some of these exceptions include take for scientific 

purposes, public display, subsistence use by Alaska Natives, and unintentional incidental take 

coincident with conducting lawful activities. Take is defined in the MMPA to include the 

“harassment” of marine mammals. “Harassment” includes any act of pursuit, torment, or 

annoyance which “has the potential to injure a marine mammal or marine mammal stock in the 

wild” (Level A harassment), or “has the potential to disturb a marine mammal or marine 

mammal stock in the wild by causing disruption of behavioral patterns, including but not limited 

to, migration, breathing, nursing, breeding, feeding, or sheltering” (Level B harassment).

The Secretaries of Commerce and of the Interior have primary responsibility for implementing 

the MMPA. The Department of Commerce, through the NMFS, has authority with respect to 

whales, porpoises, seals, and sea lions. The remaining marine mammals, including polar bears, 

walruses, and sea otters, are managed by the Department of the Interior through the FWS. Both 

agencies are responsible for the promulgation of regulations, the issuance of permits, the conduct 

of scientific research, and enforcement as necessary to carry out the purposes of the MMPA.

U.S. citizens who engage in a specified activity other than commercial fishing (which is 

specifically and separately addressed under the MMPA) within a specified geographical region

may petition the Secretaries to authorize the incidental, but not intentional, taking of small 

numbers of marine mammals within that region for a period of not more than five consecutive 

years (16 U.S.C. 1371(a)(5)(A)). The Secretary “shall allow” the incidental taking if the 

Secretary finds that ``the total of such taking during each five-year (or less) period concerned 

51
will have a negligible impact on such species or stock and will not have an unmitigable adverse 

impact on the availability of such species or stock for taking for subsistence uses.” If the 

Secretary makes the required findings, the Secretary also prescribes regulations that specify: (1) 

permissible methods of taking, (2) means of effecting the least practicable adverse impact on the 

species, their habitat, and their availability for subsistence uses, and (3) requirements for 

monitoring and reporting. The regulatory process does not authorize the activities themselves, 

but authorizes the incidental take of the marine mammals in conjunction with otherwise legal 

activities described within the regulations.

Similar to promulgation of incidental take regulations, the MMPA also established an expedited 

process by which U.S. citizens can apply for an authorization to incidentally take small numbers 

of marine mammals where the take will be limited to harassment (16 U.S.C. 1371(a)(5)(D)). 

These authorizations are limited to one-year and as with incidental take regulations the Secretary 

must find that the total of such taking during the period will have a negligible impact on such 

species or stock and will not have an unmitigable adverse impact on the availability of such 

species or stock for taking for subsistence uses. NMFS refers to these authorizations as 

Incidental Harassment Authorizations.

Certain exceptions from the prohibitions on taking are provided. The MMPA exempts coastaldwelling Alaska Natives from the prohibitions on the taking of marine mammals for subsistence 

purposes. Sections 101(b)(3) and 103 of the MMPA provide for subsistence harvest regulations 

for marine mammal stocks designated as depleted under that Act, after notice and administrative 

hearings as prescribed by the MMPA. Section 119 of the MMPA allows the Secretary of 

Commerce to enter into cooperative agreements with Alaska Native organizations to conserve 

marine mammals and provide co-management of subsistence uses.

Under the MMPA, NMFS also evaluates and provides permits for the “taking” of large whale 

species for those engaged in scientific research focused on those species.

Under the authority of the ESA and the MMPA, NMFS issued a final rule (66 FR 29502, May 

31, 2001) effective in 2001 in waters within 200 nautical miles of Alaska making it unlawful for 

a person subject to the jurisdiction of the United States to a) approach within 100 yards of a 

humpback whale, b) cause a vessel or other object to approach within 100 yards of a humpback 

whale or c) disrupt the normal behavior or prior activity of a whale. Exceptions to this rule 

include approaches permitted by NMFS; vessels which otherwise would be restricted in their 

ability to maneuver; commercial fishing vessels legally engaged in fishery activities; state, local 

and Federal government vessels operating in official duty; and the rights of Alaska Natives. 

Additional regulations such as the NMFS right whale regulations in the U.S. North Atlantic and 

other regional or local maritime speed zones help reduce the threat of vessel collisions involving 

humpback whales. The ship collision reduction rule established regulations to limiting vessel 

speeds to no more than 10 knots applicable to all vessels 65 feet (19.8m) or greater in length in 

certain locations and at certain times of the year along the east coast of the U.S. Atlantic 

seaboard (73 FR 60173). NMFS has the authority under the MMPA and the ESA to promulgate 

further regulations to address the threat of vessel collisions with endangered large whale species. 

Endangered Species Act (ESA) 

The ESA (16 U.S.C. 1531 et seq.) provides a program for the conservation of imperiled species 

and the ecosystems upon which they depend. The lead federal agencies for implementing the 

52
ESA are the FWS and the NMFS. Under the ESA, species may be listed as either endangered or 

threatened. “Endangered” means a species is in danger of extinction throughout all or a 

significant portion of its range. “Threatened” means a species is likely to become endangered 

within the foreseeable future throughout all or a significant portion of its range. For the purposes 

of the ESA, species are defined to include subspecies, varieties, and for vertebrates, distinct 

population segments. The ESA requires federal agencies to conduct their activities in such a way 

as to conserve listed species. Section 7 of the ESA also requires federal agencies, in consultation 

with the FWS and/or NMFS, to ensure that activities they authorize, fund or carry out are not 

likely to jeopardize the continued existence of any listed species (or species proposed for listing) 

or result in the destruction or adverse modification of designated or proposed critical habitat of 

such species. NMFS has conducted scores of Section 7 consultations with the United States 

Coast Guard (USCG), the Army Corps of Engineers, the Bureau of Ocean Energy Management 

and other agencies to ensure actions by these agencies do not adversely affect listed large whale 

species, including humpback whales. The ESA forbids the import, export, or interstate or 

foreign sale of species listed as endangered without a special permit. It also makes “take” of 

species listed as endangered illegal—forbidding the killing, harming, harassing, pursuing, or 

removing the species from the wild. Any or all of these protections may be provided to a species 

listed as threatened through regulations issued under ESA section 4(d).

Outer Continental Shelf Lands Act (OCSLA) 

The Outer Continental Shelf Lands Act (OCSLA) established federal jurisdiction over 

submerged lands on the outer continental shelf (OCS) seaward of the state boundaries (3-mile 

limit) in order to expedite exploration and development of oil and gas resources on the OCS. 

Implementation of OCSLA is delegated to the Minerals Management Service (now known as the 

Bureau of Ocean Energy Management, Regulation and Enforcement) of the Department of the 

Interior. OCSLA mandates that orderly development of OCS energy resources be balanced with 

protection of human, marine and coastal environments. Through consistency determinations, the 

OCSLA helps to ensure that OCS projects do not adversely impact humpback whales or

humpback whale habitat. 

Pelly Amendment to the Fisherman’s Protection Act

Section 8 of the Fishermen’s Protective Act, also known as the Pelly Amendment, was added to 

this 1954 statute by P.L. 92-219 (85 Stat. 786) in December 1971. The section originally 

required the Secretary of Commerce to report to the President when he or she determines that 

nationals of a foreign country are diminishing the effectiveness of an international fishery 

conservation program. The President is then authorized to direct the Secretary of the Treasury to 

prohibit the importation of fish products from the offending nation for such duration as he or she 

determines appropriate and to the extent that such prohibition is consistent with the General 

Agreements on Trade and Tariffs.

The Pelly Amendment was expanded by P.L. 95-376 (92 Stat. 714), September 18, 1978, to 

authorize the President to embargo wildlife products (including all fish not previously covered) 

whenever the Secretary of Commerce or the Secretary of the Interior certifies that nationals of a 

foreign country are engaging in trade or taking that diminishes the effectiveness of an 

international program in force with respect to the United States for the conservation of 

endangered or threatened species.

53
The Secretary of Commerce and Secretary of the Interior began certifying nations in 1974 for 

whaling violations (Japan and USSR). Norway was certified in 1987 and several times 

thereafter. Japan has been certified three times, the last being in 2000, and Iceland has been 

certified several times, including 2011 for whaling activities. Economic sanctions on marine 

products have not been imposed by the U.S. against these nations. 

Coast Guard Activities 

On February 18, 2005, the USCG announced a Port Access Route Study (PARS) of Potential 

Vessel Routing Measures to Reduce Vessel Strikes of North Atlantic Right Whales (Department 

of Homeland Security USCG, 70 FR 8312). Potential vessel routing measures were analyzed 

and considered to adjust existing vessel routing measures in the northern region of the Atlantic 

Coast, which included Cape Cod Bay, the area off Race Point at the northern end of Cape Cod, 

and the Great South Channel. The USCG used the information from the PARS to prepare and 

submit a report to Congress on May 8, 2006. The USCG announced the results of the PARS on 

May 24, 2006 (71 FR 29876). NMFS recommended realigning and amending the location and 

size of the western portion of the TSS in the approach to Boston, Massachusetts. The TSS was 

revised in 2007 and the new configuration appeared on nautical charts soon thereafter. 

On November 19, 2007, the USCG announced a second PARS to Analyze Potential Vessel 

Routing Measures to Reduce Vessel Strikes of North Atlantic Right Whales while also 

Minimizing Adverse Effects on Vessel Operations (72 FR 64968). The study area included 

approaches to Boston, MA, specifically, a northern right whale critical habitat in the area east 

and south of Cape Cod, MA, and the Great South Channel, including Georges Bank out to the 

exclusive economic zone boundary. In the second PARS, the USCG recommended establishing 

a seasonal Area to be Avoided (ATBA) and amending the southeastern portion of the TSS to 

make it uniform throughout its length. On behalf of the United States, the USCG submitted a 

series of proposals to the IMO to modify the TSS and to establish an ATBA which were 

subsequently endorsed by the IMO (Silber et al. 2012) and as described in the IMO’s 

publication, “Ships’ Routing”, 2008. In 2009, the TSS was revised and the ATBA was 

established. This was followed by a notice in the Federal Register announcing these changes (75 

FR 77529) and NOAA added the changes to applicable nautical charts. While the measures are 

designed specifically for the North Atlantic right whale, they are expected to benefit humpback 

whales co-occurring in these areas. 

In 2007, a program of auto-detection buoys and real-time whale vocalization detection 

information was incorporated into the Boston TSS as mitigation for liquefied natural gas (LNG) 

ship strike risk, primarily as a result of an ESA Section 7 consultation with the Maritime 

Administration. This program, stipulated as a condition of the consultation, was designed to 

reduce the threat of vessel collisions with right whales and other listed large whale species, 

including humpback whales in and around the boundaries of Stellwagen Bank National Marine 

Sanctuary. When right whales are auto-detected in the vicinity, LNG vessels are required to 

travel at speeds of 10 knots or less, a measure that almost certainly reduces the likelihood of 

vessel strikes of humpback whales occurring in the area as well.

TSSs are in place for San Francisco Bay and the Santa Barbara Channel to ensure safety of 

navigation. These TSSs were amended in June 1, 2013 to lessen the possibility of fatal vessel 

collisions with humpback whales and other listed large whale species. Modifications include 

54
narrowing and extending the Northern and Western approaches while the inbound lane of the 

Santa Barbara Channel TSS has been shifted shoreward to reduce the co-occurrence of ships and 

whales and reduce the likelihood of a vessel/whale collision.

National Park Service Activities

The U.S. Park Service has jurisdiction of marine waters (through the Fish and Wildlife 

Coordination Act) in Glacier Bay National Park and Preserve (established 1980; modified 1985). 

The following regulations are in place to protect humpback whales occurring there in the 

summer: restrictions on the number of vessels entering park waters; restrictions on vessel 

operating conditions in the known presence of humpback whales, mandatory vessel operating 

requirements in certain designated “whale waters”, mandatory vessel speed limits at certain 

times and locations; mandatory boater education for boaters entering the area, regulations 

restricting the harvest of humpback whale prey species and ship board observers to quantify ship 

strikes and interactions between cruise ships and whales. 

National Marine Sanctuary Act - Marine Sanctuaries and Marine Protected Areas (MPA)

Under the National Marine Sanctuaries Act, NOAA has broad discretion to enact guidelines and 

regulations provide protection to a number of large whale species, including the humpback whale 

in key aggregation locations. Humpback whales routinely occur in Stellwagen Bank; Gulf of 

the Farrallones, Channel Islands, Monterey Bay, Cordell Bank, and Olympic Coast National 

Marine Sanctuaries. The Hawaiian Islands Humpback Whale National Marine Sanctuary was 

established primarily to provide protections to a key North Pacific humpback whale 

breeding/nursery area. The Stellwagen Bank and Gulf of the Farallones National Marine 

Sanctuaries, in particular, have active humpback whale research programs and/or have 

established vessel speed advisories, whale approach guidelines, and other measures to reduce 

human threats to humpback and other large whale species.

B.4.3 Regional or National Regulations other than United States

Numerous nations have defined marine protected areas and sanctuaries that provide some 

protection to humpback whales (Hoyt 2011), and various nations have developed local 

regulations or guidelines governing whale watching activities (O’Connor et al. 2009). Hundreds 

of national laws also exist related directly or indirectly to the conservation of marine mammals 

(Appendix B). Where appropriate, some of these are discussed in more detail in the DPSspecific sections. 

B.5 Other natural or manmade factors affecting its continued existence

Competition with Fisheries

The BRT discussed the issue of competition with fisheries at length. In some areas, (e.g.,

Northern Gulf of Maine and Southeast Alaska) fishermen encircle feeding humpback whales and 

harvest fish from the bait balls upon which humpback whales feed (D. Matilla, unpublished 

observation). However, there is no evidence that this impacts the individuals or significantly 

depletes the food source. In a review of the evidence for interspecific competition in baleen 

whales, Clapham and Brownell (1996) found it to be extremely difficult to prove that interspecific competition comprises an important factor in the population dynamics of large whales. 

55
The BRT discussed the high level of fishing pressure in the region occupied by the 

Okinawa/Philippines population (a small humpback whale population). Although specific 

information on prey abundance and competition between whales and fisheries is not known in 

this area, overlap of whales and fisheries has been indicated by the bycatch of humpback whales 

in set-nets in the area. The BRT determined that competition with fisheries is a medium threat 

for this DPS given the high level of fishing and small humpback whale population, and a low or 

unknown threat for all other DPSs. 

Aquaculture

Aquaculture is not known to be a significant threat to humpback whales. Some entanglements 

have been recorded off Australia. Colombia has substantial aquaculture activity in inshore areas, 

but there is no information regarding the impact of this activity on humpback whales. The BRT 

determined that for most areas aquaculture does not pose a significant threat to humpback whales 

and should be assigned a low threat level. For Okinawa/Philippines, the Arabian Sea and the 2nd

western North Pacific population, sufficient information was not available for the threat level to 

be determined.

Anthropogenic Noise

Humans introduce sound intentionally and unintentionally into the marine environment for 

navigation, oil and gas exploration and acquisition, research, and military activities, to name a 

few. Noise exposure can result in a range of impacts, from those causing little or no impact to 

those being potentially severe, depending on the source, level, and various other factors. 

Response to noise varies by many factors, including the type and characteristics of the sound 

source, distance between the source and the receptor, characteristics of the animal (e.g., hearing 

sensitivity, behavioral context, age, sex, and previous experience with sound source) and time of 

day or season. Noise may be intermittent or continuous, steady (non-impulsive) or impulsive, 

and may be generated by stationary or moving sources. As one of the potential stressors to 

marine mammal populations, noise may seriously disrupt communication, navigational ability, 

and social patterns. Humpback whales use sound to communicate, navigate, locate prey, and 

sense their environment. Both anthropogenic and natural sounds may cause interference with 

these functions.

Anthropogenic sound has increased in all oceans over the last 50 years and is thought to have 

doubled each decade in some areas of the ocean over the last 30 or so years (Croll et al. 2001; 

Weilgart 2007). Low-frequency sound comprises a significant portion of this increase and stems 

from a variety of sources including that primarily from shipping, and an increasing amount from 

oil and gas exploration in some areas, as well as research and naval activities. Understanding the 

specific impacts of these sounds on mysticetes is difficult. However, it is clear that the 

geographic scope of potential impacts is vast as low-frequency sounds can travel great distances 

under water, but these sound have the potential to reduce communication space (e.g., Shipping 

was predicted to reduce communication space of singing humpback whales in the northeast by 

8%; Clark et al. 2009).

Humpback whales do not appear to be often involved in strandings related to noise events. 

There is one record of two whales found dead with extensive damage to the temporal bones near 

the site of a 5,000kg explosion which likely produced shock waves that were responsible for the 

56
injuries (Ketten et al. 1993; Weilgart 2007). Other detrimental effects of anthropogenic noise 

include masking and possible temporary threshold shifts. Masking results from noise interfering 

with cetacean social communication, which may range greatly in intensity and frequency. Some 

adjustment in acoustic behavior is thought to occur in response to masking and humpback songs 

were found to lengthen during low-frequency active (LFA) sonar activities (Miller et al. 2000). 

This altered song length persisted two hours after the sonar activities stopped (Fristrup et al.

2003). Researchers have also observed diminished song vocalizations in humpback whales 

during remote sensing experiments 200 km away from the whales’ location in the Stellwagen 

Banks National Marine Sanctuary (Risch et al. 2012). Hearing loss can also possibly be 

permanent if the sound is intense enough but there is great variability across individuals and 

other factors making it difficult to determine a standardized threshold. 

Excessive noise exposure may be damaging during early individual development, may cause 

stress hormone fluctuations, and/or may cause whales to leave an area or change their behavior 

within it (Weilgart 2007). Some responses are subtle and may occur after the exposure. 

Humpback whales exposed to underwater explosions and drilling associated with construction 

activities did not appear to change their behavior in reaction to the surveys but did appear to have 

reduced orientation abilities. Higher rates of fatal entanglement in fishing gear were observed in 

the area when whales were exposed to excessive noise, although the cause for this elevated 

entanglement rate was unclear (Ketten et al. 1993; Todd 1996). Some studies have found little 

reaction to noise and indicate potential tolerances to anthropogenic sound over short time and 

small spatial scales (Croll et al. 2001). 

There is likely an important distinction between immediate individual reactions to noise and 

long-term effects of noise exposure to populations. The cumulative and synergistic effects may 

be more harmful than studies to date have been able to assess. Though some researchers have 

argued that habituation to sound may occur, this can easily be confused with hearing loss or 

individual differences in tolerance levels (Bejder et al. 2006). Scientifically recommended 

mammal sound exposure levels have been made and vary depending on the sound source 

strength and the species of marine mammal(s) present (Southall et al. 2007). NMFS has recently 

updated guidance for temporary threshold shifts and permanent threshold shifts (see: 

http://www.nmfs.noaa.gov/pr/acoustics/guidelines.htm).

The issue of anthropogenic noise has been an area of intensive research but population-level 

impacts on cetaceans have not been confirmed. There is little definite information regarding, for 

example, the interruption of breeding and other behaviors or a resulting reduction in population 

growth or mortality of individuals. Therefore, the BRT considered this to be a low threat for all 

DPSs.

Vessel Collisions

Collisions between vessels and whales, or ship strikes, often result in life-threatening trauma or 

death for the cetacean. Impact is often initiated by forceful contact with the bow or propeller of 

the vessel. Ship strikes of humpback whales are typically identified by evidence of massive 

blunt trauma (fractures of heavy bones and/or hemorrhaging) in stranded whales, propeller 

wounds (deep slashes or cuts) and fluke/fin amputations on stranded or live whales (e.g. Wiley 

and Asmutis 1995).

57
Laist et al. (2001), Jensen and Silber (2003), Vanderlaan and Taggart (2007), and 

VanWaerebeek and Leaper (2008) compiled information available worldwide regarding 

documented collisions between ships and large whales (baleen whales and sperm whales). 

Humpback whales were the second-most commonly reported victims of vessel strikes (following 

fin whales). Of 292 recorded strikes contained in the Jensen and Silber (2003) database, 44 were 

of humpback whales. As of 2008, there were >143 recorded ship strikes involving humpback 

whales worldwide (Van Waerebeek and Leaper 2008); however the reported number is likely not 

a full representation of the actual number (particularly in the Southern Hemisphere) as many 

likely go undetected or unreported (Williams et al. 2011). Reporting of ship strikes is highly 

variable internationally, with reports required from vessels in the domestic waters of Australia, 

the U.S. and New Zealand but not in other countries. Measures to reduce ship strikes have been 

considered by the IMO Marine Environment Protection Committee and relevant IMO 

subcommittees (IWC 2010a).

Ship strike injuries were identified for 8% (10 of 123) of dead stranded humpback whales 

between 1975-1996 along the U.S. east coast, 25% (9 of 36) of which were along mid-Atlantic 

and southeast states (south of the Gulf of Maine) between Delaware Bay and Okracoke Island 

North Carolina (Wiley and Asmutis 1995). Ship strikes made up 4% of observed humpback 

whale mortalities between 2001-2005 (Nelson et al. 2007) and 7% between 2005-2009 (Henry et 

al. 2011) along the U.S. east coast, and the Canadian Maritimes. Among strandings along the 

mid and southeast U.S. coastline during 1975-1996, 80% (8 of 10) of struck whales were 

considered to be less the 3 years old based on their length (Laist et al. 2001). This suggests that 

young whales may be disproportionately affected. However, those waters are thought to be used 

preferentially by young animals (Swingle et al. 1993; Barco et al. 2002). It should be noted that 

ship strikes do not always produce external injuries and may therefore be underestimated among 

strandings that are not examined for internal injuries. 

In 1999, NMFS and the United States Coast Guard established two Mandatory Ship Reporting 

systems aimed at reducing ship strikes of North Atlantic right whales. When ships greater than 

300 gross tons enter two key right whale habitats--one off the northeast U.S. and one off the 

southeast U.S.--they are required to report to a shore-based station. In return, ships receive a 

message about whales, their vulnerability to ship strikes, precautionary measures the ship can 

take to avoid hitting a whale, and locations of recent sightings. While these systems were 

designed to protect right whales specifically, they are expected to also reduce the risk of ship 

strikes to other large whales, including humpback whales (National Marine Fisheries Service 

2008).

Whale strike mitigation measures currently in place for some vessels and regions include using 

dedicated observers (Weinrich and Pekarik 2007), speed reduction in some important habitat 

areas (73 FR 60173, 10 October, 2008), and shifting of shipping lanes away from areas of whale 

concentration to accommodate humpback whales and other species. Passive acoustic monitoring 

in areas of high shipping traffic also has promise for notifying mariners of whales in the area, as 

this method is relatively inexpensive, although detection is limited to vocalizing whales and 

specific source locations can be hard to determine (Silber et al. 2009). Based on this 

information, the BRT considers the threat of vessel collisions to be low to moderate, depending 

on region, and generally increasing. 

58
Fishing Gear Entanglements

Humpback whales may break through, carry away, or become entangled in fishing gear. Whales 

carrying gear may die at a later time, become debilitated or seriously injured, or have normal 

functions impaired, but with no assurance of the incident having been recorded. Of the nations 

reporting to the IWC between 2003-2008, 64.7% (n=11) noted humpback whale by-catch in their 

waters (Mattila and Rowles 2010). Whales have been documented carrying gear by fishery 

observer programs, opportunistic reports, and stranding networks. Some countries (e.g., U.S., 

Canada, Australia, South Africa) have well-developed reporting and response networks that 

facilitate the collection of information on entanglement frequency and impacts. However, such 

programs do not guarantee that entanglements are detected; fewer than 10% of humpback whale 

entanglements involving Gulf of Maine humpback whales are reported, despite a strong outreach 

and response network (Robbins and Mattila 2004). Furthermore, opportunistic reports that are 

not screened by experts do not necessarily yield accurate information about events, including 

gear type, configuration and original site of entanglement (Robbins et al. 2007b). The likelihood 

of receiving reports likely varies world-wide due to differences in observer awareness, reporting 

mechanisms and possible negative implications for reporting fishermen (Mattila and Rowles 

2010).

A study of gear removed from a subset of whales off the U.S. East Coast showed that 89% 

involved pots/traps or gillnet gear (Johnson et al. 2005). However, a wide range of gear types 

were represented and every part of the gear was found to be capable of entanglement (Johnson et 

al. 2005). The authors concluded that any line in the water column poses a potential risk of 

entanglement to humpback whales. This is further supported by the wide range of entangling 

gear reported in the South Pacific (Neilson 2006; Lyman 2009), Newfoundland (Lien et al. 1992)

and member nations of the IWC (Mattila and Rowles 2010).

More than half of the humpback whale entanglements examined off the U.S. East Coast involved 

entanglements around the tail (Johnson et al. 2005). The mouth and flippers are also known 

attachment sites, but their frequency is more difficult to assess. Scar-based studies have been 

developed to systematically study the frequency of non-lethal entanglement involving the tail 

(Robbins and Mattila 2001; Robbins and Mattila 2004). These techniques have been used in the 

Gulf of Maine (e.g., Robbins and Mattila 2001; Robbins and Mattila 2004; Robbins et al. 2009), 

Southeast Alaska (Neilson et al. 2009) and more broadly across the North Pacific Ocean 

(Robbins et al. 2007a; Robbins 2009). All populations studied in this manner to date have 

detected individuals with entanglement-related injuries. Annual research in the Gulf of Maine 

since 1997 has shown that a high percentage of individuals exhibit entanglement injuries and that 

new injuries are acquired at an average annual rate of 12% (Robbins et al. 2009). A two-year 

study in Southeast Alaska confirmed frequencies of entanglement injuries that were comparable 

to the Gulf of Maine (Neilson et al. 2009). Research undertaken across the North Pacific as part 

of the SPLASH project further suggests that entanglement is pervasive, but that interaction rates 

may be highest among coastal populations (Robbins et al. 2007a; Robbins 2009).

Both eye-witness reports and scar-based studies suggest that independent juveniles are 

significantly more likely to become entangled than adults (Robbins 2009). Calves exhibit a 

lower frequency of entanglement, likely due to having less time in which to have encountered 

gear (Neilson et al. 2009). Sex differences in entanglement frequency have been observed in 

59
some locations and time intervals (Robbins and Mattila 2001; Neilson et al. 2009), but these 

effects have not persisted in longer studies (Robbins and Mattila 2004). 

Entanglement may result in only minor injury, or potentially may significantly affect individual 

health, reproduction or survival. In one study, females with entanglement injuries produced 

fewer calves than females with no evidence of entanglement; such impacts on reproduction are 

still under investigation (Robbins and Mattila 2001). Mark-recapture studies of the fate of 

entangled whales in the Gulf of Maine suggest that juveniles are less likely than adults to survive 

(Robbins et al. 2008). Observed entanglement deaths and serious injuries in that region are 

known to exceed what is considered sustainable for the population (Glass et al. 2009). Most 

deaths likely go unobserved and preliminary studies suggest that entanglement may be 

responsible for 3-4% of total mortality, especially among juveniles (Robbins et al. 2009).

Much more is known about fishing gear entanglement in the Northern Hemisphere than in the 

Southern Hemisphere. The BRT noted the commercialization of bycatch off Japan, meaning an 

entangled whale is legally allowed to be killed and sold on the market (Lukoschek et al. 2009). 

Therefore, entanglement often leads to death for humpback whales in this region. While the 

number of reported bycaught animals is not large (3-5), the number of reports has been 

increasing and reports may not reflect the actual number caught. The BRT also noted that the 

Mexico population has one of highest scar rates from nets and lines in the North Pacific, 

indicating a high entanglement rate. Based on this information, the BRT concluded that the 

severity of the threat of fishing gear entanglements varies depending on region, ranging from low 

to high. 

Climate Change

Climate change has received considerable attention in recent years, with growing concerns about 

global warming and the recognition of natural climatic oscillations on varying time scales, such 

as long-term shifts like the Pacific Decadal Oscillation or short-term shifts, like El Niño or La 

Niña. Evidence suggests that the biological productivity in the North Pacific (Lowry et al. 1988; 

Quinn and Niebauer 1995) and other oceans could be affected by changes in the environment. 

Recent work has found that copepod distribution has shown signs of shifting in the North 

Atlantic due to climate change (Hays et al. 2005). Increases in global temperatures are expected 

to have profound impacts on arctic and sub-arctic ecosystems, and these impacts are projected to 

accelerate during this century (ACIA 2004; IPCC 2007).

The IWC has held two workshops on the topic of climate change and cetaceans (IWC 1997; IWC 

2010a) and the reports of these meetings provide useful summaries on the current state of 

knowledge on this issue, and on the large uncertainties associated with any projections of impact.

It is generally accepted that cetaceans are unlikely to suffer problems because of changes in 

water temperature per se (IWC 1997). Rather, global warming is more likely to effect changes 

in habitats that in turn potentially affect the abundance and distribution of prey in these areas. 

Factors such as ocean currents and water temperature may render currently used habitat areas 

unsuitable and influence selection of migration, feeding, and breeding locations for humpback 

and other whales. Changes in climate and oceanographic processes may also lead to decreased 

productivity of, or lead to different patterns in, prey distribution and availability. Such changes 

could affect whales that are dependent on this prey. While these regional or ocean basin-scale 

changes may occur, the actual magnitude and resulting impacts are not known.

60
All cetaceans have undoubtedly lived through considerable variation in climate (including 

multiple ice ages, and significant warming events) over the course of their evolutionary history. 

However, there is little knowledge regarding the ways in which cetaceans dealt with climate 

change in the past. Examination of bones related to Basque whaling in Canada indicate that the 

range of bowhead whales (Balaena mysticetus) in the North Atlantic shifted south during the socalled Little Ice Age in medieval times (McLeod et al. 2008). This almost certainly reflected a 

shift in the distribution of prey because of habitat and associated productivity changes, and it 

likely reflects the ability of large whales to adapt and extend their range when necessary.

There are no data on similar historical shifts by humpback whales. Considerable plasticity in the 

winter distribution of the species is suggested by the fact that the use of Hawai’i as a major 

breeding ground appears to be a relatively recent phenomenon which occurred sometime in the 

20th century (Herman 1979); the reason for such a shift is not known, but it is important to 

recognize that the humpback’s winter distribution is not tied to prey resources or biological 

productivity, a situation which presumably affords the species with flexibility in its colonization 

of breeding habitats.

Climate change may disproportionately affect species with specialized or restricted habitat 

requirements. The best-known example of this involves dependence upon sea ice, which is 

thought to represent a major problem for polar bears (Ursus maritimus), given that the species 

primarily hunts pagophilic ringed seals (Phoca hispida) (Schliebe et al. 2006). This represents a 

relatively simple and clear-cut example of cause and effect in the climate change debate; 

unfortunately, the situation for humpback whales and other cetaceans is not nearly as simple, 

given the complexity of the ecosystems in which they live. Climate change may exacerbate 

situations in which populations are already small and/or significantly affected by other 

anthropogenic impacts (such as entanglement or ship strikes). Species which possess little 

ability to disperse or colonize new habitats will also be particularly vulnerable.

None of these factors apply to humpback whales, with the possible exception of the Arabian Sea 

population, which is thought to be small and vulnerable to entanglement, shipping-related issues 

and possibly pollution. Furthermore, the uniquely restricted range of this non-migratory 

population is currently tied to seasonal monsoon-driven biological productivity in a relatively 

small region; the impact of climate change on this productivity is unknown, as is the ability of 

these humpback whales to shift their range as may be needed.

As noted by IPCC (2007), species in general potentially respond in one of three ways to major 

changes in climate: redistribution, adaptation, or extinction. Based upon what is known to date, 

redistribution is the most likely response for most humpback whales. Most large whales, 

including humpbacks, undertake extensive movements, both during a feeding season and on 

migration. These broad ranges (which routinely encompass much of an ocean basin), together 

with the animals’ ability to withstand prolonged periods of fasting through utilization of fat 

reserves in their blubber, potentially provide the whales with a means to adapt their ranges in 

response to major climate-related spatial shifts in biological productivity, notably by seeking out 

new habitats. This may in fact already be occurring in some places; humpback whales have 

recently been observed in the eastern Chukchi and Beaufort Seas (Clarke et al. 2014 in review), 

north of their usual range; this could represent the beginnings of a response to habitat changes 

relating to diminishing sea ice in the Arctic, although it might also simply reflect a growing 

population expanding its range. Prior to extensive whaling, humpback whales appear to have 

61
been quite common in at least the western (Russian) Chukchi Sea (Zenkovich 1954; Tomilin 

1967), and are still observed there today (Clarke et al. 2014 in review).

The BRT determined that the level of the threat of climate change facing the Southern 

Hemisphere populations was slightly better understood than the Northern Hemisphere 

populations. Warming waters are thought to be correlated with a decrease in krill production in 

the Southern Ocean, and this threat is likely to increase. The future negative impact implied by a 

low threat assignment is dependent on a substantial decrease in krill populations, a subsequent 

negative impact on prey resource availability to humpback whales, and lack of suitable alternate 

prey such as fish.

The Southern Ocean is regarded as a relatively simple ecosystem, but even here there are 

substantial problems in quantifying even the most basic parameters such as prey abundance. 

Changes in this ecosystem are also driven by cyclic variability on the scale of years to decades 

(Murphy et al. 2007). Disentangling climate change effects from other forms of variability 

including periodic physical forcing, requires time series of data that are typically scarce or nonexistent in the Southern Ocean (Quetin et al. 2007). The responses of the Southern Ocean

ecosystem to climate change are likely to be complex. Sea ice decreases may actually enhance 

overall primary production but could reduce ice algae production which occurs at a critical time 

for krill larvae (Arrigo and Thomas 2004). On the other hand, the location of upwelling of 

nutrient-rich deep water may change and result in enhanced primary production in areas that are 

otherwise unfavorable to krill (Prezelin et al. 2000).

The problems in assessing the relatively “simple” Southern Ocean illustrate the huge problems 

involved in predicting future changes in dynamic ecosystems, on scales that range from eddies 

and fronts to entire ocean basins. Ecosystem models are crude at best. Full ecosystem models 

involve innumerable parameters, yet data to quantify these - let alone interactions among them -

frequently do not exist.

The second IWC climate change workshop (IWC 2010c) noted that data sets for use in assessing 

impact and modeling the effects of climate change must have: extensive duration (20-30 years or 

more of information); good temporal resolution to capture variability on inter-annual and longer 

scales; and sufficient spatial scale. Although long-term studies of humpback whales exist in 

various locations in both hemispheres, these are often compromised by issues such as sampling 

bias, data gaps and inconsistency of methods; furthermore, parallel data of sufficient resolution 

on environmental variables are often unavailable. The caveat above regarding the difficulty of 

disentangling climate change effects from other variables applies equally to determining the 

reasons for any observed changes in demographic parameters of humpback whales.

It is instructive and rather sobering to compare the conclusions of the two IWC climate change 

workshops, separated as they were by more than a decade. The report of the 1996 workshop 

(IWC 1997) notes that: “...given the uncertainties in modeling climate change at a suitable scale 

and thus modeling effects on biological processes... at present it is not possible to model in a 

predictive manner the effects of climate change on cetacean populations.” Thirteen years later, 

the second workshop came to much the same conclusion (IWC 2010c), finding that: 

“...improvements in climate models, as well as models that relate environmental indices to whale 

demographics and distribution, had occurred. However, all models remain subject to 

considerable uncertainty.”

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The BRT assigned climate change a low threat level to all Southern Hemisphere populations 

based on current impacts to the populations. The threat posed by climate change to Northern 

Hemisphere humpback whale populations is very uncertain, but the BRT thought it unlikely that 

climate change was a major extinction risk factor. Melting and receding ice sheets may open 

more feeding habitat for humpback whales in the Northern Hemisphere. However, humpback 

whales in the Northern Hemisphere do not feed primarily in Arctic waters (which are likely to be 

the most significantly altered by climate change).

Overall, it is clear that humpback whales worldwide have exhibited considerable resilience 

despite a whaling history that removed the great majority of animals from most populations. 

This resilience, together with the species’ flexibility in diet and apparent plasticity in its 

distribution, provides some optimism that humpbacks can adapt to significant environmental 

changes wrought by global warming. Although we cannot predict how climate change may 

affect humpback whales in the long term, at present most studied populations appear to be 

recovering well and it seems very unlikely that any population faces extinction as a result of 

climate issues. The primary question is not whether climate change could ever cause extinction, 

but rather whether climate change could drive a humpback whale DPS to extinction within some 

finite time frame (or could move a DPS from threatened to endangered in the foreseeable future). 

In this regard, it is essential to maintain and improve long-term research programs so that 

humpback whale populations can be monitored for changes that may occur as a result of future 

environmental changes. 

C. Overview of Assessment of Extinction Risk

The BRT discussed at length the type of information relevant to extinction risk that is available 

for the 15 different humpback whale DPSs. This potentially includes information such as 

population size, population trends, age structure, diversity, recent fecundity, and survivorship, as 

well as external risk factors such as habitat degradation or potential catastrophic events. It is also 

possible to evaluate extinction risk through modeling scenarios of the future fate of a population; 

this is termed a Population Viability Analysis (PVA). The BRT discussed how extinction risk 

would be evaluated for each humpback whale population and how to define extinction risk. The 

BRT also evaluated whether PVAs would be a useful tool in the extinction risk evaluation of 

humpback whale populations. 

C.1 Relationship between population size and trend and extinction risk

Populations that are declining or of small size are thought to be at greater risk of extinction 

(Gilpin and Soulé 1986). Small population size can be used as a measure of extinction risk 

because theoretical models show that small populations can have relatively high extinction risks 

solely from internal processes (Mace et al. 2008). Many different levels of low population size 

have been used as indicators of extinction risk in the literature, though no single number can 

serve as the standard for all cases and all factors. Mace et al. (2008) provide a concise summary 

of the relationship between population size and trends with extinction risk. From basic theory it 

is possible to draw broad generalizations about the relationships among population size, 

population growth rates, fluctuations in population growth rates, and extinction times (Lande 

1993; Lande 1998). Populations that are seriously declining are always at risk of extinction, with 

population size having little effect on extinction risk. There is a steep ramping down of critical

63
population sizes that reflects what is known from theoretical studies about the general 

relationships between population size and time to extinction under various kinds of 

environmental and demographic stochasticity (Lande 1993; Lande 1998), with smaller 

population sizes associated with shorter mean times to extinction, and vice versa.

Demographic stochasticity is the process whereby random variation in births and deaths among

individuals alone can lead to population fluctuation and possible extinction (Goodman 1987; 

Lande 1993). There is little debate about the existence of demographic stochasticity and the 

extinction risk it causes. From theoretical models, populations of fewer than 100 individuals are 

at high risk of extinction from demographic stochasticity (Mace et al. 2008), whereas 

populations above 100 have decreasing levels of risk. Empirical data confirm that this is the 

case, as populations less than 100 have been documented to have a high risk of extinction. For 

example, Legendre et al. (Legendre et al. 1999) found that for introduced populations in New 

Zealand, extinction probability was very high for populations less than 100, and declined to 

relatively lower levels for populations greater than ~250; they attributed the primary cause of 

extinction to demographic stochasticity. Similarly, Berger (1990) found that populations of 

bighorn sheep greater than 100 persisted much longer than populations that were much less than 

100.

Genetic effects can occur in smaller populations and can also contribute to extinction risk. 

Geneticists speak of the effective population size, which is the size of an ideal population of 

breeding organisms that would experience the effects of drift or inbreeding to the same degree as 

the population being studied (ideal refers to a hypothetical population in the Hardy Weinberg 

sense with a constant population size, equal sex ratio, and no immigration, emigration, mutation, 

or selection). A general guideline is that a minimum effective population size of at least 50 

sexually mature individuals is required to prevent short-term ill effects of inbreeding, and an 

effective population size of 500 is needed to prevent the accumulation of deleterious recessive 

alleles and safeguard genetic variability over hundreds of years (Gilpin and Soulé 1986). 

Franklin (1980) and Soulé (1980) both also proposed 50 and 500 as threshold effective 

population levels (Wilcox 1986), where an effective population size of 50 protects from 

inbreeding and 500 maintains overall genetic variability for the long-term. Because effective 

population size is often about 1/5 to 1/3 of a population’s actual size (Frankham 1995), total 

population sizes need to be considerably higher in order for the effective size to meet these 

guidelines. Assuming the lower value (1/5), this results in a 5 times multiplier to convert from 

effective population size to total population size. Therefore, effective population sizes of 50 and 

500 convert to total population sizes of 250 and 2500, respectively. These total population levels 

have been proposed for use in conservation applications. For example, Allendorf et al. (1987)

proposed (for declining populations) to use a threshold of 250 for total population size to 

categorize a population as having a very high risk of extinction, and a threshold for total 

population size of 2,500 for a high risk of extinction (corresponding explicitly to effective 

population sizes of 50 and 500, respectively). 

Some authors have suggested that even larger effective population sizes on the order of 5,000 are 

needed to preserve quantitative trait variation over thousands of years (Lynch and Blanchard 

1998; Lynch and Lande 1998; Frankham 1999). On the other hand, the guidelines are intended 

64
to apply to isolated populations, and even low levels of gene flow from other populations will 

greatly reduce the loss of genetic diversity due to small local effective size (e.g., Tajima 1990). 

Small populations are also at risk of extinction from random environmental variation or 

catastrophes, and the risk becomes more significant as the variation becomes large in relation to 

the population growth rate (Goodman 1987). When environmental variance is incorporated into 

extinction risk models it has been found that expected persistence time, in contrast to models 

having only demographic variance, does not increase rapidly with larger population sizes 

(Goodman 1987). In general, population levels need to be higher (relative to levels considered 

safe from extinction risk from demographic stochasticity) to have a relatively low risk of 

extinction. The magnitude and frequency of environmental variance and catastrophes affecting a 

population can be hard to estimate, making prediction of future conditions less certain. 

Therefore, determining a population level that is safe from extinction risk from environmental 

variance is difficult. However, it is clear that to minimize extinction risk from environmental 

variance, population levels more on the order of the thresholds suggested for protection from 

genetic affects (250 and 2500) are necessary, rather than a level (e.g., 100) that protects only 

from demographic stochasticity. Some guidance can be found in a meta-analysis of trend data 

from 529 vertebrate species, where population models incorporating environmental variance 

were fit to the data extrapolated into the future (Brook et al. 2006). They found that the initial 

population size that provided relatively high persistence for 100 years had a median value of 

~2,600 across all species.

In summary, it is generally recognized that small population size can be a useful proxy for 

extinction risk, particularly in concert with information about trends in abundance. As noted 

above, a variety of specific abundance level thresholds have been suggested in the literature as 

reference points for relative levels of extinction risk (Gilpin and Soulé 1986; Mace et al. 2008)

(Allendorf et al. 1987). It is possible to identify multiple population thresholds, where higher 

thresholds correspond to greater mean times to extinction, and lower overall risk of extinction 

(Allendorf et al. 1987; Mace et al. 2008). As mentioned above, Allendorf et al. (1987) proposed 

thresholds of 250 for a very high risk of extinction and 2500 for a high risk of extinction. 

Similarly, Mace et al. (2008) proposed threshold levels of 50 mature individuals for an extremely 

high risk of extinction, 250 mature individuals for a very high risk of extinction, and 1000 mature 

individuals for a high risk of extinction. For whale populations approximately half of the 

population is mature, so the corresponding thresholds for total population size are approximately 

100, 500, and 2000, respectively. 

Various population thresholds suggested above have been proposed for use in species 

categorization or ranking schemes (e.g., Allendorf et al. 1987; Mace and Lande 1991; Mace et 

al. 2008), where population size is one of a number of possible metrics used to evaluate 

extinction risk. In particular, the system proposed by Mace and Lande (1991) has been used in a 

global evaluation of species extinction risk, and those standards, later modified by Mace et al.

(2008) have become established in the scientific literature for over two decades. Keith et al.

(2004), for example, used a retrospective analysis of data from eighteen pairs of species (one 

extinct and one extant) to test risk-ranking protocols, including the Mace et al. (2008) criteria. 

They found that those criteria were useful in forecasting actual extinction risk. Mace et al.

(2008) note their proposed system and the criteria have been widely used by conservation 

65
practitioners and scientists. Those criteria are now one indicator being used to assess the 

biodiversity target established by the Convention on Biological Diversity 2010. Additionally, in 

a survey of 180 countries that are signatory to the Convention on Biological Diversity, Miller et 

al. (2007) found that of the countries that have or will develop a national threatened species list, 

82% incorporated the Mace et al. (2008) criteria into national conservation strategies. The utility 

of the categorization scheme has also been evident in the use of the results of the scheme in 

further analyses, such as the worldwide review of drivers and hotspots of marine mammal 

extinction risk by Davidson et al. (2012).

Following the discussion above, although slightly different numbers have been used in different 

cases, it emerges that there is fairly widespread agreement on the utility of using threshold 

population levels such as these as indicators of relative extinction risk:

1. Total population size of > 100 – provides protection from extinction risk from 

demographic stochasticity;

2. Total population size of > 500 – provides protection from genetic risks of inbreeding 

and from moderate environmental variance; 

3. Total population size > ~2,000-2,500 – provides maintenance of genetic diversity for 

long-term persistence and protection from substantial environmental variance and 

catastrophes.

Therefore, as part of the evaluation of extinction risk, the Humpback Whale BRT summarized 

information about population size for each DPS, as well as what is known about trends in 

abundance. The BRT agreed to categorize the abundance of each DPS relative to these 

thresholds, in decreasing order of the risk of extinction:

1. Total population size < 100;

2. Total population size < 500;

3. Total population size < 2,000;

4. Total population size > 2,000.

These categories are designed to concisely summarize one metric – the relative extinction risk of 

each DPS due to small population size alone. Where uncertainty in population size spans a range 

across a threshold, the DPS was identified as falling into a range of relative extinction risk, not 

just a single category. Various authors have equated these population thresholds to verbal 

descriptions of relative risk such as extremely high, very high, and high etc., recognizing that 

these risks actually exist upon a continuum (Allendorf et al. 1987; Mace et al. 2008). The BRT 

considered that a DPS with a total population size >2,000 was not likely to be at risk due to low 

abundance alone. The BRT considered any DPS with a population size <2,000 to be at 

increasing risk from factors associated with low abundance, and the lower the population size the 

greater the risk. Populations with an abundance <500 were considered by the BRT to be at high 

66
risk due low abundance, and populations <100 were considered to be extremely high risk due to 

low abundance. Some BRT members expressed concern about using a single threshold number 

as a quantitative decision, expressing the concern that appropriate numbers can be difficult to 

choose and decisions may be somewhat arbitrary. In light of this and the absence of strong 

quantitative data for some populations, the BRT decided to carefully consider the abundance of 

each DPS but would not use an abundance threshold as the sole criterion for evaluating 

extinction risk.

C.2 Applicability of Population Viability Analysis

PVA models are used to integrate various risks a population faces into an estimate of the 

probability the population will go extinct. PVAs sometimes involve fairly complex models, with 

many parameters that need to be specified, or sometimes they can be a fairly simple

extrapolation of a trend. Population models used may include demographic and environmental 

variability, as well as factors such as Allee effects. Often an age-structured model is used and a 

variety of other factors are included, such as density dependence and catastrophes (large 

mortality events). Several papers have summarized best practices in the use of PVAs (Beissinger 

and Westphal 1998; White 2000). A workshop conducted by the U.S. Marine Mammal 

Commission concluded PVA was the preferred method for evaluating extinction risk in marine 

mammal populations, if sufficient information is available (Marine Mammal Commission 2008).

PVAs have been used in some other recent status reviews of marine mammals (e.g., Krahn et al.

2004a; Oleson et al. 2010), but not in others (e.g., Boveng et al. 2009; Boveng et al. 2013).

After some discussion, the BRT concluded that developing and applying PVAs to the humpback

whale DPSs would not provide much additional information beyond evaluation of abundance 

and trend data. The main reason for this is that those DPSs with sufficient abundance and trend 

information to conduct a quantitative PVA all have high abundance and positive trends such that 

a PVA is not necessary to evaluate extinction risk, and those DPSs that appear to be at lower 

abundance and higher risk do not have sufficient data to conduct a useful PVA. 

C.3 Evaluation of Extinction Risk

The BRT evaluated extinction risk using the best available quantitative and qualitative 

information. In particular, the BRT carefully examined available information on abundance, 

trends in abundance, spatial distribution, genetic diversity, and threats for each DPS.

The BRT used the following definitions for overall extinction risk:

High Risk: a species or DPS has productivity, spatial structure, genetic diversity, and/or 

a level of abundance that place(s) its persistence in question. The demographics of a 

species/DPS at such a high level of risk may be highly uncertain and strongly influenced 

by stochastic and/or small population effects. Similarly, a species/DPS may be at high 

risk of extinction if it faces clear and present threats (e.g., imminent destruction, 

modification, or curtailment of its habitat; or disease epidemic) that are likely to create an 

imminent risk of extinction. 

67
Moderate Risk: a species or DPS is at moderate risk of extinction if it exhibits 

characteristics indicating that it is likely to be at a high risk of extinction in the future. A 

species/DPS may be at moderate risk of extinction due to projected threats and/or 

declining trends in abundance, productivity, spatial structure or diversity. 

Not at Risk: a species or DPS is not at risk of extinction.

The BRT discussed an appropriate time period over which to evaluate extinction risk. This is an 

important consideration, because over a sufficiently long time horizon all species will eventually 

go extinct. The risk of extinction within a specified time period can also be made to be 

arbitrarily small simply by choosing a very short time period over which to evaluate extinction 

risk. After some discussion, the BRT decided to evaluate extinction risk over a time frame of 

approximately 60 years, which corresponds to about three humpback whale generations. The 

BRT concluded it could be reasonably confident in evaluating extinction risk over this time 

period because current trends in both the biological status of the species and the threats it faces

are reasonably foreseeable over this period of time. 

The BRT used the structured decision making process described in the introduction to assess 

uncertainty among extinction risk categories. After evaluating and discussing all of the available 

information, each BRT member allocated 100 points into the three risk categories based on that 

BRT member’s confidence that the extinction risk of the DPS was described by each category. 

For example, if a BRT member were entirely confident a DPS was at high risk of extinction, he 

or she would place all 100 points into the high risk category. Alternatively, distributing points 

between two or even all three risk categories would reflect uncertainty in whether a given 

category reflects the true status.

C.4 Assessment of a significant portion of its range

The ESA defines an endangered species as “any species which is in danger of extinction 

throughout all or a significant portion of its range...” and threatened species as “any species 

which is likely to become an endangered species within the foreseeable future throughout all or a 

significant portion of its range.” However, the ESA does not define the terms ‘significant 

portion of its range’ or ‘foreseeable future.’ The Services issued a ‘‘Final Policy on 

Interpretation of the Phrase ‘Significant Portion of Its Range’ in the ESA’s Definitions of 

‘Endangered Species’ and ‘Threatened Species’’ (79 FR 37577; July 1, 2014). While the policy 

was in draft form, the Services were to consider the interpretations and principles contained in 

the Draft Policy as non-binding guidance in making individual listing determinations, while 

taking into account the unique circumstances of the species under consideration. The Draft 

Policy provided that: (1) If a species (the ESA definition of which includes DPSs) is found to be 

endangered or threatened in a significant portion of its range, the entire species is listed as 

endangered or threatened, respectively, and the ESA protections apply across the species’ entire 

range; (2) a portion of the range of a species is ‘‘significant’’ if the portion’s contribution to the 

viability of the species is so important that, without that portion, the species would be in danger 

of extinction5

; (3) the range of a species is considered to be the general geographical area within 

5 The draft final policy adds to this statement, “or likely to become endangered in the foreseeable future”, i.e., 

threatened, but the policy has not been finalized. 

68

 
which that species can be found at the time FWS or NMFS makes any particular status 

determination; and (4) if the species is not endangered or threatened throughout all of its range, 

but it is endangered or threatened within a significant portion of its range, and the population in 

that significant portion of its range is a valid DPS, we will list the DPS rather than the entire 

taxonomic species (or subspecies).

The BRT reviewed the information on threats and extinction risk to portions of the range for

each DPS. The BRT evaluated whether any portion of the range for each DPS, at present, has a 

substantially higher risk than any other part of the DPS and if these are significant. For most 

DPSs, the BRT concluded that 1) most threats were relevant to the entire DPS, and 2) the BRT

could not identify specific portions of the range of a DPS that were significant per the draft 

policy. The “significant portion of its range” analyses under the final policy would not have 

resulted in different conclusions from the analyses conducted under the draft policy. 

C.5 Humpback whale recovery plan

NMFS released a final recovery plan for the humpback whale in 1991 (NMFS 1991). The plan 

provides several types of recovery goals, focusing in particular on populations in the North 

Atlantic and North Pacific. The plan proposed that recovery would be biologically successful 

when humpback whales occupy all of their former range in sufficient abundance to buffer against 

normal environmental variation or anthropogenic catastrophes such as oil spills. The plan 

recommended that populations grow to at least 60% of their historical (pre-hunting) abundance 

to be considered recovered, but did not identify specific numerical targets due to uncertainty 

surrounding historical abundance levels. As an interim goal, the plan suggested a doubling of 

population sizes within 20 years, which corresponds to an annual exponential growth rate 

approximately 3.5%. In the sections on each DPS below we note where information is available 

to assess this criterion. Most DPSs where trend data are available have an estimated population 

growth rate of > 3.5%, although the period of measurement doesn’t always correspond to 

precisely 20 years. 

In its risk assessment, the BRT considered the threats and biological risk factors discussed in the 

recovery plan. For example, the abundance thresholds considered by the BRT are based on the 

levels necessary to buffer populations against stochastic variation, and the BRT considered and 

made use of statistical information on abundance and trends as recommended by the plan. The 

BRT also evaluated the threats identified in the recovery plan based on information obtained and 

updated in the intervening 20 years. Two decades after the recovery plan was finalized, the 

historical size of humpback whales populations continues to be uncertain (see e.g. Ruegg et al.

2013 and references therein). The BRT therefore focused its biological risk analysis primarily 

on recent abundance trends and whether absolute abundance was sufficient for biological 

viability. 

The BRT considered the information in the recovery plan, but also updated this information in 

some important ways. Most notably, although the recovery plan discussed stock structure and 

discussed goals for specific major breeding populations in the North Atlantic and North Pacific, 

it did not identify DPSs, noting that further evaluation of the stock structure would require more 

detailed genetic analysis than was available at the time. In addition, the recovery plan focused 

69
exclusively on the North Atlantic and North Pacific populations, whereas the BRT was charged 

with evaluating status worldwide. 

D. Threats and Extinction Risk Analysis Results, by DPS

Abundance and trend information available for each DPS is summarized in (Table 7 and Table 

8), along with information on the severity of each threat (Table 9). Details on the abundance, 

trends and risk factors for each DPS are described below.

D.1 West Indies

D.1.1 Abundance

As discussed above, this DPS consists of the humpback whales whose breeding range includes 

the West Indies and whose feeding range primarily includes the Gulf of Maine, eastern Canada, 

and western Greenland. While many West Indies whales also use feeding grounds in the central 

(Iceland) and eastern (Norway) North Atlantic, many whales from these feeding areas appear to 

winter in another location. The breeding range of this DPS within the West Indies is the entire 

Antillean arc, from Cuba to the Gulf of Paria, Venezuela. However, within this range local 

densities vary widely. By far the largest concentrations occur in the Atlantic waters of the 

Dominican Republic, notably the offshore platform reef systems of Silver and Navidad Banks; 

local abundance elsewhere in the West Indies is one or two orders of magnitude lower (Clapham 

and Mead 1999).

An abundance estimate for the entire North Atlantic was calculated from photo identification 

data from all feeding areas collected during the YONAH project from 1992 to 1993, using a 

Chapman 2-sample estimator, where the two samples were feeding areas in 1992 and feeding 

areas in 1993 (Stevick et al. 2003). This estimate included incorporation of an error rate in 

addition to sample pooling across years to collectively improve the estimates. Abundance was 

estimated at 11,570 (95% CI 10,290 to 13,390) individuals (Stevick et al. 2003). Although this 

figure is larger and more precise than any previous estimate, it is likely a negatively biased 

estimate for the entire ocean basin due to heterogeneity in capture probabilities across the North 

Atlantic (Stevick et al. 2003). Although this estimate mostly reflects the abundance of the West 

Indies population, it also includes the abundance of the Cape Verde Islands/Northwest Africa 

DPS because of the inclusion of all whales from Iceland and Norway.

Stevick et al. (2003) also estimated abundance from YONAH data for just the West Indies 

breeding population by using a Chapman 2-sample estimator, but where one sample was from 

the feeding grounds and the other sample was from the West Indies breeding ground. The 

feeding ground samples were restricted to only data from the Gulf of Maine, Canada, and 

Greenland; the exclusion of Iceland and Norway data removes whales from the Cape Verde 

Islands/Northwest Africa DPS from the analysis. In this analysis, the feeding ground samples 

represent the mark, with their capture probability in the West Indies estimated and applied to the 

number of whales identified in the West Indies. This should therefore represent an estimate of 

the West Indies population. This carries the assumption that West Indies whales from the 

Iceland and Norway feeding areas (which were not included in the mark) have the same capture 

70
probability as the other West Indies whales (from GOM, Canada, and Greenland). Should whales 

from a separate breeding area migrate to the northwestern Atlantic to feed, there would be a 

positive bias in these estimates, but this is no evidence any whales do this. The most accurate 

estimate made using this method for the YONAH data was 10,752 (CV = 6.8%; Stevick et al.

2003).

Stevick et al. (2003, Table 3) also used earlier (pre-YONAH) data from 1979 to 1991 to make 

additional estimates in the same manner via a feeding-breeding ground comparison. Those 

estimates ranged from 6,918 to 12,582, with CVs ranging from 18 to 39%.

The YONAH project also included the collection of biopsy samples and genetic identification of 

individuals. A Chapman 2-sample estimator was also applied to the genetic identification data, 

again using the feeding grounds (Gulf of Maine, Canada, and Greenland) as the mark, and the 

West Indies breeding ground as the recapture. This resulted in an estimate of 10,400 (95% CI 

8000-13,600;Smith et al. 1999). Note that this is nearly identical to the photo-based estimate 

using an identical estimator (10,752 photo vs. 10,400 genetic). 

The West Indies genetic samples were also used to estimate abundance for the West Indies

population by using a Chapman 2-sample estimator applied to a breeding-breeding ground 

comparison for the two YONAH years of 1992 and 1993. The estimate of the population was 

much lower using this method (7,698 Palsbøll et al. 1997), which was attributed to substantial 

heterogeneity in capture probability on the breeding grounds (heterogeneity in capture 

probability means that individual whales have different capture probabilities, which violates one 

assumption of the Chapman estimator). Indeed, when the data were separated into male and 

female datasets, the estimate for males was 4,894 whereas the estimate for females was 2,804, 

even though the sex ratio is known to be approximately equal on the feeding grounds. It is 

thought that this is due to females having a relatively short duration on the breeding ground and 

perhaps also arriving and leaving outside the period of sampling; in contrast, males have a longer 

duration that spans most or all of the breeding season. Interestingly, doubling the males-only 

estimate of 4,894 (assuming a 50:50 sex ratio in the population) leads to a population estimate of 

9,788, which was only slightly lower than the feeding-breeding ground estimates. 

Although there may also be capture heterogeneity on the feeding ground, it is thought that the 

capture heterogeneities there are different from those on the breeding ground, and therefore when 

put together in a feeding-breeding ground mark-recapture, they do not cause a large negative 

bias. In contrast, in comparing two samples with the same heterogeneity in capture probability, 

such as the breeding-breeding ground comparison, there can be substantial negative bias. In the 

North Pacific, Barlow et al. (2011) similarly concluded that a feeding-breeding ground 

comparison was more robust and provided a higher estimate of abundance than breedingbreeding ground comparisons, which had a strong negative bias. The migration between the 

feeding ground and breeding ground effectively randomizes the sampling in the two areas. This 

approach also avoids many of the sources of heterogeneity that would result from sampling in 

only one seasonal habitat (Smith et al. 1999). Moreover, Barlow et al. (2011) demonstrated this 

effect through simulation. They found that if individual heterogeneity was the same in the 

marked sample as in the recaptured sample, this introduced negative bias of 21% in their 

example (based on the SPLASH project throughout the North Pacific, which was analogous to 

the YONAH project in its scope). In contrast, they found that using the same range of 

heterogeneity in capture probability but with different values in different samples (as would be 

71
true in a feeding-breeding ground comparison) resulted in a very small bias. Barlow et al. (2011) 

also investigated sex-biased sampling, as apparently occurs on the breeding ground, but again 

found that bias from this effect is small if one of the two capture occasions is unbiased with 

respect to sex, as should be the case on the feeding grounds. Therefore, as previously concluded 

by Stevick et al. (2003), the best estimates of the abundance of the West Indies population from 

the YONAH data are the estimates using the feeding-breeding ground comparisons, which are 

10,752 (from photos, Stevick et al. 2003) and 10,400 (from genetic IDs; Smith et al. 1999). 

Additional sampling was conducted in the West Indies in 2004 and 2005 in order to obtain an 

updated abundance estimate for the West Indies population (More of North Atlantic Humpbacks 

(MONAH) project; (Clapham 2003; Waring et al. 2012) and the BRT reviewed a preliminary 

analysis of these data. A Chapman 2-sample estimator was applied to the MONAH genetic 

identification data, using the feeding grounds (Gulf of Maine only) as the mark, and the West 

Indies breeding ground as the recapture, resulting in an estimate of 12,312 (95% CI 8688-15,954;

NMFS unpublished data). This estimate is nearly directly comparable to the genetic estimate of 

10,400 for 1992-93 (Smith et al. 1999), with the exception that the earlier YONAH estimate used 

marked animals from Canada and West Greenland in addition to the Gulf of Maine. If it can be 

assumed that whales from Canada and Greenland have the same capture probability in the West 

Indies as do whales from the Gulf of Maine, this should not introduce any bias. The MONAH 

estimate of 12,312 is consistent with the increasing trend for the West Indies shown in Stevick et 

al. (2003), though it suggests the increasing trend in the population has slowed down (see Trends 

section below).

In contrast, a genetic male-only breeding-breeding ground Chapman 2-sample estimator for the 

MONAH data from the West Indies leads to a lower estimate of abundance (3,414; NMFS 

unpublished data) than the comparable estimate for YONAH (4,894 Palsbøll et al. 1997). In 

wide area projects like YONAH and MONAH involving a complex migratory species like the 

humpback whale, there are details in sampling issues that can be complicated and potentially 

important to consider. One concern is that there was considerable variability in the arrival and 

stay duration of the biologists on Silver Bank during the West Indies breeding ground fieldseasons among and between the years of YONAH and MONAH. For YONAH, samples were 

acquired between Day of Year (DOY) 30 and 80 during 1992 and between DOY 18 and 72 for 

1993. If one limits a mark-recapture to data collected during the overlapping time frame DOY

(30,72) and re-calculates a modified Chapman estimate on those data, one gets a male estimate 

for YONAH of 3,867 (2605, 5130; NMFS, unpublished data), which is lower than the estimate 

of 4894 calculated by Palsboll et al. (1997) from the same untruncated data. It is still larger than 

the estimate of 3,414 calculated from MONAH data, but does suggest the nature of the problem. 

The MONAH field seasons were from DOY 14 to 70 in 2004 and DOY 21 to 67 in 2005. The

MONAH field seasons had other issues as well, with substantial bad weather in 2004 and a 

change in protocol by the ship’s captain in 2005 whereby the ship was anchored farther from the 

reef and thus in a larger swell, reducing the sampling opportunities because of greater difficulties 

in launching the skiffs. It is also possible to use a Chao estimator on each season of the MONAH 

West Indies data, breaking each field season into 3 time periods, and incorporating both timevarying capture probability and individual heterogeneity. The Chao estimator resulted in 

estimates of ~4500 for both field seasons (NMFS, unpublished data), suggesting that the ability 

to account for individual heterogeneity does increase the estimate substantially, and this can be 

taken as evidence for substantial heterogeneity in the breeding ground data. Most importantly, as 

72
discussed above, a breeding-breeding ground comparison introduces two large sources of bias 

from sex-biased sampling favoring males and from having the same source of individual 

heterogeneity in both samples. 

It is not clear that there is sufficient information to clarify exactly what is going on with regards 

to the sampling differences between YONAH and MONAH, and whether this is the cause of the 

differences in abundance in the breeding-breeding ground estimates. Given all of the above, the 

BRT concluded that the feeding-breeding ground estimates are more robust, and that therefore 

the estimate of 12,312 would be considered the best available abundance estimate for the West 

Indies population from the 2004-05 MONAH data.

Abundance in feeding areas

The abundance of the DPS is considered to be the abundance from the West Indies, but we also 

summarize abundance estimates from feeding areas here. The most recent estimate for the Gulf 

of Maine was 902 (CV=0.41) in 1999 (Clapham et al. 2003a). An abundance estimate from the 

TNASS aerial surveys in 2007 in eastern Canada (including the Scotian Shelf, Gulf of St. 

Lawrence, Newfoundland, and Labrador) was 2,080 humpback whales (95% CI: 1,337-3,172) 

(Lawson and Gosselin 2009). A Mark-Recapture Distance Sampling estimate of abundance from 

aerial line-transect surveys conducted off West Greenland for the year 2007 was 3,272 (CV = 

0.50) (Heide-Jorgensen et al. 2012). The TNASS survey in 2007 in Iceland resulted in an 

estimate of 11,572 (95% CI 4,502 to 23,807; Pike et al. 2010), but preliminary estimates from 

genetic data suggest roughly half or less of the Iceland whales and relatively few Norwegian 

whales migrate to the West Indies (e.g., Punt et al. 2006). Although these surveys used different 

methodologies and occurred in different years, note that the total abundance from these areas 

(Gulf of Maine, eastern Canada, West Greenland, and using half of the Iceland estimate) sums to 

~12,000, in the same ballpark as estimates from the West Indies. 

D.1.2 Trends

D.1.3 Trends in the West Indies breeding grounds

Stevick et al. (2003) estimated the average rate of increase for the West Indies breeding 

population at 3.1% per year (SE = 0.5%) for the period 1979-1993, slightly below the rate 

required for a twenty year doubling time. This was based on fitting an exponential trend to 20 

abundance estimates calculated from photo-identification data, where a Chapman estimator was 

applied to two samples pooled across 2 years, where the first was from the feeding ground and 

the second was from the breeding ground (discussed above in the Abundance section). It was 

noted that the original analysis in Stevick et al. (2003) calculated abundance from each pooled 

feeding ground sample twice, by matching it to a different sequence of breeding ground years 

(e.g., 1979-80 feeding ground was matched to both 1979-80 breeding ground and also to 1980-

81 breeding ground, producing two abundance estimates). This appears to be a form of using the 

same data twice, and could potentially lead to an over-estimate of the precision of the trend 

estimate. Therefore, we re-calculated the trend analysis using only one set of abundance 

estimates for each time period, calculated in the same manner as the best abundance estimate 

from YONAH of 10,752 (e.g., using the 1979-80 matched to the 1979-80 data), leaving a total of 

11 abundance estimates from 1979-80 to 1992-93. Our revised estimate of the trend for this time 

73
period was still 3.1% (SE=1.2%); as expected the precision was lower but the trend was still 

significantly different from 0.0 (p=0.025). When the MONAH estimate of 12,312 was added to 

the analysis the increase from 1979-80 to 2004-05 was estimated to be 2.0% (SE=0. 6%) per 

year, lower than for the earlier time period, but the increase was still significantly different from 

0.0 (p=0.008) (Figure 8). Although this is considered the best estimate of trend for the West 

Indies population, as a sensitivity test we also estimated the trend of the population using the 

breeding-ground-only estimate from MONAH of 6,828 (NMFS, unpublished data) instead of the 

feeding-breeding ground estimate of 12,312. In that test, the trend was essentially zero and there 

was no significant increase or decrease. If the lower abundance estimates is taken at face value, 

however, it would suggest the population initially increased and then decreased. However, given 

the concerns raised about the breeding-ground only estimate from MONAH and other indications 

of generally increasing abundance (see below), the results of this sensitivity test were not given 

much weight in the BRT’s final conclusions.

Figure 8. Revised trend analysis for NA humpback West Indies breeding population, based on feeding-breeding ground 

mark-recapture abundance estimates (Stevick et al. 2003; NMFS unpublished data). 

Note that only 11 abundance estimates from Table 3 of Stevick et al. (2003) were used (see text for explanation).

Given that the population growth rate has appeared to slow, it is reasonable to examine whether 

the population appears to be leveling off, such as would happen as a population approaches 

carrying capacity. Using AICc as a measure of model fit, the fit of a logistic model to the same 

abundance data as in Figure 8 was about the same as the fit of a linear model (Figure 9), meaning 

the data provide roughly equal support to both models. Therefore, no conclusion can be reached 

on whether the Silver Bank population is still increasing or is leveling off, as yet. This is 

unsurprising given that only the one estimate in 2004-05 suggests a leveling off, which is not 

enough data to support a strong conclusion.

74
Figure 9. A comparison of the fit of a linear model and a simple logistic model to the abundance data from Figure 8. 

The AICc for the two models were only different by 0.5, indicating the data support both models equally well.

D.1.3.1 Trends on the feeding grounds

Gulf of Maine

Barlow and Clapham (1997) estimated the Gulf of Maine feeding population (part of the West 

Indies breeding population) to be increasing at a rate of 6.5% from 1979-1991. However, 

Clapham et al. (2003a) estimated a lower growth rate of 0-4% for the population from 1992 

through 2000. Population growth rates were calculated using demographic parameters estimated 

from photo-identification mark-recapture6 studies including reproductive rates (birth intervals 

and maturation ages) and non-calf survival rates. A subsequent study confirmed both low 

average reproductive rates and calf survival during much of the 1992-2000 period (Robbins 

2007). The average estimated calf survival rate for the period 2000-2005 (0.664, 95% CI: 0.517-

0.784) fell between the values assumed by Clapham et al. (2003a) of 0.51 to 0.875, and did not 

6

Mark returns, “mark-recapture,” or “sight-resight,” is a method of estimating abundance based on a known number 

of tagged or identified individuals recaptured in consecutive samplings, which is extrapolated to represent a 

proportion of the overall population size.

75

 
include neonatal mortality prior to arrival on the feeding ground (Robbins 2007). No population 

growth rate estimates are available for this more recent time period.

Greenland

Aerial line-transect surveys were conducted off West Greenland 8 times between 1984 and 2007 

(Heide-Joergensen et al. 2012). A Mark-Recapture Distance Sampling estimate of abundance for 

the year 2007 was 3,272 (CV = 0.50). An annual rate of increase for 1984-2007 estimated from 

these data was 9.4% (SE = 0.01), which was significantly different from 0.0. There was roughly 

similar effort across the different years of the surveys, and therefore the estimated increase is 

apparent from the raw number of sightings per survey, which increased from 5-7 whales in the 

first 3 surveys to 20-22 whales in the last 3 surveys. This indicates the number of whales in 

Greenland has increased substantially over this time period. The estimated increase rate is high 

but just within plausible bounds for humpback whales based on their life history (Zerbini et al.

2010; Heide-Joergensen et al. 2012). Therefore, it is possible this increase is due solely to 

internal dynamics and not from the movement of whales into this area from other feeding areas, 

but there is no movement information for later years to attempt to confirm this.

Iceland 

Sigurjónsson and Gunnlaugsson (1990) used an index based on systematic sightings records 

from whaling vessels kept between 1970 and 1988 to derive an annual rate of increase of 11.6% 

for humpback whales off western Iceland. From abundance surveys, Pike et al. (2005) estimated 

a trend for humpback whales in Iceland waters from encounter rate data from 1987 through 2001 

of ~15% per year, which they note is beyond the boundary of the maximum possible rate of 

increase for humpback whales (Zerbini et al. 2010); it is not clear whether immigration into this 

feeding area may exist and contribute to this observed increase (Pike et al. 2005), whether the 

survey method employed was biased or unreliable (Smith and Pike 2009), or whether by 

sampling chance alone the estimate was too high. This latter possibility is supported by the fact 

that a similar abundance estimate was lower in the TNASS survey in 2007, suggesting the 15% 

increase was an over-estimate (Pike et al. 2010). However, the data do strongly suggest an 

increasing trend in Iceland over the 1987 to 2007 time period.

D.1.3.2 Conclusions on trend

Overall, the West Indies population was estimated to be increasing slowly over the time period 

1980 to 2005, but there is not sufficient evidence to statistically conclude the population has 

leveled off, such as would occur for a population reaching carrying capacity. In contrast, 

estimates from feeding areas in the North Atlantic indicate strongly increasing trends in Iceland 

(1979-88 and 1987-2007), Greenland (1984-2007), and the Gulf of Maine (1979-1991). There is 

some indication that the increase rate in the Gulf of Maine has slowed in more recent years. It is 

not clear why the trends appear so different between the feeding and breeding grounds. A 

possible explanation would be that the Silver Bank breeding ground has reached carrying 

capacity, and that an increasing number and percentage of whales are using other parts of the 

West Indies as breeding areas. Observers in the eastern Antilles (the Windward islands) have 

reported what appear to be increasing numbers of humpback whales in the region of Guadeloupe 

and Martinique; this might suggest an increasing and/or expanding population, although it is not 

clear how much such observations are a function of possibly increased observer effort in the 

area. The only recent dedicated effort in this region was a visual and acoustic survey conducted 

by Swartz et al. (2003), which found a low density of whales from the Virgin Islands to 

76
Venezuela. Although it was not possible to undertake a quantitative comparison with the results 

of surveys conducted in the 1970’s (Levenson and Leapley 1978), Swartz et al. (2003) noted that 

the low density of humpback whales observed in their survey was similar to that observed in the 

two much earlier studies, and concluded that local abundance in the eastern Antilles remained 

low.

If local abundance has indeed increased in some areas other than Silver Bank, it would suggest 

that the West Indies population is larger than estimated by the MONAH study, and that the 

increase rate of the overall population may be higher than the 2% we estimate.

D.1.4 Threats Analysis

Habitat or Range Curtailment

As elsewhere, human population growth and associated coastal development represent potential 

threats to this population in certain areas of the West Indies, as well as in regions of high human 

population density in the high-latitude feeding range. The major breeding habitats of Silver and 

Navidad Banks are sufficiently remote from land that direct human impact is for the most part 

unlikely. The largest concentration of humpback whales in a West Indies habitat that is adjacent 

to the coast occurs in Samaná Bay, Dominican Republic (Mattila et al. 1994). There, tourism 

has spurred an increase in coastal development, which has presumably introduced a rise in runoff 

and effluent discharge into the waters of the bay. To date, there is no evidence of observable 

impact on the humpback whales that visit the region, but no studies have been conducted; that 

the whales do not feed in these tropical waters likely decreases their risk from such point source 

pollution. Silver Bank, Navidad Bank, and portions of Samaná Bay have been designated by the 

Dominican Republic as a humpback whale Sanctuary (Hoyt 2013). 

As noted above, although whales are found elsewhere in the West Indies, densities outside 

Dominican waters are relatively low. Much of the additional habitat is in the waters of small 

islands in the Leeward and Windward groups, where any coastal runoff is likely to be effectively 

dispersed by highly dynamic water movements driven by frequently strong trade winds.

In some feeding grounds, coastal runoff, vessel traffic and other human activities represent a 

potential threat to humpback whales from this DPS. This is likely to be most pronounced off the 

Mid-Atlantic and northeastern United States, and least relevant in remote offshore areas such as 

Greenland, Labrador and the Barents Sea. A study of contaminants in humpback whales from 

the Gulf of Maine found elevated levels of polychlorinated biphenyls (PCBs), polybrominated 

diphenyl ethers (PBDEs), and chlordanes (Elfes et al. 2010), although the authors concluded that 

these likely did not represent a conservation concern.

Extensive oil and gas development and extraction occurs in the southern portion of the 

humpback whales' West Indies range, in the Gulf of Paria off Venezuela, but nothing is known 

of the impacts of this on the whales (Swartz et al. 2003). Energy exploration and development in 

this area are expected to increase. The U.S. assesses the environmental impacts of proposed oil 

and gas activities, including seismic and other offshore surveys, in the Mid- and South-Atlantic 

region. 

An UME involving humpback whales occurred off Cape Cod in late 1987 that was tied to 

dinoflagellate poisoning (harmful algal blooms or “red tide”) (Geraci et al. 1989); such events 

77
have been linked to increased coastal runoff. Additional UMEs occurred in the Gulf of Maine in 

2003 (12-15 dead humpback whales on Georges Bank) and 2006-7 (minimum of 21 whales), 

with no cause yet determined but HABs potentially implicated (Waring et al. 2009).

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

A native whaling operation targeting humpback whales exists in St Vincent and the Grenadines. 

Whalers from the St Vincent and the Grenadines island of Bequia have a quota from the IWC; 

most recently, Bequia was given a “block” quota of up to 24 whales over a six-year period 

(2013-2018) (IWC 2012). The Scientific Committee of the IWC considers that the allowed 

quota would have no impact on the growth rate of this population (IWC 2012).

Humpback whales represent a major attraction for tourists in many parts of the world, and in the 

West Indies their presence supports a large seasonal whale-watching industry in Samaná Bay 

(Dominican Republic). Although humpback whales can become remarkably habituated to 

ecotourism-based vessel traffic, whale-watching excursions have the potential to disturb or even 

injure animals. On feeding grounds such as the Gulf of Maine, where a large whale-watching 

industry exists, the extreme reaction of habitat displacement has not been observed; this may

partly be due to the existence of some guidelines for the operation of whale-watching tours, as 

well as the fact that the whales are tied to specific areas by a key resource (i.e., food). Since 

whales do not eat while in sub-tropical waters in winter, they are theoretically far less 

constrained in their choice of habitat; consequently, if the whales are faced with high enough

pressures from noise or other disturbance, they might be able to leave one breeding area and 

move to another. 

It is not clear whether recent anecdotal reports linking a decline in humpback whale abundance 

in Samaná Bay with increased cruise ship traffic are valid, but the potential exists to drive whales 

out of a breeding ground. The large number of whale-watching vessels and increasing presence 

of cruise ships in Samaná Bay suggests that it is very important to assess the effect of this traffic 

on the behavior and habitat use of the whales there.

Currently, disturbance from whale watching is probably not a major concern for Silver Bank. 

Although a small number of dive boats operate “swim-with-whales” tours there, their activities 

are regulated by the Dominican government, and are limited to a very small section of the 

available habitat. There is currently no commercial or recreational activity on Navidad Bank.

With the exception of the Gulf of Maine, elsewhere in the North Atlantic there is minimal 

utilization of humpback whales for whale-watching or ecotourism.

This population is exposed to some scientific research activities in waters off the U.S., Canada, 

and West Indies, but at relatively low levels. Adverse population effects from research activities 

have not been identified, and overall impact is expected to be low and stable.

Disease or Predation

There are no recent studies of disease in this population, but also no indication that it is a major 

risk. 

A study of apparent killer whale attacks in North Atlantic humpback whales found scarring rates 

ranging from 8.1% in Norwegian waters to 22.1% off western Greenland; scarring rates among 

whales observed in the West Indies ranged from 12.3% to 15.3% (Wade et al. 2007). It is clear 

78
that most killer whale attacks occur on first-year calves prior to arrival in high-latitudes (Wade et 

al. 2007). However, this is not regarded as a serious threat to population growth.

Other Natural or Human-Related Threats 

The largest potential threats to the West Indies DPS are entanglement in fishing gear and ship 

strikes; these occur primarily in the feeding grounds, with some documented in the mid-Atlantic 

U.S. migratory grounds. There are no reliable estimates of entanglement or ship-strike 

mortalities for most of the North Atlantic. For the Gulf of Maine feeding population, for the 

period 2003 through 2007 the minimum annual rate of human-caused mortality and serious 

injury (from both entanglements and ship collisions) averaged 4.4 animals per year (Waring et 

al. 2009). Off Newfoundland, an average of 50 humpback whale entanglements (range 26-66) 

was reported annually between 1979 and 1988 (Lien et al. 1988); another 84 were reported 

entangled in either Newfoundland or Labrador from 2000-2006 (Waring et al. 2009). Not all 

entanglements result in mortality (Waring et al. 2009). However, all of these figures are likely to 

be underestimates, as not all entanglements are observed. A study of entanglement-related 

scarring on the caudal peduncle of 134 individual humpback whales in the Gulf of Maine 

suggested that between 48% and 65% had experienced entanglements (Robbins and Mattila 

2001).

Underwater noise can potentially affect whale behaviour, although impacts are unclear. 

Concerns about effects of noise include behavioral disruption, interference with communication, 

displacement from habitats and, in extreme cases, physical damage to hearing (Nowacek et al.

2007). Singing humpback whales have been observed to lengthen their songs in response to lowfrequency active sonar (Miller et al. 2000) and reduce song duration from distant remote sensing 

(Risch et al. 2012). Because of the low level of human activity on Silver and Navidad Banks, 

noise is currently not a concern in this area. Samaná Bay, however, already has much vessel 

activity and therefore has the potential for considerable impact on whales from noise. Noise 

sources include whale-watching vessels, which approach whales closely and thus presumably 

create a loud acoustic environment in close proximity to the animals, and cruise ships, which 

may be more distant but whose size guarantees that, at certain frequencies, noise levels in the bay 

will be very high. There are also additional sources in the form of container ships or other 

commercial vessels that enter the bay periodically. Underwater noise levels are expected to 

increase. 

Offshore aquaculture was considered a low, but increasing, threat to this population. 

Competition with fisheries is a low threat to this population. 

Overall population level effects from global climate change for this population are not known; 

nonetheless, any potential impacts resulting from this threat will almost certainly increase. 

Currently, climate change does not appear to pose a significant threat to the growth of this 

population. 

D.1.5 Extinction Risk

The West Indies DPS has a substantial population size and appears to be experiencing consistent 

growth (Stevick et al. 2003), although the available growth and abundance data are about 10

years old. The North Atlantic humpback whale population was the subject of a Comprehensive 

79
Assessment by the IWC in 2000-2001, but the status of this population relative to its preexploitation size remains unclear (IWC 2002a). There has been no commercial or scientific 

whaling on this population for several decades, and although humpback whales remain the target 

of a small native hunt in St Vincent and the Grenadines and West Greenland, no significant 

impact on the population is likely from these catches.

The West Indies DPS was considered by the majority of the BRT to not be at risk of extinction 

(82% of votes)7. The potential for this population to be at moderate or high risk of extinction 

received 17% and 1% of votes, respectively. The votes for moderate or high risk largely reflects 

uncertainty stemming from potentially high rates of entanglement and/or ship strikes in some 

portions of the its range, and the occurrence in the Gulf of Maine of recent multiple UMEs.

D.1.6 Significant portion of its range

As noted above, there are some regional differences in threats for the West Indies DPS. 

However, the BRT concluded that the effect of any geographically localized threats would be 

seen in the status of the DPS as a whole. The BRT was unable to identify portions of the DPS 

that both faced particularly high threats and were so significant to the viability of the DPS as a 

whole that if lost would result in remainder of the DPS being at high risk of extinction. The BRT

therefore concluded that the DPS was not at risk in a significant portion of its range.

D.2 Cape Verde Islands/Northwest Africa

The population abundance and population trend for the Cape Verde Islands/Northwest Africa 

DPS are unknown. The Cape Verde Islands photo-identification catalog contains only 88 

individuals from a 20-year period (1990-2009) (Wenzel et al. 2010). Of those 88 individuals, 20 

(22.7%) were seen more than once; 15 were seen in two years, 4 were seen in three years and 1 

was seen in four years. The relative high re-sighting rate suggests a small population size with 

high fidelity to this breeding area, although the DPS may also contain other, as yet unknown, 

breeding areas (Wenzel et al. 2010). 

D.2.1 Threats Analysis

The BRT evaluated a variety of factors that could pose a risk to this DPS but rated many threats 

of unknown severity due to the lack of knowledge about the inferred additional breeding area. 

Habitat or Range Curtailment

Habitat conditions for this DPS are poorly known. Some members of the population use the 

waters around the Cape Verde Islands for breeding and calving, but where the remaining 

hypothesized fraction goes is unknown. The BRT noted that if the remaining portion of the 

population occurs in the coastal waters of West Africa (a plausible hypothesis, albeit one for 

which there is currently no evidence), it is likely to be exposed to more threats, which would 

7 The BRT conducted its initial evaluation of extinction risk prior to the availability of the 2004/2005 abundance 

estimates provided by the MONAH program. After reviewing the preliminary analysis of these data, as described in 

this section, the BRT concluded by consensus that the original extinction risk evaluation remained valid after 

considering the new information. 

80

 
increase with increased coastal development. In considering the Cape Verde Islands population, 

it was noted that oil spills occur off West Africa, but these levels are thought to be lower than in 

some other regions and the impact of non-catastrophic spills on humpback whales when they are 

on the breeding grounds was not considered significant. The threat of energy exploration to the 

Cape Verde Islands/Northwest Africa population was considered low.

There is little to no information on the impacts of HABs on this DPS. 

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Because the breeding range of this DPS is largely unknown, the importance of anthropogenic 

disturbance (from activities such as whale-watching, offshore aquaculture, fishing gear 

entanglements, and scientific research) of this DPS is largely unknown. At present, threats 

appear low relative to other populations, but again, much of the distribution of the population is 

unknown. There is no current or planned commercial whaling in this area.

Disease or Predation

There is little to no information on the impacts of disease, predation, or parasites on this DPS. 

Other Natural or Human-Related Threats 

There is little to no information on the impacts of vessel collisions, climate change, or 

anthropogenic noise on this DPS, although each is expected to increase. Competition with 

fisheries and offshore aquaculture were considered low threats to this DPS. 

D.2.2 Extinction Risk

The BRT found it very difficult to rate the extinction risk for this DPS because so little is known 

about that portion of the DPS breeding away from the Cape Verde Islands. Early commercial 

whaling analyses seem to indicate that the abundance of this DPS was substantial, but offers little 

in the way of explaining why it has not recovered similarly to most other DPSs. “High risk” 

received 32% of the votes, “moderate risk” received 43% of the votes, and “not at risk” received 

25% of the votes. The BRT noted that only 88 individuals have been catalogued over a 20-year 

period and there is no information available regarding where else other individuals may be if the 

population is larger. They emphasized that it is impossible to discern if the whales in the Cape 

Verde Islands are their own population or part of a larger population, which would translate into 

two very different risk levels. This uncertainty is reflected in the spread of the voting results. 

D.2.3 Significant portion of its range

The BRT concluded that the Cape Verde Islands/North Africa DPS was likely to be at least at 

moderate risk throughout its entire range. The BRT could not rule out that portions of the range 

of this DPS are at high risk, but this was largely due to a lack of information on the complete 

range of the DPS.

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D.3 North Pacific DPSs

D.3.1 Abundance

Recent estimates of abundance for the entire North Pacific basin are derived from the 

comprehensive data collected during the SPLASH project. A preliminary estimate of 18,302 

individuals was calculated from the SPLASH data (Calambokidis et al. 2008). This estimate was 

significantly larger than any previous estimates for the basin and is greater than some of the 

published estimates of pre-whaling abundances (Rice 1978). However, this estimate has been 

superseded by a re-analysis of the SPLASH data by correcting for some of the known biases, 

such as those caused by not sampling calves and by births and deaths between sampling periods

(Barlow et al. 2011) , yielding an updated estimate of 21,808 (CV=0.04) whales in the North 

Pacific Ocean. This new estimate may still be an underestimate of actual humpback whale 

abundance due to biases that could not be corrected for using the available data.

Calambokidis et al. (2008) approximated the size of the whale populations frequenting each 

breeding area at: 10,000 individuals in Hawaii; 6,000-7,000 animals in the collective areas in 

Mexican waters; 1,000 for the Western Pacific areas; and 500 for Central America, for a total of 

17,500-18,500. Barlow et al. (Barlow et al. 2011) did not apportion their estimate of 21,808 to 

individuals breeding areas, but the proportions are likely to be similar to those estimated by 

Calambokidis et al. (2008) and therefore about 20% larger than the Calambokidis et al. (2008) 

estimates.

D.3.2 Trends

The only mark-recapture study of North Pacific humpback whale abundance on a basin scale 

other than the SPLASH project was the NPAC study, based on photographic identifications of 

individual whales from 1990-1993 from three wintering regions (Hawaii, Mexico, Japan) and 

feeding areas from California to the Aleutian Islands (Calambokidis et al. 1997). Calambokidis 

et al. (2008) compared the NPAC best estimate of 6,010 to the SPLASH results and estimated an 

annual increase of 4.9% over the 13-year time span, considerably higher than the interim 

recovery goal. Comparing the SPLASH results to the basin-wide estimate made in 1966 by 

Johnson and Wolman (1984) of approximately 1,200 individuals, Calambokidis et al. (2008)

estimated a 6.8% annual increase for the 39-year time span. However, this is contingent upon 

the reliability of the 1966 estimate, which is questionable because of limited spatial coverage.

Growth rates have been calculated on regional scales, including ~8% per year for the U.S. West 

Coast from 1991-2008 (Calambokidis 2009) and 6.6% per year for the Alaskan Peninsula and 

Aleutian Islands from 2001-2003 (Zerbini et al. 2010). Dahlheim et al. (2009) calculated a 

10.6% annual increase in population size in Southeast Alaska between 1991 and 2007.

Calambokidis et al. (2008) also calculated trends for Hawaii and Asia comparing regional 

estimates from the NPAC study (1990-1993) and the SPLASH study (2004-2006). The Hawaii 

population showed an annual growth rate of 5.5-6.0% and the western Pacific population an 

annual growth rate of 6.7%. The western Pacific estimate is less robust; sampling effort was 

82
significantly greater in the SPLASH study, which may upwardly bias the western Pacific trend 

estimate (Calambokidis et al. 2008).

D.4 Hawaii

The size of the population that uses the waters surrounding the Hawaiian Islands for mating and 

calving was estimated in 2008 to be about 10,000 individuals (Calambokidis et al. 2008). The 

most recent growth rate was estimated between 5.5% and 6.0% for this population 

(Calambokidis et al. 2008).

D.4.1 Threats Analysis

Habitat or Range Curtailment

Other than its Hawaiian Islands breeding area, this population inhabits some of the least

populated areas in the United States (Alaska) and Canadian (Northern British Columbia) coastal 

waters. Coastal development, which may include such things as port expansion or waterfront 

development, is possible in both the U.S. and Canada; runoff from coastal development in 

Hawaii and continued human population growth are potential threats. Confidence in information 

about, and documentation of, these activities and their impacts is moderate. Given continued 

human population growth in the region and the need to develop alternate energy sources, such as 

offshore wind farms and wave or tidal generators, the threat can be expected to increase.

This population had the lowest levels of DDTs, PCBs, and PBPEs observed for North Pacific 

humpback whales sampled on all their known feeding grounds except Russia, between 2004 and 

2006; in particular, levels were lower than observed in humpback whales from the U.S. West 

Coast, as well as the North Atlantic’s Gulf of Maine (Elfes et al. 2010). The levels observed in 

all areas are considered moderate and not expected to have a significant effect on population 

growth (Elfes et al. 2010). Confidence in this information is moderate, but the trend is unknown.

There have been proposals to open exploration and drilling in the southeastern Bering Sea, 

notably in the North Aleutian Basin. While in 2010 this region was removed from consideration 

for oil and gas lease sales, if such activity were authorized in the future it would represent a 

potential threat to this population’s feeding grounds. There has been a moratorium on offshore 

oil drilling in the waters of Northern British Columbia since 1972, but there has also been a 

recent proposal to lift the ban, driven largely by local government (British Columbia Energy Plan 

2007). If so, this potential threat could increase in this portion of the habitat as well.

Naturally occurring biotoxins from dinoflagellates and other toxins are known to exist within the 

range of this population. Although humpback whale mortality as a result of exposure has not 

been documented in this population, it has been reported from other feeding grounds, so is 

considered a possibility. The occurrence of HABs is expected to increase with the growth of 

various types of human- related activities, and with increasing water temperatures. The level of 

confidence in exposure to HABs and in these assertions is moderate.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

83
There are no planned commercial whaling activities in this population’s range, however, modest 

aboriginal hunting has been proposed in British Columbia (Reeves 2002). Certainty in this 

information is considered relatively high and the magnitude is expected to remain stable.

This population is exposed to whale-watching activities in both its feeding and breeding grounds, 

but at medium (Hawaii) to low levels (Alaska and British Columbia). Adverse population 

effects from whale-watching have not been documented, and overall impact of whale-watching 

is expected to be low and stable.

This population is exposed to some scientific research activities in both U.S. and Canadian 

waters, but at relatively low levels. Adverse population effects from research activities have not 

been identified, and overall impact is expected to be low and stable.

Disease or Predation

Evidence of killer whale attacks (15-20%) in the humpback whales found in Hawaiian waters is 

moderate (Steiger et al. 2008) and lower for Alaska and Canada. This is not regarded as a 

serious threat to population growth. Shark predation likely occurs as well, although evidence 

suggests the primary targets are the weak and unhealthy. Certainty in this information is 

considered relatively high and the magnitude is expected to remain stable.

There are no known reports of unusual disease or mass mortality events for this population. 

Trends may increase slightly in response to other stressors, such as warming oceans and other 

stressors that may compromise immune systems.

Levels of parasitism in this population are not well known, although approximately 2/3 of 

humpback whales in Hawaii show some evidence of permanent, raised skin lesions, which may 

be a reaction to an, as yet unknown, parasite (Mattila and Robbins 2008). However, there is no 

evidence that these “bumps” impact health or reproduction, or cause mortality. Trends in the 

severity of this threat are unknown.

Other Natural or Human-Related Threats 

There is suspected interaction with the herring fishery in Southeast Alaska, but impacts to 

humpback whales are considered to be modest; the level of certainty in this information is 

moderate and currently under study and impacts are considered stable because the herring fishery 

is regulated. There is a potential for humpback whales to compete with fisheries in British 

Columbia as well, as they also have a herring fishery, as well as a “krill” fishery.

Currently two modest offshore aquaculture sites are located in Hawaii, and their placement 

overlaps with humpback habitat. However, there have been no known fatal interactions and 

indirect impacts from food, waste, or medicines being provided to the cultivated species are 

likely to be low, as humpback whales do not feed in Hawaii. The level of certainty in this 

information is high. However, if these and other operations expand to areas of high use by the 

whales, at a minimum they could physically exclude humpback whales from some of their 

preferred habitat. Deep water, finfish aquaculture in Alaska is currently prohibited. However, 

some shellfish and herring “pond” aquaculture does exist close to shore. There are no known 

fatal encounters with this type of aquaculture in Alaska; however, there are documented cases of 

humpback whales becoming entangled in herring “pond” and other aquaculture gear in British 

Columbia (Baird 2003). There have been proposals to allow finfish aquaculture in Alaska, 

84
which would increase the threat from this activity in this portion of the population’s range. The 

indirect impacts of aquaculture (e.g., on health and abundance of prey) is not well known. Given 

decreasing catches of wild fish stocks, and resulting strong incentives to expand aquaculture, this 

threat is likely to increase.

This population is likely exposed to moderate levels of underwater noise resulting from human 

activities, which may include, for example, commercial and recreational vessel traffic, and 

activities in Naval test ranges. Overall population-level effects of exposure to underwater noise 

are not well established, but exposure is likely chronic. As vessel traffic and other activities are 

expected to increase, the level of this threat is expected to increase. The level of confidence in 

this information is moderate.

The range of this population includes some centers of human activities in both Canadian and 

U.S. waters. Reports of vessel collisions in Hawaii have increased since 2003, when an 

extensive educational campaign and hotline number were initiated; however the percentage of 

these that result in fatality is unknown. Collisions have also been reported from Alaska and 

British Columbia (where shipping traffic has increased 200% in twenty years) (Neilson et al.

2012). The level of certainty in this information is high. A reasonable assumption is that the 

level of the threat will increase in proportion with increases in global commerce. Although 5-10 

ship strikes are reported per year in Hawaii and the actual number of ship strikes is estimated to 

be potentially one order of magnitude greater than this (Lammers et al. 2003), the threat level 

was still considered minimal given the very large population size and the fast rate of growth 

observed in this population.

Recent studies of characteristic wounds and scarring indicate that this population experiences a 

high rate of interaction with fishing gear (20-71%), with the highest rates recorded in Southeast 

Alaska and Northern British Columbia (Neilson et al. 2009). However, these rates represent 

only survivors. Fatal entanglements of humpback whales in fishing gear have been reported in 

all areas (where such records are kept) but, given the isolated nature of much of their range, 

observed fatalities are almost certainly under-reported. Recent studies in another humpback 

whale feeding ground, which has similar levels of scarring, estimate that the actual annual 

mortality rate may be as high as 3.7% (Angliss and Outlaw 2008). There is a high level of 

certainty with regard to this information. The threat is considered to be medium.

Overall population level effects from global climate change are not known; nonetheless, any 

potential impacts resulting from this threat will almost certainly increase. Climate change was 

not considered to be a major risk to this population currently, however. The level of confidence 

in the magnitude of this threat is low.

D.4.2 Extinction Risk

The Hawaiian DPS is large and growing and the overall level of threats was considered to be 

low. This DPS is and will be exposed to some threats from some human activities, the most 

severe being entanglement in fishing gear; however, these threats are not expected to 

significantly diminish population growth.

85
In voting on extinction risk, 98% of votes were for “not at risk” and 2% were for “moderate 

risk”. The votes in the “moderate risk” category reflected uncertainty regarding fishing gear 

entanglements and the potential for increased vessel collisions. 

D.4.3 Significant portion of its range

There are some regional differences in threats for the Hawaii DPS. However, the BRT 

concluded the effect of any geographically localized threats would be seen in the status of the 

DPS as a whole. The BRT was unable to identify portions of the DPS that both faced 

particularly high threats and were so significant to the viability of the DPS as a whole that if lost 

would result in the remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

D.5 Central America

Individual humpback whales in the Central America DPS migrate from breeding grounds off 

Costa Rica, Panama, Guatemala, El Salvador, Honduras, and Nicaragua to feeding grounds off 

California, Oregon and Washington. A preliminary estimate of abundance of the Central 

America population is ~500 from the SPLASH project (Calambokidis et al. 2008), or ~600 based 

on the reanalysis by Barlow et al. (Barlow et al. 2011). There are no estimates of precision 

associated with these estimates, so there is considerable uncertainty about the actual population 

size. Therefore, the actual population size could be somewhat larger or smaller than 500-600, 

but the BRT considered it very unlikely to be as large as 2,000 or more. The size of this 

population is relatively low compared to most other North Pacific breeding populations 

(Calambokidis et al. 2008). Though no specific growth rate has been estimated for this 

population, the growth rate for the entire North Pacific population is estimated at 4.9% 

(Calambokidis et al. 2008). The California/Oregon feeding population is comprised of a mixture 

from this DPS and other whales from the Mexico DPS; this feeding population has been 

estimated to be growing at a rate of ~8% per year from 1991-2008 (Calambokidis et al. 2008). 

However, given that the Central America population is estimated to be a small proportion of the 

whales in California/Oregon, this does not necessarily mean that the Central America population 

is growing. Therefore, the trend of the Central America population was considered unknown.

D.5.1 Threats Analysis

Habitat or Range Curtailment

Human population growth and associated coastal development, including port expansions and 

the presence of water desalinization plants, are some of the potential threats to this population. 

The presumed migratory route for this population lies in the coastal waters off Mexico and 

includes numerous large and growing human population centers from Central America north 

along the Mexico and U.S. coasts. The California and Oregon feeding grounds are the most 

“urban” of all the North Pacific humpback whale feeding grounds resulting in relatively constant 

anthropogenic exposure for the individuals of this population. However, the high degree of 

coastal development is not preventing the increase of humpback whales in this area and it is 

considered to be a low level threat.

86
Associated with this proximity to urban areas is a high level of exposure to man-made 

contaminants. Elevated levels of DDTs, PCBs, and PBPEs have been observed in “southern 

California” humpback whales; levels were higher than observed in humpback whales from the 

North Atlantic’s Gulf of Maine feeding ground (Elfes et al. 2010). These levels may be linked to 

historical dumping of DDTs off the Palos Verdes Peninsula, CA (Elfes et al. 2010). However, 

the levels observed are not expected to have a significant effect on population growth (Elfes et 

al. 2010). DDT and PCB levels are likely to decrease in feeding areas because use of these 

chemicals has been banned in the U.S., but PBDEs may still be increasing.

Energy exploration and development activities are present in this population’s habitat range. 

There are currently numerous active oil and energy leases and offshore oil rigs off the U.S. west 

coast. Offshore LNG terminals have been proposed for California and Baja California. The 

feeding grounds for this population are therefore an active area with regard to energy exploration 

and development. However, there are no plans at present to open the West Coast to further 

drilling. Alternative energies, such as wind and wave energy, may be developed in the future in 

this region. Currently, the threat posed to this population by energy exploration and 

development is low, and is considered stable. 

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Whale-watching tourism and scientific research occur, at relatively low levels, on both the 

feeding and breeding grounds of this population as well as along the migratory route. Whalewatching is highly regulated in U.S. waters. Many Central American countries also have whalewatching guidelines and regulations in the breeding ground of this population. Whale-watching 

is therefore not considered a threat to this population. Scientific research activities such as 

observing, collecting biopsies, photographing, and recording underwater vocalizations of whales 

occurs throughout this population’s range, though no adverse effects from these events have been 

recorded.

No whaling currently occurs in this population’s range. 

Disease or Predation

There is little information on the impacts of disease, parasites or algal blooms on this population. 

Harmful algal blooms (HABs) of dinoflagellates and diatoms exist within the feeding range of 

this population, but there have been no records of humpback whale deaths as a result of 

exposure. The occurrence of HABs is expected to increase with the growth of various types of 

human-related activities but does not pose a threat to this population currently.

Though the occurrence and impacts of predation on humpback whales is not well understood, 

some evidence of killer whale and shark attacks exists for this DPS. Evidence of killer whale 

attacks is relatively high in California waters, with 20% of humpback whales showing scars from 

previous attacks (Steiger et al. 2008). Scars from attacks are believed to have originated in the 

winter when whales are in Mexican and Central American waters. However, this is not regarded 

as a serious threat to population growth. Shark predation likely occurs as well, though it is not 

known to what degree but it does not appear to be adversely impacting this population. 

Other Natural or Human-Related Threats 

There is no evidence to suggest that competition with fisheries poses a threat to this population. 

Humpback whales in southern and central California feed on small schooling fish including 

87
sardine, anchovy and herring all of which are commercially harvested species. In addition, they 

also feed on krill, which are not harvested off the U.S. west coast. Humpback whales are known 

to be foraging generalists. Although their piscivorous prey is subject to naturally- and 

anthropogenically-mediated fluctuations in abundance, there is no indication that fishery-related 

takes are substantially decreasing their food supply. 

This population is likely exposed to relatively high levels of underwater noise resulting from 

human activities, including commercial and recreational vessel traffic, and activities in U.S. 

Navy test ranges. Exposure is likely chronic and at relatively high levels. It is not known if 

exposure to underwater noise affects humpback whale populations, and this threat does not 

appear to be significantly impacting current population growth. 

Vessel collisions and entanglement in fishing gear pose the greatest threat to this population. 

Especially high levels of large vessel traffic are found in this population’s range off Panama, 

southern California, and San Francisco. Several records exist of ships striking humpback whales 

(Carretta et al. 2008; Douglas et al. 2008), although it is likely that not all incidents are reported. 

Two deaths of humpback whales were attributed to ship strikes along the U.S. West Coast in 

2004-2008 (Carretta et al. 2010). Ship strikes are probably underreported and the level of 

associated mortality is also likely higher than the observed mortalities. Vessel collisions were 

determined to pose a medium risk (level 2) to this population, especially given the small 

population size. Shipping traffic will probably increase as global commerce increases; thus, a 

reasonable assumption is that the level of ship strikes will also increase. 

Between 2004 and 2008, 18 humpback whale entanglements in commercial fishing gear off 

California, Oregon, and Washington were reported (Carretta et al. 2010), although the actual 

number of entanglements may be underreported. Effective fisheries monitoring and stranding 

programs exist in California, but are lacking in Central America and much of Mexico. Levels of 

mortality from entanglement are unknown and do vary by region, but entanglement scarring rates 

indicate a significant interaction with fishing gear. Currently there is no aquaculture activity on 

the feeding grounds of this population, though migrating individuals may encounter some 

aquaculture operations in very coastal waters off Mexico. Humpback whales in this DPS are not 

considered to be adversely affected by aquaculture. 

Overall population level effects from global climate change are not known; nonetheless, any 

potential impacts resulting from this threat will almost certainly increase. Humpback whales 

feeding off southern and central California have a flexible diet that includes both krill and small 

pelagic fishes. Acidification of the marine environment has been documented to impact the 

physiology and development of krill and other calcareous marine organisms which may reduce 

their abundance and subsequent availability to humpback whales in the future (Kurihara 2008). 

However, the diet flexibility of humpback whales in this region may give this population some 

resilience to a climate change effect on their prey base compared to Southern Hemisphere 

humpback whales that have a more narrow krill-based diet. Currently, climate change does not 

pose a significant threat to the growth of this population. 

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D.5.2 Extinction Risk

The Central America DPS has a relatively small population size (Calambokidis et al. 2008). The 

estimated number of mature individuals may be less than 250 and there are no data available to 

determine a population-level growth rate for this DPS, which adds uncertainty to the current 

status of this DPS. In light of historical records of whaling on the feeding grounds of this 

population and neighboring feeding grounds, this population likely remains well below preexploitation size despite observed positive population trends in other populations over the past 

decades. The Bay City, WA shore station took 1,331 humpback whales from 1911-1919 

(Clapham et al. 1997). Shore stations at Moss Landing and Trinidad in California took 1,871 

humpback whales between 1919 and 1926 (Clapham et al. 1997). When combined with records 

from factory ships operating off Alaska and the shore station at Bay City, WA, 5,084 humpback 

whales were taken from 1919-1926 (Clapham et al. 1997). From 1956-1965, a further 841 

humpback whales were killed by California shore whaling stations, likely depleting this 

population again while numbers were still low from the earlier 1900s (Clapham et al. 1997). 

Entanglement scarring rates in this population indicate a significant interaction with fishing gear 

and vessel collisions may be impacting population growth to a small degree. The Central 

America DPS is therefore considered to be at moderate risk of extinction over the next three 

generations (a conclusion that was supported by 56% of votes by the BRT). The potential for 

this DPS to be at high risk of extinction was also considered and received 28% of the votes, 

largely reflecting uncertainty regarding population size and population trend. The potential for 

this DPS to not be at risk was given 16% of the votes. 

D.5.3 Significant portion of its range

The BRT concluded that the Central America DPS was likely to be at moderate to high risk 

throughout its entire range. The BRT concluded that the threats identified are likely to impact 

the DPS in its entirety. The BRT therefore concluded that the DPS was at moderate-to-high risk 

throughout its range and not at high risk in only a significant portion of its range. 

D.6 Mexico

A preliminary estimate of abundance of the Mexico DPS is 6,000-7,000 from the SPLASH 

project (Calambokidis et al. 2008), or higher (Barlow et al. 2011). There are no estimates of 

precision associated with that estimate, so there is considerable uncertainty about the actual 

population size. However, the BRT was confident that the population is likely to be much 

greater than 2000 in total size. Estimates of population growth trends do not exist for the 

Mexican population by itself. Although no specific growth rate has been estimated for this 

population, the growth rate for the entire North Pacific population is estimated at 4.9% 

(Calambokidis et al. 2008). The California/Oregon feeding population is comprised of a mixture 

from this DPS and whales from the Central America DPS; this feeding population has been 

estimated to be growing at a rate of ~8% per year from 1991-2008 (Calambokidis et al. 2008). 

Whales from Mexico comprise the majority of whales in this feeding area, which indicates this 

population is very likely increasing. Similarly, some whales from Mexico migrate to the Gulf of 

Alaska, where a growth rate of 6.6% per year was observed from 1987-2003 for the area ranging 

from the Shumagin Islands through Kodiak Island (Zerbini et al. 2006a). Finally, between 1991 

89
and 2007, a 10.6% annual increase in population size was calculated for Southeast Alaska 

(Dahlheim et al. 2009), which is close to the maximum biologically plausible level. Given the 

evidence of population growth throughout most of the primary feeding areas of the Mexico DPS 

(California/Oregon, Gulf of Alaska from the Shumagins to Kodiak), it was considered unlikely 

this DPS was declining, but the BRT noted that a reliable, quantitative estimate of the population 

growth rate for this DPS is not currently available.

D.6.1 Threats Analysis

Habitat or Range Curtailment

Breeding locations used by this population (and migratory routes to get to aggregation areas) are 

adjacent to large human population centers. The population may, therefore, be exposed to 

adverse effects from a number of human activities, including fishing activities (possible 

competition with fisheries), effluent and runoff from human population centers as coastal 

development increases, activities associated with oil and gas development, and a great deal of 

vessel traffic. 

Southern California humpback whales were found to have the highest levels of DDT, PCBs, and 

PBDEs of all North Pacific humpback whales sampled on their feeding grounds (Elfes et al.

2010). The DDT levels detected were greater than those found in the typically more 

contaminated Gulf of Maine humpback whales possibly due to the historical dumping of DDT 

off Palos Verdes Peninsula (Elfes et al. 2010). It is not possible to state unequivocally if 

population level impacts occur as a result of these contaminant loads, but Elfes et al.(2010)

suggested the levels found in humpback whales are unlikely to have a significant impact on their 

persistence as a population.

There are currently numerous active oil and energy leases and offshore oil rigs off the U.S. west 

coast. Offshore LNG terminals have been proposed for California and Baja California. The 

feeding grounds for this population are therefore an active area with regard to energy exploration 

and development. However, there are no plans at present to open the West Coast to further 

drilling. Alternative energies, such as wind and wave energy, may be developed in the future in 

this region. Currently, the threat posed to this population by energy exploration and 

development is low, and is considered stable. 

Naturally occurring biotoxins from dinoflagellates and other organisms are known to exist within 

the range of this population, although there are no records of known humpback whale deaths 

attributable to biotoxin exposure in the Pacific. The occurrence of HABs is expected to increase 

with nutrient runoff associated with the growth of various types of human-related activities. The 

level of certainty in the impacts of exposure to HABs is moderate.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

No whaling currently occurs in this DPS’ range. 

The Mexico humpback whale DPS is exposed to some whale watching activities in both U.S. 

and Mexican waters, but at low levels. Adverse effects from whale watching have not been 

documented, and overall impact of whale watching is expected to be low and stable.

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This population is exposed to some scientific research activities in both U.S. and Mexican 

waters, but at relatively low levels. Adverse effects from research activities have not been 

identified, and overall impact is expected to be low and stable.

Under Mexican law, all marine mammals are listed as “species at risk” and are protected under 

the General Wildlife Law (2000). Amendments to the General Wildlife Law to address impacts 

to whales by humans include: areas of refuge for aquatic species; critical habitat being extended 

to aquatic species (including cetaceans), prohibition of the import and export of marine mammals 

for commercial purposes (enacted in 2005), and protocol for stranded marine mammals (2011). 

Mexican Standard 131 on whale watching includes avoidance distances and speeds, limits on 

number of boats, and protection from noise (no echo sounders). Two protection programs for 

humpback whales (regional programs for protection) have been proposed for the regions of Los 

Cabos and Banderas Bay (Bahia de Banderas). 

Disease or Predation

With regard to natural mortality, and considering all feeding areas assessed, the California 

population had a higher incidence of rake marks attributed to killer whale attacks (20%) than 

other populations (Steiger et al. 2008). Most of the attacks are thought to occur on calves in 

breeding/calving areas, and levels observed in the California group likely result from a 

propensity for killer whale attacks in Mexican breeding areas (Steiger et al. 2008). Though a 

factor in the ensured longevity of this population, it does not appear to be preventing population 

recovery (Steiger et al. 2008).

There is little to no information on the impacts of disease or parasites on this DPS. 

Other Natural or Human-Related Threats 

This population is likely exposed to relatively high levels of underwater noise resulting from 

human activities. These may include, for example, commercial and recreational vessel traffic, 

and activities in U.S. Navy test ranges. The overall population-level effects of exposure to 

underwater noise are not well-established, but exposure is likely chronic and at relatively high 

levels. As vessel traffic and other activities are expected to increase, the level of this threat is 

expected to increase. The level of confidence in this information is moderate.

Of the 17 records of stranded North Pacific humpback whales in the NMFS stranding database, 

three involved fishery interactions, two were attributed to vessel strikes, and in five cases the 

cause of death could not be determined (Carretta et al. 2010). Specifically, between 2004 and 

2008, 14 humpback whales were reported seriously injured in commercial fisheries offshore of 

California and two were reported dead. What proportion of these represent the Mexican 

breeding population is unknown. Fishing gear involved included gillnet, pot, and trap gear 

(Carretta et al. 2010). Between 2004 and 2008, there were two humpback whale mortalities 

resulting from ship strikes reported and eight ship strike attributed injuries for unidentified 

whales in the California-Oregon-Washington stock as defined by NMFS, and some of these may 

have been humpback whales (Carretta et al. 2010).

Overall population level effects from global climate change are not known; nonetheless, any 

potential impacts resulting from this threat will almost certainly increase. The BRT concluded 

that currently climate change is not a risk to the DPS, but the level of confidence in the 

magnitude of this threat is poor. 

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D.6.2 Extinction Risk

Overall, the DPS is estimated to contain in the range of 6,000-7,000 individuals and is likely 

growing at a rate of about 4.9% or more per year (Calambokidis et al. 2008). Considering the 

current estimated size and growth of this DPS, coupled with an assessment of threats that are not 

expected to severely curtail growth or threaten the existence of the DPS as a whole, the BRT

allocated 92% of votes to “not at risk” of extinction, and 8% of votes to “moderate risk” of 

extinction. The 8% of votes for “moderate risk” reflect the threat of entanglement and the 

unknown severity of the threats disease and parasites, but given the large (and increasing) 

population size, these threats are not likely to significantly impact the DPS. 

D.6.3 Significant portion of its range

There are some regional differences in threats for the Mexico DPS, and some evidence for minor 

substructure within the DPS due to multiple breeding locations associated with somewhat 

distinctive feeding grounds. However, the BRT was unable to identify portions of the DPS that 

faced particularly high threats compared to other portions of the DPS or that appeared to be at 

high risk of extirpation. The BRT therefore concluded that the DPS was not at risk of extinction 

in only a significant portion of its range.

D.7 Okinawa/Philippines DPS and Second West Pacific DPS

The BRT agreed it is likely that the Western North Pacific (WNP) includes two DPSs: one that 

winters primarily in the Ryukyu Islands (e.g., Okinawa) and the Philippines, and a second that 

winters, primarily, in an unknown location. Both DPSs are thought to overlap in Ogasawara, 

similar to the mixing of whales from the Eastern North Pacific in Baja, Mexico. 

The abundance of humpback whales in the WNP is estimated to be around 1,000, based on the 

photo-identification, capture-recapture analyses from the years 2004-2006 by the SPLASH 

program (Calambokidis et al. 2008). This estimate assumed that the two primary sampling 

regions, Okinawa and Ogasawara, represented a single intermingling population - there are no 

estimates of abundance for the two proposed DPSs individually. The growth rate of the WNP is 

estimated to be 6.9% (Calambokidis et al. 2008) between 1991-93 and 2004-06, although this 

could be biased upwards by the comparison of earlier estimates based on photo-identification 

records from Ogasawara and Okinawa with current estimates based on the more extensive 

records collected in Ogasawara, Okinawa and the Philippines during the SPLASH program. 

However, the overall number of whales identified in the Philippines was small relative to both 

Okinawa and Ogasawara, so any bias may not be large. Given the possible bias in the rate of 

increase and the fact that it represents a combination of one DPS with at least a portion of a 

second DPS, it is not possible to make a definite statement about the rate of increase of either 

DPS. Overall recovery seems to be slower than in the Central and Eastern North Pacific. 

Humpback whales in the WNP remain rare in some parts of their former range, such as the 

coastal waters of Korea, and have shown no signs of a recovery in those locations (Gregr 2000; 

Gregr et al. 2000).

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D.7.1 Threat Analysis

Habitat or Range Curtailment

Humpback whales in the WNP (both of the DPS described above) are at some risk of habitat loss 

or curtailment from a range of human activities. Confidence in information about, and 

documentation of, these activities is relatively good, except on the unknown breeding grounds of 

the Second West Pacific DPS. Given continued human population growth and economic 

development in most of the Asian region, these threats can be expected to increase.

Coastal development, including shipping, and habitat degradation are potential threats along 

most of the coast of Japan, South Korea and China. Organochlorines and mercury are found in 

relatively high levels in most cetaceans along the Asian coast (Simmonds 2002). Although the 

threat to the health of these DPS is unknown, the accumulation of these pollutants can be 

expected to increase over time. 

The BRT noted that the Sea of Okhotsk currently has a high level of energy exploration and 

development and these activities are likely to expand with little regulation or oversight. They 

determined that the threat posed by energy exploration to the Okinawa/Philippines DPS is 

medium, but noted that there was low certainty regarding this since specifics of feeding location 

(on or off the shelf) are unavailable. If feeding activity occurs on the shelf in the Sea of 

Okhotsk, energy exploration in this area could impact what is likely one of the most depleted 

subunits of humpback whales. 

As above, naturally occurring biotoxins from dinoflagellates and other organisms are known to 

exist within the range of these DPS, although known humpback whale deaths attributable to 

biotoxin exposure do not exist in the Pacific. The occurrence of HABs is expected to increase 

with the growth of various types of human- related activities. The level of confidence in the 

predicted increase is moderate.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

There are no proposals for scientific, aboriginal/subsistence or commercial hunting of humpback 

whales in the North Pacific under consideration by the IWC at this time. Some degree of illegal, 

unreported or unregulated (IUU) exploitation, including ‘commercial bycatch whaling’, has been 

documented in both Japan and South Korea through genetic identification of whale meat sold in 

commercial markets (Baker et al. 2000; Baker et al. 2006). Some degree of IUU exploitation is 

also possible in other regions within the range of humpbacks in the WNP humpback, including 

Taiwan and the Philippines, given past histories of whaling. The full extent of IUU exploitation 

is unknown. Official reports of whales taken as bycatch entanglement and destined for 

commercial markets are considered to be incomplete (Lukoschek et al. 2009).

There is some whale-watching and non-lethal scientific research in Japanese waters, primarily in 

Ogasawara and Okinawa, but this is at low levels and not thought to pose a risk to this DPS.

Disease or Predation

The evidence of killer whale attacks is low (6-8%) relative to other North Pacific humpback 

whales (Steiger et al. 2008). Certainty in this information is considered moderate and the 

93
magnitude is expected to remain stable. There are no reports of disease in this population and 

levels of parasitism are unknown. Trends in the severity of disease and parasitism are also 

unknown.

Other Natural or Human-Related Threats 

The WNP DPSs are likely to be exposed to relatively high levels of underwater noise resulting 

from human activities that may include commercial and recreational vessel traffic, and military 

activities. Overall population-level effects of exposure to underwater noise are not well 

established, but exposure is likely chronic and at relatively high levels. As vessel traffic and 

other activities are expected to increase, the level of this threat is expected to increase. The level 

of confidence in this information is moderate.

The likely range of the Okinawa/Philippines DPS includes some of the world’s largest centers of 

human activities and shipping. Although reporting of ship strikes is requested in the Annual 

Progress reports to the IWC, reporting by Japan and Korea is likely to be poor. A reasonable 

assumption, although not established, is that shipping traffic will increase as global commerce 

increases; thus, a reasonable assumption is that the level of the threat will increase. The threat of 

ship strikes was therefore considered to be medium for the Okinawa/Philippines DPS and 

unknown for the Second West Pacific DPS.

The Fisheries Agency of Japan considers whales to be likely competitors with some fisheries, 

although direct evidence of these interactions is lacking for humpback whales in the region 

(other than net entanglement). Whales along the coast of Japan and Korea are at risk of 

entanglement related mortality in fisheries gear, although overall rates of net and rope scarring 

are similar to other regions of the North Pacific (Brownell et al. 2000). The threat of mortality 

from any such entanglement is high given the incentive for commercial sale allowed under 

Japanese and Korean legislation (Lukoschek et al. 2009). The reported number of humpback 

whale entanglements/deaths has increased for Japan since 2001 as a result of improved reporting, 

although the actual number of entanglements may be underrepresented in both Japan and Korea 

(Baker et al. 2006). The level of confidence in understanding the minimum magnitude of this 

threat is medium for the Okinawa/Philippines DPS and low for the Second West Pacific DPS, 

given the unknown wintering grounds and primary migratory corridors. 

Overall population level effects from global climate change are not known; nonetheless, any 

potential impacts resulting from this threat will almost certainly increase. The level of 

confidence in the magnitude of this threat is poor. 

D.7.2 Extinction Risk

Humpback whales in the WNP are exposed to a number of known and suspected direct and 

indirect threats from human activities. The levels of these threats are higher than in most other 

regions of the world and are expected to increase, rather than decline. Humpback whales remain 

rare in parts of their former range and overall recovery seems to be slower than most other 

populations around the world. An assessment of the WNP humpback whale (as a single 

population) has been submitted to the IUCN Cetacean Specialist Group with the 

recommendation that the population be listed as Vulnerable VU (D1) Category and criteria 

(Brownell Jr. et al. 2010).

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In voting on extinction risk for the Okinawa/Philippines DPS, 36% of the votes were high risk, 

44% were moderate risk and 21% were not at risk (percent of votes in each category is rounded 

to nearest whole number). In voting on extinction risk for the second WNP DPS, 14% of the 

votes were high risk, 47% were moderate risk and 39% were not at risk. 

D.7.3 Significant portion of its range

The BRT concluded that both Western Pacific DPSs were likely to be at moderate-to-high risk 

throughout their entire ranges. The BRT concluded that the threats identified are likely to impact 

the DPSs in their entirety. The BRT therefore concluded neither Western Pacific DPS was at 

high risk of extinction in only a significant portion of its range. 

D.8 West Australia

Abundance of northbound humpback whales in the southeastern Indian Ocean in 2008 was 

estimated at 21,750 (95% CI = 17,550-43,000) based upon line transect survey data (Hedley et 

al. 2009). The current abundance appears likely close to the historical abundance for the DPS, 

although there is some uncertainty of the historical abundance due to difficulties in allocating 

catch to specific breeding populations (IWC 2007a). The current abundance is large relative to 

any of the general guidelines for viable abundance levels (see earlier discussion). The rate of 

population growth is estimated to be ~10% annually since 1982, which is at or near the estimated 

physiological limit of the species (Bannister 1994; Bannister and Hedley 2001) and well above 

the interim recovery goal.

D.8.1 Threats Analysis

Habitat or Range Curtailment

The threat posed by energy development to the Western Australia population was considered 

medium because of the substantial number of oil rigs and the amount of energy exploration 

activity in the region inhabited by the whales (indicator CO-26 in (Beeton et al. 2006)). 

Additionally, there are proposals for many more oil platforms to be built in the near future,

which are highly likely to be executed (Department of Industry and Resources 2008). 

Coastally populated areas are increasing rapidly, and while the threat associated with coastal 

development is currently considered low, it is expected to increase. Although contaminant levels 

in humpback whales in this region are unknown, the threat level was considered low given what 

is known of contaminant levels in other populations.

There have been no records of humpback whale deaths as a result of exposure to HABs in this 

DPS, thus the threat is considered low. 

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

No whaling occurs in this DPS’ range. 

95
Whale-watching tourism and scientific research occur, at relatively low levels, throughout this 

DPS’ range. Therefore, these threats are considered low. 

Disease or Predation

There are no recent studies of disease or parasitism in this DPS, but there are no indications that 

they represent a substantial threat to the DPS. 

Other Natural or Human-Related Threats 

Competition with fisheries is considered a low threat to humpback whales off the coast of 

Western Australia due to the lack of spatial and temporal overlap with fisheries and whales. The 

threat of offshore aquaculture is considered low, but aquaculture activities may be increasing in 

this region. In the Southern Hemisphere, humpback whales feed almost entirely on krill 

(Euphausia superba). There is a regulated commercial harvest of krill, but harvest levels are 

currently small and there is no evidence that this threatens the food supply of humpback whales 

(Everson and Goss 1991; Nicol et al. 2008).

Coastally populated areas are increasing rapidly, with associated development of ports bringing 

increased risks of ship strikes. All ship strikes in Commonwealth waters must be reported by 

law, and a summary of these has been provided to the IWC annually since 2006. Since this time 

there has only been one report concerning a possible humpback ship strike in Western Australian 

waters (IWC 2009b). The threat of ship strikes in Western Australia is considered low, but likely 

increasing. 

There are 25 records of humpback whale entanglement events between 2003 and 2008 in this 

region, with western rock lobster fishing gear most frequently implicated (Doug Coughran pers 

comm. IWC 2004a; IWC 2005a; IWC 2006a; IWC 2007c; IWC 2008). A rise in marine fishing 

debris has also been reported for the region (Environment Western Australia 2007), which 

suggests that there may be an increasing risk of entanglement.

Climate change may impact the West Australia DPS of humpback whales in multiple ways. Sea 

level rise, ocean warming and ocean acidification may all negatively impact the reef system 

providing shallow, protected waters for breeding. Ocean acidification also has a documented 

impact on krill growth and development (Kurihara 2008), the primary prey item for Southern 

Hemisphere humpback whales. Krill are tightly associated with sea ice (Brierley et al. 1999; 

Brierley et al. 2002), and decreasing sea ice may negatively impact krill abundance and/or 

distribution. Decreases in krill abundance have been observed around the Antarctic Peninsula 

(Atkinson et al. 2004). Overall population level effects from global climate change and 

anthropogenic noise are not known and the threat was ranked low; nonetheless, any potential 

impacts resulting from these threats will almost certainly increase.

D.8.2 Extinction Risk

The BRT did identify some threats to the DPS, particularly extensive oil and gas development 

near the breeding grounds and migratory areas along the western Australian coast, some risk 

from entanglement in coastal fisheries, and the potential effects of climate change on the DPS’ 

Southern Ocean prey base. The BRT concluded, however, that large population size and the 

demonstrated high growth rate of the DPS indicate that these threats are not significantly 

96
impacting the DPS now, and would need to become much more severe to create a moderate or 

high risk of extinction in the future. As a group, the BRT was confident (97% of likelihood 

points) that the Western Australia DPS is not at risk of extinction (3% of likelihood points were 

attributed to moderate” risk of extinction).

D.8.3 Significant portion of its range

The BRT concluded that the effect of any geographically localized threats would be seen in the 

status of the DPS as a whole. The BRT was unable to identify portions of the DPS that both 

faced particularly high threats and were so significant to the viability of the DPS as a whole that 

if lost would result in remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

D.9 East Australia

Abundance of the east Australia DPS was estimated to be 6,300-7,800 (95% CI: 4,040-10,739) in 

2005 based on photo-ID data (Paton and Clapham 2006; Paton et al. 2008; Paton et al. 2009). 

The annual rate of increase is estimated to be 10.9% for humpback whales in the southwestern 

Pacific Ocean (Noad et al. 2008), well above the interim recovery goal. This estimate of 

population increase is very close to the biologically plausible upper limit of reproduction for 

humpbacks (Zerbini et al. 2010). The surveys presented by Noad et al. (2005; 2008) have 

remained consistent over time, with a strong correlation (r > 0.99) between counts and years.

D.9.1 Threats Analysis

Habitat or Range Curtailment

Whales migrating southward to the feeding grounds as well as a portion of those migrating north, 

follow the east coast of Australia and many or most are confined to a narrow corridor near the 

coast (Bryden 1985; Noad et al. 2008) passing several large cities. Increasing coastal 

development is possible in these areas, but they represent a minor portion of the total migratory 

route. As with coastal development, sources of pollution for the east Australia DPS are 

concentrated in a few locations along the migratory route. The breeding area for this DPS is 

primarily within the Great Barrier Reef Marine Park (Chittleborough 1965; Simmons and Marsh 

1986), which has a comprehensive set of state and federal protection laws. However, during 

tropical floods, farmland runoff may bring significant quantities of pollutants (pesticides, 

fertilizers) down several rivers that empty into the Great Barrier Reef area (Haynes and 

Michalek-Wagnera 2000). To date there are no known documented impacts of contaminants on 

humpback whale survival and fecundity. Oil and gas exploration and drilling are prohibited 

within the Great Barrier Reef Marine Park. However, oil and gas production occurs in Bass 

Strait (Australian Government 2006), a region used by some whales of this DPS as they migrate 

to feeding grounds. Overall, these threats were considered to pose a low risk to this DPS.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Anthropogenic disturbance of this DPS occurs primarily on the breeding ground. Whalewatching tourism in eastern Australia (Queensland) has seen an annual average growth rate of 

8.5% since 1998 (this includes boat and land-based operations and both whale- and dolphin97
watching trips O'Connor et al. 2009). In New South Wales, boat-based whale- and dolphinwatching has seen a 2.6% increase between 2003 and 2008. However, Queensland has a 

substantial whale-watching management program (O'Connor et al. 2009), including restricting 

access to areas deemed essential for humpback conservation, and Australia has national whalewatching guidelines. With these regulations in place, the threat level was considered low. 

Scientific research activities on this DPS occur at the feeding grounds, breeding grounds and 

along the migratory route. Photo-identification studies, biopsy efforts and other field studies do 

exist. However, adverse effects from research activities have not been documented and threats 

are considered low. Finally, proposed scientific whaling in the Antarctica feeding grounds 

would occur in areas where the east Australia DPS is known to feed (Nishiwaki et al. 2007). 

However, at this time no whaling in these feeding grounds is occurring. Should proposed 

whaling take place, impacts to this DPS should be revisited with information on where the 

whaling will occur.

Disease or Predation

There is little to no information on the impacts of disease, parasites or predation on this DPS. 

Evidence for killer whale interaction is documented, and 17% of photo-identified humpback 

whales in east Australia show scarring on their flukes, most of which is consistent with 

interactions with killer whales (Naessig and Lanyon 2004). There is no evidence to suggest that 

this level of predation is outside the norm for the DPS. Given the population size and current 

growth rate, disease, predation and parasitism seem unlikely to pose a significant threat to this 

DPS. 

Other Natural or Human-Related Threats 

There is no published information on negative impacts of offshore aquaculture, competition with 

fisheries or HABs on this DPS. In the Southern Hemisphere, humpback whales feed almost 

entirely on krill (Euphausia superba). There is a regulated commercial harvest of krill, but 

harvest levels are currently small and there is no evidence that this threatens the food supply of 

humpback whales (Everson and Goss 1991; Nicol et al. 2008).

Vessel collisions and entanglement in fishing gear pose the greatest anthropogenic risks to the 

east Australia DPS. Thirteen ship-strike incidents and five deaths have been reported between 

2003 and 2008 (summarized in Fleming and Jackson 2011) and an additional ship-strike was 

recorded in 2009 with the whale being seriously injured (IWC 2010a). Both fishing vessels and 

commercial vessels have been involved in these incidents. Given the probable increase in 

fishing, tourism and commercial shipping, the threat is likely to increase. Entanglements are 

regularly reported along the east coast of Australia and 57 entanglements have been documented 

between 2003-2008, with 13 confirmed deaths (Fleming and Jackson 2011). In addition, six 

humpback whales were entangled in shark control nets and released in 2009 (IWC 2010b). 

These totals are likely underestimates as not all entanglements are reported and some are not 

identified to species. The majority were recorded in shark nets and occurred along the migratory 

route (Fleming and Jackson 2011). Although not insignificant, given the population size and 

estimated growth rate, the threat level posed by these factors is considered low. Anthropogenic 

noise is also a possible threat to this DPS. There are several commercial shipping routes through 

the Great Barrier Reef breeding ground and along the coastal migratory route that likely result in 

some underwater noise exposure. Migration through Bass Strait would also expose whales to 

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energy exploration and production noise. There is no information concerning exposure of 

whales to underwater military activities. 

Climate change may impact the east Australia DPS of humpback whales in multiple ways. Sea 

level rise, ocean warming and ocean acidification may all negatively impact the reef system 

providing shallow, protected waters for breeding. Ocean acidification also has a documented 

impact on krill growth and development (Kurihara 2008), the primary prey item for Southern 

Hemisphere humpback whales. Krill are tightly associated with sea ice (Brierley et al. 1999; 

Brierley et al. 2002), and decreasing sea ice may negatively impact krill abundance and/or 

distribution. Decreases in krill abundance have been observed around the Antarctic Peninsula 

(Atkinson et al. 2004). Overall population level effects from global climate change and 

anthropogenic noise are not known and the threat was ranked low; nonetheless, any potential 

impacts resulting from these threats will almost certainly increase.

D.9.2 Extinction Risk

The east Australia DPS has a relatively high abundance (2005 estimate: 6300-7800; Paton et al.

2008). This may be an underestimate as it is thought some demographic groups were likely 

unequally captured during the mark-recapture period (Paton et al. 2008; Paton et al. 2009). 

Population growth rate estimates have been steady at 10.6 – 10.9% since 1978 (Noad et al. 2005; 

Noad et al. 2008), a level thought to be near the maximum intrinsic potential of the species 

(Zerbini et al. 2010) and well above the interim recovery goal. The evaluation of population 

growth rates by Noad et al. (2008) appears to be sound with accepted methodologies applied 

consistently through time. It should be noted, however, that the status of this DPS with respect 

to pre-whaling conditions has not yet been determined due to difficulties in allocating feeding 

ground catches among the tropical breeding grounds. The majority of catches (~70%) were 

concentrated in the years 1958-1961, notably very large illegal takes by the USSR; this led to the 

complete collapse of the east Australian coastal whaling industry in 1962 (Clapham and 

Ivashchenko 2009; Clapham et al. 2009; Fleming and Jackson 2011).

Because of the relatively high abundance and growth rate, the overall threats to the DPS are 

deemed low. Furthermore, humpback whales in Australian waters are protected by the 

Australian Whale Sanctuary, which extends 200nm from Australia’s coast. However, ship 

strikes and entanglements are recorded on a near annual basis and changes in climate could 

negatively impact their prey resource in the future. There is also a potential for resumption of 

whaling on their feeding ground (Nishiwaki et al. 2007). However, the latter two threats are 

seen as potential rather than current threats. In voting on extinction risk, 96% of votes were for 

“not at risk” and 4% were for “moderate risk.” The votes in the “moderate risk” category 

reflected uncertainty regarding entanglement and ship strike rates.

D.9.3 Significant portion of its range

The BRT concluded that the effect of any geographically localized threats would be seen in the 

status of the DPS as a whole. The BRT was unable to identify portions of the DPS that both 

faced particularly high threats and were so significant to the viability of the DPS as a whole that 

if lost would result in remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

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D.10 Oceania

The Oceania humpback whale population is of moderate size (3,827 whales in New Caledonia, 

Tonga, French Polynesia and Cook Islands combined; CV=0.12) (South Pacific Whale Research 

Consortium et al. 2006); however, no trend information is available for this DPS. The 

population is quite subdivided and the population estimate applies to an aggregate (although it is 

known that sub-populations differ in growth rates and other demographic parameters). There are 

some areas of historical range extent that have not rebounded and other areas without historical 

whaling information (Fleming and Jackson 2011). There is uncertainty regarding which 

geographic portion of the Antarctic this population uses for feeding. The complex population 

structure of humpback whales within the Oceania region creates higher uncertainty regarding 

demographic parameters and threat levels than for any other DPS.

D.10.1 Threats Analysis

Habitat or Range Curtailment

Surface run-off from nickel strip mines causes habitat degradation and pollution of lagoons in 

New Caledonia, which is one of the largest producers of nickel globally, yet the effect on the 

surrounding marine environment has been poorly monitored (e.g. de Forges et al. 1998; Labrosse

et al. 2000; Metian et al. 2005). The threat to humpback whales in Oceania from coastal 

development and contaminants was considered low overall. 

The BRT considered the threats of energy exploration and development and offshore aquaculture 

to the Oceania population to be low but increasing, due to the expected growth of these activities 

over the next several decades. 

The level of threat posed by HABs to humpback whales in Oceania is unknown.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Some local whaling of humpback whales was carried out in French Polynesia (Rurutu), the Cook 

Islands and Tonga during the 20th century (Reeves 2002) but this has ceased since 1960 at 

Rurutu (Poole 2002), and since 1978 elsewhere (IWC 1981). Whale sanctuaries (local waters 

where whaling is prohibited) have since been declared in the Exclusive Economic Zones of 

French Polynesia, Cook Islands, Tonga, Samoa, American Samoa, Niue, Vanuatu, New 

Caledonia and Fiji (Hoyt 2005), while whales are protected in New Zealand waters under the 

New Zealand Marine Mammal Protection Act.

Humpback whales are under threat from unregulated scientific whaling in the Antarctic waters 

directly to the south of Oceania. None have been taken to date, but an annual catch of 50 

humpback whales was proposed by Japan in the 2007/2008 season (Nishiwaki et al. 2007), as 

part of its JARPA II research program. This has been held in abeyance while Japan considers 

that progress is being made by the IWC in its meetings on the “Future of the IWC.” It is not 

known if the proposed take of humpback whales will be reinstated at a future time; however, the 

effect of this level of annual take on regional population recovery could be substantial. 

Whale-watching tourism exists in all four of the principal survey sites in Oceania, with strong 

growth in the last decade. There is no boat-based, dedicated whale watching industry in 

American Samoa at present. Whale watching guidelines are in place in Tonga and New 

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Caledonia, while boat-based whale watching in the Cook Islands, Samoa and Niue is minimal 

(O'Connor et al. 2009). Humpback whales have been at particular risk from excessive boat 

exposure through whale watching in the Southern Lagoon of New Caledonia, where there are 

currently 24 working operators. Levels of exposure have been unusually high (peaking during 

weekend periods), with boats <100m from calves 40% of the time and each whale exposed to an 

average of 3.4 boats for two hours daily (Schaffar and Garrigue 2008). In 2008, commercial tour 

operators voluntarily signed a code of conduct and subsequent compliance with this code has 

significantly reduced the level of daily exposure to boats (South Pacific Whale Research 

Consortium 2009). Whale watching and other recreational or research-related activities were 

deemed by the BRT to pose a low level of threat in this region.

Disease or Predation

Mattila and Robbins (2008) reported raised skin lesions along the dorsal flanks of humpback 

whales in American Samoa. The lesions differ morphologically from the ‘depressed’ lesions 

caused by cookie cutter sharks and appear to persist for long periods on the skin, rather than 

either erupting or healing. There are no reports of these lesions in whaling records, suggesting 

that this phenomenon is recent. The cause of these lesions is currently unknown (Mattila and 

Robbins 2008), but they are not considered a threat to the population. 

Other Natural or Human-Related Threats

There is little information available from the South Pacific regarding entanglement with fishing 

gear; two humpback whales have been observed in Tonga entangled in rope in one instance and 

fishing net in another (Donoghue, pers. comm.). One humpback mother (with calf) was reported 

entangled in a longline in the Cook Islands in 2007 (South Pacific Whale Research Consortium

2008). Entanglement scars have been seen on humpback whales in American Samoa, but there 

are not enough data to determine an entanglement rate. Available evidence suggests that 

entanglement is a potential concern in regions where whales and stationary or drifting gear in the 

water overlap (Mattila et al. 2010). The threat of entanglements was ranked low for the Oceania 

population. 

There is little information available from the South Pacific regarding ship strikes. This threat 

was ranked low but is expected to increase as vessel activity in the region increases. Similarly, 

this population is likely exposed to moderate levels of underwater noise resulting from human 

activities, which may include, for example, commercial and recreational vessel traffic. Overall 

population-level effects of exposure to underwater noise are not well established, but as vessel 

traffic and other activities are expected to increase, the level of this threat is expected to increase.

In the Southern Hemisphere, humpback whales feed almost entirely on krill (Euphausia 

superba). There is a regulated commercial harvest of krill, but harvest levels are currently small 

and there is no evidence that this threatens the food supply of humpback whales (Everson and 

Goss 1991; Nicol et al. 2008). The threat of competition with fisheries was considered low for 

the Oceania DPS. 

Climate change may impact the Oceania DPS of humpback whales in multiple ways. Sea level 

rise, ocean warming and ocean acidification may all negatively impact the reef system providing 

shallow, protected waters for breeding. Ocean acidification also has a documented impact on 

krill growth and development (Kurihara 2008), the primary prey item for Southern Hemisphere

humpback whales. Krill are tightly associated with sea ice (Brierley et al. 1999; Brierley et al.

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2002), and decreasing sea ice may negatively impact krill abundance and/or distribution. 

Decreases in krill abundance have been observed around the Antarctic Peninsula (Atkinson et al.

2004). Overall population level effects from global climate change and anthropogenic noise are 

not known and the threat was ranked low; nonetheless, any potential impacts resulting from these 

threats will almost certainly increase.

D.10.2 Extinction Risk

The magnitude of each threat facing this population is unknown or fairly low except for 

entanglement. The voting results showed a spread in point allocation, conveying some 

uncertainty in the extinction risk of this population. The majority of the votes were for “not at 

risk” (68% of votes), followed by “moderate risk” (29% of votes) and, then “high risk” (3% of 

votes). Numerous BRT members noted the lack of trend information, which influenced the 

distribution of their likelihood points. Two regions where trend information exists (Cook Strait 

and Fiji) have low or zero growth rates. Some BRT members noted that there are a relatively 

large number of whales but believed that extinction risk could be greater if the population growth 

rate is actually negative. Given the lack of data on population growth, the BRT noted their 

uncertainty in the population’s recovery potential pending any significant impact on population 

abundance. BRT members also noted that IUCN has listed the Oceania population as 

‘endangered’, because of the severe depletion by past commercial and current illegal whaling 

and the apparently slow rate of recovery. 

D.10.3 Significant portion of its range

The Oceania DPS has potentially somewhat greater substructure than most other humpback 

whale DPS due its extended breeding range, although a lack of strong genetic structure indicates 

there is likely to be considerable demographic connections among these areas. Some threats, 

such as whale watching in the Southern Lagoon of New Caledonia, appear to be localized. 

Nonetheless, the BRT was unable to identify any specific areas where threats were sufficiently 

severe to be likely to cause local extirpation. The BRT therefore concluded that this DPS is not 

likely to be at high risk in any significant portion of its range. 

D.11 Southeastern Pacific

Individuals of the Southeastern Pacific population migrate from breeding grounds between Costa 

Rica and northern Peru to feeding grounds in the Magellan Straits and along the Western 

Antarctic Peninsula. Though no quantitative growth rate information is available for this 

population, abundance estimates over a 13-year period suggest that the population size is 

increasing, and abundance was estimated to be 6,504 (95% CI 4270-907) individuals in 2005-

2006 (Félix et al. 2006a; Félix et al. 2011). Total abundance is likely to be larger because only a 

portion of the DPS was enumerated. 

D.11.1 Threats Analysis

Habitat or Range Curtailment

Human population growth and associated coastal development, including port development, 

disruption and possible partitioning of the marine habitat and increased turbidity in coastal 

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waters, are potential threats to this population. The presumed migratory route for this population 

lies in the coastal waters off Costa Rica, Panama, Colombia, Ecuador, Peru, and Argentina and 

includes some large human population centers in both Central and South America. Currently, 

the high degree of coastal development in this population’s habitat is not substantially affecting 

the population’s size or growth rate and it is considered to be a low-level threat.

Little has been published regarding contaminant levels in this region. However, levels of DDTs, 

PCBs, and PBPEs are typically lower in Southern Hemisphere feeding areas than off the east or 

west coasts of the U.S., but little research has been done to confirm lower contaminant levels 

among Southern Hemisphere whales (Fleming and Jackson 2011). DDT and PCB levels are 

likely to decrease in feeding areas because use of these chemicals has been banned in many 

countries, but PBPE use may still be increasing. Man-made contaminants are not considered to 

be a significant threat to this population.

Energy exploration and development activities are present in this population’s habitat range. Oil 

and gas production is currently increasing in the Gulf of Guayaquil, Ecuador (Félix and Haase 

2005). A large number of oil tankers transit through the Straits of Magellan yearly, a notoriously 

difficult route to navigate. At least one oil spill has resulted from a ship running aground there 

(Morris 1988). Energy development is likely to expand if oil and gas reserves are discovered in 

other locations but it does not currently pose a threat to this population. 

Harmful algal blooms (HABs) of dinoflagellates and diatoms exist within the feeding range of 

this population, but there have been no records of humpback whale deaths as a result of exposure 

in this area. The occurrence of HABs is expected to increase with increased run-off and nutrient 

input from human- related activities; however, HABs do not pose a threat to this population 

currently. 

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Whale-watching tourism and scientific research occur, at relatively low levels, throughout this 

population’s range. Whale-watching tourism occurs along all of the South and Central American 

countries bordering the habitat of this DPS. Whale-watching industry growth has been 

significant and approximately half of these countries have whale-watching guidelines in place 

(Hoyt and Iníguez 2008). Though some change in behavior of whales near tourism boats has 

been noted, whale-watching does not pose a threat to this population currently. Scientific 

research activities such as observation, biopsying, photographic studies and recording of 

underwater vocalizations of whales occur in both the breeding and feeding habitats and along 

this population’s migratory route though no adverse effects from these events have been 

recorded. 

No whaling occurs in this population’s range. 

Disease or Predation

There is little information available on the impacts of disease or parasitism on this population.

Predation does not appear to be a current threat to this population. Killer whale attacks on 

humpback whales have been observed in this region and scarring from killer whale and 

potentially false killer whale and shark attacks has been documented from photographic 

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catalogues (Flórez-González et al. 1994; Scheidat et al. 2000; Félix and Haase 2001). The 

scarring rate is lower than in some other populations.

Other Natural or Human-Related Threats 

In the Southern Hemisphere, humpback whales feed almost entirely on krill (Euphausia 

superba). There is a regulated and growing commercial krill fishery, but harvest levels are 

currently small and there is no evidence that this threatens the food supply of humpback whales 

(Everson and Goss 1991; Nicol et al. 2008).

Aquaculture activities are high in waters of Argentina and Chile, but the impact of these 

activities on this population of humpback whales has not been documented and is likely low if 

few whales use these inland areas. Entanglement was determined to pose a medium threat to this 

population based on stranding and entanglement observations and spatial and temporal overlap 

with aquaculture activities.

This population is likely exposed to relatively high levels of underwater noise resulting from 

human activities, including commercial and recreational vessel traffic, and activities in naval test 

ranges, and these levels are expected to increase. Especially high levels of large vessel traffic are 

found off Panama (over 12,000 ship transits annually) and in the Magellan Straits. Naval 

exercises occur around much of the South American coast annually. It is not known if 

underwater noise exposure affects humpback whale populations, but this does not currently 

appear to pose a significant threat to this population. 

No ships have reported striking humpback whales in this region but incidents may be underreported and stranding reports indicate some contribution from vessel collisions (Capella Alzueta

et al. 2001; Castro et al. 2008). Shipping traffic will probably increase as global commerce 

increases; thus, a reasonable assumption is that the level of vessel collisions will increase. 

Currently, ship strikes are considered a low level threat to this population. 

Entanglement in fishing gear poses the most significant risk to this population. The majority of 

entanglements involve gillnets and purse seines (Félix et al. 1997; Capella Alzueta et al. 2001; 

Alava et al. 2005; Castro et al. 2008). The artisanal fishing fleet in Ecuador numbers over 

15,000 vessels. Scarring rates indicate that close to one third of all observed animals have 

experienced some level of entanglement (Alava et al. 2005). These scarring rates are similar to 

those observed off the northeast coast of the U.S. Less research effort in the Southeast Pacific 

region compared to the northeast coast of the U.S. suggests that this reported scarification rate 

may even be an underestimate of the actual level of entanglement occurring in the Southeast 

Pacific. The number of dead and entangled whales off Colombia has increased over the last two 

decades (Capella Alzueta et al. 2001). Calves comprise over half of all observed entanglement 

events, a disproportionate value in light of the calf to adult ratio in the population (Engel et al.

2006; Neto et al. 2008). 

Overall population level effects from global climate change and anthropogenic noise are not 

known and the threat was ranked low; nonetheless, any potential impacts resulting from these 

threats will almost certainly increase. Humpback whales in the Southern Hemisphere feed 

almost entirely on krill (Euphausia superba) and acidification of the marine environment has 

been documented to impact the physiology and development of krill and other calcareous marine 

organisms, potentially reducing their abundance and subsequent availability to humpback whales 

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in the future. The life cycle of Euphausia superba is tied to sea ice, making this prey species 

vulnerable to warming effects from climate change. Decreases in krill abundance have been 

observed around the Antarctic Peninsula (Atkinson et al. 2004).

D.11.2 Extinction Risk

The Southeastern Pacific DPS has a relatively high abundance (2005-2006 estimate: 6,500 

individuals). The growth rate has not been quantitatively estimated, but the qualitative trend in 

abundance estimates indicates the population is likely to be growing. In light of historical 

whaling records from the feeding and breeding grounds, recovery from exploitation is estimated 

to be between 30% and 70% (IWC 2007b) but the data are considered relatively unreliable given 

the absence of trend estimates for this specific population. Entanglement scarring rates in this 

population indicate a significant interaction with fishing gear (Capella et al. 2008) and pose the 

greatest threat to this population. Krill stocks may become more variable or may decrease in 

upcoming decades due to climate change. Given the large population size and apparent positive 

population growth, this population is considered to be not at risk of extinction over the next three 

generations (93% of votes). The potential for this population to be at moderate risk of extinction 

was also considered and received 7% of the votes, largely reflecting uncertainty regarding 

population trend. 

D.11.3 Significant portion of its range

The BRT concluded that the effect of any geographically localized threats would be seen in the 

status of the DPS as a whole. The BRT was unable to identify portions of the DPS that both 

faced particularly high threats and were so significant to the viability of the DPS as a whole that 

if lost would result in remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

D.12 Brazil

The most recent abundance estimate for this population comes from aerial surveys conducted off 

the coast of Brazil in 2002-2005 (Andriolo et al. 2010). These surveys covered the continental 

shelf between 6o and 24o

30’S and provided a best estimate of 6,400 whales (95% CI = 5,000-

8,000) in 2005. This estimate corresponds to nearly 24% of this population’s pre-exploitation 

abundance (Zerbini et al. 2006d). Nearly 80% of the whales are found in the Abrolhos Bank, the 

eastern tip of the Brazilian continental shelf located between 16 and 18o

S (Andriolo et al. 2010). 

The best estimate of population growth rate is 7.4%/year (95% CI = 0.5-14.7%) for the period 

1995-1998 (Ward et al. 2011).

D.12.1 Threats Analysis

Habitat or Range Curtailment

Human population growth and associated coastal development represent potential threats to 

coastal populations of humpback whales. These can take many forms, including chemical 

pollution, increase in ship traffic and underwater noise levels. The coast of Brazil has 

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experienced various levels of human development within the range of humpback whales. These 

are of greater intensity along the northeastern coast of the country (between 5o and 12o S), where 

large human settlements are found (the three main cities – Salvador, Recife and Natal - have 1-3 

million inhabitants and have observed population increases of 3% per year since the early 1970s) 

(Instituto Brasileiro de Geografia e Estatistica 2010). Such population growth has resulted in a 

substantial rise in effluent discharge in coastal areas used by humpback whales during the

breeding season. The stretch of the coast where the largest concentration of humpback whales is 

found (Abrolhos Bank, 16o

-18oS) has not had the same level of human growth and is relatively 

pristine compared to areas farther to the north. 

There is no evidence that human population growth has had any major direct impact on western 

South Atlantic humpback whales. In fact, this population has shown strong signs of recovery in 

the same period in which human growth occurred adjacent to the breeding grounds. Shifts in 

habitat use and abundance may have occurred on a local basis, but no studies have been 

conducted to assess these changes. Effects of chemical pollution are largely minimized because 

these whales don’t feed in the tropical wintering grounds. The feeding grounds for western 

South Atlantic humpback whales are located in relatively remote offshore areas in the Southern 

Ocean where human activities have been minimal. While potential impacts are unknown, they 

are probably small in these areas. The current threat of coastal development to this population 

was ranked as low, but is considered to be increasing. 

The construction of new ports along the coast of Brazil has been stimulated by the country’s 

recent economic growth as well as the rapid development of the oil and gas industry. Therefore, 

a resultant increase in ship traffic will likely increase the probability of ship strikes and possibly 

result in greater humpback whale mortality off Brazil. The threat posed by energy exploration 

and development was ranked low but increasing. 

The effects of contaminants on this population are unknown. The occurrence of HABs is 

expected to increase with increased run-off and nutrient input from human-related activities; 

however, HABs do not pose a threat to this population currently.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

A seasonal humpback whale-watching industry exists in some parts of the wintering grounds off 

Brazil. In the Abrolhos Bank, the area of greatest humpback whale concentration, whalewatching is usually associated with other tourist activities. The Bank contains large coral reef 

formations and the associated biological diversity makes this region an important 

diving/snorkelling center. Diving with whales is prohibited by federal law in Brazil, but 

opportunistic whale-watching occurs during diving trips (Morete et al. 2003). Most whalewatching operations are concentrated within the Abrolhos National Park and therefore are highly 

controlled. The maximum number of boats allowed within the park is 15 (Hoyt 2000). Despite 

great potential, expansion of whale-watching in this region is difficult because of poor tourism 

infrastructure and because whales are far away from the coast relative to other areas (Cipolotti et 

al. 2005).

A more established whale-watching industry operates farther to the north, near Praia do Forte 

and Salvador. Most whale watching tours in Bahia State depart from Praia do Forte (Hoyt and 

Iníguez 2008). In other parts of the humpback wintering grounds (e.g. Ilhéus, Itacaré, Porto 

Seguro) whale-watching can occur in an opportunistic fashion. Often, fishermen are hired to 

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take groups of tourists to see whales, but these are unregulated and occasional. Because of the 

relatively small scale, whale-watching activities possibly cause limited, if any, impact on 

humpback whale populations in Brazil. This threat is considered low. 

There is currently no commercial whaling in this region. 

This humpback whale population is exposed to scientific research activities, but adverse effects 

from research activities have not been identified, and overall impact is expected to be low and 

stable.

Disease or Predation

There are studies of disease in the western South Atlantic humpback whale population, but no 

indication that it represents an issue. Stranded whales have shown different types of bone 

pathologies (Groch et al. 2005), but the incidence of these pathologies are not well known. 

A recent increase in humpback whale mortality has occurred along the coast of Brazil. The 

number of carcasses seen floating at sea or found ashore in 2010 (96 individuals) was nearly 3 

fold greater than the average for the period 2002-2009 (29.5 individuals). The causes for this 

increased mortality are not well understood and are under investigation (Humpback Whale 

Institute, unpublished data).

Killer whales appear to be the one of the main predators of humpback whales, especially of 

calves and immature individuals (Clapham 2000). While predation can represent an important 

source of neonatal/juvenile mortality (Steiger et al. 2008), no studies have been conducted to 

assess its effects on this population.

Other Natural or Human-Related Threats 

The threats posed by offshore aquaculture and competition with fisheries were considered low 

for the Brazil population of humpback whales. 

Entanglements in various types of fishing nets have been increasing in the wintering areas 

(Zerbini and Kotas 1998) but there is no current estimate of mortality. Reports from fishermen 

indicate that a large proportion of entanglements are comprised of calves (Zerbini and Kotas 

1998). In the past 20 years, the number of entanglement cases observed or reported has 

increased substantially as is the proportion of whales seen in wintering grounds with evidence 

(e.g., scars) of entanglement in fishing gear (Siciliano 1997; Groch et al. 2008)). Interactions of 

humpback whales with fisheries have been observed throughout the wintering ground and they 

seem to be increasing as the population grows and re-occupies new or historical habitats. 

However, there is currently no assessment on the proportion of entanglements resulting in 

mortality and no estimates of fishery-related mortality for this population. The threat of 

entanglements was considered low but increasing. 

Ship collisions are a well-known cause of mortality in humpback whales (Laist et al. 2001), but 

their incidence among humpback whales in the western South Atlantic is not well known. 

Reports of collisions with whales have been provided by fishermen and recreational boaters. In 

addition, photographic/physical evidence of ship strikes has been recorded throughout the 

wintering grounds off Brazil (e.g. Marcondes and Engel 2009). These events have been 

increasing and seem to be correlated with population recovery, but their conservation 

implications require further studies. In areas of high whale density (e.g., the Abrolhos Bank), 

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collisions between whales and fishing boats have resulted in permanent damage to the boats. 

The fate of whales involved in these accidents is not known (Andriolo, unpublished data). Ship 

strikes were considered a low, but increasing, threat to this population of humpback whales.

The increase in coastal development and ship traffic, the construction of new ports and the 

expansion of the offshore oil and gas extraction have resulted in a rise of underwater noise levels 

along the breeding range of humpback whales. Concerns about effects of noise include 

disruption of behavior, interference with communication, displacement from habitats and, in 

extreme cases, physical damage to hearing (Nowacek et al. 2007). Few studies have been 

carried out to assess whether and how an increase in noise levels has impacted the western South 

Atlantic population. Research conducted in Abrolhos Bank (Sousa-Lima and Clark 2008; SousaLima and Clark 2009) showed that the number of singing whales diminished in the presence of 

low-frequency boat noise and that singing whales stopped calling and changed direction of 

movement if the sound source was within 7.5km on average. Anthropogenic noise was 

considered a low, but increasing, threat to the Brazil population of humpback whales. 

Climate change may impact the Brazil DPS of humpback whales in multiple ways. Sea level 

rise, ocean warming and ocean acidification may all negatively impact the reef system providing 

shallow, protected waters for breeding. Ocean acidification also has a documented impact on 

krill growth and development (Kurihara 2008), and krill is the primary prey item for Southern 

Hemisphere humpback whales. Krill are tightly associated with sea ice (Brierley et al. 1999; 

Brierley et al. 2002), and decreasing sea ice may negatively impact krill abundance and/or 

distribution. Decreases in krill abundance have been observed around the Antarctic Peninsula 

(Atkinson et al. 2004). Overall population level effects from global climate change and 

anthropogenic noise are not known and the threat was ranked low; nonetheless, any potential 

impacts resulting from these threats will almost certainly increase.

D.12.2 Extinction Risk

Western South Atlantic humpback whales were heavily exploited by commercial whaling. This 

was the first Southern Hemisphere population to be hunted in the Southern Oceans in the early 

1900s (Tønnessen and Johnsen 1982). It is estimated that nearly 30,000 whales were killed by 

whalers between 1904 and 1963, with nearly 27,000 catches coming from coastal waters of 

South Georgia (Allison 2006). Currently, the population is relatively large and appears to be 

growing steadily (Ward et al. 2011). A recent Comprehensive Assessment conducted by the 

IWC (IWC 2007a) estimated that the stock was reduced to nearly 3-5% of the 1900 population 

size and that is had recovered to 24-32% of its pre-exploitation size in 2006 (Zerbini et al.

2006d; IWC 2007a).

Given the large population size and apparent positive population growth, this population is 

considered to be not at risk of extinction over the next three generations (96% of votes). The 

potential for this population to be at moderate risk of extinction was also considered and received 

4% of the votes. 

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D.12.3 Significant portion of its range

The BRT concluded that the effect of any geographically localized threats would be seen in the 

status of the DPS as a whole. The BRT was unable to identify portions of the DPS that both 

faced particularly high threats and were so significant to the viability of the DPS as a whole that 

if lost would result in remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

D.13 Gabon/Southwest Africa

The lower and upper bounds of the abundance estimate for Iguela, Gabon are 6,560 (CV=0.15) 

for 2001-2004 and 8,064 (CV=0.12) for 2001-2005. These were generated using mark-recapture 

genetic data, and numerous other (generally similar) estimates are available depending on model 

assumptions (Collins et al. 2008). There are no trends available for this population, and it is not 

entirely clear how the estimates relate to potential subdivision within the DPS (Collins et al. 

2008). Using a Bayesian estimation methodology, Johnston and Butterworth (2008) estimate the 

Gabon population to be in the range of 65-90% of its pre-exploitation size.

D.13.1 Threats Analysis

Habitat or Range Curtailment

For humpback whales utilizing the waters of central western Africa, expanding offshore 

hydrocarbon extraction activity now poses an increasing threat (Findlay et al. 2006). The degree 

to which humpback whales are affected by offshore hydrocarbon extraction activity is not known 

but it is believed that long term exposure to low levels of pollutants and noise, as well as the 

drastic consequences of potential oil spills, could have conservation implications. 

The Gulf of Guinea region suffers from pollution and habitat degradation, both from major 

coastal cities (Lagos, Accra, Libreville, Porto-Nevo) which dispense raw sewage and untreated 

toxic waste into the marine environment (United Nations Environment Programme 1999), and 

from unregulated foreign trawling and oil and gas developments (Chidi Ibe 1996). The practice 

of mining construction materials from the near-shore coastal zone (e.g. sand and gravel) is also 

common in this region, which contributes to habitat degradation (Chidi Ibe 1996). The threat of 

coastal development is considered low, but increasing. 

Certain naturally occurring biotoxins from dinoflagellates and other organisms may exist within 

the range of this population, although humpback whale deaths as a result of exposure have not 

been documented in this population. The occurrence of HABs is expected to increase with the 

growth of various types of human-related activities. The level of confidence in the predicted 

increase is moderate.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Whale-watching in the Gulf of Guinea region is small in scale, with small humpback whalewatching industries documented in Benin, Gabon, São Tomé and Príncipe (O'Connor et al.

2009). Whale-watching in South Africa is mainly focused on right whales, with humpback 

whales watched opportunistically. Boat-based whale-watching has grown 14% in the last 

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decade, and is concentrated in the western Cape region; South Africa now numbers among the 

top ten destinations for whale-watching worldwide (O'Connor et al. 2009). There are regulations 

in place for all whale-watching activity in South Africa (Carlson 2007). Whale-watching in 

Namibia is primarily focused on dolphins, and has seen 20% growth since 2008. The threat 

posed to this population by whale-watching is considered low. 

This humpback whale population is exposed to scientific research activities, but adverse effects 

from research activities have not been identified, and overall impact is expected to be low and 

stable.

No commercial whaling occurs in this population’s range. If there is an aboriginal hunt at 

Pagalu it is estimated to be 3 or less individuals per year.

Disease or Predation

There are no reports of disease in this population and levels of parasitism are unknown. 

Predation likely occurs, though it is not known to what degree but it does not appear to be 

adversely impacting this population.

Other Natural or Human-Related Threats 

There is no known/reported competition with fisheries; this threat is therefore considered low 

and stable. The threat of offshore aquaculture is considered low. 

Certain potential and real effects on cetaceans and other fauna are expected to increase due to the 

growth of industry activities, including noise disturbance from seismic surveys (Richardson et al.

1995). Changes in their behavioral patterns or displacement from migratory, mating, and 

especially important calving and nursing habitats could impact reproductive success and calf 

survival during critical stages of development. 

Rapid increases in shipping and port construction throughout the Gulf of Guinea (Van 

Waerebeek et al. 2007) are likely to increase the risks of ship strikes for humpback whales. 

Whales are reported as stranding in Benin, with wounds suspected as originating from ship 

strikes (Van Waerebeek et al. 2007). There are no dedicated stranding networks in the region 

and ship strikes with oil tankers and other vessels have not been documented. Collisions with 

vessels are not likely to be a major threat considering the size of the population.

There are entanglement risks for humpback whales in these regions, including a growing 

commercial shrimp industry off Gabon (Walsh et al. 2000), and an expansion in unregulated 

fishing by foreign fleets in Gulf of Guinea waters (Collins pers. comm., Chidi Ibe 1996; 

Brashares et al. 2004). Entanglement in fishing gear occurs but it is not likely to be a major 

threat considering the size of the population. 

Climate change may impact the Gabon/SW Africa of humpback whales in multiple ways. Sea 

level rise, ocean warming and ocean acidification may all negatively impact the reef system 

providing shallow, protected waters for breeding. Ocean acidification also has a documented 

impact on krill growth and development (Kurihara 2008), and krill is the primary prey item for 

Southern Hemisphere humpback whales. Krill are tightly associated with sea ice (Brierley et al.

1999; Brierley et al. 2002), and decreasing sea ice may negatively impact krill abundance and/or 

distribution. Decreases in krill abundance have been observed around the Antarctic Peninsula 

110
(Atkinson et al. 2004). Overall population level effects from global climate change and 

anthropogenic noise are not known and the threat was ranked low; nonetheless, any potential 

impacts resulting from these threats will almost certainly increase.

D.13.2 Extinction Risk

The population has an abundance estimate of >8000 animals (Collins et al. 2008) but trend 

information is unavailable. The Gabon/Southwest Africa region appears to serve a variety of 

purposes with some individual whales remaining in the area through the year while some utilize 

the area for feeding and others for mating. Boom-bust cycles in whaling records indicate some 

degree of substructure within this population historically. It is unclear how many oil rigs are in 

the region but there is heavy vessel traffic along the coast of southwest Africa. There is also 

seismic activity in the area as energy exploration is expanded. There are very few records of 

entanglement (1 record in 1996). Whale-watching has increased by 14% in the last decade in the 

region though the focus of the industry is on right whales. 

This population is considered to be not at risk of extinction over the next three generations (93% 

of votes). The potential for this population to be at moderate risk of extinction was also 

considered and received 7% of the votes, largely reflecting uncertainty regarding population 

trend. 

D.13.3 Significant portion of its range

The BRT concluded that there was some evidence for population substructure within the DPS, 

based on an extensive breeding range with some significant genetic differentiation among 

breeding locations (Rosenbaum et al. 2009). However, the BRT was unable to identify any 

portions of the DPS that both faced particularly high threats and were so significant to the 

viability of the DPS as a whole that if lost would result in the remainder of the DPS being at high 

risk of extinction. The BRT therefore concluded that the DPS was not at risk in a significant 

portion of its range.

D.14 Southeast Africa/ Madagascar

The most recent abundance estimates for the Madagascar population were from surveys of 

Antongil Bay, 2000-2006 (Cerchio et al. 2009). Estimates using data from 2004-2006 and 

involving “closed” models of photo-identification of individuals and genotype data were 7,406 

(CV = 0.37, CI: 2106-12706) and 6,951 (CV = 0.33, CI: 2509-11394), respectively. Additional 

estimates were made using various data sets (e.g., photo-identification and genotype) and 

models, estimating 4,936 (CV = 0.44, CI: 2137-11692), and 8,169 individuals (CV = 0.44, CI 

3476-19497, Cerchio et al. 2009). The mark-recapture data were derived from surveys over 

several years and thus may represent the abundance of whales breeding off Madagascar, in 

addition to possibly whales breeding in Mayotte and the Comoros (Ersts et al. 2006), and to a 

smaller degree from the East African Mainland (Razafindrakoto et al. 2008).

Earlier estimates exist, including one of 2,532 (CV = 0.27) individuals (Best et al. 1996) based 

on surveys of the continental shelf region across the south and southeast coasts of Madagascar in 

1994. However, these surveys likely did not cover the full distribution of humpback whales in 

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the area. Data from a 1991 survey yielded an estimate of 1,954 whales (CV = 0.38) (Findlay et 

al. 1994). A subsequent line transect survey in 2003 included a larger region of the coast 

(Findlay et al. 2011). From these, two estimates were generated in 2003: 6,664 whales (CV = 

0.16); and 5,965 (CV = 0.17) when data were stratified by coastal regions.

Two trends in relative abundance have been calculated from land-based observations of the 

migratory stream passing Cape Vidal, east South Africa in July 1998-2002, and July 1990-2000. 

The first was an estimate of 12.3% per year (Findlay and Best 2006) (however, this estimate is 

likely outside biological plausibility for this species (Bannister and Hedley 2001; Noad et al.

2008); Zerbini et al. 2010); and the second is 9.0% (an estimate that is within the range 

calculated for other Southern Hemisphere breeding grounds (e.g. Ward et al. 2006; Noad et al.

2008; Hedley et al. 2009). Both rates are considered with caution because the surveys were short 

in duration. It is not certain that these estimates represent the growth rate of the entire DPS. 

Given this uncertainty, and the uncertainty from the short duration of the surveys, it is likely the 

DPS is increasing, but it is not possible to provide a quantitative estimate of the rate of increase 

for the entire DPS. 

D.14.1 Threats Analysis

Habitat or Range Curtailment

Human populations are growing rapidly in coastal areas in Madagascar and East Africa, which 

may contribute, generally, to humpback whale habitat degradation and related negative 

influences.

Until recently, oil and gas reserves in east Africa were largely unexplored. However, recently, a 

number of offshore seismic oil and gas surveys have been conducted in Mozambique, Tanzania, 

Madagascar and the Seychelles. As a result, drilling is now either underway or planned in all of 

these regions (Frynas 2004; Findlay et al. 2006). As noted elsewhere, such activity brings 

threats of increased underwater noise from the exploration and development phases themselves, 

and increased vessel activity; the possibility of an oil spill; possible habitat degradation from 

such things as drill spoils and dredging; and vessel collisions. In Madagascar, offshore 

development has been concentrated on the northwest coast; in Mozambique it is concentrated in 

the Mozambique Basin, Zambezi delta region, while development in Tanzania has been most 

focused on coastal Zanzibar. Humpback whales occur seasonally in all of these regions. 

Apparently, there are no local, national, or regional measures in place or contemplated to reduce 

the impact of these threats. 

Levels of exposure of humpback whales in this region to various pollutants are not known, nor is 

the occurrence of HABs. Trends in the extent of this threat likewise are not known.

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

Whale-watching activities are growing rapidly in waters off Mozambique; yet, these are poorly 

regulated (O'Connor et al. 2009). Most of these activities are locally based and involve 

motorized boats, recreational fishing boats, and dive boats. There is a voluntary code of conduct 

for operators, but at present this is poorly upheld and no formal regulations or enforcement are 

currently in place (O'Connor et al. 2009). Whale-watching in South Africa is mainly focused on 

right whales, although the industry at St Lucia in KwaZulu Natal province is focused on 

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southwestern Indian Ocean humpback whales. Recent political instability in Madagascar has 

limited the growth rate of whale-watching activities in this region, although growth between 

1998-2008 was still estimated at about 15%, with the main industry focused on humpback 

whales frequenting the Ile Ste Marie/Antongil Bay region, and over 14,000 tourists participating 

in whale watch tours by 10-15 operators in 2008 (O'Connor et al. 2009). This industry has 

recently developed some guidelines for the protection of humpback whales, which was passed as 

legislation in 2000 with local regulations for Ile Sainte Marie (Fleming and Jackson 2011) and 

Antongil Bay (Journal Officiel de la Republique de Madagascar 2000). Whale watch tourism in 

Mayotte is small-scale, but has expanded rapidly, from no industry in 1998 to 10,000 annual

whale watchers in 2008 (O'Connor et al. 2009), with a focus on a range of cetacean species. In 

the Mascarene Islands, the expanding whale-watching industry in La Réunion (3,000 tourists 

estimated in 2008) is currently unregulated, while in Mauritius large cetacean watching is a 

minimal component of the whale watch industry and is therefore unlikely to have much impact 

(O'Connor et al. 2009). An industry for watching humpback whales in Mauritius commenced in 

2008 (Fleming and Jackson 2011).

No commercial whaling occurs in this population’s range. This humpback whale population is 

exposed to scientific research activities, but at low levels. Adverse effects from research 

activities have not been identified, and overall impact is expected to be low and stable.

Disease or Predation

There is little to no information on the impacts of disease, parasites, or predation on this DPS. 

Other natural or human-related threats

There is little known/reported interaction with fisheries, nor are there any current or planned 

offshore aquaculture sites in the region. These threats are therefore considered low and stable.

Information regarding fisheries and other activities is limited. Kiszka et al. (2009) and 

Razafindrakoto et al. (2008) provided summaries of humpback whale entanglement and 

strandings based on interviews with artisanal fishing communities. Substantial gillnet fisheries 

have been reported in the near-shore waters of the coasts of mainland Africa and Madagascar; 

and to a lesser extent in the Comoros Archipelago, Mayotte and Mascarene Islands, where such 

practices are hindered by coral reefs and a steep continental slope bathymetry (Kiszka et al.

2009). Stranding reports and observations from Tanzania and Mozambique have mostly 

implicated gillnets, with most Madagascan entanglements associated with long-line shark fishing 

(Razafindrakoto et al. 2008). In Mayotte, humpback whales have been observed with gillnet 

remains attached to them (Kiszka et al. 2009), although no fatalities have yet been documented. 

Industrial fishing operations, including longlines and drift longlines on fish aggregation devices, 

purse seine and midwater trawling occur in waters off Mauritius. The extent of bycatch and 

entanglement in these waters is unknown (Kiszka et al. 2009). Strandings and by-catch data 

from 2001-2005 from South Africa indicated an estimated 15 humpback whales entangled in 

shark nets (large-mesh gillnets) in KwaZulu Natal province (only one death) while a total of nine 

stranded whales were reported from the south and east coasts (IWC 2002b; IWC 2003; IWC 

2004b; IWC 2005b; IWC 2006b). Fishing activities are prohibited in localized marine protected 

areas in Mayotte, Moheli (in the Comoros Archipelago), Madagascar (northeast coast), Aldabra 

(under protection as a UNESCO World Heritage Site) and the coastal region between Southern 

Mozambique and South Africa.

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The range of this population includes some growing centers of human activities. Although there 

are no known records of ship struck humpback whales in this region, the amount of vessel traffic 

suggests this is probably a low-level threat. However, a reasonable assumption is that the 

amount of vessel traffic, and the level of the threat, is likely to increase as commercial shipping, 

recreational boating, and whale-watching, oil and gas exploration and development, and fishing 

activities increase.

This population is likely exposed to relatively high levels of underwater noise resulting from 

human activities, including, for example, commercial and recreational vessel traffic, and 

activities related to oil and gas exploration and development. Overall population-level effects of 

exposure to underwater noise are not well established, but exposure is likely chronic and at 

moderate levels. As vessel traffic and other activities are expected to increase, the level of this 

threat is expected to increase. The level of confidence in this information is moderate.

Climate change may impact the Southeast Africa/Madagascar DPS of humpback whales in 

multiple ways. Sea level rise, ocean warming and ocean acidification may all negatively impact 

the reef system providing shallow, protected waters for breeding. Ocean acidification also has a 

documented impact on krill growth and development (Kurihara 2008), and krill is the primary 

prey item for Southern Hemisphere humpback whales. Krill are tightly associated with sea ice 

(Brierley et al. 1999; Brierley et al. 2002), and decreasing sea ice may negatively impact krill 

abundance and/or distribution. Decreases in krill abundance have been observed around the 

Antarctic Peninsula (Atkinson et al. 2004). Overall population level effects from global climate 

change and anthropogenic noise are not known and the threat was ranked low; nonetheless, any 

potential impacts resulting from these threats will almost certainly increase.

D.14.2 Extinction Risk

Overall, the population is estimated to contain in the range of 6,000-8,000 individuals and is 

likely growing. The principal threat to humpback whales in this population is entanglement in 

fishing gear (ranked a moderate threat). Given the size and growth of this population and threats 

that are not expected to severely curtail growth or threaten the existence of the population as a 

whole, this group is considered not at risk of extinction (96% of votes; 4% of votes for 

“moderate” risk of extinction). 

D.14.3 Significant portion of its range

The BRT concluded that the effect of any geographically localized threats would be seen in the 

status of the DPS as a whole. The BRT was unable to identify portions of the DPS that both 

faced particularly high threats and were so significant to the viability of the DPS as a whole that 

if lost would result in remainder of the DPS being at high risk of extinction. The BRT therefore 

concluded that the DPS was not at risk in a significant portion of its range.

D.15 Arabian Sea

Mark-recapture studies using tail fluke photographs collected in Oman from 2000-2004 yielded a 

population estimate of 82 individuals (95% CI: 60-111). However, sample sizes were small, and 

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there are various sources of possible negative bias including insufficient spatial and temporal 

coverage of the population’s suspected range (Minton et al. 2010b).

Reproductive rates in this population are not well understood. Cow-calf pairs were very rarely 

observed in surveys off the coast of Oman, composing only 7% of encounters in Dhofar, and not 

encountered at all since 2001. Soviet whaling catches off Oman, Pakistan and northwestern

India also included low numbers of lactating females (3.5% of mature females) relative to 

pregnant females (46% of mature females) (Mikhalev 1997). 

No trend data are available for this population. A low proportion of immature whales (12.4% of 

all females) was also found, even though catches were indiscriminate with respect to sex and 

condition (Mikhalev 1997), suggesting that either calf mortality in this population is high, 

immature animals occupy areas that have not been surveyed, or that the whales have 

reproductive ‘boom and bust’ cycles which respond to high annual variation in productivity. The 

BRT noted that the entire region has not been surveyed; however, in areas where the whales are 

likely to be, not many whales have been observed. The BRT noted that this is a very small 

population but felt that there was some uncertainty in abundance estimates. 

Habitat or Range Curtailment

The BRT determined that the threat posed by energy exploration to the Arabian Sea population 

should be classified as high given the small population size and the present levels of energy 

activity. A catastrophic event similar to that of the Deepwater Horizon Oil Spill in the Gulf of 

Mexico could be devastating to this population, especially in light of the year-round presence of 

humpback whales in this area. 

The effect of pollutants on cetaceans is a concern in the region, as the Arabian Sea is a center of 

intense human activity with poor sea circulation, so pollutants can persist for long periods 

(Minton 2004). Since the 1970s, the coastal and marine infrastructure in Oman has developed at 

a rapid rate, with over 80% of the population now living within 13 miles from the coast, and 

expanding development of oil and gas resources and fishing fleets (Minton 2004). The threats 

from coastal development and contaminants are ranked low but increasing. 

Utilization for Commercial, Recreational, Scientific, or Educational Purposes

This humpback whale population is exposed to minimal scientific research and whale-watching 

activities. The adverse effects from these activities have not been identified, and overall impact 

is expected to be low and stable.

No commercial whaling occurs in this population’s range, although 238 humpback whales were 

illegally killed in the Arabian Sea by the USSR in 1966 (Mikhalev 1997).

Disease or Predation

Liver damage was detected in 68.5% of necropsied humpback whales in this area during Soviet 

whaling in 1966, with degeneration of peripheral liver sections, cone-shaped growths up to 20cm 

in diameter and blocked bile ducts (Mikhalev 1997). While this pathology was consistent with 

infection by trematode parasites, none were identified during necropsy, and the causes of this 

liver damage remain unknown. 

115
Poisonous algal blooms and biotoxins have been implicated in some mass fish, turtle, and 

possibly cetacean, mortality events on the Oman coast, although no events have yet been known 

to include humpback whales. Coastal run-off from industrial activities is likely to be increasing 

rapidly, while regular oil spills in shipping lanes from tankers also contribute to pollution along 

the coast (e.g. Shriadah 1999). Tattoo skin lesions were observed in 26% of photo-identified 

whales from Oman (Baldwin et al. 2010). While not thought to be a common cause of adult 

mortality, it has been suggested that tattoo skin disease may differentially kill neonates and 

calves that have not yet gained immunity (Van Bressem et al. 2009). The authors also suggested 

that this disease may be more prevalent in marine mammal populations that experience chronic 

stress and/or are exposed to pollutants that suppress the immune system.

Other Natural or Human-Related Threats 

The primary prey of humpback whales in Oman (Sardinella sp.) is also consumed by tuna and 

other commercial pelagic fish targeted by gillnet fisheries, but the severity of the threat of 

competition with fisheries is unknown. 

The BRT did not have information about offshore aquaculture activities in the Arabian Sea. 

Humpback whales in the Arabian Sea are exposed to a high level of vessel traffic (Baldwin 2000; 

Minton 2004; Kaluza et al. 2010) so the threat of ship strikes was considered medium for this 

small population.

This population is likely exposed to relatively high levels of underwater noise resulting from 

human activities, including, for example, commercial and recreational vessel traffic, and 

activities related to oil and gas exploration and development. Overall population-level effects of 

exposure to underwater noise are not well-established, but exposure is likely chronic and at 

moderate levels. As vessel traffic and other activities are expected to increase, the level of this 

threat is expected to increase. 

There is high fishing pressure in areas off Oman where humpback whales are sighted. Eight live 

humpback whale entanglement incidents were documented between 1990-2000, involving 

bottom set gillnets often with weights still attached and anchoring the whales to the ocean floor 

(Minton 2004). Minton et al. (2010b) examined peduncle photographs of humpback whales in 

the Arabian Sea and concluded that at least 33% had been entangled in fishing gear at some 

stage. The threat of fishing gear entanglements in the Arabian Sea is considered high and 

increasing. 

The threat posed by climate change on the Arabian Sea humpback whales was determined to be 

slightly higher than on the other DPSs and was assigned medium threat level. This higher threat 

level is based on the more limited movement of this population that both breeds and feeds in the 

Arabian Sea. Changing climatic conditions may change the monsoon-driven upwelling that 

creates seasonal productivity in the region. While Northern Hemisphere individuals may be able 

to adapt to climatic changes by moving farther north, Arabian Sea individuals have less 

flexibility for expanding their range to cooler regions. 

Evidence that this population has undergone a recent genetic bottleneck and is currently at low 

abundance (Minton et al. 2010b) suggests that there may be an additional risk of impacts from 

increased inbreeding (which may reduce genetic fitness and increase susceptibility to disease). 

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At low densities, populations are more likely to suffer from the ‘Allee’ effect, where inbreeding 

and the heightened difficulty of finding mates reduces the population growth rate in proportion 

with reducing density.

D.15.1 Extinction Risk

This population is genetically and demographically isolated from other humpback whale 

populations in the southern Hemisphere. The small population size, restricted range, and high 

rates of entanglements and other anthropogenic impacts put this population at considerable risk. 

The Arabian Sea DPS was considered by the majority of the BRT to be at high risk of extinction 

(87% of votes). The potential for this population to be at moderate risk of extinction received 

13% of votes, reflecting some uncertainty in the designation of “high risk” for this DPS.

D.15.2 Significant portion of its range

The BRT concluded that the Arabian Sea DPS is likely to be at high risk of extinction throughout 

its range, so it was not necessary to conduct an analysis of extinction risk in a significant portion 

of the DPS’s range. 

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IV. Summary of risk assessment

A. Evaluation of Abundance and Trends

The BRT’s assessment of what is known about the abundance and trends of each DPS is 

summarized in Table 7 and Table 8 below. In the North Atlantic Ocean, the abundance of the 

West Indies DPS is much greater than 2,000 individuals and is increasing moderately. However, 

little is known about the total size of the Cape Verde Islands DPS, and its trend is unknown.

In the Pacific Ocean, the abundances of the Mexico and Hawaiian DPSs are known to be much 

greater than 2,000 individuals and are thought to be increasing moderately. The abundance of 

the Central American DPS is thought to be about 500 individuals with unknown trend, and that 

of the Okinawa/Philippines DPS is thought to be about 1,000 individuals with unknown trend. 

Little is known about the abundance of the Second West Pacific DPS, but it is likely to number 

at least 100 or more, with unknown trend. 

In the Southern Hemisphere, all seven DPSs are thought to be greater than 2,000 individuals in 

population size. The two Australian DPSs are both large and increasing rapidly. The Brazil DPS 

is increasing either rapidly or moderately. The Southeastern Pacific and Southeast Africa/ 

Madagascar DPSs are thought to either be increasing or stable. The trends of the Oceania and 

Gabon/Southwest Africa DPSs are unknown.

The estimated abundance of the Arabian Sea DPS is less than 100, but its entire range was not 

surveyed, so it could be somewhat larger. Its trend is unknown.

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Table 7. Summary of abundance for each DPS. 

Population level >1000 mature 

individuals 

(>2000 total)

< 1000 

mature 

individuals

(<2000 total)

<250 mature 

individuals

(<500 total)

<50 mature 

individuals

(<100 total)

Atlantic Ocean

West Indies

Cape Verde Islands plus 

Northwest Africa

Pacific Ocean

Hawaii

Central America

Mexico

Okinawa/ Philippines 

Second West Pacific

Southern Hemisphere

West Australia

East Australia

Oceania

Southeastern Pacific

Brazil

Gabon/Southwest Africa

Southeast Africa/ 

Madagascar

Arabian Sea

Arabian Sea

NOTE: Details on abundance are in the Threat and extinction risk analysis by DPS section. The level of 

abundance the DPS is estimated to be at is shaded. If there is uncertainty in the abundance level of the DPS, 

all categories that could apply are shaded. The number of mature individuals was taken to be approximately 

one-half of the total population size. The columns represent relative risk of extinction, increasing from left to 

right (see section B.1 for further detail).

120
Table 8. Summary of what is known about the trends in abundance for each DPS.

Population trend Increasing 

Strongly

Increasing 

moderately

Stable/little 

trend

Declining Unknown

Atlantic Ocean

West Indies

Cape Verde Islands plus 

Northwest Africa

Pacific Ocean

Hawaii

Central America

Mexico

Okinawa/ Philippines 

Second West Pacific

Southern Hemisphere

West Australia

East Australia

Oceania

Southeastern Pacific

Brazil

Gabon/Southwest Africa

Southeast Africa/ 

Madagascar

Arabian Sea

Arabian Sea

NOTE: Details are provided in the Threat and extinction risk analysis by DPS section. The category of trend 

that the DPS is thought to be undergoing is shaded. If there is substantial uncertainty in the trend, all 

categories that may apply are shaded. If no reliable information on trend for the DPS is available, the last 

column (“unknown”) is shaded.

B. Evaluation of Threats

The BRT’s assessment of the current and imminent threats to each DPS is summarized in (Table 

9). In the North Atlantic Ocean, the threats of HABs, vessel collisions, and fishing gear 

entanglements are likely to moderately reduce the population size and/or the growth rate of the 

West Indies DPS. All other threats, with the exception of climate change (unknown severity), 

are considered likely to have no or minor impact on population size or the growth rate of this 

DPS. For the Cape Verde Islands plus Northwest Africa DPS, the threats of HABs, disease, 

parasites, vessel collisions, fishing gear entanglements and climate change are unknown. All 

121
other threats to this DPS are considered likely to have no or minor impact on the population size 

and/or growth rate. 

In the Pacific Ocean, all threats are considered likely to have no or minor impact on population 

size and/or the growth rate or are unknown, with the following exceptions: Energy development, 

whaling, and competition with fisheries are considered likely to moderately reduce the 

population size or the growth rate of the Okinawa/Philippines DPS. Vessel collisions are 

considered likely to moderately reduce the population size or the growth rate of the Central 

America and Okinawa/Philippines DPSs. Fishing gear entanglements are considered likely to 

moderately reduce the population size or the growth rate of the Hawaii, Central America, and 

Mexico DPSs and likely to seriously reduce the population size or the growth rate of the 

Okinawa/Philippines DPS. In general, there is great uncertainty about the threats facing the 

Second West Pacific DPS. 

In the Southern Hemisphere, all threats are considered likely to have no or minor impact on 

population size and/or the growth rate or are unknown, with the exception of energy exploration 

posing a moderate threat throughout Western Australia and the west coast of Africa, and fishing 

gear entanglements posing a moderate threat to the Colombia, and Southeast Africa/Madagascar, 

DPSs. 

The Arabian Sea DPS faces unique threats given that the whales do not migrate, but instead feed 

and breed in the same, relatively constrained geographic location. Energy exploration and 

fishing gear entanglements are considered likely to seriously reduce the population’s size and/or 

growth rate, and disease, vessel collisions and climate change are likely to moderately reduce the 

population’s size or growth rate.

122
Table 9. Severity of current or imminent threats to humpback whales, by DPS. coastal development Contaminants Energy exploration & development HABs Whaling Whale-watching Scientific research activities

Killer whale and 

shark predation

Disease

Parasites

competition with 

fisheriesoffshore 

aquaculture

Anthropogenic 

Noise

Vessel collisions

Fishing gear 

entanglements

Climate Change

West Indies 1* 1 1* 2* 1 1 1 1 1 1 1 1* 1* 2* 2 unkn

* CVI + NW 

Africa

1* 1 1 unkn

*

1 1 1 1 unkn unkn 1 1 1* unkn

*

unkn unkn

* Hawaii 1* 1 1* 1* 1 1 1 1 1 1 1 1* 1* 1* 2 unkn

* Central 

America

1* 1 1 1* 1 1 1 1 1 1 1 1 1* 2* 2 unkn

* Mexico 1* 1 1 1* 1 1 1 1 unkn unkn 1 1 1* 1* 2* unkn

* Okinawa/ 

Philippines

1* 1* 2* unkn 2* 1 1 1 unkn unkn 1 unkn 1* 2* 3 unkn

* 2nd West 

Pacific

1 unkn unkn unkn unkn 1 1 unkn unkn unkn unkn unkn 1* unkn unkn unkn

* West 

Australia

1* 1 2* 1 1 1 1 1 1 1 1 1* 1* 1* 1* 1*

East 

Australia

1* 1 1 1 1 1* 1 1 1 1 1 1 1* 1* 1* 1*

Colombia 1* 1 1* 1* 1 1 1 1 1 1 1 1 1* 1* 2 1*

Brazil 1* unkn 1* 1* 1 1* 1 1 unkn unkn 1 1 1* 1* 1* 1*

Gabon/SW 

Southwest 

1* 1 1* 1* 1 1 1 1 1 1 1 1* 1* 1 1 1*

Mozamb/E

SA/Mad 

1* unkn 1* unkn 1 1* 1 unkn unkn unkn 1 1 1* 1* 2 1*

Oceania 1 1 1* unkn 1 1* 1* 1 1 1 1 1* 1* 1* 1 1*

Arabian 

Sea

1* 1* 3* unkn 1 1 1 unkn 2 unkn unkn unkn 1* 2* 3* 2*

123
Severity of Threat

1 = Low or none, threat is likely to have no or minor impact on population size or the growth rate

2 = Medium, threat is likely to moderately reduce the population size or the growth rate of the population

3 = High, threat is likely to seriously reduce the population size or the growth rate of the population

4 = Very High, threat is likely to eliminate the DPS

unkn = Severity of threat is unknown

* = trend of threat is increasing

124
C. Summary of Extinction Risk Conclusions

The BRT conducted its analysis using the best available science and experts’ opinions and 

concluded (summarized in Table 10):

• There are at least 15 discrete and significant population segments for humpback whales 

globally, according to the criteria outlined the joint NMFS/FWS DPS policy;

• Nine DPSs are not at risk of extinction with high certainty (>80% of votes): the West 

Indies, Hawaii, Mexico, west Australia, east Australia, Colombia, Brazil, 

Gabon/Southwest Africa, and Southeast Africa/Madagascar;

• The Oceania DPS is not at risk of extinction with moderate certainty (68% of votes) with 

some support for moderate risk of extinction (29% of votes); 

• Both the Okinawa/Philippines and Central America DPSs were between moderate and 

high risk of extinction (<20% of votes for not at risk of extinction for each DPS), but the 

distribution of votes among the risk categories indicates uncertainty;

• The Arabian Sea DPS is at high risk of extinction (87% of votes); and

• There was considerable uncertainty regarding the risks of extinction of two of the DPSs 

due to a general lack of data: the Cape Verde Islands plus Northwest Africa and the 

Second West Pacific.

Table 10. Summary of extinction risk assessments.

Distinct Population Segment High 

Risk

Moderate 

Risk

Not at 

Risk

West Indies 1% 17% 82%

Cape Verde Islands plus Northwest Africa 32% 43% 25%

Hawaii 0% 2% 98%

Central America 28% 56% 16%

Mexico 0% 8% 92%

Okinawa/Philippines 36% 44% 21%

Second West Pacific 14% 47% 39%

West Australia 0% 3% 97%

East Australia 0% 4% 96%

Oceania 3% 29% 68%

Southeastern Pacific 0% 7% 93%

Brazil 0% 4% 96%

Gabon/Southwest Africa 0% 7% 93%

Mozambique/East South Africa and Comoros 

Archipelago/Madagascar

0% 4% 96%

Arabian Sea 87% 13% 0%

125
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tell us about the stock identity and feeding grounds of humpback whales in the western 

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growth in humpback whales from life-history data. Marine Biology. 157(6):1225-1236.

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southern Brazil. Report of the International Whaling Commission. 48:519-523.

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156
Appendix A: Question posed to the ad-hoc committee on taxonomy within the Society 

for Marine Mammalogy

The humpback whale Biological Review Team requested help from the Ad-hoc Taxonomy 

Committee of the Society for Marine Mammalolgy in determining whether subspecies are likely 

to exist within the global species (Megaptera novaeangliae). The BRT sent a questionnaire and 

related background information (below) to William Perrin, the chair of the Ad-hoc Taxonomy 

Committee, who then distributed it to the membership of that committee (C. Scott Baker, 

Annalisa Berta, Daryl J. Boness, Robert L. Brownell, Jr., Daryl P. Domning, Ewan Fordyce, 

Rebecca M. Hamner, Thomas A. Jefferson, James G. Mead, Larissa Rosa de Oliveira, Dale W. 

Rice, Patricia E. Rosel, John Y. Wang, and Tadasu Yamada, which includes two members of the 

BRT). Their conclusions, summarized by Perrin, are presented in Section II. B. 

Questionnaire

Are humpback whales (Megaptera novaeangliae) that feed in the North Atlantic, North Pacific, 

Southern Oceans and Arabian Sea likely to belong to different sub-species? Based on your 

expert opinion, please rate the likelihood that humpback whales in the following adjacent regions 

belong to different subspecies (rate likelihood as high, medium, or low). Please fill out this 

table, but feel free to provide additional commentary.

Region 1 Region 2 Likelihood

(high, medium, low)

North Pacific North Atlantic

North Pacific Southern Oceans

North Atlantic Southern Oceans

Arabian Sea Southern Oceans

Background 

A biological review team (BRT) has been convened to assess the status of humpback whales 

under the U.S. Endangered Species Act (ESA). The BRT can recommend the designation of 

distinct population segments (DPS) which are treated as “species” under the provisions of the 

ESA. One of the criteria used to designate a population as a DPS is whether loss of that 

population would result in a significant gap in the range of the taxon. The taxon would be the 

entire species or (if present) subspecies. Taxonomy is therefore an important component in 

managing species under the ESA. Subspecies taxonomy in cetaceans has lagged behind that of 

other taxa (Reeves et al. 2004). However, the BRT is obligated to make their designations based 

on “best available science”. If subspecies are likely to exist but have not yet been recognized or 

nomenclature has not yet been resolved, the BRT can take this into consideration in their 

designation of distinct population segments for humpback whales.

157
Rice (1998) reviewed previous sub-species designations for humpback whales. Tomilin (1946) 

named a Southern Hemisphere sub-species (M. n. lalandii) based on body length, but this length 

difference was not substantiated in subsequent studies. The populations around Australia and 

New Zealand were described as another subspecies (M. n. novazelandiae) based on color 

patterns and length (Ivashin 1958). Rice (1998) noted that the percent separability between 

putative sub-species is “not quite as high as is customarily required for division into subspecies” 

and that genetic analyses using restriction-fragment length polymorphisms is not congruent with 

the proposed regional division. Rice (1998) recommended that Megaptera novaeangliae be 

considered monotypic. 

The 2004 cetacean taxonomy workshop (Reeves 2004) proposed the following guidelines for 

determining cetacean subspecies: 

In addition to the use of morphology to define subspecies, the subspecies concept should 

be understood to embrace groups of organisms that appear to have been on independent 

evolutionary trajectories (with minor continuing gene flow), as demonstrated by 

morphological evidence or at least one line of appropriate genetic evidence. 

Geographical or behavioral differences can complement morphological and genetic 

evidence for establishing subspecies. As such, subspecies could be geographical forms or 

incipient species.

Evidence

Reproductive Seasonality: Humpback whales breed and calf in July-November in the Southern 

Hemisphere and in Jan-May in the Northern Hemisphere (including the Arabian Sea). It is not 

known if reproductive seasonality in baleen whales is determined genetically or whether it 

results from a learned behavior (migration to a particular feeding destination) combined with a 

physiological response to day length. 

Behavior: The most obvious behavioral difference is that migrations to and from high latitudes 

are in opposite times of the calendar year for Southern Hemisphere and most Northern 

Hemisphere populations, following the difference in reproductive seasonality. A Northern 

Hemisphere exception to this migration pattern is found in the Arabian Sea where a nonmigratory population is found. Although these behavioral differences could be learned, they 

could also be innate, genetically determined traits. Obviously, singing and other mating 

behaviors also follow the differences in reproductive seasonality.

Color patterns: Humpback whales in the Southern Hemisphere tend to have a much more white 

pigmentation on their bodies which is especially noticeable laterally (Matthews 1937; 

Chittleborough 1965). This has been noted in eastern and western Australia, the Coral Sea, and 

Oceania, but might not be characteristic of all Southern Hemisphere populations. Rosenbaum et 

al. (1995) ranked ventral fluke coloration patterns from one (nearly all white) to five (nearly all 

black) and compared whales from several breeding areas. He found that over 80% of humpback 

whales in eastern and western Australia were in Category 1, and that less than 10% of whales in 

three breeding areas in the North Pacific were ranked in that category. Only 36% of Southern 

Hemisphere whales in Colombia were classified in Category 1, but Colombian whales were still, 

on average, whiter than North Pacific whales. A higher frequency of flippers with white dorsal 

pigmentations is found in the North Atlantic compared to the North Pacific (Clapham 2009). 

158
Genetics: Baker and Medrano-Gonzalez (2002) review the worldwide distribution of mtDNA 

haplotypes. They find three major clades with significant differences among major ocean basins 

(Figure 1), but they did not find reciprocal monophyly. The North Pacific only included the AE 

and CD clades, the North Atlantic only included the CD and IJ clades, and the Southern Oceans 

included all three. In a more recent comparison, Baker (pers. comm.) found no shared 

haplotypes between the North Pacific and North Atlantic. Based on mtDNA, Rosenbaum et al.

(2009) estimated an average migration rate of less than one per generation between the Arabian 

Sea and neighboring populations in the southern Indian Ocean. Migration rates among 

neighboring populations within the Southern Hemisphere were generally much larger. In a 

review of mtDNA and nuclear DNA (nDNA) variation among ocean basins and among regions 

within basins, Jackson et al. (2014) found that gene flow between among regional populations 

within the Southern Hemisphere oceans is 20-60 times higher than gene flow between the 

Southern Hemisphere and the two Northern Hemisphere ocean basins.

Summary

An often-cited criterion for separation of subspecies is the ability to differentiate 75% of 

individuals found in different geographic regions. Based on this criterion, differences in the 

calendar timing of mating and reproduction could be used to distinguish close to 100% of 

Northern Hemisphere from Southern Hemisphere individuals, but it is not known if this 

genetically determined. Based on mtDNA haplotypes that have been identified to date, 

haplotype could be used to distinguish 100% of North Pacific from North Atlantic individuals, 

but some haplotypes from both ocean basins are shared with the Southern Ocean. Genetic 

exchange across hemispheres is 1-2 orders of magnitude less than genetic exchange among 

populations within an ocean basin. Ventral fluke color patterns can be used to correctly 

differentiate >80% of whales in eastern and western Australia from the whales in the North 

Pacific (Rosenbaum et al. 1995).

References

Baker, C. S. and L. Medrano-Gonzalez. 2002. Worldwide distribution and diversity of 

humpback whale mitochondrial DNA lineages. In C. J. Pfeiffer (ed.) Molecular and Cell 

Biology of Marine Mammals. Krieger Publ. Co., Malabar, Florida.

Chittleborough, R. G. 1965. Dynamics of two populations of the humpback whale, Megaptera 

novaeangliae (Borowski). Australian J. Marine and Freshwater Research 61(1):33-128.

Clapham P. J. 2009. Humpback Whale. In Encyclopedia of Marine Mammals. Academic Press.

Ivashin, M. V. 1958. The color type of the humpback whale body (Megaptera nodosa

Bonneterre) of the southern part of the Indian Ocean. Informationnyj Sbornik VNIRO 2:61-65 

(in Russian).

Matthews, L. H. 1937. The humpback whale, Megaptera nodosa. Discovery Reports, 17:7-92. 

Reeves, R.R., W.F. Perrin, B.L. Taylor, C.S. Baker and M.L. Mesnick (eds.). 2004. Report of 

the Workshop on Shortcomings of Cetacean Taxonomy in Relation to Needs of Conservation 

and Management, 30 April to 2 May, La Jolla, California. NOAA-Technical MemorandumNMFS-SWFSC-363, 94pp.

159
Rice, D. W. 1998. Marine Mammals of the World. Systematics and Distribution. Society for 

Marine Mammalogy Special Publication No. 4. 231pp.

Rosenbaum, H., et. al. 1995. Variations in ventral fluke pigmentation of humpback whales, 

Megaptera novaeangliae, world-wide. Marine Ecology Progress Series, 124:1-7.

Rosenbaum HC, Pomilla C, Mendez M, Leslie MS, Best PB, et al. 2009 Population Structure of 

Humpback Whales from Their Breeding Grounds in the South Atlantic and Indian Oceans. PLoS 

ONE 4(10): e7318. doi:10.1371/journal.pone.0007318.

Tomilin, A. G. 1946. Thermoregulation and the geographical races of cetaceans. 

(Termoregulyatsiya I geograficheskie racy kitoobraznykh.) Doklady Akad. Nauk CCCP 

54(5):465-472. (English and Russian). 

Figure 1. From Baker & Medrano 2002.

160
Appendix B: List of national laws related to conservation of marine mammals. Source: http://faolex.fao.org/faolex/. 

Country Title Web site

AMS Chapter 9 of Title 24 - Fishing. www.asbar.org

ARG Resolución No 907/2012 - Medidas de Conservación 

aprobadas por la Comisión para la Conservación de los 

Recursos Vivos Marinos Antárticos.

www.infoleg.gov.ar

ARG Ley No 4.567 - Declara al Delfín Franciscana (Pontoporia 

blainvillei) especie protegida en la Provincia de Río 

Negro.

www.legisrn.gov.ar

ARG Resolución No 539/2010 - Apruébanse las condiciones 

sanitarias para autorizar la importación de mamíferos 

marinos a la República Argentina con destino a 

oceanarios.

www.infoleg.gov.ar

ARG Resolución Ministerial No 86/2010 - Crea el Programa 

Red de Rescate, Rehabilitación y Reintroducción de 

Fauna Marina de la Provincia de Buenos Aires.

ARG Ley No 5.714 - Prohíbese la actividad de acercamiento o 

persecución de la Ballena Franca Austral.

www.infoleg.gov.ar

ARG Ley No 4.115 - Prohíbe la captura de todo mamífero 

marino en aguas y costas de jurisdicción provincial.

www.legisrn.gov.ar

ARG Decreto No 598/03 - Reglamenta la Ley No 25.052, que 

prohíbe la caza o captura de ejemplares de orca 

161
(Orcinus orca).

ARG Ley No 25.577 - Prohíbe la caza o captura de cetáceos en 

todo el territorio nacional.

ARG Ley No 25.052 - Prohíbe la caza o captura de ejemplares 

de orca (Orcinus orca).

ARG Resolución No 351/95 - Reglamento de oceanarios. www.medioambiente.gov.ar

ARG Ley No 176 - Prohíbe el acercamiento a cualquier 

especie de mamífero marino y zonas de nidificación de 

aves en las costas y mar de jurisdicción provincial.

ARG Ley No 23.094 - Declara monumento natural a la ballena 

franca austral dentro de las aguas jurisdiccionales 

argentinas y sujeto a las normas establecidas por la Ley 

No 22.351.

AUS Exhibited Animals Protection Act 1986. www.austlii.edu.au

AUS National Parks and Wildlife Act 1974. www.austlii.edu.au

AUS Wildlife Act 1975. www.legislation.vic.gov.au

AUS Whales Protection Act, 1988. www.thelaw.tas.gov.au

AUS Nature Conservation (Whales and Dolphins) 

Conservation Plan 1997.

www.legislation.qld.gov.au

AUS Nature Conservation (Dugong) Conservation Plan 1999. www.legislation.qld.gov.au

162
AUS Environment Protection and Biodiversity Conservation 

Act 1999.

www.austlii.edu.au

AUS Environmental Reform (Consequential Provisions) Act 

1999 (Act No. 92 of 1999).

www.austlii.edu.au

AUS Environment Protection and Biodiversity Conservation 

Regulations 2000.

www.austlii.edu.au

AUS Adelaide Dolphin Sanctuary Act 2005. www.legislation.sa.gov.au

AUS National Parks and Wildlife (Protected Animals - Marine 

Mammals) Regulations 2010.

www.legislation.sa.gov.au

AUS Exhibited Animals Protection Regulation, 2010. www.austlii.edu.au

AUS Wildlife (Marine Mammals) Regulations, 2009. www.legislation.vic.gov.au

AUS Antarctic Seals Conservation Repeal Regulations 2007 

(SLI No. 143 of 2007).

www.austlii.edu.au

AUS Adelaide Dolphin Sanctuary Regulations, 2005. www.austlii.edu.au

BER Fisheries (Protected Species) Order 1978. www.bermudalaws.bm

BHA Seal Fisheries (Crown Colonies and Protectorates) 

Orders in Council, 1913 (Cap. 242).

laws.bahamas.gov.bs

BHA Whaling Industry (Regulation) Act (Newfoundland, 

Colonies, Protectorates and Mandated Territories) 

Order, 1936 (Cap. 242).

laws.bahamas.gov.bs

BHA Fisheries Resources (Jurisdiction and Conservation) laws.bahamas.gov.bs

163
Regulations, 1986 (Cap. 244).

BLZ Wildlife Protection Regulations 1982. www.belizelaw.org

BRA Decree No. 3.939 on the Inter-ministerial Commission 

on Marine Resources (CIRM).

www.senado.gov.br

BRA Order No. 5 regulating maritime traffic in order to 

protect dolphins in the archipelago of Fernando de 

Noronha Island.

BRA Order No. 40-N creating the National Centre for the 

Management and Protection of Sirenia - 'Peixe-Boi'.

BRA Order No. 2.306 prohibiting intentional disturb of all 

species of cetaceans into the brazilan territorial sea.

BRA Act No. 7.643 prohibiting the catching of Cetaceans. www.bdtextual.senado.gov.br

BRA Order No. N-11 prohibiting the capture of marine 

mammals (little cetaceans, sea lions, marine seals and 

manaties into brazilian territorial sea).

BRA Decree-Law No. 221 promoting and protecting fishing 

activity.

www.bdtextual.senado.gov.br

CAM Sub-Decree No. 15 (RGC) on creation of a commission to 

conserve and develop tourism zone for freshwater 

dolphins in the Mekong River.

CAN Marine Mammal Regulations (SOR/93-56). www.gc.ca

164
CAN Marine Activities in the Saguenay-St. Lawrence Marine 

Park Regulations (SOR/2002-76).

www.gc.ca

CAY Seal Fishery Ordinance (No. 8 of 1921).

CHI Decreto No 38 - Reglamento general de observación de 

mamíferos, reptiles y aves hidrobiológicas y del registro 

de avistamiento de cetáceos.

CHI Decreto No 1.892 - Establece veda extractiva para el 

recurso lobo marino común en área y período que 

indica.

CHI Decreto No 1.612 - Fija valor de sanción de especies 

hidrobiológicas que indica, período 2009-2010.

CHI Decreto No 230 - Declara monumento natural a las 

especies de cetáceos que indica.

CHI Decreto No 179 - Establece prohibición de captura de 

especies de cetáceos que se indican en aguas de 

jurisdicción nacional.

CHI Decreto No 1.571 - Suspende temporalmente la veda 

extractiva del recurso Lobo marino común en la XII 

Región y establece cuota anual de captura para años 

2008 y 2009.

CHI Decreto No 1.471 - Fija valor de sanción de especies 

hidrobiológicas que indica, período 2007-2008.

CHI Decreto No 243 - Establece cuota anual de captura del 

165
recurso lobo marino para el año 2006.

CHI Decreto No 276 - Fija los valores de sanción de especies 

hidrobiológicas.

CHI Decreto No 366 - Veda extractiva para el recurso Lobo 

marino común.

CHI Decreto No 287 - Medidas de conservación adoptadas 

por la Comisión para la Conservación de los Recursos 

Vivos Marinos Antárticos en su XVI reunión de 1997.

CHI Resolución No 896 - Fija tamaño mínimo y regula 

implementos para la extracción del recurso lobo marino 

común en la I y II Región.

CHN Whaling Industry (Regulation) Ordinance (Chapter 

496).

www.hklii.org

COK Marine Resources Act 2005 (No. 7 of 2005). www.paclii.org

COK Cook Islands Declaration on the establishment of a 

whale sanctuary.

COL Resolución No 1.499 - Asigna el límite de mortalidad de 

delfines para el año 2014.

www.imprenta.gov.co

COL Resolución No 375 - Prohíbe el aleteo de tiburón y 

reglamenta los procedimientos para su manejo y 

control.

www.imprenta.gov.co

COL Resolución No 1.035 - Asigna el límite de mortalidad de www.imprenta.gov.co

166
delfines para el año 2013.

COL Resolución No 446 - Reasigna y ajusta el límite de 

mortalidad de delfines para el año 2012.

www.imprenta.gov.co

COL Resolución No 1.596 - Medidas de conservación sobre 

poblaciones de atunes aleta amarilla, barrilete, patudo y 

especies afines que se aprovechan en el Océano Pacífico 

Oriental (OPO), para el año 2011.

www.imprenta.gov.co

COL Resolución No 3.651 - Distribuye el límite de mortalidad 

de delfines para el año 2011.

www.imprenta.gov.co

COL Resolución No 4.159 - Distribuye el límite de mortalidad 

de delfines para el año 2009.

www.imprenta.gov.co

COL Resolución No 523 - Reglamenta la pesca de atún en el 

Océano Pacífico Oriental.

www.imprenta.gov.co

COL Resolución No 2 - Reglamenta la pesca del atún para 

embarcaciones cerqueras mayores de 400 toneladas de 

capacidad de acarreo en el Océano Pacífico oriental.

COL Decreto No 1.608 - Reglamenta el Código Nacional de los 

Recursos Naturales Renovables y de Protección al 

Medio Ambiente, en materia de fauna silvestre.

COS Decreto No 34.327/MINAE/MAG - —Declara las aguas 

interiores, del mar territorial y de la Zona Económica 

Exclusiva como santuario para las ballenas y delfines.

www.imprenal.go.cr

167
COS Acuerdo No 415/AJDIP - Reglamento para la protección, 

aprovechamiento y comercialización del tiburón y de la 

aleta del tiburón.

www.gaceta.go.cr

COS Resolución No 430/AJDIP - Manual de procedimientos 

para el control de la trazabilidad y certificación del atún 

denominado dolphin safe"."

COS Sistema de seguimiento y verificación del atún 

capturado con y sin mortalidad de delfines.

CRO Regulation on the protection of fish and other marine 

organisms.

www.nn.hr

CUB Decreto No 63 - Prohibe la pesca del manatí en aguas 

jurisdiccionales.

CZE Decree implementing certain provisions of the Act on 

trade in endangered species.

www.zakonyprolidi.cz

DEN Order No. 288 on the use of acoustic deterrent devices 

(pingers) in certain fisheries.

www.retsinformation.dk

DEN Order No. 259 on Wildlife Damages. www.retsinformation.dk

DEN Order No. 203 on the use of acoustic deterrents 

(pingers) in certain fisheries.

www.retsinformation.dk

DJI Décret no 85-103/PR/AG portant sur la protection de la 

faune et des fonds sous-marins et modifiant le décret no 

80-62.

168
DJI Décret no 80-62/PR/MCTT du 25 mai 1980 portant sur 

la protection de la faune et des fonds sous-marins.

DOM Resolución No 1/08 - Reglamento sobre la tenencia, 

manejo y exhibición de especies de mamíferos marinos.

DOM Decreto No 319/86 - Crea un santuario para mamíferos 

marinos llamado Santuario de Ballenas Jorobadas del 

Banco de la Plata.

ECU Acuerdo No 18 - Establece sistema de seguimiento y 

verificación del atún capturado en el Océano Pacífico 

Oriental (OPO).

ELS Acuerdo No 96 - Crea el Sistema de seguimiento y 

verificación del atún capturado por buques en aguas 

territoriales de El Salvador.

EUR Commission Regulation (EU) No. 737/2010 laying down 

detailed rules for the implementation of Regulation (EC) 

No. 1007/2009 of the European Parliament and of the 

Council on trade in seal products.

europa.eu.int

EUR Regulation (EC) No. 1007/2009 of the European 

Parliament and of the Council on trade in seal products.

europa.eu

EUR Council Regulation (EC) No. 520/2007 laying down 

technical measures for the conservation of certain 

stocks of highly migratory species and repealing 

Regulation (EC) No. 973/2001.

europa.eu

169
EUR Council Regulation (EC) No. 1967/2006 concerning 

management measures for the sustainable exploitation 

of fishery resources in the Mediterranean Sea, 

amending Regulation (EEC) No. 2847/93 and repealing 

Regulation (EC) No. 1626/94.

europa.eu

EUR Council Regulation (EC) No. 812/2004 laying down 

measures concerning incidental catches of cetaceans in 

fisheries and amending Regulation (EC) No. 88/98.

europa.eu

EUR Council Regulation (EC) No. 882/2003 establishing a 

tuna tracking and verification system.

europa.eu

EUR Council Regulation (EC) No. 1936/2001 laying down 

control measures applicable to fishing for certain stocks 

of highly migratory fish.

europa.eu

EUR Council Decision 1999/337/EC on the signature by the 

European Community of the Agreement on the 

International Dolphin Conservation Programme.

europa.eu

EUR Council Directive 83/129/EEC concerning the 

importation into Member States of skins of certain seal 

pups and products derived therefrom

europa.eu

EUR Council Regulation (EEC) No. 348/81 on common rules 

for imports of whales or other cetacean products.

europa.eu

FAL Whale Fishery Ordinance (No. 9 of 1936).

FAL Whaling Regulations.

170
FIN Decree of the Ministry of Interior relative to fishing and 

the catch of seals in certain convention areas within the 

territorial waters of the Russian Federation in he Gulf of 

Finland (No. 917 of 1993).

FRA Arrêté portant interdiction de capturer et de détruire 

les dauphins.

FRA; MAY Arrêté du 1er juillet 2011 fixant la liste des 

mammifères marins protégés sur le territoire national 

et les modalités de leur protection.

FRA; MAY Arrêté fixant la liste des mammifères marins protégés

sur le territoire national.

FRA; MAY Arrêté du 1er juillet 2011 fixant la liste des 

mammifères marins protégés sur le territoire national 

et les modalités de leur protection.

FRA; MAY Arrêté fixant la liste des mammifères marins protégés 

sur le territoire national.

FRA; NCA Délibération de l'assemblée de la province Sud n° 03-

2004/APS du 31 mars 2004 relative à la protection des 

mammifères marins.

www.juridoc.gouv.nc

FRA; NCA Délibération du congrès n° 397 du 13 août 2003 relative 

à la création d'un sanctuaire baleinier.

www.juridoc.gouv.nc

FRA; NCA Délibération n° 98 du 25 juillet 1990 relative à 

l'institution d'une commission des ressources marines.

www.juridoc.gouv.nc

171
GBR Behring Sea Award Act 1894. www.opsi.gov.uk

GBR Whaling Industry (Regulation) Act 1934. www.opsi.gov.uk

GBR Marine (Scotland) Act 2010 (Consequential Provisions) 

Order 2010 (S.I. No. 2870 of 2010).

www.opsi.gov.uk

GBR Seal Products Regulations 2010 (S.I. No. 2068 of 2010). www.opsi.gov.uk

GBR Marine (Scotland) Act 2010 (2010 asp 5). www.opsi.gov.uk

GBR Conservation of Seals (England) Order 1999 (No. 3052 

of 1999).

www.opsi.gov.uk

GBR Fisheries Act 1981 (Chapter 29). www.opsi.gov.uk

GBR Seal Fisheries (North Pacific) Act 1912. www.opsi.gov.uk

GBR Seal Fisheries Act 1875 (Official Revised Edition 31 

October 1978).

www.opsi.gov.uk

GBR Conservation of Seals Act, 1970 (Chapter 30). www.opsi.gov.uk

GRE Ministerial Decision No. AP 0546/?.5471/?S58 notifying 

the withdrawal of Greece from the International 

Convention for the Regulation of Whaling and from the 

relevant Protocol.

www.et.gr

GRE Ministerial Joint Decree No. 30781/1521 establishing 

measures for the protection of the MONACHUSMONACHUS" Mediterranean seal and its habitat."

GRL Statutes on narwhal hunting with nets in the 

management areas Ammassalik and Ittoqqortoormiit in 

www.lovgivning.gl

172
East Greenland.

GRL Order No. 4 on the protection and hunting of large 

whales.

www.lovgivning.gl

GRL Order No. 17 on leisure-hunting license. www.lovgivning.gl

GRL Order No. 18 on commercial hunting license. www.lovgivning.gl

GRL Order No. 7 on conservation and hunting of beluga and 

narwhal.

www.lovgivning.gl

GRL Order No. 16 on the protection and hunting of seals. www.lovgivning.gl

GRL Order No. 12 on the reporting of catch and wounding of 

large whales.

www.lovgivning.gl

GRL Order No. 20 on walrus protection and hunting. www.lovgivning.gl

GRL Order No. 3 on recreational hunting evidence. www.lovgivning.gl

GRL Order No. 30 on whale hunting restrictions. www.lovgivning.gl

GRL Order No. 13 relaon whale hunting restriction. www.lovgivning.gl

GUA Acuerdo que prohíbe la pesca con fines comerciales y de 

sustento del delfín.

ICE Act on Fishing Outside of Icelandic Jurisdiction.

ICE Act on Fishing in Iceland's Exclusive Fishing Zone.

IRE Sea-Fisheries (Incidental Catches of Cetaceans in www.agriculture.gov.ie

173
Fisheries) Regulations 2007 (S.I. No. 274 of 2007).

IRE Whale Fisheries Act, 1937 (Extension to Mammals of 

the order Cetacea) Order, 1982.

www.bailii.org

IRE Whale Fisheries Act, 1937 (Extension to Sperm Whales) 

Order, 1937.

www.bailii.org

IRE Whale Measurement Regulations (No. 2), 1937. www.bailii.org

IRE Whale Fisheries Act 1937. www.bailii.org

ISR Fisheries Rules.

ISR Fisheries Ordinance.

ITA Ministerial Decree No. 469 laying down provisions in 

matter of keeping of live dolphins belonging to Tursipos 

Truncatus species, in accordance with article 17, 

paragraph 6 of Act No. 93 of 23 March 2001.

www.comune.jesi.an.it

ITA Decree of 3 May 1989 regulating the fishing for 

cetaceans, turtles and sturgeon.

JAP Regulations for Whaling of Small Type (as amended by 

Ordinance No. 54 of July 8, 1952).

JAP Regulations for factory-ship type fisheries (Ministry of 

Agriculture and Forestry Ordinance No. 30).

174
KAZ Ministerial Decree No. 1140 regarding validation of 

charges for the compensation of damage caused by 

infringement of legislation on protection, reproduction 

and management of wildlife species.

KEN Fisheries (General) Regulations (Cap. 378). www.kenyalaw.org

KEN Fisheries Act (Cap. 378). www.kenyalaw.org

KOR Conservation and Management of Marine Ecosystems 

Act.

www.moleg.go.kr

LEB Resolution No. 125/1 of 1999 prohibiting to fish whales, 

seals and marine turtles.

MAS Marine Mammal Protection Act 1990 (Public Law 1990-

84).

www.paclii.org

MAT Tourism Authority (Dolphin and Whale Watching) 

Regulations 2012 (GN No. 154 of 2012).

www.gov.mu

MAT Fisheries and Marine Resources Act 2007 (Act No. 27 of 

2007).

MAU Décret no 86-620 portant création de la réserve satellite 

du Cap blanc.

MAY; JUA; GLO; BDI Arrêté préfectoral no 32/DG/01-TAAF portant 

interdiction de la chasse aux cétacés dans les zones 

économiques exclusives française des îles éparses et de 

Mayotte, pour une période de dix ans.

175
MEX Aviso mediante el cual se da a conocer al público en 

general la temporada 2013-2014 para llevar a cabo 

actividades de observación de ballenas.

MEX Aviso mediante el cual se da a conocer al público en 

general la temporada 2012-2013 para llevar a cabo 

actividades de observación de ballenas.

MEX Norma Oficial Mexicana NOM-131-SEMARNAT-2010: 

Establece lineamientos y especificaciones para el 

desarrollo de actividades de observación de ballenas, 

relativas a su protección y la conservación de su hábitat.

MEX Aviso mediante el cual se da a conocer al público en 

general la temporada 2009-2010 para llevar a cabo 

actividades de observación de ballenas.

MEX Decreto que modifica la Ley general de vida silvestre.

MEX NOM-135-SEMARNAT-2003: Regulación de la captura, 

transporte, manejo y manutención de mamíferos 

marinos en cautiverio.

MEX NOMEM-136-ECOL-2002: Establece las especificaciones 

para garantizar el bienestar de los mamíferos marinos 

en cautiverio.

MEX NOM-131-ECOL-1998: Especificaciones para el 

desarrollo de actividades de observación de ballenas, 

relativas a su protección y la conservación de su hábitat.

176
MEX Tasa máxima de captura incidental de delfines durante 

las operaciones de pesca de túnidos con redes de cerco 

en el Océano Pacífico Oriental.

MEX Tasa máxima de captura incidental de delfines durante 

las operaciones de pesca de túnidos con redes de cerco 

en el Océano Pacífico Oriental.

MEX NOMEM-074-ECOL-1996: Lineamientos y 

especificaciones para la regulación de actividades de 

avistamiento en torno a la ballena gris y su hábitat, así 

como las relativas a su protección y conservación.

MEX Tasa máxima de captura incidental de delfines durante 

las operaciones de pesca de tunidos con redes de cerco 

en el Océano Pacífico Oriental.

MEX Zona de refugio para ballenas y ballenatos.

MIC Chapter 1 of Title 29 of the Pohnpei State Code -

Pohnpei State Fisheries Protection Act of 1995.

www.vanuatu.usp.ac.fj

MLT Marine Mammals Protection Regulations, 2003 (L.N. 

203 of 2003).

www.doi.gov.mt

MOR Arrêté du Ministre des pêches maritimes et de la marine 

marchande no 2134-93 relatif à l'interdiction 

temporaire de pêcher des phoques-moines et autres 

mammifères marins ainsi que de certaines autres 

espèces marines.

NAM Marine Resources Act, 2000 (Act 27 of 2000).

177
NAM Regulations relating to the exploitation of marine 

resources (No. 241 of 2001).

NIC Resolución No 23/02 - Conservación y utilización 

sostenible de las especies de la familia delfínidos.

www.asamblea.gob.ni

NIU Whale Sanctuary Regulations 2003. www.paclii.org

NOR Act relative to the catching of polar bears. www.lovdata.no

NOR Decree No. 1 of 1969 to prohibit the hunting of seals 

without a permit.

www.lovdata.no

NOR Decree No. 5 of 1969 relative to the hunting for seals. www.lovdata.no

NOR Decree on prohibition to import animals and infectious 

substances.

www.lovdata.no

NOR Decree No. 195 of 1998 to regulate fishing by 

Norwegian vessels in the Antarctic (CCALMR-area).

www.lovdata.no

NOR Act No. 15 of 1999 relative to the right to participate in 

fishery and hunting of marine animals (Participation 

Act).

www.lovdata.no

NOR Decree to regulate hunting for minke whales (No. 312 of 

2000).

www.lovdata.no

NOR Decree No. 799 of 2001 to regulate the exportation of 

minke whales.

www.lovdata.no

NOR Decree No. 57 of 2003 relative to a notification duty 

relative to landing and sale of fish.

www.lovdata.no

178
NOR Decree No. 151 of 2003 to provide rules for the hunting 

of seals in the West Arctic Sea and the East Arctic Sea.

www.lovdata.no

NOR Act No. 37 of 2008 relating to the management and 

conservation of living marine resources (Marine Living 

Resources Act).

www.lovdata.no

NOR Decree No. 106 of 2011 relative regulate the hunting of 

seals in the West Arctic Sea and the East Arctic Sea in 

2011 and relative to participation in such hunting.

www.lovdata.no

NOR Regulation No. 1124 on cessation of minke whales 

hunting in 2013.

www.lovdata.no

NOR Regulation No. 340 on access and regulation of minke 

whale hunting in 2013.

www.lovdata.no

NOR Regulation No. 183 on participation and hunting of seals 

in the West- and East- Ice in 2013.

www.lovdata.no

NOR Regulation No. 267 on capture of minke whales in 2012. www.lovdata.no

NOR Regulation No. 240 on participation in hunting minke 

whales in 2012.

www.lovdata.no

NOR Regulation No. 108 on the right to participate in seal 

hunting in the West Ice and East Ice in 2012.

www.lovdata.no

NOR Regulation No. 1272 on quotas in coastal hunting for 

seals in 2012.

www.lovdata.no

179
NOR Decree No. 681 of 2010 relative to a register for the 

storage of electronic information on catch and activities 

of fishing and hunting vessels.

www.lovdata.no

NOR Decree No. 1745 of 2009 to provide for the management 

and conservation of seals on the Norwegian coast.

www.lovdata.no

NOR Decree No. 263 of 2009 to regulate the hunting of seals 

in the West Arctic Sea and the East Arctic Sea in 2009.

www.lovdata.no

NOR Decree No. 88 of 2009 on participation in the hunting of 

seals in the West Arctic Sea and the East Arctic Sea in 

2009.

www.lovdata.no

NOR Directive No. 1276 of 2008 to provide hunting quotas 

for coast seals in 2009.

www.lovdata.no

NOR Decree No. 370 of 2006 relative to maximum quotas in 

the catching of minke whales in 2006.

www.lovdata.no

NOR Directive No. 451 of 2003 relative to maximum quotas 

in hunting for minke whales in 2003.

www.lovdata.no

NOR Delegation of authority pursuant to the Act regulating 

importation and exportation of goods (No. 618 of 1998).

www.lovdata.no

NOR Decree relative to meat control, hygiene and related 

matters in relation with the preparation and marketing 

of whale meat (No. 298 of 1997).

www.lovdata.no

NOR Decree relative to export licences and the exportation of 

fish and fish products and marine mammals and 

www.lovdata.no

180
products of marine mammals (No. 598 of 1993).

NOR Decree to prohibit hunting for Ross-seals (No. 1 of 

1968).

www.lovdata.no

NOR Royal Decree relative to the entry into force of Acts 

concerning Norwegian fisheries limits for Jan Mayen 

(No. 3471).

www.lovdata.no

NOR Decree No. 3 of 1953 to regulate catching of fur seals 

and elephant seal on Bouvet Island and Peter I. Island.

www.lovdata.no

NOR; JMN; SVA Decree No. 336 of 2011 to regulate hunting for minke 

whales in 2011.

www.lovdata.no

NOR; JMN; SVA Decree No. 268 of 2009 to regulate hunting for minke 

whales in 2009.

www.lovdata.no

NOR; JMN; SVA Decree No. 249 of 2005 to regulate hunting for minke 

whales in 2005.

www.lovdata.no

NOR; SVA Decree No. 1743 of 2009 relative to position reporting 

and electronic reporting of Norwegian fishing and 

hunting vessels.

www.lovdata.no

NOR; SVA; JMN Decree No. 291 of 2011 relative to access to 

participation in the catching of minke whales in 2011.

www.lovdata.no

NOR; SVA; JMN Decree No. 265 of 2009 relative to access to 

participation in the catching of minke whales in 2009.

www.lovdata.no

181
NZE Marine Mammals Protection Act, 1978 (Act No. 80 of 

1978).

www.legislation.govt.nz

NZE Marine Mammals Protection (Banks Peninsula 

Sanctuary) Notice, 1988.

www.legislation.govt.nz

NZE Marine Mammals Protection Regulations, 1992. www.legislation.govt.nz

NZE Marine Mammals Protection (Auckland Islands 

Sanctuary) Notice, 1993.

www.legislation.govt.nz

NZE Biosecurity Act, 1993 (Act No. 95 of 1993). www.legislation.govt.nz

NZE Marine mammals protection (Clifford and Cloudy Bay 

Sanctuary) Notice, 2008.

www.legislation.govt.nz

NZE Marine mammals protection (West Coast North Island 

Sanctuary) Notice, 2008.

www.legislation.govt.nz

NZE Marine mammals protection (Te Waewae Bay 

Sanctuary) Notice, 2008.

www.legislation.govt.nz

NZE Marine mammals protection (Catlins Coast Sanctuary) 

Notice, 2008.

www.legislation.govt.nz

PAN Resolución No 22 - Requisitos para la expedición de 

certificados de exportación de aletas de tiburón.

www.gacetaoficial.gob.pa

PAN Decreto No 9 - Protege al tiburón ballena. www.gacetaoficial.gob.pa

PAN Resolución No 1 - Norma el avistamiento de cetáceos en 

aguas jurisdiccionales.

www.asamblea.gob.pa

182
PAN Resolución No 2 - Norma la recolección de mamíferos 

marinos para cautiverio.

www.asamblea.gob.pa

PAN Ley No 13 - Establece el corredor marino de Panamá.

PAU Marine Protection Act of 1994.

PER Decreto Supremo No 026/01/PE - Prohíbe la caza de 

diversas especies de ballenas y la captura de todas las 

especies de tortugas marinas.

PER Decreto Supremo No 003/02/PE - Sistema de 

seguimiento y verificación del atún capturado por 

buques atuneros de cerco.

PER Resolución No 588/96/PE - Condiciones ambientales y 

de cuidado para el adecuado mantenimiento y bienestar 

de los cetáceos menores en cautiverio.

PER Decreto Supremo No 002/96/PE - Reglamento para la 

protección y conservación de los cetáceos menores.

PHI Fisheries Administrative Order No. 185 banning the 

taking or catching, selling, purchasing and possessing, 

transporting and exporting of Dolphins.

www.tanggol.org

PIT Local Government Regulations. www.government.pn

PNG Whaling Act. www.paclii.org

PNG Fauna (Protection and Control) Maza Wildlife 

Management Area Rules 1979.

www.paclii.org

183
PNG Fauna (Protection and Control) Act 1966. www.paclii.org

POR Regional Legislative Decree No. 15/2013/M approving 

the Regulation for Observation of Marine Vertebrates 

within the Autonomous Region of Madeira.

www.dr.pt

POR Decree No. 19/2004 approving the Agreement on the 

Conservation of Cetaceans of the Black Sea, 

Mediterranean Sea and Contiguous Atlantic Area, 

(ACCOBAMS).

POR Regional Legislative Decree No. 9/99 regulating whale 

watching within Azorian waters.

POR Regional Decree No. 11/97/M creating the Natural 

Reserve of 'Sítio da Rocha do Navio'.

POR Regional Decree No. 14/90/M creating the Special 

Protected Area of 'Ilhas Desertas'.

POR Decree-Law No. 263/81 approving the Regulation on 

marine mammals protection.

RUS Order No.86 of 1994 of the Federal Fisheries Committee 

regarding validation of the Provisional Regulation on 

the modalities and terms of issuing fishing 

authorization to foreign legal and natural persons, 

Russian enterprises with the foreign participation for 

catch of aquatic biodiversity in EEZ and continental 

shelf of the Russian Federation.

184
RUS Order No.82 of 2004 of the Federal Fisheries Committee 

regarding issuing fishing licences for catch (harvest) of 

aquatic biodiversity for coastal fisheries to the users of 

the Sakhalin Region in the Far Eastern basin for the 

period of 2004.

RUS Order No. 313 of the Federal Fisheries Agency 

validating the list of aquatic biological resources 

authorized for fisheries.

www.fishcom.ru

RUS Joint Order No. 23 of the Ministry of Agriculture and of 

the Federal Fisheries Agency regarding the elaboration 

and validation of total allowable catch.

www.lawrussia.ru

RUS Order No. 85 of the Ministry of Agriculture validating 

the list of aquatic biological resources industrial 

fisheries, artisanal and sport fishing of which, and also 

protection thereof by the regional authorities shall not 

be carried out.

http://base.consultant.ru

RUS Order No. 85 of the Ministry of Agriculture validating 

the list of biological resources, the industrial fisheries, 

artisanal and sport fishing of which and the protection 

thereof shall not be regulated by the regional executive 

bodies.

sevrv.ru

RUS Order No.330 of 2004 of the Ministry of Agriculture 

regarding setting quotas for catch of aquatic 

biodiversity for proper needs (personal consumption) 

of scanty indigenous population and ethnic 

communities of Koryak Autonomous Area for the period 

185
of 2004.

RUS Order No.297 of 2004 of the Ministry of Agriculture 

regarding issuing fishing licences (permits) for catch 

(harvest) of aquatic biodiversity for industrial purposes 

for coastal fisheries to the applicants of the Koryak 

Autonomous Area in the Far Eastern basin for the 

period of 2004.

RUS Order No.227 of 2004 of the Ministry of Agriculture 

regarding issuing fishing licences (permits) for catch 

(harvest) of aquatic biodiversity for industrial purposes 

for coastal fisheries to the applicants of the Kamchatka 

Region in the Far Eastern basin for the period of 2004.

RUS Governmental Ordinance No.1948-r of 2003 regarding 

validation for the period of 2004 of total allowable catch 

(harvest) of aquatic biodiversity for proper 

consumption (personal consumption) of indigenous 

scanty population and ethnic communities of the North, 

Siberia and the Far East of the Russian Federation.

RUS Governmental Ordinance No.1644-r of 2003 regarding 

validation of total allowable catch for the period of 2004 

in freshwater inland water basins, inland sea, territorial 

sea, continental shelf, EEZ of the Russian Federation, in 

the Azov sea, Caspian sea and the lower reaches of the 

186
rivers flowing into them, as well as in the Amour river.

RUS Order No. 32 of the Federal Fisheries Committee 

regarding validation of the Regulation on the structure 

and the functioning of the ichthyologic branches of the 

basin fishing inspections attached to the Committee.

www.dalryba.vladivostok.ru

RUS Governmental Ordinance No.1603-r of 2002 regarding 

validation of total available catch for the period of 2003 

of aquatic biodiversity in the internal sea, territorial sea 

and Exclusive Economic Zone of the Russian Federation.

RUS Governmental Ordinance No.1551-r of 2001 regarding 

validation for the period of 2002 of total allowable catch 

of aquatic biodiversity in internal sea, territorial sea, 

continental shelf and Exclusive Economic Zone of the 

Russian Federation.

RUS Ministerial Decree No. 1582-p granting hunting 

authorization for two Groenlandian whales for the 

needs of small indigenous populations living on the 

territory of Tchukotka Autonomous Region of the 

Russian Federation.

www.law.optima.ru

RUS Ministerial Decree No. 967 of 1992 regarding 

participation of the Russian Federation in the 

187
International Convention for the Regulation of Whaling.

RUS Fisheries Regulation No. 141 on artisanal and sport 

fishing in the water bodies of the Sea of Azov, Manych 

water reservoirs, water bodies of Kalmykia and 

Stavropol region subordinated to the fisheries basin 

institution of the Sea of Azov.

www.ohota.novochek.ru

RUS Order No. 349 of the Fisheries Ministry validating the 

Regulation on conservation and catch of marine 

mammals.

www.dalryba.vladivostok.ru

RUS Statute of Fishing Inspection (1970).

SAF Sea Birds and Seals Protection Act.

SAF Sealing Regulations. www.enviroleg.co.za

SAF Regulations to amend the Regulations for the 

management of boat based whale watching and 

protection of turtles (No. R. 819 of 2009).

www.info.gov.za

SAF Regulations for the management of boat based whale 

watching and protection of turtles (No. R. 725 of 2008).

www.info.gov.za

SAF Marine Living Resources Act (No. 18 of 1998). www.enviroleg.co.za

SAF Notice on Assignment of certain provisions of the Sea 

Birds and Seals Protection Act. to the administrators of 

the provinces of Cape of Good Hope and Natal (Proc. No. 

8 of 1993).

www.enviroleg.co.za

188
SAF Sea Birds and Seals Protection Regulations (GN. R. 1168 

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1994.

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los cetáceos.

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SPA Real Decreto No 942/2001 - Programa de seguimiento y 

verificación del atún capturado en el área del Acuerdo 

relativo al Programa Internacional para la Conservación 

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SRL Fauna and Flora Protection Ordinance.

SRL Fishing Operations Regulations of 1996.

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STH Spear Guns Control Order, 2006 (Cap. 91). www.sainthelena.gov.sh

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TON Fisheries (Conservation and Management) Regulations 

189
1994.

TON Fisheries Regulations 1992. www.tonga-law.to

TUK Law No. 230-I on protection and rational management 

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TUR Circular No. 33/1 on commercial fishing activity into 

marine and inland waters (1999-2000).

UKR Order No. 129 of the Ministry of Agrarian Policy 

validating Fisheries Regulations for the period of 2005.

UKR Ministerial Decree No. 1126 validating the Regulation 

on the modalities of carrying out artisanal and sport 

fishing.

URU Ley No 19.128 - Decláranse al mar territorial y a la zona 

económica exclusiva de la República “Santuario de 

Ballenas y Delfines”.

URU Resolución S/n - Apruébanse las modificaciones a los 

Apéndices de la Convención sobre el Comercio 

Internacional de Especies Amenazadas de Fauna y Flora 

Silvestre (CITES).

URU Decreto No 261/002 - Regula las actividades 

relacionadas con la observación y el acercamiento a los 

ejemplares de diferentes especies de ballenas por 

particulares.

www.presidencia.gub.uy

URU Decreto No 238/998 - Medidas para reducir la 

mortalidad incidental y caza ilegal de pinnipedios y de 

190
cetáceos.

URU Decreto No 149/997 - Actualiza la reglamentación 

referente a la explotación y dominio sobre riquezas del 

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VAN Maritime (Protection of Mammals) Regulations (Cap 

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VIE Decision No. 131/2004/QD-TTg approving the Aquatic 

Resource Protection and Development Program till

2010.

VIE Regulation on Management and Conservation of Marine 

Resources.

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192
Appendix C: Response to Peer Review Comments

The BRT enlisted the help of the Marine Mammal Commission (MMC) to coordinate 

scientific peer review of the June 2012, version of the status review report. The MMC 

received comments from five reviewers and these reviews were provided, without 

attribution, to the BRT. The reviews and a summary of how the BRT responded to them 

are provided below. 

Reviewer 1

Attached are various editorial suggestions and comments on the draft humpback whale 

status review. I read parts of the global review by Flemming and Jackson but did not 

comment on it as it’s already a final NOAA Tech report. I am glad to see this effort and 

overall thought the BRT did a yeoman’s job sorting through and summarizing a huge 

amount of information and factors. I also thought the bottom line results on stock 

delineation and the degree to which each of the stocks is endangered was reasonable and 

well supported by the available scientific information. That said, there are a number of 

serious and not so serious flaws in the analyses. I tried to summarize the points noted in 

the attached below. Some may be relatively easy to correct, but others probably could be 

corrected without reconvening the BRT. Among those flaws are the following: 

1. One of the most troubling flaws was the scoring system the used to evaluate 

expert opinion. I agree that expert opinion is a reasonable and appropriate way to 

evaluate stock status relative to ESA listing criteria, but the system the BRT used seems 

flawed. It includes three categories: high risks, moderate risk, and not at risk. There is 

no low risk category even though the risk analyses frequently categorizes various threats 

as being low risk. Indeed they conclude that some species are between moderate and 

“not at risk,” which falls into a category they did not consider. If they had a low risk 

category, I suspect at least some stocks – principally those considered to be a greater risk 

– would have received much lower “not at risk” scores.

Response: We agree that there are some benefits to having more, and therefore finer, 

risk categories. However, ultimately the species (or DPS) needs to be categorized into 

one of the three ESA risk categories (endangered, threatened, not listed), so the use of 

three categories in the status review makes sense in that context. The description of 

threats and the narrative description of status also allows for discussion of more nuanced 

risk status than is provided in just the three categories. Finally, distributing ‘votes’ 

among multiple categories also allows for a finer gradation of risk status than would be 

the case otherwise. 

193
2. The scoring table in Appendix D showing the vote results decisions on the degree 

of endangerment seems so central to the findings (and short enough) it should be included 

in the main body of the text – and perhaps even in the executive summary. I would move 

it up into both the conclusions and the executive summary.

Response: We agree, and have moved this table into the main text.

3. The report notes that the BRT considered the possibility of there being three or 

four unrecognized subspecies of humpback whales. After seeking the opinion of the 

SMM Committee on Taxonomy, a majority of the BRT agreed there were likely three 

subspecies (North Atlantic, North Pacific, and Southern Hemisphere) and then based that 

opinion, proceeded to analyze DPSs. I do not feel this is either appropriate or necessary. 

It seems inappropriate to assume three subspecies until such a decision has been 

published and vetted in the scientific literature and it becomes accepted by the scientific 

community. Notwithstanding the respected opinion of the SMM Committee, it is not the 

place of the BRT or listing process to decide whether new subspecies should be 

recognized. That is a role for the scientific literature based on a thorough analysis 

relevant data beyond the scope of the BRT. By assuming 3 subspecies, any listing 

decision based on the BRT’s advice would presumably have to be reflected in listing 

DPSs according to their assumed three subspecies model which is not currently supported 

in the scientific literature. Moreover, the need to consider subspecies seems irrelevant in 

this case. That is, it seems to me all of the identified DPS could be supported assuming 

the species is monophyletic with now subspecies. In almost every case, the principle 

supporting rational for the DPS is that the absence of a stock would leave a significant 

gap in the range. This is no less true for a single global species than it is assuming three 

subspecies. Thus the debate and analysis about subspecies seems superfluous and 

distracting. I would suggest either deleting that discussion entirely, or at least leaving it 

as a question needing further research and not basing the DPS analysis on an assumption 

of subspecies. The discussion of DPSs could still be lumped under the three ocean basins 

as a matter for presentation convenience without considering each basin a separate 

subspecies and arrive at the same conclusions. The referenced precedence for 

considering possible subspecies set by the Southern Resident Killer whale was in my 

view more a political decision than a scientifically based argument. I would hate to see 

that situation become a precedent for future analyses.

Response: We agree that the sub-species question is a difficult one. However, because 

the ESA specifically mentions sub-species and because marine mammal sub-species may 

be somewhat under described due to the difficulty of access to specimens (Reeves et al. 

2004a), the BRT concluded that some discussion of potential humpback whale subspecies would be useful. In response to this and similar comments, however, we made 

substantial revisions to the discussion of sub-species in the report. In particular, the 

revised report focuses on describing the major differences among humpback whales 

inhabiting different ocean basins, and simply notes that these differences may be 

194
consistent with sub-species. Because of the major differences among ocean basins, the 

report focuses primarily on assessing the question of whether there are DPS within ocean 

basins, but also discusses whether any DPS so identified are also discrete and significant 

with respect to the global taxon. With some possible exceptions (noted in the report), the 

BRT agrees with the reviewer that the DPS identified in the report meet the DPS criteria 

regardless of whether the larger taxon in question relates to an ocean basin or the global 

species. Finally, the report cites a recently published study that proposes three subspecies of humpback. 

4. In some cases where there were different possible alternatives regarding regional 

stock structure (e.g. North Atlantic) , the BRT used the same process of allocating 100 

points to different options that they used to evaluate DPS risks and reported the results in 

a table. In other cases, such as the division between the Central American and southeast 

Pacific stocks (p 33-34) it notes a “majority” or “consensus” view but does not provide 

the scores. The report should be consistent in providing scores wherever there were a 

range of possible options considered.

Response: The BRT made some decisions by consensus, as noted in the report. The 

structured decision making process, particularly for population structure issues, was only 

employed when the BRT concluded that there was substantial uncertainty.

5. The discussion of the Okinawa/Philippines stock (with which they lump in 

Ogasawara) and the unknown second western population seemed confusing and not 

particularly convincing. The suggestion that Ogasawara is part of the migratory corridor 

for Okinawa/Philippines stock does not seem convincing. Ogasawara is nearly 1000 

miles due east of Okinawa and would not appear to be along the same route whales 

would take to the Philippines. The background document mentions that there have been 

a few photo ID matches between the Okinawa and Ogasawara, but that the Ogasawara 

whales had a distinct genetic signature. It is not clear to why the Ogasawara whales are 

not part of the “second western” stock whose calving grounds have yet to be identified 

(but may in part include Ogasawara) and instead should be considered part of the 

migratory corridor to the Philippines while Okinawa is considered part of the calving 

range for that population. This is a confusing situation but I think a better job could be 

done laying out the basis for the supposed second western population, why it is 

apparently different from the Ogasawara whales, and why Ogasawara is considered only 

part of the migratory corridor while Okinawa is considered part of the calving range.

Response: We have edited the report to try to clarify our reasoning. 

6. The DPS analysis seems to assume all mating occurs on the winter calving 

grounds. Some added discussion of the potential for mating either on the northern 

feeding grounds or along the migratory corridor seem important. If whales do mate on 

feeding grounds where different stock intermingle, it could significantly undermine 

195
support for the DPS analysis. As a related point, I seriously doubt whales in the Southern 

Hemisphere stick to the narrow Antarctic wedges Identified as their summer feeding 

areas. Rather I imagine there is more overlap and intermingling then suggested in their 

model (which was based on an IWC model. Thus, it seems important to state why whales 

are not thought breed in shared feeding or migratory corridors.

Response: We agree with the reviewer regarding the likely overlap of feeding areas in 

the southern hemisphere, and have revised the report to clarify this point. Regarding 

breeding locations, it is widely believed that, while occasional mating may occur on 

feeding grounds or on migration, the great majority of mating and conceptions take place 

in winter breeding areas and the report references studies supporting these observations. 

In addition, any breeding activity that occurs at what are generally considered to be 

feeding locations would be reflected in the patterns of genetic diversity considered by the 

BRT, and low levels of breeding at these areas do not therefore reduce support for the 

DPS analysis.

7. According to page 3, the BRT was asked not to review the ESA listing criterion 

on “adequacy of existing regulatory mechanisms.” Yet the threats analyses for several 

different stocks mentions and seem to reflect consideration of various national laws, 

guidelines and other such management measures. For example, for the Oceania stock, 

they dismiss future whaling as a threat given various whale sanctuaries and national laws 

prohibiting whaling. Similarly for the east Australia stock as part of the rationale for 

concluding the stock was at low risk of extinction is a statement that Australian waters 

are protected by the Australian Whale Sanctuary.

Response: We agree that there was an inconsistency within the report on this point. In 

fact the BRT did consider the effects of existing regulatory mechanisms on the current 

status. The revised report clarifies that the BRT considered these effects, and includes 

additional explicit discussion of adequacy of existing regulatory mechanisms. 

8. The report is generally very well written, but there are parts, particularly the 

general description of threats in Section A.2 that need some further editing. I have 

included some suggestions. There also are incorrect references and inaccurate and 

incomplete information in the “vessel collision” in section A.2.4. See corrections on 

attached.

Response: The report has been edited for clarity and accuracy per the reviewer’s 

comments.

9. I would simplify stock names for convenience and rely on the text to say what 

parts of the range are included in that stock. For example the reference to the 

196
“Mozambique/East South Africa/Comoros Archipelago/Madagascar” stock could be 

simplified to the Southeast Africa/Madagascar stock or simply the Southeast Africa 

stock. Similarly, the “Cape Verde plus Northwest Africa” stock could be simplified to 

the Cape Verde stock or Norwest Africa stock. Also, at times the report goes to 

considerable length to note that the Arabian stock is not in the Southern Hemisphere, but 

at others is seems to forget that distinction and lump them in even though it is north of the 

equator. The report should be consistent in noting this is not a Southern Hemisphere 

stock.

Response: We agree, and have edited the report for consistency and simplicity of names.

10. The discussion of research threats should include invasive tagging. I do not 

believe it is a significant risk, but it is probably one of the greatest risks that research 

poses for individual whales and as such should not be omitted from the assessment of 

research effects.

Response: The report has been edited to include discussion of tagging.

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Reviewer 2

No general comments – all comments were as comments in file (see Table C1 for 

responses).

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Reviewer 3

In general, from my perspective, I think they have done a pretty good job on this task. 

They have certainly taken it seriously and attacked it in a thorough, sensible manner, 

investing lots of intellectual firepower. Allie Fleming and Jen Jackson did a yeoman job 

of pulling things together in the first place, as acknowledged, and the BRT seems to have 

thought things through carefully. So I think overall, what the MMC can and should offer 

is commendation for a job well done, plus added comments on how things can be 

improved in a final document. Basically though, I think the judgments on how to define, 

and assess, the DPSs are reasonable and well justified.

No response necessary. 

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197
Reviewer 4

Please see attached for BRTs document with comments inserted and a stand-alone 

document with three primary comments and supporting material in an appendix

A couple of other points and question:

1. I have added my graduate student to this, as she was helpful in the process especially 

for combing through past IWC reports. I hope that was OK.

2. I provided a broader review but also had some specific comments and questions for 

DPSs. These are areas where we have greatest familiarity. But I hope this doesn't come 

across as 'our monkey isn't on the list. That isn't the case as to why I raised the issues. 

Actually, we have spent the better part of the last 8 (and even 12 years) reviewing 

humpback whales at IWC--including North Atlantic, and several SH assessments. The 

issues we point out are the populations that actually have more complex population subdivisions that others --and now some of the assessments completed in the earlier days are 

going back and re-evaluating evidence for population structure. I believe these points are 

well-substantiated, and just don't want to have an appearance of self-interest.

3. So what are the next steps in the process and how can we stay engaged?

I hope all of this is helpful and what you were expecting from my review.

Response: See response to specific comments in Table C1.

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Reviewer 5

Given the constraints of the DPS focus I think the BRT did an outstanding job of 

synthesizing a lot of information. The presentation and writing was clear and well 

organized. 

I will address each of the recommended review topics as listed in your email. However, I 

am not as familiar with the non-North Pacific populations; hence I won’t be able to give 

those adequate review. 

• Is the information presented accurate and current? (If they are aware of additional or 

more current relevant information, we would appreciate it if they would provide copies of 

all additionally suggested references.) 

The information was for the most part current. Suggested additions or changes are:

198
1. There was one reference that cited the SAR instead of the publication. I suggest 

that be changed (page 6 Angliss and Outlaw to Gabriele et al.1996).

Response: The reference was corrected. 

2. In the overview there was no mention of the age of humpbacks and the 

discrepancy in the whaling literature (see Gabriele et al 2010). Longevity seems critical 

to assessing risk of extinction and I am curious why the omission? 

Response: As noted in the introduction, the BRT report provides only a brief summary of 

the biology and ecology of humpback whales, deferring a more detailed discussion to the 

companion report of Fleming and Jackson (2011). That report does discuss maximum 

ages. 

3. A paper on trend (rate of increase), survival and abundance in Southeast Alaska 

was recently accepted for a final revision and will be published soon (see Hendrix et al.

in Press). These results should be used as the most up to date and best data available for 

this population.

Response: This paper was not available to the BRT during the course of their 

deliberations and was therefore not included in the report. It does not appear that the 

information in the paper would change the basic conclusions of the report, however.

4. There are a number of references to strong migratory link with Mexico and 

Southeast Alaska. This simply is not true. SEAK has very few MX whales. I can find 

sources if needed but Jorge Urban’s paper on MX migratory destinations should be a 

good start. The genetics papers from MX including SPLASH reports should be used as 

well. 

Response: We agree and corrected this mistake.

5. Genetic diversity for the Gulf of Alaska is described in Witteveen et al. 2011. 

This could be added to the genetic diversity background or in the specific region.

Response: This paper was not available to the BRT during the course of their 

deliberations and was therefore not included in the report. It does not appear that the 

information in the paper would change the basic conclusions of the report, however.

199
6. Interactions (not specifically competition) with fisheries are described in Rice et al 

2011 and these papers have been accepted for publication in Fisheries Oceanography. I 

can provide full citations if necessary.

Response: This paper was not available to the BRT during the course of their 

deliberations and was therefore not included in the report. It does not appear that the 

information in the paper would change the basic conclusions of the report, however.

7. Update on vessel collisions in AK has been published. Neilson et al. 2012. This 

paper should replace the IWC 2007 version and is updated and more thorough.

Response: The reference was updated. 

• Does the information presented sufficiently make the case for the designation of 

potential DPSs based on the agency policy described in the document?

Yes I believe the BRT did a good review and assessment. Although I don’t have 

evidence to say this with any certainty, I am not 100% convinced Ogasawara is not a 

standalone breeding area or used as both a pass through and a breeding area. 

• Are the extinction risk assessment approaches appropriate and sufficient?

Yes the approach for assessing risk was sufficient with the exception of a discussion as to 

how long humpbacks can live. 

• Does the threats assessment accurately and sufficiently summarize the threats facing 

the identified DPSs?

For the most part, yes, the BRT assessed threats. However, the aquaculture issue was 

mis- represented for Alaska. Alaska prohibits fish farming for finfish but does have an 

aquaculture program (ocean ranching) for salmon. Humpbacks feed at the release sites 

upon salmon smolts and fry which complicates returns to the commercial fisheries (see 

Straley et al 2010). The sections on aquaculture in Alaska need to be accurate. The issue 

of predation on releases needs to be added both as a competition factor and threat (eating 

fish who were fed fish meal while held in net pens). There is low risk of entanglement 

from net pens.

Response: If we understand the comment correctly, the reviewer is referring to releases 

of hatchery salmon, which are very common throughout the entire Pacific Rim. We did 

not consider such releases to be “aquaculture” per se, and the BRT did not directly 

evaluate risks from whales preying on hatchery salmon. Although this issue may be 

worth further investigation, it does not appear to be a significant risk at this time.

• Are the conclusions in the report clear and well justified?

200
The BRT and the writer of the document clearly presented the conclusions.

Suggested references in order from review answers 1 to 7:

Gabriele, C.M., J.M. Straley, L.M. Herman, and R.J. Coleman. (1996) Fastest 

documented migration of a North Pacific humpback whale. Marine Mammal Science, 

12(3):457-464.

Gabriele, C.M., et al. (2010) Sighting history of a naturally marked humpback whale 

(Megaptera novaeangliae) suggests ear plug growth layer groups are deposited annually. 

Marine Mammal Science, 26(2):443–450.

Straley, J. et al. (2010) Preliminary investigations of humpback whale predation at 

salmon enhancement facilities on eastern Baranof Island, southeastern Alaska, April to 

June 2010. University of Alaska Southeast, 1332 Seward Ave, Sitka, AK 99835 19pp.

Hendrix, N., J. Straley, C. Gabriele and S. Gende (In Press) Bayesian estimation of 

humpback whale (Megaptera novaeangliae) population abundance and movement 

patterns in southeast Alaska. Canadian Journal of Fisheries and Aquatic Sciences

Witteveen, B. et al. (2011) Using movements, genetics and trophic ecology to 

differentiate inshore from offshore aggregations of humpback whales in the Gulf of 

Alaska Vol. 14: 217–225, 

Neilson, Janet L., Christine M. Gabriele, Aleria S. Jensen, Kaili Jackson, and Janice M. 

Straley (2012) Summary of Reported Whale-Vessel Collisions in Alaskan Waters

Volume 2012 Article ID 106282

Response: We thank the reviewer for the information, and have added most of these 

references as appropriate. 

201
Comment # p. # Comment Response

1 v This is strange to say before a review of genetics and to even include 

such speculation. Who is on that committee?

The executive summary is necessarily brief, but the main 

body of the report provides much more information on 

this topic. Based on numerous comments related to the 

sub-species question, we have also modified the text in 

both body of report and the executive summary to better 

qualify the uncertainty surrounding possible sub-species. 

We provided a list of committee members as a footnote. 

2 v This sounds premature to me. Would it not be better to say something 

like “... on the assumption that at least three subspecies will 

eventually be described, named, and recognized.”

We agree, and have revised draft provides a more 

nuanced view of the sub-species question. 

3 v Sub-species debates have been going on for quite some time. Most 

recently the NOAA-SWFSC has taken favor with sub-species 

definitions following on a ‘journal club’ and a pre-meeting workshop 

at the 2009 SMM meeting in Quebec City. One of the major 

problems with sub-species approaches is the arbitrary nature of such 

evaluations. This statement seems to be guided on a combination of 

biogeography, long-term movements and identity, and genetics. 

However the genetic differentiation of the Arabian Sea population 

from all other populations around the world (See Pomilla et al 2005; 

Pomilla et al-IWC report) is more significant than many other ocean 

basin comparisons and yet it is being grouped with the Southern 

Hemisphere humpbacks. Furthermore, it was at the 2002 IWC and in 

a taxonomic review by Brownell and Perrin that of all the humpback 

whale populations worldwide, the Arabian Sea population merited 

sub-specific status. The problem is how this information is uniformly 

and consistently applied, particularly as it relates to management 

decisions. I agree that there are divisions below the species level for 

humpbacks but whether those are DPS or sub-species.

The sub-species section was revised considerably to 

reflect this and other comments. In the revised draft, we 

focus more on the degree of divergence among whales 

from difference ocean basin and the possibility (only) that 

this divergence may be consistent with sub-species. The 

updated report also cites more recent literature on this 

topic. 

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4 vi For this analysis this is too vague a term and should be changed to 

mating areas. How well known are mating areas. While we know 

they mate in the tropics, is that the only part of their range this 

occurs?

We do not agree with this comment. Among other things, 

the unit to manage is a “population” not an “area”. The 

fact that specific mating areas are not all identified does 

not matter at this level. The existing text has been 

retained; however, a footnote has been inserted after the 

first mention of “breeding areas” to define the term as 

used in this document. 

5 vi This is a double-may phrase – makes no sense. Potentially means 

could and could means potentially so why use both?

We have corrected the text. 

6 vi Why not just Southeast Africa/Madagascar DPS to simplify? We agree, and made this change.

7 vi It would be good to clarify here if these are all ages or just mature. We agree, and have edited to clarify.

8 vii It would be good to clarify here if these are all ages or just mature. We agree, and have edited to clarify. 

9 vii This whole statement is correct if at first DPS are defined correctly in 

a two-step process. First, define the unit to conserve and then 2nd 

evaluate status, trend and probability to extinction (similar to IWC, no 

loss of distinct demographic unit). But what about other possible 

DPSs not fully considered. For example the B2 sub-population, 

genetically distinct (albeit low levels of genetic differentiation) and 

possibly containing only a few hundred animals. 

The BRT's approach was to identify the best supported 

DPS configurations and evaluate extinction risk of each 

DPS identified. With only a few exceptions (e.g., West 

Pacific 2, Cape Verde Islands), the BRT was sufficiently 

confident in the DPS configurations that evaluation of 

additional, less supported configurations would not be 

considered useful. 

10 vii What about noise/ interference with communications? That might be 

added to climate change

Noise was considered and ranked as low but increasing 

threat. 

11 vii Why include this one reference in Ex. Sum. Delete? We agree, and deleted the reference. 

12 vii This paragraph is about the NORTH Pacific subspecies, no? If so, 

should say so here.

Text was clarified. 

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13 vii Should be more specific From noise? Oil spills? Ship traffic? or all 

of the above?

This is further explained in the body of the document.

14 vii Whaling. Isn’t this the same as “directed takes”? And where in the 

region are humpback whales whaled?

This is further explained in the body of the document.

15 vii Moderately (or minor) reduce pop growth through combined effects 

or each individually? Need to define moderate in terms of effect on 

population growth... or perhaps PBR

Modified with "each" to clarify individually.

16 vii The west coast of Africa has extensive oil and gas leases currently 

proposed and in operation. This is not highlighted at all and was 

discussed in the IUCN review of SH humpbacks and during the IWC 

reviews. I have to take complete exception with the fact that the 

review can find a concern off Western Australia from energy 

exploration for a population that was reviewed to be several times 

larger than the populations off west Africa. This is simply incorrect 

and erroneous. NB. This information was provided to the BRT via 

Jackson and Flemming report. See supporting Materials #1

We agree that oil and gas extraction is a potential threat 

and added text that acknowledges this.

17 vii This seems irrelevant. Issue is whether there are threats where ever 

they are

We disagree; in this case the population faces increased 

risks due to its location in a relatively constrained 

geographic location. 

18 vii How about prey availability, given it is the only species that feeds in 

the subtropics which are generally less productive and subject to 

extensive fishing.

Prey availability was unknown, and this is stated later in 

the report.

19 vii This is the Western Gray Whale of humpback whales and yet it isn’t 

getting appropriate attention. We are in the process of trying to get a 

Conservation Management plan set in motion at IWC, but requires 

government interest and effort and support.

No change necessary.

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20 vii Unclear. Does this mean the BRT worked “collectively” (which 

would be implicit and therefore unnecessary to say)? Or the BRT 

evaluated the collective array of threats facing each DPS? Or?

Removed "collectively".

21 viii Past, present, or future? Text was clarified.

22 viii Needs more explanation. Just who and how many on the BTR and 

what are the boundaries of bins in terms of points?

This is further explained in the body of the document.

23 viii Although I don’t’ believe the subspecies question is as important as 

this report makes it out to be, I note that the decision to consider a 

three subspecies structure is not noted here.

We agree with the comment that the sub-species question 

is not likely to influence the DPS designations to any 

great degree, and have added a section on this in the body 

of the report. 

24 viii Does this mean then that there are some insignificant DPSs as well? Removed significant.

25 viii Variously referred to as Southeastern Pacific, Columbia/Ecuador, and 

other names throughout. Need to be consistent.

We agree, and have edited the document for consistency.

26 viii If it’s not “not at risk” or moderate risk, then it must be at high risks We edited to report the percentage support for each of the 

three categories. 

27 viii This is not a score This is correct, but no revision is necessary.

28 1 Was that comprehensive evaluation this document? If so, should be 

“began a” and should make the connection more explicit. If not, is 

there a citation for the 2010 review?

Text was clarified per reviewer's suggestion.

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29 2 The evaluations of humpbacks in other fora such as IWC also strive to 

determine DPS and are documenting them within these basins. 

Whether these can be assessed in a rigorous way is another story. But 

they appear to exist and would potentially double the number of DPS 

identified by this Review.

As discussed in the report, a DPS has a specific 

interpretation under the ESA, as described in the joint 

USFWS-NMFS DPS Policy. Units identified by the IWC 

do not necessarily conform to this definition, which states 

that a population must be both 'discrete' and 'significant' 

in order to be considered a DPS. This issue is discussed 

at length in the report.

30 2 By whom? We deemed it unnecessary to include these details here.

31 2 Also subspecies? As noted in the report, the BRT concluded that it would 

be useful to evaluate the sub-species question. 

32 2 Aren’t BRTs supposed to make recommendations to the agency re 

listing?

The BRT was tasked with evaluating biological status and 

threats, not making a listing recommendation. 

33 3 Understand that this is limited by ESA, but for some of the DPSs, the 

extent of current and emerging threats to limit recovery may need to 

be considered. Thus the risk of extinction may just be too high a bar.

We evaluated status with respect to the risk categories 

described in the report. We agree that understanding 

factors limiting recovery is also important information to 

consider, however, and edited the text to make this point. 

34 3 For me, this is a missed opportunity. It would have been more work 

for the BRT, but this would have been an interesting and valuable 

exercise. It would have at least provided something to discuss or 

challenge below the ‘risk of extinction’ level. Do we know why the 

BRT was not asked?

The report has been edited to clearly state the charge to 

the BRT and the purpose of the report.

35 5 Why not assume no information on three subspecies and just review 

re DPS and leave subspecies question to later research. Does it make 

a difference if a DPS is a DPS of a species or subspecies?

We now describe the differentiation among ocean basins 

more clearly and discuss whether or not these differences 

might be consistent with sub-specific divergence. We 

added a section discussing whether the 'taxon' of 

reference (possible sub-species based on ocean basins 

versus the global species) makes any difference to 

identified DPS.

206
36 5 This seems more ad hoc than should fly for this review. What about 

the considerable debate about whether sub-species exist and whether 

one can reliably, consistently, and rigorously delimit subspecies? 

**See supporting materials #2

We do not think this report is the appropriate venue to 

present a detailed discussion regarding the nature or 

validity of sub-species. The BRT accepted the opinion of 

experts who have specifically reviewed this question and 

proceeded on that basis. However, we also edited the 

report to make it clear that we are primarily describing 

differentiation among ocean basins that may be consistent 

with potential sub-species.

37 6 It would be helpful if this figure included dots with labels for breeding 

grounds.

This figure has been deleted, as a subsequent figure 

shows the breeding grounds. 

38 8 To be useful for identifying DPSs given policy guidance, this section 

should discuss what is known about where the whales mate. It is 

noted elsewhere that they mate on calving grounds, but it is not clear 

whether there is any information to suggest they may mate on feeding 

grounds or elsewhere. A definitive statement about such possibilities 

(i.e., there is no evidence they mate on feeding grounds or this is 

unknown) would be helpful.

We have edited this section for clarity per the reviewer's 

suggestions.

39 9 Sounds like a pretty safe upper limit but not very realistic. No change necessary.

40 9 This is a strange section heading given previous headings We modified heading.

41 9 I think this overstates the singularity of the DR concentration (Silver 

and Navidad Banks) to the neglect of numerous other smaller 

concentrations in the Greater and Lesser Antilles and along the coast 

of Venezuela.

We revised the text to discuss the other areas.

207
42 10 Some mention of Roman and Palumbi seems warranted, even if the 

results/conclusions are disputed.

Roman and Palumbi’s paper is important but does not 

deal directly with current trends, which is the section 

here; rather the debate surrounding this paper centers on 

the size of the North Atlantic humpback whale population 

prior (perhaps greatly prior) to whaling. We have added a 

reference to the issue, however, in the context of a new 

section related status to the recovery plan.

43 10 There is information on survival probability in Rosenbaum et al. 2002 

Journal of Heredity on this matter as well. **See supporting materials 

#3

While Rosenbaum et al. (2002) has survival information, 

it is more of a model that we do not feel would add 

significantly to this section.

44 10 If so, why is only one of these provided in the paragraph? Text has been clarified.

45 10 To be useful for the purpose of determining DPSs given the policy 

guidance, these genetic sections should discuss the extent to which 

there is a detectable genetic difference between the various 

populations. Where this has not yet been analyzed it should be so 

noted.

We agree, and have added this here and elsewhere in 

relevant sections of the document. 

46 10 Has a “Gulf of Maine” population been introduced in this report yet? Yes.

47 11 This sounds really strange to me. What are ‘inland’ waters, and might 

it not be significant that ‘inland and coastal’ waters are the areas most 

easily and often observed where feeding behavior can be 

documented?

Removed "inland "

48 11 Not sure what is meant here by ‘territorial’ waters. Within 12nmi of 

shore? Also, saying that ‘more than half feed’ is hard to interpret –

more than half spend some time, from a little to a lot, feeding in US 

territorial waters, or more than half of their aggregate annual nutrition 

is obtained in same, or??

Text was clarified.

208
49 11 I remain reluctant to be so strong about this point. There is lots of 

turnover, I’m told, in the animals on the DR banks through the winter, 

and lots of other areas where the whales sing, nurse etc. in the wider 

Caribbean region.

Text was clarified.

50 11 “Broad” in what sense? As in widely spaced from each other? Or 

large? Another general point is that using the term “breeding” loosely 

with migratory cetaceans is problematic. Conflating mating, calving, 

and nursing leads to confusion and muddle. Important these terms be 

clearly defined and used consistently.

Text was clarified.

51 11 Why this level of detail for SPLASH but not YONAH? Probably less 

for SPLASH is better?

We disagree, and believe the level of detail provided (a 

brief summary) for the SPLASH and YONAH projects is 

appropriate. Citations to both studies are provided for 

readers desiring a greater level of detail.

52 11 Measure of uncertainty The 18,302 estimate was an average between feeding and 

breeding ground estimates, no measure of uncertainty was 

given in the original document.

53 12 Earlier “best” estimates were reported, so seems unnecessary to report 

the preliminary estimate, particularly given the lack of uncertainty.

The text simply attempts to summarize the current 

literature.

54 12 Perhaps worth saying something here re validity of the ratios even if 

the absolute numbers don’t quite line up with Barlow et al.?

We agree, and have edited the text accordingly.

55 12 Is the Johnson and Wolman estimate credible? Text was clarified.

56 12 Logic here not clear. Why the “however”? Removed "however".

209
57 13 While the Arabian Sea population likely has SH origin, it should not 

be lumped in with SH populations. It shows the greatest 

differentiation of any of the DPSs compared to one another. By this 

very nature, it actually ‘throws a wrench’ into why it would be 

considered the same sub-species in the Southern Hemisphere when it 

is extremely differentiated from all populations, even more than the 

other sub-species are to one another or at the same level. So by the 

logic applied, if you we are to go that route, it should be its own subspecies. 

Text has been clarified.

58 13 Including the Arabian Sea in the introduction to Section I is confusing 

as the reader then expects the population to be discussed as part of 

this section rather than Section J.

Text has been clarified.

59 13 Lower level of detail regarding trends, in terms of time frame, 

citations etc, than for N. Pacific?

We do not feel that the somewhat greater detail for the 

North Pacific is unjustified given the scope and greater 

precision of the SPLASH estimate and the delisting 

petition focused specifically on these populations.

60 13 So the east Africa DPS was assessed at IWC as having one trend at 

this rate. Compare to humpback whales off the east coast of 

Madagascar (C3 breeding sub-stock, DPS) that potentially had a much 

reduced rate of recovery. See IWC 2009 or 2010. **See supporting 

materials #4

These general overview statements of the southern 

hemisphere populations have been deleted from this 

section, which now focuses only on population structure 

issues. Information available for the abundance and 

trends of each DPS is now discussed in the extinction risk 

section. The difference between a flat trend and an 

inability to measure a trend is now clarified. 

210
61 13 Not obvious what this means. Does it mean the Gabon and SE Pacific 

populations could be increasing, decreasing, stable – any of those? No 

evidence exists one way or the other? Whereas for Oceania there is 

sufficient evidence to say something and it indicates stability? I.e. I 

think it would be important to clarify the difference between nonavailability of data and inability to discern.

These general overview statements of the southern 

hemisphere populations have been deleted from this 

section, which now focuses only on population structure 

issues. Information available for the abundance and 

trends of each DPS is now discussed in the extinction risk 

section. The difference between a flat trend and an 

inability to measure a trend is now clarified. 

62 13 Overall, there is now increasing evidence that greater complexity in 

population structure exists within each of the SH oceanic populations. 

What implications does this have for DPS? This information is 

starting to come out and much of thes points in the review were 

completed before 2011 (around 2010).

The information we are aware of is discussed in the DPS 

section. Per earlier comments, we have modified the text 

to more clearly describe information on available patterns 

of genetic differentiation, and compare these patterns in 

different parts of the species' range.

63 14 Overall, these sections do not take into account Rosenbaum et al 

2009, PloS ONE which provides the most comprehensive and largest 

SH humpback whale genetic assessment and provides key evidence 

for DPSs within the oceanic regions. I know this is taken up later but 

the key results are not given adequate or correct assessment based on 

what the BRT has proposed as DPSs compared to what we have 

published, evaluated at IWC, etc...

We now cite and discuss the results of Rosenbaum et al.

2009.

64 14 Check reference. Possibly not published as this data has recently been 

submitted to Conservation Biology: Rosenbaum, HC., Maxwell, S., 

Kershaw, F. & Mate, B. “Quantifying broad scale movements and 

range-wide cumulative potential impacts for humpback whales in the 

South Atlantic Ocean.” For the purpose of the BRT and the NOAA 

technical report, this is the updated reference to Rosenbaum and Mate 

2006

As far as we are aware, this paper has not yet been 

published.

211
65 14 Not sure about the wording here as all migrations would at some point 

have to occur in” Antarctic offshore waters”. Rather, there may be a 

migratory route that follows the coastline of Africa and one or more 

that occur in offshore African waters, for example, as whales move 

offshore to follow the Walvis Ridge as ~18*S. There is direct satellite 

telemetry evidence of this in the Rosenbaum et al. paper described in 

Comment I4. As such, this section should be expanded to reflect the 

length of the SWIO section on migration below. **See supporting 

materials #5

The offending clause was deleted in the final version. 

66 14 This section for example insufficiently characterizes distribution and 

population structure that exists within the southeast Atlantic. The 

IWC SC has reviewed this information for approximately the last 5-7 

years and has concluded that there is strong evidence for 2 breeding 

sub-stocks, and thus 2 DPSs in this region. To say that this “This 

section is organized by breeding ground stocks and is generally 

consistent with IWC management units for the Southern 

Hemisphere,” is misleading and doesn’t take into account the degree 

to which information exists and has been reviewed and verified. 

**See supporting materials #5--BUT IN PARTICULAR, The 

complexity that exists in the North Pacific Ocean and is becoming 

better understood may be similar in some ways to what we are seeing 

along the west coast of Africa. Certainly similar in some of the 

geographic extent and possible latitudinal separation of breeding 

stocks with associated feeding grounds. The available evidence we 

have points that way.

The BRT reviewed the available evidence for population 

structure in this area, including the latest information 

from the IWC. We disagree that "sub-stocks" would all 

necessarily meet the criteria described in the joint NMFSFWS DPS policy. 

212
67 15 This paragraph and migratory pathways are given too much weight 

based on a single publication where singing was detected. It does not 

take into account some of the more recent evidence for these 

populations that show connectivity and movements between 

migratory streams. Importantly, the concern is that for some areas, 

there was a reliance on older information that may be more familiar 

and not as strong a focus on assimilating new information.

Text was clarified.

68 15 Also, see Van Waerebeek, K. et al. “A newly discovered wintering 

ground of humpback whale on the Northwest African continental 

shelf exhibits a South Atlantic seasonality signature.” Paper 

SC/64/SH4 presented to the IWC scientific committee, Panama, 2012.

This information was not available to BRT to review and 

include in the report.

69 15 From this year’s IWC, evidence emerging that greater complexity for 

population structure than previously and traditionally thought. **See 

supporting materials #6

The BRT reviewed the available evidence for population 

structure.

70 15 Footnote to mark—recapture first time used several pages earlier 

instead?

Text has been clarified.

71 16 But what is meant here by the SW Atlantic? Is this estimate from 

photo-id data obtained mainly or entirely on the Brazil wintering 

grounds? Should make this clear.

Text has been clarified.

72 16 Would it not be just as likely that Brazil whales go to other parts of 

the Antarctic rather than staying N of 60?

Given the coverage of the surveys reported by Branch, we 

consider dispersal to other parts of the Antarctic to be 

unlikely.

73 16 See IWC 2012 (for report of SH 2011) for which abundance estimates 

were chosen and why. **See supporting materials #7

Comment is unclear; the section in question does not 

discuss abundance estimates. 

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74 16 This is hard to comprehend. The numbers given apply to a ‘portion’ 

of a very large area. Would it not be helpful to readers if something 

were explained here about implications? For example, is it reasonable 

to conclude that 6000-8000 is about it for the entire region, or could 

there be twice, three times etc. that many? Or what?

This has been moved to the extinction risk section. The 

text has been modified to reflect that the population to 

which the estimates apply is somewhat uncertain due to 

some degree of substructure within the DPS. 

75 16 Again, the reader is left to his own devices here. Should he see these 

numbers from the two different areas as corroborative, additive, or 

what? Also, whereas the method is given for the Cerchio estimates, 

none is indicated for the Findlay one.

Added Findley method. This whole topic has been 

moved to the extinction risk section, where the various 

estimates are now described in greater detail. 

76 16 In my opinion and that of the IWC, these abundances represent two 

separate DPSs one along east Africa and one off Madagascar.

There is now some discussion of the differences among 

these areas. Based on the information available to the 

BRT, we do not believe these two sub-areas meet both 

criteria (discrete and significant) to be considered separate 

DPS.

77 16 See my point above about concern for Western Australia and energy 

development, especially when it is far more extensive off Western 

Africa.

The West Africa section was modified per the reviewer's 

comment; the BRT saw no need to modify the Western 

Australia section.

78 17 Similar clarity is needed for the Africa estimates above. Comment not clear.

79 17 Method? The number was right but citation was incorrect; has now 

been published as Felix et al. 2011 - have made correction 

in text.

80 17 Annual rates? Yes.

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81 17 This trend only applies to one of the potential sub-stocks C1 which 

could be a DPS. This is a problem with this report that I am 

continually pointing out. By going to the 15 DPS, it is very easy to 

apply apples to oranges. There are many holes with other DPSs in 

terms of available data, but by ‘lumping’, one gets the appearance that 

certain data (especially trend which is important) could apply across 

the whole SW Indian Ocean for example.

This section has been moved into the extinction risk 

section, where the limitations of the trend inferences are 

more fully discussed. 

82 17 Some general statement the first time trend data is noted about 

maximum plausible rate would be good, rather than note it within 

individual sections

This is done on page 10 in Chapter II section F.

83 18 I guess this answers my question, above. No response necessary.

84 18 Are there older trends? Some of the other trends discussed are from 

~20 years ago.

This section has been moved to the extinction risk section 

where it is treated in more detail.

85 18 There is also nuclear genetic information available for some substocks and potential DPS. 

This section has been revised to focus more on genetic 

differentiation among populations.

86 18 And northern hemisphere populations? But looking at the number of 

haplotypes listed in sections below doesn’t seem like it is all that 

much more diverse?

Deleted S. Hemisphere.

87 18 The Breeding Stock B1/B2 substructure should be at least referred to 

here even if it is not considered as two DPSs. Two hypotheses 

currently stand: i) A single population with a wide ranging 

distribution that displays temporal heterogeneity in migration giving 

the genetic signal of two subpopulations; or ii) the existence of two 

genetically distinct subpopulations resulting from different breeding 

grounds (breeding ground for B2 not yet identified but assumed to lie 

further north of Gabon (see Van Waerebeek, K. et al. IWC paper in 

comment I4).

This structure is now explicitly discussed.

215
88 18 I presume the number of haplotypes is at least somewhat influenced 

by sample size, so it seems like reporting sample size in each case 

would be warranted. 65 haplotypes from 70 samples would tell you 

something very different than 65 haplotypes from 500 samples....

Sample size has been added.

89 18 More recent evidence of connectivity between these populations is 

available. **See supporting materials #8

It is not clear from the comment which populations are 

referred to. 

90 18 So, can the same thing not be said about this stock as was said above 

about the Brazil stock? Genetically diverse?

This section has been revised to focus more on levels of 

genetic diversity among populations as this is most 

relevant to determining discreteness. 

91 18 I’m sure these comparisons of genetic diversity in the different stocks 

are important for assessment and conservation decision making, but 

how and why aren’t obvious to the average non-geneticist. The details 

given here are proportionally greater than those given for the 

abundance estimates, but without some coaching, I don’t see how 

most readers will be able to interpret and apply this stuff.

This section has been revised to focus more on levels of 

genetic diversity among populations as this is most 

relevant to determining discreteness. 

92 19 This implies East Australia is part of Oceania? Removed "other".

93 19 Symbol use is not consistent Corrected text.

94 19 and therefore... Text was clarified.

95 19 If Arabian Sea is treated separately from Southern Hemisphere 

populations then it should not be mentioned in the intro to the section 

above. 

Text was clarified.

96 20 The Arabian Sea is in the northern hemisphere. If they are in the Gulf 

of Aden presumably they could go through the Suez? Also with 

animals off Sri Lanka it seems like eastern movements to connect 

with the western North Pacific are possible.

Text was clarified.

216
97 20 Has there been a comparison with far western North Pacific samples 

collected during SPLASH? Either way this should be stated.

Added text to this section.

98 20 I think this is an important point that needs to be kept in mind. Not 

that this population isn’t in big trouble, or that it’s not sufficiently 

discrete to be classified and managed separately. What worries me is 

the degree to which this estimate is negatively biased, and how that 

could affect things down the road if/when it is “discovered” that there 

are quite a few more animals in the population. Recent examples are 

NA right whales and western Pacific gray whales.

We understand the reviewer's point, but believe the level 

of detail is sufficient as it stands. If new information 

becomes available, it can be considered at that time.

99 20 I keep reading this over and over again, trying to divine the take-home 

message of the entire paragraph. No luck. Once more, the lack of 

some kind of interpretive guidance as to what all the ‘facts’ mean, or 

even might mean, makes me wonder what the point of this document 

is. If just to compile facts and leave all interpretation to some other 

process, then I suppose that’s ‘ok’. But....

Text was clarified.

100 20 Perhaps it is because I don’t study humpbacks but I find it strange that 

this comparison is “among all southern hemisphere breeding grounds” 

given that this population is in the northern hemisphere and is 

thought to be non-migratory (i.e., different from all S. hemisphere, 

and for that matter, northern hemisphere populations). At the least the 

genetic diversity should be compared to both N. and S. hemisphere 

populations

Removed S. Hemisphere.

101 20 Report haplotype diversity stats Text was revised to add this information.

102 21 This is the most critical point and why I raise the point about 

consistency above. If anything that would merit sub-species (if we 

think to use this designation), then this would be one. Compare this 

level of differentiation with other SH populations to those that exist 

between NA, NP, and SH

We have revised the sub-species discussion. We also 

clarify that the Arabian Sea population is a DPS under 

any global taxonomic scenario.

217
103 23 This issue is not adequately described. First, additional explanation is 

needed as to why it makes a difference for determining a DPS if one 

considers humpbacks to be a single species with not subspecies vs 

several subspecies. In all cases the main rational for DPS findings is 

that their loss would represent a significant range reduction. In what 

case might one of these 15 DPSs not qualified as such if there were no 

subspecies. Second I do not believe the BRT and listing process is the 

appropriate place to make decisions about whether there are multiple 

unnamed subspecies. If the current scientific consensus and literature 

do not recognize subspecies, this group should not step in to express 

its view. Third, if there were multiple sub-species, what does that 

mean in terms of how the species would be listed? Would the ESA 

list have to note DPSs under three unnamed subspecies that have not 

been recognized in the scientific literature? That seems like a bad 

precedent.

We have revised this whole section to deemphasize the 

importance of identifying sub-species. Rather, we have 

noted that the differentiation among ocean basis is 

substantial (possibly to the level of sub-species) and 

therefore focus largely on whether there are any DPS 

within ocean basins. We have also added a discussion of 

whether any or all so-identified DPS are also DPS when 

considered with reference to the global taxon.

104 23 I think most taxonomists would agree that subspecies don’t ‘exist’ –

they are a construct that is used to sort variability (yes, species are 

too, but obviously the scale is different). My suggestion would be to 

change the wording here to say something like: Although in recent 

decades no subspecies of humpback whales have been recognized, it 

is relevant to consider whether such recognition is likely in the near 

future.

We agree, and have edited the text along these lines.

105 23 Line spacing changes Corrected text.

106 23 Again, I think this phrasing misleads, implying that a subspecies is 

other than just a classificatory construct.

Text has been clarified.

107 23 Again, I think this phrasing misleads, implying that a subspecies is 

other than just a classificatory construct.

We agree, and have edited the text accordingly.

108 24 It is not a taxonomic committee; it’s just a committee on taxonomy. We agree, and have edited the text accordingly.

218
109 24 See above comment. Until the best information (meaning published 

information and not the opinion of any particular group of experts) 

has determined there are multiple species, it should be assumed to be 

one species with no subspecies..

In response to this and similar comments, we have 

extensively revised the section on sub-species and also 

conclude that the DPS identified are, for the most part, 

not very sensitive to the sub-species designations. We 

also note that several sub-species of humpback whale 

have now been proposed in the scientific literature.

110 24 Herein lies the problem with subspecies......it is very subjective 

process between populations (for which significant differences can be 

measured) and species (for which objective measures to delineate 

units exist under certain species definitions. I think the BRT did the 

most reasonable process to look at sub-species, but the broader 

question is should they have? What value does it add?

We have significantly revised the discussion of potential 

sub-species to address this and other similar comments. 

111 24 Whoa. Assuming, as implied, that “this opinion” refers to the numbers 

just cited, does it mean the BRT consists of “noted experts on 

cetacean taxonomy”? I don’t think that was the intention, but the 

syntax certainly points in that direction.

Text was clarified.

112 24 I guess I should give up on this – I know I’ll be overruled. See comments on sub-species above.

113 25 Inconsistent approach to 3 vs 4 subspecies Text has been clarified.

114 25 This phenomenon occurs in the eastern South Atlantic regularly, and 

is noted in our publications.

Removed "eastern Pacific".

115 25 But those “current studies” have been very limited. We don’t agree that the studies concerned have been so 

limited as to leave open the possibility that the Cape 

Verdes hosts a large number of unobserved whales. It is 

clear from several surveys of various islands in this group 

that the density of humpbacks there is low.

116 25 Jann et al. (2003) provide direct (photographic) evidence linking Cape 

Verdes with Iceland and it should be cited here.

Citations were added.

219
117 25 Not clear why no mention is made of the evidence discussed by 

Reeves, Clapham and Wetmore (2002) and more extensively by 

Charif et al. (Mar Mamm Sci 17:751-68).

Added citations to text.

118 25 What is the basis for considering this a region separate from other 

parts of the Eastern (Norway) population since they both are said to 

go to Eastern NA calving areas? Consider deleting the reference to a 

central NA region?

As noted in the text, the basis for these divisions lies in 

genetic differences among whales from these three 

regions (Larsen et al. 1996). Larsen, A. H., J. 

Sigurjónsson, N. Øien, G. Vikingsson, and P. J. Palsbøll. 

1996. Population genetic analysis of mitochondrial and 

nuclear genetic loci in skin biopsies collected from central 

and northeastern North Atlantic humpback whales 

(Megaptera novaeangliae): population identity and 

migratory destinations. Proceedings of the Royal Society 

of London Part B, 263:1611-1618.

119 25 Again, I worry about what this means – mating, calving, nursing, two 

or all three?

Text was clarified.

120 25 Does this include Iceland? Yes, based references cited earlier in the report.

121 26 I don’t think this makes any sense, if, as stated earlier, the ‘breeding 

unit’ is the relevant unit for present purposes.

Amended the text by replacing "when lumped together" 

with "which include..."

122 26 I agree with this although I also think it would be only fair to 

acknowledge the strong asymmetry in sample size between the two 

areas.

Text was revised to add this information.

123 26 Evidence for this? Certainly larger than seems to be present 

nowadays, but large is a relative and imprecise term.

Text was clarified.

220
124 26 I just don’t get this. The Cape Verdes are “near Northwest Africa” (of 

course this depends on the meaning of “near” (see “large,” above)). 

I’m concerned about that lack of any whaling or other evidence for 

such an area elsewhere in the region. It’s hard for me to imagine, 

given that the American whalers managed to find the so-called Cintra 

Bay right whale ground, that they would not also have found any 

concentration of “breeding” humpbacks that was of appreciable scale 

etc.

The reviewer’s contention that American whalers would 

have found a large concentration of humpback whales if 

one existed ignores two things. First, the hunting of 

humpback whales (“humpbacking”) by Yankee whalers 

was a secondary aspect of the industry, which was 

primarily interested in sperm whales and balaenids; 

humpbacks were generally a lot less valuable in terms of 

oil and baleen and thus were the focus of a subset of 

whalers who typically operated for only a year or so in the 

North Atlantic (rather than the multi-year voyages of, say, 

sperm whalers). Thus, there was not much incentive for 

most whalers to make a search for humpbacks a principal 

focus of a voyage. Second, there are examples of whalers 

possibly “missing” what might have been significant 

concentrations of animals elsewhere (e.g. humpbacks on 

Silver Bank, and perhaps right whales in the Bay of 

Fundy).

125 26 Some reference to the Johnston et al. 2007 Endangered Species 

Research paper and the Lammers et al. 2011 MEPS paper seems 

appropriate, given that Lammers et al actually proposed the NWHI 

may be this additional breeding area

The text was edited to add these references.

126 27 How does this differ at the species and subspecies levels? That is if 

they are different at a subspecies level, would they not also be 

different at a species level. If so the discussion above about whether 

and how many subspecies there are seem irrelevant and distracting 

could be deleted

The section on sub-species was significantly revised to 

deal with this and similar comments. 

127 27 Uniqueness does not have degrees. A signature is either unique or it is 

not. Need to rephrase to say what is meant here.

Text was clarified.

221
128 27 From each other and from all other populations – I think this needs to 

be said explicitly if true.

Text was clarified.

129 27 This doesn’t seem to make sense. What is the basis for believing 

Ogaswara whales simply pass through the area? Also, the Ogasawara 

Islands are some 1000 mi due east of Okinawa and seem unlikely to 

on the same migratory path. Both Ogasawara and Okinawa could be 

on a migratory path to the Philippines but if the genetics say 

Ogasawara whales are genetically distinct from the 

Philippines/Okinawa whales, why is it considered Ogasawara whales 

why are parto ot that stock?

Text was revised to explain more fully.

130 29 So when complexity is evaluated and exists based on genetic and 

demographic evidence, DPSs were found to exist for the North 

Pacific. Based on available evidence, there should be several more 

DPSs for SH populations.

We disagree with this comment. In both the NP and the 

SH, we lumped proximate breeding locations with no 

strong genetic differentiation or other evidence of 

discreteness into common DPS.

131 29 See previous comment. Further explanation needed as to why this 

area might only be part of a migratory route rather than a destination

Text was revised to add this information.

132 29 This section does not sufficiently summarize available genetic 

differentiation which is essential for DPS delineation. The 

differentiation results contained in Rosenbaum et al. 2009 and 

Olavarria et al. are essential for DPS evaluation and could 

significantly inform DPS (and have significantly informed IWC Stock 

Assessments).

We revised to focus more on genetic differentiation and 

cite these references.

133 29 Is this word appropriate here? Not sure, seems a little prejudgmental. Removed "discrete".

134 29 I understand why this is written as it is but don’t think it’s necessary

and could confuse some readers.

We agree, and have edited the text accordingly.

222
135 30 Is this figure correct? Seems to show feeding areas, not breeding 

areas? Some reference to the A/B, B/C areas of overlap should be 

noted in the caption

We agree with the comment, and have replaced with 

figure 1 reproduced from IWC 2011, which shows the 

IWC hypothesized stock structure with breeding and 

feeding locations.

136 30 For consistency, the scores for this conclusion should be provided. 

Being able to compare scores between regions also helps with 

interpreting those other scores

Text was clarified.

137 30 So this makes it sound like “breeding” here means something specific, 

probably mating per se (independently of calving and nursing).

Text was clarified.

138 30 Isn’t the Great Barrier Reef part of eastern Australia? Why this 

distinction?

Text was clarified.

139 30 Again, why no votes? Was everyone willing to provide all 100 votes 

in this one scheme? Hard to believe some would not have put at least 

a few points in other breakdown options. Knowing the degree of 

certainty on the BRT is important.

The BRT made some decisions by consensus, as noted in 

the report. The structured decision making process, 

particularly for population structure issues, was only 

employed when the BRT concluded that there was 

substantial uncertainty.

140 30 This is the justification for Section J above. So need to amend the 

introduction to Section I.

Text was clarified.

141 30 score? The BRT made some decisions by consensus, as noted in 

the report. The structured decision making process, 

particularly for population structure issues, was only 

employed when the BRT concluded that there was 

substantial uncertainty.

142 30 This is a strange construction, comparing a population to “other ... 

grounds.” Oranges and grapefruit?

Text has been clarified.

143 30 But this isn't one Text has been clarified.

223
144 31 But connections to the western Pacific seem quite plausible given 

“Arabian Sea” animals around Sri Lanka?

It is a long way and many degrees of longitude from the 

Arabian Sea to the western North Pacific; and it is not 

clear if the humpbacks occasionally found around Sri 

Lanka have any connection to the Arabian Sea. While we 

do not preclude the possibility of a connection with the 

North Pacific, based on current evidence this cannot be 

more than speculation.

145 31 Yes but sample size for the Philippines, the population with the 

highest likelihood of interchange, is small

Text was revised to add this information.

146 31 Names could be simplified Text has been clarified.

147 31 Since this was already covered just a paragraph or two above, I think 

you can delete this

Agree; text has been clarified.

148 31 For the humpback populations assessed to date and where there is 

sub-structure, this list does not reflect what has been found by the 

IWC.

We discuss the relationship between the DPS we identify 

and the IWC population structure.

149 31 Perhaps add parenthetical re Arabian Sea. Text has been clarified.

150 31 Since you were so careful above not to lump the Arabian population 

in the “Southern Hemisphere Group” why do it here?

Text has been clarified.

224
151 32 Note: this is an expansion of the policy criterion 2 which is any 

significant gap in its range. While I appreciate both feeding and 

breeding areas were considered, I don't know that you need to 

separate them here. What about the migratory corridor. Is it possible 

whales mate during migration? Are not migratory corridors a 

significant part of their range? Clearly treats along migratory 

corridors are a concern. I would combine them as in the policy 

statement but leave your discussion of this criteria as it is with an 

explanation why migratory corridors were not considered when 

evaluating this criterion.

In the revised text we clarified that we were simply 

applying the existing ‘gap in the range’ criteria; the 

breakdown between feeding and breeding ranges was 

purely for convenience of discussion and should be 

considered an expansion of the policy. 

152 32 I am not convinced this term belongs in the mainstream of mysticete 

biology. It seems to me that the features discussed below fall 

comfortably under the terms behavior and ecology and therefore the 

diversity of behavior and ecology is what should be at issue here, 

rather than something ill-defined and not readily understood (and that 

provides a better “fit” to the significance criteria as they are given.

Text was clarified.

153 32 This is not in the Southern Hemisphere and there are other 

populations that eat fish. It is however the only population living 

entirely in the tropics and is therefore unique.

We agree, and have edited the text accordingly.

154 33 score? The BRT made some decisions by consensus, as noted in 

the report. The structured decision making process, 

particularly for population structure issues, was only 

employed when the BRT concluded that there was 

substantial uncertainty.

155 33 So now they have ‘risen’ from proposed to putative. Is this the right 

place to be advancing this subspecies cause? I think not.

The entire sub-species section has been revised, and 

terminology regarding the possibility that whales from 

different ocean basins could be considered different subspecies has been made consistent throughout the report.

225
156 33 ‘where documented geographic overlap between hemisphere 

populations occurs’ NB—it may also occur among populations of 

humpback whales in the eastern South Atlantic.

We are unaware of any solid evidence documented. 

157 33 I find this reasoning bizarre. Text was clarified.

158 33 There we are. Now the subspecies are no longer qualified by an 

adjective!

The entire sub-species section has been revised, and 

terminology regarding the possibility that whales from 

different ocean basins could be considered different subspecies has been made consistent throughout the report.

159 33 This would be true even if there were no subspecies. The entire sub-species section has been revised, and 

terminology regarding the possibility that whales from 

different ocean basins could be considered different subspecies has been made consistent throughout the report.

160 33 Again, bizarre wording as here we have population segments 

constituting portions of feeding range. One is whales and the other is 

acreage.

Text was clarified.

161 33 Yes, there is some overlap. But there also appears to be some 

uncertainty about the total feeding range of CVI animals, so you 

cannot say this so conclusively and unreservedly.

Agree; text has been clarified.

226
162 33 I would suggest noting that the Cape Verde Islands (and perhaps also 

the Central American) population are also significant because there is 

some evidence that these areas are the only areas identified to date 

that may be use by individuals from both the N & S Hemisphere and 

thus are among the few areas were there might be an opportunity for 

genetic exchanges between the Hemispheres.. the Missing western 

North pacific calving grounds might be another given the NP genetic 

signal in the SE Pacific population.

The Pacific coast of Central America is known from 

photo-id matches to host humpbacks from both Northern 

and Southern Hemisphere populations, so the first point 

here is correct with regard to that area, although such a 

statement probably belongs elsewhere in the document 

rather than here. There is no direct evidence that the 

Cape Verde Islands host austral whales (the reviewer 

refers to a match between the CVI and the Antarctic 

Peninsula – this is wrong, and perhaps s/he is confusing 

this with matches between the Peninsula and the Pacific 

coast of Central America). Finally, the reviewer’s idea 

about the “missing” North Pacific breeding area is 

completely speculative.

163 33 Do they constitute “most” of the feeding whales in that part of the 

range?

Text has been clarified.

164 33 If it is the majority of the individuals that count, do not the eastern 

North Atlantic “breeding” populations make up the majority of 

whales feeding in the northern parts of the eastern North Atlantic?

Text was clarified.

165 33 But don’t these breeding groups constitute a majority of the whales 

feeding from Vancouver south? 

Yes, but the text was referring to significance with regard 

to each other, not HI or WP. Section was edited for 

clarity. 

166 33 Elsewhere it was the majority of whales on a feeding ground that 

determined whether a group was significant

Text was clarified.

167 34 Again what degree of overlap is required to make a DPS finding? The BRT did not attempt to quantify this criterion, but 

rather considered this factor, along with others, in making 

a qualitative assessment of whether the whales utilized 

different feeding areas. 

227
168 34 So, to many readers, and probably users, this will be plucked out of 

context and suddenly there will be literature referring to ‘the Arabian 

Sea subspecies’. Sorry, but that’s the most parsimonious interpretation 

of this sentence as is, if lifted out of context.

Text has been clarified.

169 34 Yes, this terminology makes more sense than the alternative which 

would follow from the earlier phraseology – e.g. “unique cultural 

features”?

No response necessary.

170 34 score? The BRT made some decisions by consensus, as noted in 

the report. The structured decision making process, 

particularly for population structure issues, was only 

employed when the BRT concluded that there was 

substantial uncertainty.

171 34 Which might, might it not, call into question the subspecies split that 

has now become a fait accompli? In which case this argument gets 

circular, or specious.

The entire sub-species section has been revised, and 

terminology regarding the possibility that whales from 

different ocean basins could be considered different subspecies has been made consistent throughout the report.

172 34 What about photo matches between the Cape Verde Islands and the 

Antarctic Peninsula? Does that not also indicate a potential for 

genetic exchange between the N/S Hemispheres and make that 

portion of its range ecologically unique?

The Pacific coast of Central America is known from 

photo-id matches to host humpbacks from both Northern 

and Southern Hemisphere populations, so the first point 

here is correct with regard to that area, although such a 

statement probably belongs elsewhere in the document 

rather than here. There is no direct evidence that the 

Cape Verde Islands host austral whales (the reviewer 

refers to a match between the CVI and the Antarctic 

Peninsula – this is wrong, and perhaps s/he is confusing 

this with matches between the Peninsula and the Pacific 

coast of Central America). Finally, the reviewer’s idea 

about the “missing” North Pacific breeding area is 

speculative.

228
173 34 I’m afraid that using this logic, and perhaps influenced by a bias of 

BRT individuals that aren’t familiar with geographies around Africa, 

that additional DPSs in Breeding Stock B and C have not been 

sufficiently considered. This may also be the case for other areas that 

are now starting to examine population subdivision after completing 

single, broad comprehensive assessments. This may not be in the 

BRTs remit to ‘open up’ debate to some of the most recent IWCs or 

publications for 2012.

We disagree. Most SH populations have very modest 

levels of genetic divergence from each other, the one 

exception being SEP. 

174 36 This is a key table and would be much easier to interpret if the no 

columns were deleted. All that counts are the yeses and if they are 

not yes, the reader will figure out it’s also a “no”

Added a new table that shows pairwise comparisons 

among populations.

175 36 I think this is wrongheaded. Not clear what s/he feels is wrong.

176 36 disagree Not clear what s/he feels is wrong.

177 36 This very much upweighs the differences from the SE Pacific and 

Arabian Sea, and downgrades all the other oceanic differences (and 

sub-population structure detected)

The footnote was actually not really reflective of how the 

BRT considered genetic data. We have revised to make it 

clear that the BRT considered all available genetic data in 

evaluating DPS structure.

178 37 I think there has been a bias in BRT knowledge and/or review of 

material. 8 of the 15 DPSs come from either the NP or SP (Pacific 

Ocean). For the S. Atlantic and Indian Ocean, a total of 4 DPSs exist, 

but this does not fully consider the information previously published 

or summarized by the IWC. 

The BRT reviewed the information available, and 

believes its DPS conclusions are reasonable. 

179 37 Show overlap between DPS 4 and 11 Done. 

180 38 And also because of possible overlap and genetic exchange between 

N & S Hemisphere whales?

We disagree; to our knowledge there is no evidence of 

this.

229
181 39 Since this includes the Northwestern Hawaiian Islands, yet all the 

studies to date focus within the main Hawaiian Islands, it would 

probably be good to specify main Hawaiian Islands, particularly given 

the NWHI could be the missing western Pacific DPS

Text was clarified.

182 40 As noted above, the basis believing this is a mixed in with the 

Okinawa/Philippines does not seem well supported and seems to me 

to be more likely part of the second western breeding group based on 

geography and genetics.

Text was clarified.

183 42 And possibly further north...sat tag evidence of whales continuing 

past Ghana (Rosenbaum et al. submitted to ConBio), and see Van 

Waerebeek, K. et al. “A newly discovered wintering ground of 

humpback whale on the Northwest African continental shelf exhibits 

a South Atlantic seasonality signature.” Paper SC/64/SH4 presented 

to the IWC scientific committee, Panama, 2012. The fact that the 

entire breeding distribution has not yet been determined for this 

population might be relevant in terms of the uncertainty of the status 

of this population.

Text was revised to add this information.

184 42 ~18*S is where some whales diverge from the African coastline 

during the southern migration, but uncertain that they actually begin 

to feed at this latitude. Satellite telemetry evidence suggests that 

whales still continue direct migratory south to the more productive 

regions of the Southern Ocean Convergence Zone (inc. Bouvet Island) 

(Rosenbaum et al., submitted to ConBio).

This paper was not available to the BRT at the time of the 

review.

185 42 By this logic C1 and C3 are considerably differentiated, lack of 

matches—similar to that suggested for other areas of NP.

The degree of genetic divergence appears to be much 

lower among these areas than among the areas we have 

identified as DPS, however.

230
186 43 Longitude scale shifted ~45 degrees E! Show overlap between 4 and 

11 – listed as Columbia and Ecuador but doesn’t even include 

Columbia on map

The maps are only intended to illustrate rough locations 

of the DPS breeding locations.

187 48 This is a well-written section, fair to the facts etc. However, the logic 

of this concluding sentence is pretty strange. Taken out of context, it 

would lead the naïve reader to conclude that when the science is 

challenging, our policy is to err on the side of non-precaution. I do 

think a case could be made that the evidence for healthy, growing 

populations of humpbacks in nearly all regions where monitoring has 

been sufficient to assess trends provides a good basis for a provisional 

conclusion that contaminants are not having significant negative 

population effects. I also think though that the last clause – ‘except 

where unknown’ – completely undermines the message of the 

sentence, and it would be better if it were deleted.

Text was clarified.

188 48 What about pipelines? And what is a spill from a ‘rig’? Is that how 

one would characterize Deepwater Horizon?

Text was clarified.

189 48 And gas? Text has been clarified.

190 49 Characteristics that are relevant include much more than just ‘age’! Text was clarified.

191 49 This terminology is bizarre. It is not ‘stranding events’ that are the 

concern but rather the mortality of the animals.

Text was clarified.

192 49 The West Indies population probably was NOT ‘significantly 

impacted’ by the 1987-88 or 2003 HAB-related UMEs, judging by the 

uninterrupted pattern of population increase.

Text was clarified.

193 49 Faulty logic Comment unclear.

231
194 50 I was not aware that Norway ‘acquired’ such a permit. Actually, as 

Mike Gosliner can attest, ‘acquire’ is the wrong word entirely, since 

the countries essentially issue the permits to themselves. They are not 

conferred by the IWC as implied here. Also, use of the term 

‘originally’, especially so soon after reference to the 1946 convention, 

will be misinterpreted by some. The United States and other nations 

have used this ‘loophole’ in the past – e.g. to take gray whales (US), 

North Pacific right whales (Russia and Japan).

Text has been clarified.

195 50 This reference is now nearly 10 years old and things have changed, 

such that at least there is now a formal mechanism in place for SC 

review of permit proposals and results. Admittedly, that’s not 

regulation, but one does need to wonder how ‘regulation’ and quotasetting would be accomplished for ‘research whaling’ – I think this 

sentence is disingenuous and has no place in the review.

This is a matter of opinion. 

196 50 Those ‘meetings’ are ‘completed’. See IWC Ann Rep 2011, p7 

(agenda item 4.2).

Text was clarified.

197 50 What does this have to do with scientific whaling? It’s a non-sequitur. Text has been clarified.

198 51 This worries me, since the source cited (Reeves 2002) says nothing 

whatsoever about a block quota of 20 whales over a 5-yr period. I 

looked carefully!

Removed erroneous reference and corrected. 

199 51 I suspect the Europeans introduced themselves, but never mind. Text has been clarified.

200 51 These would be Greenland, St Vincent and the Grenadines, and ???? I 

think the honest term would be exactly two.

Text was clarified.

201 51 Poaching is, by definition, illegal. Text has been clarified.

232
202 51 These are strong accusations to be making without citing credible 

references. Is there any evidence that humpback meat found in 

markets in Korea and Japan came from anything other than ‘bycatch’?

Agree, and language has been clarified.

203 52 And satellite tagging, which is invasive Added satellite tagging.

204 53 If undocumented, how do you know they occur? Text has been clarified.

205 54 This would seem self-evident since most populations have been 

increasing steadily for decades now.

Text was clarified.

206 54 This statement begs for a reference to support it. A reference was added.

207 54 Again, this needs more support. Are the whales feeding in these 

southern areas? Right whales die in fishing nets off the SE US but that 

doesn’t mean they are feeding there. Humpback whales ‘overlap’ with 

fisheries in many parts of their range – unclear why this southern area 

would be singled out for attention here.

Was discussed as a threat in part due to the smaller size 

of this population.

208 55 Need to include reference for dB (e.g., re: 1 microPascal) to clarify 

whether this is in reference to air or water

The sentence was incorrect and has been deleted. 

209 56 More likely to be “most” rather than “many”, given the likelihood of 

strandings (<10% even for coastal populations) and even smaller 

likelihood of a detailed enough examination to confirm/rule out ship 

strike. Should be “the vast majority likely go undetected or 

unreported”. Could cite the Williams et al. 2011 Conservation Letters 

publication in support. Antonelis et al. 2007 noted that several 

hundred humpback whales likely die in Hawaiian waters each year yet 

only one or two strandings are documented (17th Biennial Conference 

abstracts).

Added the citation.

233
210 56 Has there been a comparison of strandings from ship strikes versus 

reports in these countries? I suspect compliance is low and this is 

worth noting.

We don't know of any such comparison. Making note of 

low compliance without supporting evidence would not 

be appropriate.

211 56 Laist et al is the source of the 10 of 123 whales finding and that refers 

to the entire U.S. east coast not the southeast.. They also note all but 

one of those ship strikes whales was between Delaware Bay ad 

Okracoke.

Changed reference.

212 56 Again, wrong references and inaccurate information re the 1975-1996 

data. I did not check the accuracy of the Glass reference but given 

the other errors found here, the authors should do so.

Changed reference.

213 58 Would it not be helpful here to specify which DPSs were rated where 

on the scale? Or at least refer to a relevant table?

Referenced table.

214 58 Some information on Arabian Sea entanglements could be better 

summarized as significant cause for concern for this population

Addressed in C.13

215 59 This is bizarre reasoning. The point is that ‘Arctic waters’ are being 

redefined or at least rejiggered geographically, so the ‘however’ here 

doesn’t make sense. In other words, the last sentence does not, as 

implied, negate in any way the second to last one!

Changed "however" to "Currently"

216 59 Shouldn’t this sentence come after the following one? Re-ordered sentences

217 59 The Commission’s “Report of the Workshop on Assessing the 

Population Viability of Endangered Marine Mammals in U.S. Waters” 

would be a useful reference to consult and reference on this issue. 

This report is also in the Commission’s report “The Biological 

Viability of the Most Endangered marine Mammals and the Costeffectiveness of Protection Programs. 

This section was revised to cite the suggested workshop 

report and to more fully discuss and justify the BRT’s 

decisions regarding use of PVAs for this particular status 

review. 

234
218 60 Again the above report (available on the Commission’s website), 

would be useful to consult and reference.

See above. 

219 60 In practice, five, since Near Threatened is effectively another ‘risk 

category’.

Text was clarified.

220 62 There are some respected modelers that would strongly disagree with 

this statement and the conclusion in the next sentence.

Text was revised.

221 62 Expense might be a reason for limiting use of PVAs and I agree some 

or even many may not be worth the cost but for some it I think it 

could help appreciably. This seems to be based on a poor rationale

Text was revised to explain more fully.

222 62 PVAs are not the only thing that should ever be considered. Rather 

they should be used to trigger a more subjective review per ESA 

criteria

Text was clarified.

223 62 Quantitative? All but perhaps external risk factor here is based on 

quantitative data, though there are varying degrees of uncertainty.

Changed to "measures".

224 64 But scale, and turnover, matters. I do not think this 13yr old reference 

does justice to what is now known about this population’s pattern of 

winter occurrence in the West Indies region as a whole.

This is not correct. Since the cited papers were published, 

there has been no new information (published or 

otherwise) that would change the conclusions given in the 

text regarding the relative abundance and distribution of 

humpbacks in the West Indies region. There are no data 

to indicate the existence elsewhere of any concentration 

of whales on the scale of Silver/Navidad Banks (on a 

daily basis at the peak of the winter it’s perhaps 2,000 

whales on Silver, 100 – one order of magnitude lower – in 

Samana Bay, and in some places another order of 

magnitude below Samana).

225 64 Unclear to me what a ‘geological activity’ might be in this context. Changed to "oil and gas".

235
226 66 I thought this document said earlier that the recent level of offtake by 

entanglement and ship strikes was unsustainable for the Gulf of Maine 

‘subpopulation’.

True. Not sure how this contradicts that statement.

227 67 Although I certainly agree that NW Africa is a potentially hazardous 

area for these whales to calve, nurse, and generally overwinter, I don’t 

agree that some undiscovered ground there is a ‘plausible hypothesis’, 

so ....

This is what the BRT considered a plausible hypothesis.

228 68 With only 88 whales in the catalogue, while appreciate that there is 

uncertainty, I find little basis to conclude that this population is “not 

at risk.” In general where there seem to be relatively small 

populations for which there is no good abundance or trend data, it 

does not seem appropriate or precautionary to assume the population 

is “not at risk.”

The BRT was attempted to evaluate extinction risk, not to 

be precautionary. 

229 68 So this DPS seems a good candidate for Data Deficient, but is that 

allowed? I guess not.

This was not a formal category, but the BRT noted the 

high degree of uncertainty due to limited data.

230 69 This actually might be a place to cite Reeves (2002) as there is not a 

lot of literature summarizing this.

Done.

231 70 The area should be identified. Text was clarified.

232 70 Is this considered a moderate or minor threat? Text was clarified to indicate that the threat was 

considered medium. 

233 72 any tagging? Text was clarified.

236
234 74 While I do not have difficulty accepting uncertainty as a need to 

assume the worst and err on the side of higher risk, I have trouble 

accepting the premise that that a lack of information on size and 

growth is justification for considering a species to be “not at risk.”

The BRT reviewed the available information and used 

that to categorize risk. No information absolutely was not 

equated with "not at risk"; rather limited information 

tended to lead to likelihood points being placed in 

multiple categories, reflecting uncertainty about 

extinction risk. 

235 78 It would be helpful to be consistent with terms. Moderate is used 

elsewhere.

Text was clarified.

236 79 Low risk or not at risk? There is no definition or category for low risk Text was clarified.

237 79 Same Text was clarified. 

238 79 If this is the case for Western Australia, then it has to also be for 

Gabon/West Africa given the number of range states with active and 

extensive hydrocarbon operations in their territorial waters.

Text was revised to add this information.

239 83 If this applies to eastern Australia humpbacks presumably it also 

applies to other S. Hemisphere populations that feed on Antarctic krill 

(e.g., W. Australian humpbacks).

We agree, and have edited the text along these lines.

240 83 This was not to be considered? In the revised report the BRT did consider protective 

regulations. 

241 83 It would be worth noting the uncertainty associated with this estimate The uncertainty was included.

242 84 I thought this review was not considering adequacy of regulations? In the revised report the BRT did consider protective 

regulations to the extent possible. 

243 84 This could use some additional explanation. This might reduce 

population growth from perhaps 10 % to 8 %. Is this the basis for 

considering a potentially substantial effect on recovery?

Kept as is.

237
244 85 This does not seem consistent with the above description of “some 

whaling in the 20th century.”

We do not see the inconsistency.

245 85 The breeding range for this population has been inconsistently 

presented as “Columbia and Ecuador”, “Panama, Columbia and 

Ecuador”, “Panama to northern Peru”, and now Costa Rica to 

northern Peru. Would be good to be consistent throughout

Text was clarified.

246 86 Again, seems to be considering adequacy of regulations. In the revised report the BRT did consider protective 

regulations to the extent possible. 

247 87 Chile? Comment not clear. 

248 89 But given what has been said for other populations can be expected to 

be low or non-existent

Contaminants were generally ranked as “low” except 

where data were poor, in which case they were ranked as 

"unknown."

249 91 Is this just for part of Gabon? Since they range from 6N-6S 

presumably this estimate is only for a small portion of the total range? 

This should be clarified.

Text has been clarified.

250 91 Using a Bayesian estimation methodology... BRT reviewed available material and is comfortable with 

decision.

251 91 Gabon may have a mixture of two breeding stocks to which those 

abundances cannot be prescribed. See Barendse et al 2011 for 

abundance of whales off south Africa—numbering about 500. **See 

supporting materials #9

Text has been clarified to discuss possible substructure 

within this DPS.

252 92 Cookie cutter shark wounds? No response needed. 

253 93 A major shipping lane does transect the Walvis Ridge which has been 

identified as a key migratory route for these whales. Again, incidence 

is likely to be low but worth mentioning.

Iguela region only; stated in sentence.

238
254 93 Information on Gabon and Congo contained in IWC reports but not 

cited here.

The IWC reports on climate change are referenced and 

discussed in that section.

255 93 See previous comment on updated abundance estimate. Should also 

include value range, this number alone conflicts with the previous one 

cited.**See supporting materials #7

The BRT utilized the available information.

256 93 Different from estimate above? Text was clarified.

257 93 And currently detected by genetic results that have been endorsed by 

IWC SC. **See supporting materials #5

Included earlier in text.

258 93 This is interesting information and should be included in the sections 

above.

BRT is ok with its decision.

259 93 If the BRT had considered separate DPS for B1 and B2 whales, there 

would have likely been different conclusions with respect to 

extinction risk? It might be appropriate to add a sentence here 

identifying that there are still major uncertainties and that more 

research is needed. 

Text was revised to add this information.

260 96 In particular what this estimate represents Arabian Sea humpbacks off 

Oman or the entire Arabian Sea humpback whale population has been 

questioned. Surveying in other parts of the range due to political 

issues is far more complicated than Oman.

Not particularly relevant to this paragraph. 

261 98 See Pomilla et al 2006. Text was revised to add this information.

262 100 I suggest including this appendix in the text. It’s only a page These 

are important enough to include in the body of the report not the 

appendices.

Tables are now included in the main body of the report.

263 101 And the west coast of Africa as per comments above.**See 

supporting materials #1 

Main text was revised to add this information.

239
264 101 The earlier analysis suggested whaling could have a substantial effect 

on this subpopulation if Japan were to move ahead with its pans to 

catch humpbacks in the Antarctic.

Text was revised to add this information.

265 101 I suggest referencing and moving the table in Appendix D into this 

section.

BRT reconfirmed its DPS decisions

266 101 As several DPS are potentially missing then perhaps the level of 

extinction would change in one of them (e.g. B2 subpopulation) and 

the others would remain the same.

BRT reconfirmed its DPS decisions

267 102 It is not clear how to interpret this table. An explanation is needed. Explanation has been added.

268 103 This is inaccurate. Again, DPS broken into 2, with the trend for one 

but not the other.

Text has been clarified to note that in some cases trends 

are based on a portion of a DPS.

240
RECENT TECHNICAL MEMORANDUMS

SWFSC Technical Memorandums are accessible online at the SWFSC web site (http://swfsc.noaa.gov). 

Copies are also available from the National Technical Information Service, 5285 Port Royal Road, 

Springfield, VA 22161 (http://www.ntis.gov). Recent issues of NOAA Technical Memorandums from the 

NMFS Southwest Fisheries Science Center are listed below:

NOAA-TM-NMFS-SWFSC- 530 

531 

532 

533 

534 

535 

536 

537 

538 

539 

Life CyclEModeling Framework for Sacramento River winter-run chinook 

salmon.

HENDRIX, N., A. CRISS, E. DANNER, C.M. GREENE, H. IMAKI, A. PIKE, 

and S.T. LINDLEY

(July 2014)

Assessment of the Pacific sardine resource in 2014 for U.S.A. management 

in 2014-15.

HILL, K. T., P. R. CRONE, D. A. DEMER, J. P. ZWOLINSKI, E. DORVAL, and 

B. J. MACEWICZ

(August 2014)

U.S. Pacific marine mammal stock assessments: 2013.

STIERHOFF, K. L., S. A. MAU, and D. W. MURFIN

(August 2014)

Sources of human-related injury and mortality for U.S. Pacific West Coast 

marine mammal stock assessments, 2008-2012.

CARRETTA, J. V., S. M. WILKEN, M. M. MUTO, K. WILKINSON, and 

J. RUSIN

(August 2014)

Meeting Our Nations Needs for Biological and Environmental Monitoring: 

Strategic Plan and Recommendations for A National Animal Telemetry 

Network (ATN) Through U. S. IOOS.

MOUSTAHFID, H., M. WEISE, S. SIMMONS, B. BLOCK, K. HOLLAND, J. 

AULT, J. KOCIK, D. COSTA, S. T. LINDLEY, B. MATE, S. HAYES, C. M. 

HOLBROOK, A. SEITZ, M. ARENDT, J. PAYNE, B. MAHMOUDI, C. 

ALEXANDER, P. MOORE, J. PRICE, and D. WILSON

(August 2014)

Spawning biomass of Pacific Sardine,(SARDINOPS SAGAX) estimated from 

the daily egg production method off California in 2013.

DORVAL, E., B. J. MACEWICZ, D. A. GRIFFITH, N. C. H. LO, and Y. GU.

(August 2014)

Genetic diversity and population structure in four species of cetaceans in the 

Mariana Islands.

MARTIEN, K. K., M. C. HILL, A. M. VAN CISE, K. M. ROBERTSON, S. M. 

WOODMAN, L. DOLAR, V. L. PEASE and E. M. OLESON

(August 2014.

Preliminary estimates of harbor porpoise abundance in Pacific Coast waters 

of California, Oregon, and Washington, 2007-2012.

FORNEY, K. A., J. V. CARETTA, and S. R. BENSON

(August 2014)

Report of the meeting on the use of multiple lines of evidence to delineate 

demographically independent populations.

MARTIEN, K. K., A. R. LANG, and B. L. TAYLOR

(March 2015)

Status review of the green turtle (CHELONIA MYDAS) under the Endangered 

Species Act.

SEMINOFF, J. A., C. D. ALLEN, G. H. BALAZS, P. H. DUTTON, T. EGUCHI, 

H. L. HAAS, S. A. HARGROVE, M. JENSEN, D. L. KLEMM, A. LAURITSEN, 

S. L. MACPHERSON, P. OPAY, E. E. POSSARDT, S. PULTZ, E. SENEY, 

K. S. VAN HOUTAN, and R. S. WAPLES

(March 2015)