FINAL 

RECOVERY PLAN FOR THE SPERM WHALE 

(Physeter macrocephalus) 

Office of Protected Resources 

National Marine Fisheries Service 

National Oceanic and Atmospheric Administration 

Silver Spring, Maryland 

December 2010 

 
 
FINAL 

RECOVERY PLAN FOR THE SPERM WHALE 

(Physeter macrocephalus) 

Prepared by: 

Office of Protected Resources 

National Marine Fisheries Service 

Assistant Administrator for Fisheries 

National Oceanic and Atmospheric Administration 

DEC 21 2010 

Date: ________ _ 

December 2010 i NMFS 

PREFACE 

Congress passed the Endangered Species Act of 1973 (16 USC 1531 et seq) (ESA) to provide a 

means to conserve the ecosystems upon which endangered and threatened species depend, to 

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

such steps as may be appropriate to achieve the purposes of the treaties and conventions that 

conserve such species. The National Marine Fisheries Service (NMFS) and the U.S. Fish and 

Wildlife Service share responsibility for the administration of the Act. NMFS is responsible for 

most marine mammals, including the sperm whale. This Recovery Plan was prepared at the 

request of the Assistant Administrator for Fisheries to promote the conservation of sperm whales. 

The goals and objectives of the Plan can be achieved only if a long-term commitment is made to 

support the actions recommended here. Achievement of these goals and objectives will require 

the continued cooperation of the governments of the United States and other nations. Within the 

United States, the shared resources and cooperative involvement of federal, state, and local 

governments, industry, academia, nongovernmental organizations, and individuals will be 

required throughout the recovery period. 

 
December 2010 ii NMFS 

DISCLAIMER 

Recovery plans delineate such reasonable actions as may be necessary, based upon the best 

scientific and commercial data available, for the conservation and survival of listed species. 

Plans are published by NMFS, sometimes prepared with the assistance of recovery teams, 

contractors, State agencies, and others. Recovery plans do not necessarily represent the views, 

official positions or approval of any individuals or agencies involved in the plan formulation, 

other than NMFS. They represent the official position of NMFS only after they have been 

signed by the Assistant Administrator. Recovery plans are guidance and planning documents 

only; identification of an action to be implemented by any public or private party does not create 

a legal obligation beyond existing legal requirements. Nothing in this plan should be construed 

as a commitment or requirement that any Federal agency obligate or pay funds in any one fiscal 

year in excess of appropriations made by Congress for that fiscal year in contravention of the 

Anti-Deficiency Act, 31 U.S.C. 1341, or any other law or regulation. Approved recovery plans 

are subject to modification as dictated by new findings, changes in species status, and the 

completion of recovery actions. 

LITERATURE CITATION SHOULD READ AS FOLLOWS: 

National Marine Fisheries Service. 2010. Recovery plan for the sperm whale (Physeter 

macrocephalus). National Marine Fisheries Service, Silver Spring, MD. 165pp. 

ADDITIONAL COPIES MAY BE OBTAINED FROM: 

National Marine Fisheries Service 

Office of Protected Resources 

1315 East-West Highway, 13th Floor 

Silver Spring, Maryland 20910 

301-713-2322 or 301-713-1401 

Recovery plans can also be downloaded from the NMFS website: 

http://www.nmfs.noaa.gov/pr/recovery/plans.htm 

Cover photograph by Shannon Rankin from NMFS Southwest Fisheries Science Center. 

Researchers were approaching a sperm whale for biopsy and identification photos (authorized 

under a Marine Mammal Protection Act permit). 
December 2010 iii NMFS 

ACKNOWLEDGMENTS 

The National Marine Fisheries Service gratefully acknowledges Randall R. Reeves and Gregory 

K. Silber for the initial preparation of this recovery plan. NMFS also acknowledges the 

subsequent contribution of the following people for updating the recovery plan, including 

providing access to unpublished information and reviewing the manuscript to produce this final 

plan: Jay Barlow, Robert Brownell, Jr., Monica DeAngelis, Sarah Mesnick, and Barbara Taylor. 

Special thanks goes to Simona Perry, the lead author of the “The Great Whales: History and 

Status of Six Species Listed as Endangered Under the U.S. Endangered Species Act of 1973” 

(Perry et al., 1999), which proved very useful in drafting this document. Additional thanks go to 

the following for their technical assistance, editing, and review: Kyle Baker, Shannon Bettridge, 

Phillip Clapham, Don Croll, Christina Fahy, Dan Goodman, Bob Kenney, Naomi Littlefield, 

Mike Newcomer, Larissa Plants, Susan Pultz, Amy Scholik-Schlomer, Bernie Tershy, Mason 

Weinrich, Andrew Wright, Hal Whitehead, and Chris Yates. 
December 2010 iv NMFS 

TERM AND ACRONYM LIST 

The following is a list of acronyms, abbreviations, and terms used throughout the recovery plan. 

ATOC Acoustic Thermometry of Ocean Climate 

CITES Convention on International Trade in Endangered Species of Wild Fauna 

and Flora 

dB decibels 

Delisting removal from the list of Endangered and Threatened Wildlife and Plants 

Downlisting considered for reclassification from endangered to threatened under the 

ESA 

DPS Distinct Population Segment 

EEZ Exclusive Economic Zone 

ESA Endangered Species Act 

FR Federal Register 

Hz hertz 

IWC International Whaling Commission 

kHz kilohertz 

LFA Low Frequency Active (for sonar) 

LNG Liquefied Natural Gas 

m meters 

MMPA Marine Mammal Protection Act 

mtDNA Mitochondrial Deoxyribonucleic acid 

Pa micro Pascal 

NMFS National Marine Fisheries Service 

NOAA National Oceanic and Atmospheric Administration 

PCB Polychlorinated Biphenyls 

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

SURTASS Surveillance Towed Array Sensor System 

SWSS Sperm Whale Seismic Study 
December 2010 v NMFS 

EXECUTIVE SUMMARY 

Current Species Status: Sperm whales, Physeter macrocephalus, are currently globally listed 

as “endangered” under the Endangered Species Act (ESA). Sperm whales were subject to 

commercial whaling for more than two and a half centuries and in all parts of the world. Sperm 

whale harvest was essentially unregulated until 1970, when quotas were introduced in the North 

Pacific Ocean; in 1971, quotas were introduced in the Southern Ocean. The International 

Whaling Commission (IWC) accorded sperm whales complete protection from commercial 

whaling by member states beginning with the 1981–82 pelagic season and subsequently with the 

1986 coastal season (IWC 1982). Currently, Japan takes a small number of sperm whales each 

year under an exemption for scientific research. Norway and Iceland have formally objected to 

the IWC ban on commercial whaling and are therefore free to resume whaling of sperm whales 

under IWC rules, but neither country has expressed an interest in taking sperm whales. 

The long history of whaling and the complex social structure and reproductive behavior of sperm 

whales have confounded assessments of population status and structure. Historical catch records 

are sparse or nonexistent in some areas of the world and over long periods of time, and gross 

under-reporting or mis-reporting of modern catch data has taken place on a large scale. The 

wide-ranging, generally offshore distribution of sperm whales and their long submergence times 

complicate efforts to estimate abundance. Although the aggregate abundance worldwide is 

probably at least several hundred thousand individuals, the extent of depletion and degree of 

recovery of populations are uncertain. 

Sperm whales have a global distribution and can be found in the Atlantic, Pacific, and Indian 

Oceans. Currently, the population structure of sperm whales has not been adequately defined. 

Most models have assigned arbitrary boundaries, often based on patterns of historic whaling 

activity and catch reports, rather than on biological evidence. Populations are often divided on 

an ocean basin level. Therefore, this Recovery Plan is organized, for convenience, by ocean 

basin and discussed in three sections, those sperm whales in the Atlantic Ocean/Mediterranean 

Sea, including the Caribbean Sea and Gulf of Mexico, those in the Pacific Ocean and its 

adjoining seas and gulfs, and those in the Indian Ocean. An improved understanding of the 

genetic differences between populations would allow better estimates of abundance and more 

effective management of the species. Although there is new information, existing knowledge of 

population structure for this nearly continually distributed species remains poor. 

Habitat Requirements and Limiting Factors: Populations in the Atlantic Ocean/ 

Mediterranean Sea, Pacific Ocean, and Indian Ocean have been legally protected from 

commercial whaling for the last twenty or more years, and this protection continues. Although 

the main direct threat to sperm whales was addressed by the IWC whaling moratorium on 

commercial whaling, several potential threats remain. Among the current potential threats are 

collisions with vessels, reduced prey abundance due to climate change, the possibility that illegal 

whaling or resumed legal whaling will cause removals at biologically unsustainable rates, 

contaminants and pollutants, and, possibly, the effects of increasing anthropogenic ocean noise. 

Recovery Strategy: The primary purpose of this Recovery Plan is to identify and take actions 

that will minimize or eliminate effects of human activities that are detrimental to the recovery of 
December 2010 vi NMFS 

sperm whale populations. Immediate objectives are to identify factors that may be limiting 

abundance/recovery/ productivity, and cite actions necessary to allow the populations to 

increase. The main threats to sperm whale populations include collisions with vessels, direct 

harvest, and possibly competition for resources, loss of prey base due to climate change, and 

disturbance from anthropogenic noise. Another important component of this recovery program 

is to determine population structure of the species and population discreteness. This would be a 

first step in estimating population size, monitoring trends in abundance, and enabling an 

assessment of the species throughout its range. Because sperm whales move freely across 

international borders, it would be unreasonable to confine recovery efforts to U.S. waters, and 

this Recovery Plan stresses the importance of a multinational approach to management. Ideally, 

both research and conservation should be undertaken at oceanic rather than national levels. 

Recovery Goals and Criteria: The goal of this Recovery Plan is to promote recovery of sperm 

whales to a point at which they can be downlisted from endangered to threatened status, and 

ultimately to remove them from the list of Endangered and Threatened Wildlife and Plants, 

under the provisions of the ESA. 

The recovery criteria presented in this Recovery Plan were based on the Report of the Workshop 

on Developing Recovery Criteria for Large Whales Species (Angliss et al. 2002). The sperm 

whale is currently listed as a single species on a global scale. 

Downlisting Criteria: 

Sperm whales will be considered for reclassifying from endangered to threatened when all of the 

following criteria are met: 

1. Given current and projected threats and environmental conditions, the sperm whale 

population in each ocean basin in which it occurs (Atlantic Ocean/Mediterranean Sea, Pacific 

Ocean, and Indian Ocean) satisfies the risk analysis standard for threatened status (has no more 

than a 1% chance of extinction in 100 years) and the global population has at least 1,500 mature, 

reproductive individuals (consisting of at least 250 mature females and at least 250 mature males 

in each ocean basin). Mature is defined as the number of individuals known, estimated, or 

inferred to be capable of reproduction. Any factors or circumstances that are thought to 

substantially contribute to a real risk of extinction that cannot be incorporated into a Population 

Viability Analysis will be carefully considered before downlisting takes place. 

and 

2. None of the known threats to sperm whales are known to limit the continued growth of 

populations. Specifically, the factors in 4(a)(l) of the ESA are being or have been addressed: 

 A) the present or threatened destruction, modification or curtailment of a species’ habitat or 

range; B) overutilization for commercial, recreational or educational purposes; C) disease or 

predation; D) the inadequacy of existing regulatory mechanisms; and E) other natural or 

manmade factors. See Section III, Recovery Goals, Objectives, and Criteria, for specific threatsbased criteria. 
December 2010 vii NMFS 

Delisting Criteria: 

Sperm whales will be considered for removal from the list of Endangered and Threatened 

Wildlife and Plants under the provisions of the ESA, when all of the following criteria are met: 

1. Given current and projected threats and environmental conditions, the total sperm whale 

population in each ocean basin in which it occurs (Atlantic Ocean/Mediterranean Sea, Pacific 

Ocean, and Indian Ocean) satisfies the risk analysis standard for unlisted status (has less than a 

10% probability of becoming endangered (has more than a 1% chance of extinction in 100 years) 

in 20 years). Any factors or circumstances that are thought to substantially contribute to a real 

risk of extinction that cannot be incorporated into a Population Viability Analysis will be 

carefully considered before delisting takes place. 

and 

2. None of the known threats to sperm whales are known to limit the continued growth of 

populations. Specifically, the factors in 4(a)(l) of the ESA are being or have been addressed: 

A) the present or threatened destruction, modification or curtailment of a species’ habitat or 

range; B) overutilization for commercial, recreational or educational purposes; C) disease or 

predation; D) the inadequacy of existing regulatory mechanisms; and E) other natural or 

manmade factors. See Section III, Recovery Goals, Objectives, and Criteria, for specific threatsbased criteria.

This recovery plan identifies the following actions needed to achieve recovery of sperm whales: 

1. Coordinate state, federal, and international actions to implement recovery action and 

maintain international regulation of whaling for sperm whales; 

2. Develop and apply methods to estimate population size and monitor trends in abundance; 

3. Determine population discreteness and population structure of sperm whales; 

4. Conduct risk analyses; 

5. Identify, characterize, protect, and monitor habitat important to sperm whale populations 

in U.S. waters and elsewhere; 

6. Investigate causes of and reduce the frequency and severity of human-caused injury and 

mortality; 

7. Determine and minimize any detrimental effects of anthropogenic noise in the oceans; 

8. Maximize efforts to acquire scientific information from dead, stranded, and entangled 

sperm whales; and 

9. Develop post-delisting monitoring plan. 
December 2010 viii NMFS 

Estimated Cost of Actions Necessary to Achieve Recovery, Including All Three Ocean 

Basins (estimates are in thousands of dollars): 

Year Action 

1 

Action 

2 

Action 

3 

Action 

4 

Action 

5 

Action 

6 

Action 

7 

Action 

8 

Action 

9 Total1

Atlantic 

(2025) 1,500 43,990 3,000 200 6,500 7,500 2,500 1,352 * 66,542 

Pacific 

(2025) 1,500 32,160 3,000 200 6,500 12,500 2,500 1,352 * 59,712 

Indian 

(2035) 2,500 27,490 1,500 200 6,000 8,000 2,000 47,690 

Total for 

Task 

Duration 

5,500 103,6702 7,500 600 19,000 28,000 7,000 2,704 * 173,974 

1 Total reflects cost of recovery for ocean basin. 2

 Total reflects an additional cost of $30K that is not specific to one ocean basin. * No cost associated, NMFS staff time. 

ANTICIPATED DATE OF RECOVERY: The time to recovery is not predictable with the current 

information and global listing of sperm whales. However, minimum data needed to satisfy 

criterion 1 for delisting are population structure work and ocean-basin wide surveys, which are 

estimated to take an additional 15 years from now within the Atlantic Ocean/Mediterranean Sea 

and Pacific Ocean basins (date of recovery at 2025) and likely an additional 25 years from now 

in the Indian Ocean (date of recovery at 2035). The exact date of recovery cannot be determined 

as it will likely take decades. The effectiveness of many management activities is not known on 

a global level, and currently it is impossible to predict when such measures will bring the species 

to a point at which the protections of the ESA are no longer warranted. In the future, as more 

information is obtained on the threats, their impacts on sperm whales, and how they can be 

effectively mitigated, it should be possible to make more informative projections about the time 

to recovery, and its expense. 

ESTIMATED COST OF RECOVERY (FIRST 5 FISCAL YEARS): $2.4 MILLION

TOTAL ESTIMATED COST OF RECOVERY FOR THREE OCEAN BASINS: $174 MILLION 

 
December 2010 ix NMFS 

TABLE OF CONTENTS

PREFACE ........................................................................................................................................ i

DISCLAIMER ................................................................................................................................ ii

ACKNOWLEDGMENTS ............................................................................................................. iii

TERM AND ACRONYM LIST .................................................................................................... iv

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

TABLE OF CONTENTS ............................................................................................................... ix

I. BACKGROUND .............................................................................................................. I-1

A. Brief Overview .................................................................................................................. I-1

B. Species Description, Taxonomy, and Population Structure .............................................. I-1

C. Zoogeography ................................................................................................................... I-5

D. Life History – Atlantic Ocean/Mediterranean Sea Population ......................................... I-7

D.1 Population Structure.................................................................................................. I-7

D.2 Distribution and Habitat Use .................................................................................... I-7

D.3 Feeding and Prey Selection ...................................................................................... I-9

D.4 Competition............................................................................................................... I-9

D.5 Reproduction ............................................................................................................. I-9

D.6 Natural Mortality .................................................................................................... I-11

D.7 Abundance and Trends ........................................................................................... I-11

E. Life History–Pacific Ocean Population .......................................................................... I-14

E.1 Population Structure................................................................................................ I-14

E.2 Distribution and Habitat Use .................................................................................. I-16

E.3 Feeding and Prey Selection ..................................................................................... I-18

E.4 Competition............................................................................................................. I-18

E.5 Reproduction ........................................................................................................... I-18

E.6 Natural Mortality .................................................................................................... I-18

E.7 Abundance and Trends ........................................................................................... I-19

F. Life History-Indian Ocean Population ............................................................................ I-20

F.1 Population Structure................................................................................................ I-20

F.2 Distribution and Habitat Use .................................................................................. I-20

F.3 Feeding and Prey Selection ..................................................................................... I-20

F.4 Competition............................................................................................................. I-20

F.5 Reproduction ........................................................................................................... I-20

F.6 Natural Mortality .................................................................................................... I-21

F.7 Abundance and Trends ........................................................................................... I-21

G. Threats............................................................................................................................. I-21

G.1 Fishery Interactions – LOW .................................................................................... I-21

G.1.1 Atlantic Ocean/Mediterranean Sea – LOW .................................................... I-22

G.1.2 Pacific Ocean – LOW ..................................................................................... I-23

G.1.3 Indian Ocean – UNKNOWN .......................................................................... I-25

G.2 Anthropogenic Noise – UNKNOWN ..................................................................... I-25

G.2.1 Ship Noise – UNKNOWN .............................................................................. I-28

G.2.2 Oil and Gas Exploration– UNKNOWN ......................................................... I-29

G.2.3 Military Sonar and Explosives – UNKNOWN ............................................... I-31
December 2010 x NMFS 

G.3 Vessel Interactions .................................................................................................. I-35

G.3.1 Ship Strikes – UNKNOWN BUT POTENTIALLY LOW ............................. I-35

G.3.2 Disturbance from Whale Watching and Other Vessels – LOW ..................... I-36

G.4 Contaminants and Pollutants – UNKNOWN ......................................................... I-37

G.5 Disease – LOW ....................................................................................................... I-39

G.6 Injury from Marine Debris – LOW ......................................................................... I-40

G.7 Research – LOW ..................................................................................................... I-40

G.8 Predation and Natural Mortality – LOW ................................................................ I-41

G.9 Direct Harvest – LOW ............................................................................................ I-41

G.9.1 Direct Harvest – Atlantic Ocean/Mediterranean Sea ...................................... I-43

G.9.2 Direct Harvest – Pacific Ocean ....................................................................... I-44

G.9.3 Direct Harvest – Indian Ocean ........................................................................ I-45

G.10 Competition for Resources – LOW ........................................................................ I-46

G.11 Loss of Prey Base Due to Climate and Ecosystem Change – UNKNOWN ........... I-46

G.12 Cable Laying – LOW .............................................................................................. I-47

H. Conservation Measures ................................................................................................. II-51

II. RECOVERY STRATEGY ............................................................................................. II-1

III. RECOVERY GOALS, OBJECTIVES, AND CRITERIA ............................................ III-1

A. Goals .............................................................................................................................. III-1

B. Objectives and Criteria .................................................................................................. III-1

B.1 Downlisting Objectives and Criteria ...................................................................... III-1

B.2 Delisting Objectives and Criteria ........................................................................... III-3

IV. RECOVERY PROGRAM ............................................................................................. IV-1

A. Recovery Action Outline ............................................................................................... IV-1

B. Recovery Action Narrative ............................................................................................ IV-5

V. IMPLEMENTATION SCHEDULE ............................................................................... V-1

VI. LITERATURE CITED .................................................................................................. VI-1
December 2010 I-1 NMFS 

I. BACKGROUND 

A. Brief Overview

The sperm whale, Physeter macrocephalus (Linnaeus 1758), was listed under the precursor to 

the Endangered Species Act (ESA), the Endangered Species Conservation Act of 1969, and 

remained on the list of threatened and endangered species after the passage of the ESA in 1973 

(35 FR 18319, December 2, 1970). Sperm whales are widely distributed throughout the world’s 

oceans. Although the original listing did not provide an explanation, it is understood that the 

main reason for listing is that most populations were depleted by modern whaling. Despite this 

reduction, the sperm whale remains the most abundant of the large whale species. Commercial 

whaling for this species ended in 1988 with the implementation of a moratorium against whaling 

by the International Whaling Commission (IWC), and while it is often assumed that the 

worldwide population of sperm whales has increased since the moratorium, there are insufficient 

data on population structure and abundance of inhabited ocean basins to accurately determine 

population trends. Sperm whales are still being targeted in a few areas: there is a small catch by 

primitive methods in Lamalera, Indonesia, and Japan takes sperm whales for scientific purposes. 

There is also some evidence to suggest that sperm whales are being killed illegally in some parts 

of the world, but the impact of this take is unknown. Currently, there is no good estimate for the 

total number of sperm whales worldwide. The best estimate is that there are between 200,000 

and 1,500,000 sperm whales, based on extrapolations from only a few areas that have useful 

estimates. Status of populations throughout the world’s oceans, stated in terms of present 

population size relative to “initial” (pre-whaling or carrying capacity) level, is close to 18th and 

19th century concentrations. However, a large area in the South Pacific appears to have a low 

density of sperm whales. 

Although the main direct threat to sperm whales was addressed by the IWC whaling moratorium, 

several potential threats remain. Among the current potential threats are collisions with vessels, 

entanglement in fishing gear, reduced prey due to overfishing, habitat degradation, disturbance 

from anthropogenic noise, and the possibility of illegal or resumed legal whaling at biologically 

unsustainable rates. The possible effects of pollution on sperm whales remain poorly 

understood. Although published evidence indicates that levels of mercury, cadmium, and certain 

organochlorines in sperm whale’s tissue were high enough to cause concern about toxicity, no 

clear link between contamination and strandings has been found. The sperm whale’s principle 

prey is large squid, but they will also eat large demersal and mesopelagic sharks, skates, and 

fishes. Thus, trends in fish populations, whether driven by fishery operations, human-caused 

environmental deterioration, or natural processes, may strongly affect the size and distribution of 

sperm whale populations. 

B. Species Description, Taxonomy, and Population Structure

Species Description 

The sperm whale is a cosmopolitan species, whose distribution is thought to be more extensive 

than that of any other marine mammal except the killer whale (Orcinus orca) (Rice 1989), 

ranging between 60EN and 70ES (Leatherwood and Reeves 1983). Male sperm whales can reach 

lengths of more than 18 meters (m), while females can reach lengths of up to 12.5 m. They can 

weigh up to 57 and 24 metric tons, respectively (Rice 1989). The age distribution of the sperm 
December 2010 I-2 NMFS 

whale population is unknown, but sperm whales are believed to live at least 60 years, with 

females potentially living up to 80 years (Whitehead 2003). Sperm whale annual mortality rates 

are thought to vary by age, but previous estimates of mortality rates for juveniles and adults are 

considered unreliable (IWC 1980). 

Sperm whales have a disproportionately large head, one quarter to one third of their total body 

length (Rice 1989). Their rod-shaped lower jaw is narrow and underslung, with 20–26 pairs of 

well-developed teeth in the mandibles, but the maxillary teeth are vestigial. Their eyes are 

relatively small. Sperm whales are generally dark gray in color, with white lips and often white 

areas on the belly and flanks. Their dorsal fin is low in profile, thick, and not pointed or curved, 

followed by knuckles along its spine. Photographs of distinctive markings on the dorsal fins and 

flukes of sperm whales are used in studies of life history and behavior (Whitehead and Gordon 

1986; Whitehead 1990). They have the largest brain of any animal on Earth, and their blunt 

snout houses a large reservoir of spermaceti, a high-quality oil. 

Hearing and Vocalizations 

The anatomy of the sperm whale ear indicates that it hears in the same functional acoustic 

division as bottlenose dolphins and appears tailored for ultrasonic (>20 kilohertz (kHz)) 

reception (Ketten 1994, 1997). The odontocete inner ear is primarily adapted for echolocation, 

and the ears have exceptional frequency discrimination abilities. The sperm whale may also 

possess better low frequency hearing than some of the other odontocetes, although not as low as 

many baleen whales (Ketten 1992). Southall et al. (2007) recently put sperm whales in the same 

hearing group (mid-frequency cetaceans), as “dolphins,” toothed whales, beaked whales, and 

bottlenose whales (estimated hearing range 150 Hz to 160 kHz). The only data on the hearing 

range of sperm whales are evoked potentials from a stranded male neonate, which suggest that 

neonatal sperm whales respond to sounds from 2.5 to 60 kHz, with best sensitivity at 5, 10, and 

20 kHz. 

Sperm whales produce several types of click sounds: patterned clicks (codas), usual clicks, 

creaks, and slow clicks (Weilgart and Whitehead 1988). Codas are associated with social 

behavior and interactions within social groups (Weilgart and Whitehead 1993). When sperm 

whales are socializing, they tend to repeat codas, which follow a precise rhythm and may last for 

hours (Watkins and Schevill 1977). Codas are shared between individuals of a social unit and 

are considered to be primarily for intragroup communication (Weilgart and Whitehead 1997; 

Rendell and Whitehead 2004). Usual clicks have interclick periods of 0.4 to 1 seconds and are 

heard most often when sperm whales engage in foraging/diving behavior (Whitehead and 

Weilgart 1991; Miller et al. 2004; Zimmer et al. 2005). These may be echolocation clicks used 

in feeding, contact calls (communication), and orientation during dives. Creaks are a series of 

very rapid clicks and are thought to be produced by sperm whales as they are closing on a food 

item. Slow clicks have interclick periods greater than 5 seconds and are believed to be made 

only by adult males in the context of mating. 

Generally, most of the acoustic energy from sperm whales is present at frequencies below 4 kHz, 

although diffuse energy up to and past 20 kHz has been reported (Thode et al. 2002), with source 

levels up to 236 dB re 1 Pa-m (Møhl 2003). Other studies indicate sperm whales’ wide-band 

clicks contain energy between 0.1 and 20 kHz (Weilgart and Whitehead 1993, 1997; Goold and 
December 2010 I-3 NMFS 

Jones 1995). These have source levels estimated at 171 dB re 1 Pa (Levenson 1974). Current 

evidence suggests that the disproportionately large head of sperm whales is an adaptation to 

produce these vocalizations (Norris and Harvey 1972; Clarke 1979; Cranford 1992). This 

suggests that the production of these loud, low-frequency clicks, is extremely important to the 

survival of individual sperm whales. The function of these vocalizations is relatively wellstudied (Weilgart and Whitehead 1993, 1997; Goold and Jones 1995). Long series of 

monotonous regularly spaced clicks are associated with feeding and are thought to be produced 

for echolocation. 

Taxonomy 

There is a firm and long-standing scientific consensus that only one species of sperm whale 

exists. However, scientists have disputed the species’ nomenclature and systematics. With 

regard to nomenclature, Schevill (1986, 1987) and Holthuis (1987) debated the relative merits of 

two Linnaean names for the sperm whale—catodon vs. macrocephalus. The higher-level 

taxonomy was subsequently reviewed extensively by Milinkovitch et al. (1993, 1994, 1995)and 

Milinkovitch (1995) using molecular data to argue that sperm whales (family Physeteridae) are 

the sister group to baleen whales (sub-order Mysticeti), and therefore, the toothed whales (suborder Odontoceti) are not monophyletic but rather comprise a paraphyletic group. Heyning’s 

(1997) rebuttal of that hypothesis, using cladistic analysis, has gained wide acceptance among 

cetologists (Rice 1998). 

Population Structure 

In the United States, sperm whales are managed under three constructs, all with different 

objectives and therefore, different terminology for population structure: the Marine Mammal 

Protection Act (MMPA), the IWC, and the ESA. Roughly, the MMPA protects marine mammal 

species with a goal of maintaining marine mammal population “stocks” as functioning elements 

of their ecosystem, the IWC manages whales with a goal of maintaining healthy stocks while 

authorizing harvest to meet aboriginal (and potentially commercial catches), scientific research, 

and related purposes, and the ESA seeks to avoid extinction and recover depleted species to a 

point at which they no longer need ESA protections. 

Both the MMPA and the IWC use the term “stocks” to refer to units to conserve. In this 

document, we use the term “stocks” in the context of MMPA or IWC stocks, and use the more 

generic term “populations” when referring to subunits of the same species in other contexts. The 

stock concept has been the subject of much discussion among biologists and natural resource 

managers. The MMPA defines “stock” as “a group of marine mammals of the same species or 

smaller taxa in a common spatial arrangement, that interbreed when mature.” 16 U.S.C. § 

1362(11). A recent working interpretation of this definition is a “demographically isolated 

biological population” (Wade and Angliss 1997) where internal dynamics (births and deaths) are 

far more important than external dynamics (immigration and emigration) to maintaining the 

population. The IWC continues to waver somewhere between two types of stock definitions: 

biological stocks based on genetic separation and management stocks referring to population 

units defined in functional terms of some kind (Donovan 1991). Although considerable effort 

has been expended to tighten the definition of stocks, current IWC practice continues to define 

on a case-by-case basis and only for stocks in need of current management. Thus, stock 

definition for areas with no aboriginal whaling or anticipated commercial whaling, as would be 
December 2010 I-4 NMFS 

the case for sperm whales, has not been considered for decades. 

The population structure of sperm whales has not been adequately defined. Most existing 

models have assigned arbitrary boundaries, often based on patterns of historic whaling activity 

and catch reports, rather than on biological evidence. In discussions of sperm whales, 

populations are often divided and discussed on an ocean basin level. An improved 

understanding of the genetic differences between populations would allow better estimates of 

abundance and more effective management of the species. Although there is new information, 

existing knowledge of population structure for this nearly continuously distributed species 

remains poor. 

Over the past decade, several authors have investigated population structure in sperm whales 

using sequence variation within the mitochondrial DNA (mtDNA) and/or polymorphic nuclear 

loci (e.g., microsatellites). In general, results tend to find low genetic differentiation among 

ocean basins and little evidence of subdivision within ocean basins, with the exception of some 

distinct geographic basins such as the Mediterranean Sea and Gulf of Mexico (Dillon 1996; 

Lyrholm and Gyllensten 1998; Mesnick et al. 1999a; Bond 1999; Lyrholm et al. 1999; 

Engelhaupt 2004). However, several factors complicate these studies, such as low sample sizes, 

low mtDNA haplotypic diversity, and sex biased patterns of dispersal, which alone and together 

reduce the power to detect population structure. 

The low mtDNA diversity in sperm whales requires that studies using this marker have large 

sample sizes. While sufficient sampling exists to get a rough idea of scale, sample gaps remain 

large, particularly in the North Atlantic, Western Pacific, and southern hemisphere. Mesnick et 

al. (2005) compiled over 2,473 tissue samples and 1,038 mtDNA sequences from a global 

consortium of investigators. This compilation found 28 haplotypes worldwide, defined by 24 

variable sites. The three most common haplotypes (“a”, “b,” and “c”) comprised 82% of the 

total, with haplotype “a” comprising 39% of the total. Several hypotheses for the lack of 

diversity have been proposed, such as an historic bottleneck effect on population size (Lyrholm 

et al. 1996), dissimilar environmental conditions experienced by separate matrilineal groups 

causing disparity of fecundities (Tiedemann and Milinkovitch 1999) and cultural “hitchhiking” 

in matrilineal species (Whitehead 1998). 

Additional information on population structure can be found in data sets derived from historical, 

demographic, behavioral, morphological, and acoustic sources (Baker and Palumbi 1997; 

Whitehead and Mesnick 2003a, b). As discussed by Taylor and Dizon (1996), until analyses 

with sufficient power are applied, the precautionary assumption should be that structuring exists, 

and reasonable provisional management units should be recognized on the basis of catch history, 

sighting distribution, and other data. Preliminary investigations of calving seasonality suggest, 

for example, that the sperm whales in the Gulf of California, Mexico, breed at different times 

than those in the California Current system (B.L. Taylor, pers. comm. 2006). To address the 

potential bias due to relatedness within groups, novel analytical approaches are needed. 

It is likely that population structuring exists among sperm whales. Although sperm whales are 

found throughout the world’s waters, it appears that only males penetrate to truly arctic waters, 

having been observed to move towards colder waters in the summer feeding seasons and return 
December 2010 I-5 NMFS 

to warmer water to breed. Lyrholm and Gyllensten (1998) found that the dispersal of females 

was limited, suggesting the possibility of the development of genetic differentiation. However, 

Discovery Mark data from the days of commercial whaling (260 recoveries with location data) 

show extensive movements of both males and females from U.S. and Canadian coastal waters 

into the Gulf of Alaska and Bering Sea (Omura and Ohsumi 1964; Ivashin 1967; Ivashin and 

Rovnin 1967; Ohsumi and Masaki 1975; Wada 1980; Kasuya and Miyashita 1988; Mizroch, 

pers. comm. 2008). While no firm boundaries can be drawn, there is likely very limited 

movement among the Atlantic/Mediterranean Sea, the Pacific, and the Indian Oceans. 

Moreover, the year-round presence of sperm whales in some areas (e.g., northern Gulf of 

Mexico) suggests that there may be “resident” populations in certain areas. Research currently 

underway will improve our understanding of the sperm whale’s population structure and genetic 

differences. 

C. Zoogeography 

The distribution of sperm whales extends to all deep ice-free marine waters from the equator to 

the edges of polar pack ice (Rice 1989). Sperm whales are present in many warm-water areas 

throughout the year, and such areas may have discrete “resident” populations (Watkins et al. 

1985; Gordon et al. 1998; Drout 2003; Jaquet et al. 2003; Engelhaupt 2004). While their 

aggregate distribution is certainly influenced by the patchiness of global marine productivity 

(Jaquet and Whitehead 1996), no physical barriers, apart from land masses, appear to obstruct 

their dispersal (Berzin 1972; Jaquet 1996). Rice (1989) suggested that it was reasonable to 

expect some inter-basin movement around the Cape of Good Hope (Atlantic Ocean-Indian 

Ocean) and through the passages between the Lesser Sunda Islands or round the south coast of 

Tasmania (Indian Ocean-Pacific Ocean), but he considered exchange via Cape Horn (Pacific 

Ocean-Atlantic Ocean) to be “almost entirely restricted, except possibly for a few males.” 

Figure 1. Sperm whale global range.

Pacific Ocean

Atlantic Ocean

Indian Ocean

NOTE: Map represents

approximate range of

species.

NMFS, Office of

Protected Resources

March 2009
December 2010 I-6 NMFS 

A striking feature of the sperm whale’s life history is the difference in migratory behavior 

between adult males and females. Typically adult males move into the higher latitudes and all 

age classes and both sexes range throughout tropical and temperate seas. However, there are 

areas where at least some individual males and females are present year-round in the higher 

latitudes (Mellinger et al. 2004; Mizroch pers. comm. 2009). Discovery Mark data from the 

days of commercial whaling (260 recoveries with location data) show extensive movements of 

both males and females from U.S. and Canadian coastal waters into the Gulf of Alaska and 

Bering Sea (Omura and Ohsumi 1964; Ivashin and Rovnin 1967; Ohsumi and Masaki 1975; 

Wada 1980; Kasuya and Miyashita 1988, Mizroch, pers. comm. 2009) although, of nearly 

60,000 sperm whales killed in the North Pacific above 50°N, approximately 57,000 were males 

(Mizroch and Rice 2006). Sperm whale calls have been detected year-round in the Gulf of 

Alaska (Mellinger et al. 2004). Male sperm whales are widely dispersed along the Antarctic ice 

edge from December to March (austral summer) (Gosho et al. 1984). A combination of factors, 

including wide dispersal by males, ontogenetic changes in association patterns, and female pod 

fidelity and cohesion, complicates any evaluation of population structure. An initial examination 

of global matrilineal population structure suggests that inter-oceanic dispersal of female lineages 

is limited (Dillon 1996; Lyrholm and Gyllensten 1998). However, studies of allelic variation in 

nuclear markers are needed to reveal the extent to which male dispersal might cause genetic 

mixing between oceanic populations (Bond 1999; Lyrholm et al. 1999). 

Intensive whaling may have fragmented the world population of sperm whales. While presentday concentration areas generally match those of the 18th and 19th centuries, at least one large 

area of the South Pacific (the extensive “Offshore” and “On the Line” whaling grounds between 

the Galapagos and Marquesas) appears to have a relatively low density of sperm whales today 

(Jaquet and Whitehead 1996). Further research is needed to verify that the density is in fact low, 

and if it is low, to determine the reason(s). 

In this Recovery Plan we separate description of the data into three sections: Atlantic 

Ocean/Mediterranean Sea, Pacific Ocean, and Indian Ocean. This organization follows the way 

sperm whales have been treated by both IWC and MMPA management regimes and the way that 

data are often gathered. There is no biological reason to use the equator as a boundary, as wellknown populations are known to span this artificial line. It is recognized that our understanding 

of population structure for this nearly continuously distributed species, with complex social 

structure, remains poor and that further work is needed to identify units that are both discrete and 

significant to the survival of the species. Although sperm whales are found throughout the 

world’s waters, only males penetrate to truly arctic waters and seasonal movements towards 

colder waters in the summer feeding seasons has been observed by at least the males. Therefore, 

while no firm boundaries can be drawn, there is likely very limited movement between the 

Atlantic Ocean/Mediterranean Sea, the Pacific, and the Indian Ocean. The Recovery Criteria in 

this Recovery Plan, therefore, use these three large oceanic regions. All three of these oceanic 

regions must meet the recovery criteria. Careful consideration should be given to the meaning of 

“significant,” as used in the phrase “significant portion of its range,” (per the definition of 

endangered and threatened which states that the species is endangered or threatened “throughout 

all or a significant portion of its range”) in light of our poor understanding of population 

structure. 
December 2010 I-7 NMFS 

D. Life History – Atlantic Ocean/Mediterranean Sea Population 

D.1 Population Structure 

In U.S. waters, the National Oceanic and Atmospheric Administration’s (NOAA) National 

Marine Fisheries Service (NMFS) recognizes two MMPA stocks of sperm whales: a western 

North Atlantic stock and a northern Gulf of Mexico stock (Waring et al. 2005). Two recent PhD. 

dissertations examined structure within the North Atlantic using genetic markers. Drout (2003) 

found mtDNA variation between samples collected in the Mediterranean Sea and the North 

Atlantic Ocean. Engelhaupt (2004) examined genetic variation among samples collected in the 

Gulf of Mexico, Mediterranean Sea, North Sea, and North Atlantic Ocean using mtDNA and 

nuclear genetic markers. Both studies found that all Mediterranean Sea samples were 

represented by a single mtDNA haplotype and Englehaupt (2004) found two unique haplotypes 

in the Gulf of Mexico. Both studies found significant genetic subdivision between isolated 

ocean basins (the Gulf of Mexico and the Mediterranean Sea) and the North Atlantic. It is 

important to recognize that further analyses of population structure of sperm whales in the North 

Atlantic have not been attempted, and any current designation of stocks or management units 

must be regarded as preliminary (Donovan 1991; Taylor and Dizon 1996). Recently, Gero et al.

(2008) investigated patterns of association within a social unit of sperm whales from the eastern 

Caribbean, and contrary to previous findings, found that the patterns of association among 

members of this unit were heterogeneous and that individuals had preferred associations or 

avoidances with specific individuals. Furthermore, it was determined that the intra-unit social 

complexity of a group, when the variation in sociability is controlled, is based on genetic 

relatedness, as individuals associated more with their close relative. 

D.2 Distribution and Habitat Use 

Information regarding the broad movements of sperm whales has been collected from years of 

tagging studies and analyses of commercial whaling data. For instance, a tag that was attached 

to a male sperm whale’s body off Nova Scotia in 1966 was recovered when the whale was killed 

off Spain in 1973 (Mitchell 1975). This observation provided direct evidence of movement by 

male sperm whales across the North Atlantic basin. Harpoons or harpoon fragments from the 

Azores were found in the bodies of whales killed off Iceland and Spain, indicating movement 

across large parts of the eastern North Atlantic as well (Martin 1982; Aguilar 1985; Sigurjønsson 

1985). Tagging data have also shown that sperm whales make substantial latitudinal movements 

across the equator (Ivashin 1967). 

Sperm whales inhabit the entire Atlantic basin (Rice 1989). Two of the major 19th century 

whaling grounds for sperm whales, the Southern Ground and the Charleston Ground, are situated 

directly off the eastern United States (Townsend 1935). The northern Gulf of Mexico and the 

West Indies were also visited regularly by the sperm whale whalers. 

In Mitchell’s (1972) extensive cruises covering much of the western and central North Atlantic 

Ocean, he found the highest densities of sperm whales, by far, in the “North Sargasso Sea 

Region” (30-40°N, 50-70°W) and the “Gulf Stream Region” (two discrete offshore areas 

between 40°N and 50°N—one over the Grand Banks of Newfoundland and the other over the 

North Atlantic Ridge). This is consistent with the observation by Townsend (1935) and Waring 
December 2010 I-8 NMFS 

et al. (1993), that the Gulf Stream has an important influence on sperm whale distribution. 

There has been an increase in the number of reported sperm whales in European continental shelf 

waters since the mid-1970s (Dunlop and Mellor 2008). Most available information on the 

presence of sperm whales in the United Kingdom and Ireland has come from stranding events 

along the north and west coasts of Ireland (Berrow et al. 1993) and from visual sighting records 

(Evans 1997; Evans et al. 2003; Reid 2003). Sperm whales are widely distributed throughout the 

deep waters of the North Atlantic and occur in small numbers along the shelf break north and 

west of the British Isles and Ireland (Dunlop and Mellor 2008). Visual and acoustic surveys 

conducted by Weir et al. (2001) indicate a small sperm whale population located in deeper 

waters northwest of Scotland and that sperm whales are typically found along the continental 

shelf and along the 1,000 m isobath throughout the entire year. In comparison, Weir et al.

(2001) observed few animals off the west and northwest coasts of Ireland. Dunlop and Mellor’s 

(2008) acoustic survey indicates that the sperm whale range could potentially extend towards the 

north coast of Ireland more frequently than is currently acknowledged. 

The sperm whale is the most common large cetacean in the northern Gulf of Mexico, where it 

occurs in greatest density along and seaward of the 1000 m contour (Mullin et al. 1991, 1994; 

Jefferson and Schiro 1997; Davis et al. 1998; Weller et al. 2000; WÜrsig et al. 2000; Mullin and 

Fulling 2004). They appear to prefer steep rather than shallow depth gradients (Davis et al.

1998). The spatial distribution of sperm whales within the Gulf of Mexico is strongly correlated 

with mesoscale physical features such as Loop Current eddies that locally increase primary 

production and prey availability (Biggs et al. 2005). In the north-central Gulf of Mexico, sperm 

whales are especially common near the Mississippi Canyon, where they are present year-round 

(Davis et al. 1998), and their total range includes much of the wider Caribbean region 

(Townsend 1935; Watkins and Moore 1982). There has recently been extensive work on the 

movements and habitat use of sperm whales in the Northern Gulf of Mexico, by the Sperm 

Whale Seismic Study (SWSS). These studies include habitat cruises, physical oceanographic 

analysis, and long term satellite tag deployments. Several satellite tags have operated for over 12 

months and indicate movements generally along the shelf break (700–1000 m depth) throughout 

the Gulf of Mexico, with some animals using deeper oceanic waters. Satellite tag deployments 

also have indicated large scale movements of individuals out of the Gulf of Mexico. The SWSS 

research provided detailed information on the habitat preferences and population structure of 

Gulf of Mexico sperm whales (Jochens and Biggs 2004; Jochens et al. 2008). 

Off Nova Scotia, sperm whales were found by coastal whalers mainly in continental slope waters 

50–1000 fathoms deep, especially in submarine canyons and around the edges of banks (Mitchell 

1975). Similarly, the overall distribution along the U.S. east coast is centered along the shelf 

break and over the slope (CETAP 1982; Waring et al. 2005). Very high densities occur in inner 

slope waters north of Cape Hatteras, North Carolina seaward of the 1000 m isobath during 

summer months (Mullin and Fulling 2003; Southeast Fisheries Science Center unpublished data; 

Waring et al. 2005). Sperm whales are also known to move onto the continental shelf in waters 

less than 100 m deep on the southern Scotian Shelf and south of New England, particularly 

between late spring and autumn (Whitehead et al. 1992a,b; Scott and Sadove 1997; Waring et al.

1997). 
December 2010 I-9 NMFS 

D.3 Feeding and Prey Selection 

Sperm whales are deep and prolonged divers and can therefore use the entire water column, even 

in very deep areas. Most sperm whales are found in very deep waters (>3000m) but feed at 500–

1000 m depths (where most of the food is found). As far as it is known, sperm whales feed 

regularly throughout the year. Lockyer (1981) estimated that they consumed about 3.0–3.5% of 

their body weight per day. 

A large proportion of the sperm whale’s diet consists of low-fat, ammoniacal, luminescent squids 

(Clarke 1980, 1996; Martin and Clarke 1986). In some areas of the North Atlantic, however, 

males prey heavily on the oil-rich squid Gonatus fabricii. A giant squid (Architeuthis sp.) as 

large as 12 m long and weighing 200 kg has been found in a sperm whale’s stomach (Berzin 

1972). While sperm whales feed primarily on large- and medium-sized squid, the list of 

documented food items is fairly long and diverse. Prey items include other cephalopods, such as 

octopus, and medium-and large-sized demersal fish, such as rays, sharks, and many teleosts 

(Berzin 1972; Clarke 1977, 1980; Rice 1989). The diet of large males in some areas, especially 

in high northern latitudes, is dominated by fish (Rice 1989). Lumpsuckers (Cyclopterus lumpus), 

for example, are frequently consumed by sperm whales in the Denmark Strait (Martin and Clarke 

1986). 

D.4 Competition 

May et al. (1979) provided a relatively simple example, using male sperm whales, squid, and 

krill in the Antarctic, to show how complex competition dynamics could be. According to their 

model, yield in the krill fishery is a function of both fishing effort on krill and the abundance of 

sperm whales. Sperm whales prey on cephalopods, which in turn, prey on krill. According to 

the model, the largest sustainable krill fishery in the Southern Ocean would be attained when 

sperm whales were not exploited there. 

There is no evidence that competition for prey resources is a factor limiting the abundance of 

sperm whales in the North Atlantic. Adult male sperm whales have been observed to aggregate 

near trawl nets targeting Greenland halibut (Reinhardtius hippoglossoides) in one area of the 

western North Atlantic, but they are not known to take fish from the nets (Leaper and Karpouzli 

1998). Two of the squid species eaten by sperm whales in the North Atlantic—Gonatus fabricii

and Todarodes sagittatus—are known to be important in the diets of northern bottlenose whales 

(Hyperoodon ampullatus, Gonatus only), long-finned pilot whales (Globicephala melas, both 

subspecies recognized in the North Atlantic and Southern Hemisphere), and short-finned pilot 

whales (G. macroryhncus) (Clarke 1997). However, there is no basis for assuming that 

competition for food among these three cetacean species is a factor in determining their 

population trend and abundance (Whitehead 2003). 

D.5 Reproduction 

Comprehensive information on the reproduction of sperm whales, obtained mainly from whaling 

specimens and observations made aboard catcher boats, has been reviewed by several authors 

(Best 1979; Best et al. 1984; Rice 1989). Observational studies of sperm whales during the 

1980s and 1990s, independent of the whaling industry, have improved understanding of the 
December 2010 I-10 NMFS 

complex social behavior and population dynamics of sperm whales. 

Sperm whales are organized in groups in which adult females (some related to each other and 

some not) travel with their sub-adult offspring. Mature female and immature sperm whales of 

both sexes are found in more temperate and tropical waters from the equator to around 45o

N 

throughout the year. North Pacific Discovery Mark data indicate that females were caught well 

above 50o

N and over 3,000 female sperm whales were killed above that latitude (Mizroch and 

Rice 2006). Sexually mature males join these groups throughout the winter. During the 

summer, mature male and some female sperm whales are thought to move north into the 

Aleutian Islands, Gulf of Alaska, and the Bering Sea. Based mostly on sighting surveys or land 

station whaling data, it is thought that they are often concentrated around oceanic islands in areas 

of upwelling, and along the outer continental shelf, continental slope, and mid-ocean waters 

(Hain et al. 1985; Kenney and Winn 1987; Waring et al. 1993; Waring and Finn 1995; Gannier 

2000; Gregr and Trites 2001; Waring et al. 2001). However, based on pelagic whaling data, 

sperm whales were found in large numbers in a broad band around 40oN in the northeastern 

North Pacific and a broad band around 30o

N in the northwestern Pacific (Mizroch and Rice 

2006). 

Sperm whales mature slowly. Females usually begin ovulating at 7–13 years of age and usually 

conceive at about age 9 (Rice 1989). Maturation in males usually begins in this same age 

interval, but most individuals do not become fully mature until their twenties. Prime bulls in 

their late twenties and older rove among groups of females. A male’s association with a female 

group can be as brief as several hours. Since females within a group often come into estrus 

synchronously, the male need not remain with them for an entire season to achieve maximal 

breeding success (Best and Butterworth 1980). The calving interval is estimated to be about four 

to six years (Best et al. 1984) and female sperm whales rarely become pregnant after the age of 

40 (Whitehead 2003). 

The peak breeding season for sperm whales in the North Atlantic occurs during the spring 

(March/April to June) with some mating activity taking place earlier or later, from December to 

August. Gestation lasts well over a year, with credible estimates of the normal duration ranging 

from 15 months to more than a year and a half. Lactation lasts at least two years, and the interbirth interval is 4–6 years, as mentioned above (Best et al. 1984), for prime-aged females and 

apparently much longer for 40+ year-olds. Presumably the peak breeding season in the South 

Atlantic occurs in the austral spring. 

Stable, long-term associations among related and unrelated females (Christal 1998) form the core 

units of sperm whale societies (Christal et al. 1998). Up to about a dozen females usually live in 

such groups, accompanied by their female and young male offspring. Males eventually leave 

these family groups after which they live in “bachelor schools.” The cohesion among males 

within a bachelor school declines as the animals age, although bonding is evident as males have 

mass stranded (Bond 1999). During their prime breeding period and old age, male sperm whales 

are essentially solitary (Christal and Whitehead 1997). 

Two particular aspects of the sperm whale’s reproductive biology are relevant to management. 

First, the maximal rate of increase in reproduction is very low, perhaps no more than one or two 
December 2010 I-11 NMFS 

percent per year. Second, selective killing of large males by whalers could have had the residual 

effect of reducing reproductive rates (Whitehead et al. 1997). 

D.6 Natural Mortality 

Known non-anthropogenic threats to sperm whales include predation, competition, and disease; 

however, there are many documented cases of strandings for which the cause is unknown. 

Sperm whales can live to ages in excess of 60 years (Rice 1989). The long-standing opinion has 

been that adult sperm whales are essentially free from the threat of natural predators (Rice 1989; 

Dufault and Whitehead 1995). Despite an observation off California showing a prolonged and 

sustained attack by killer whales on a pod of sperm whales (mainly adult females and juveniles) 

resulting in the severe wounding and death of some of the individuals (Pitman and Chivers 

1998), the paucity of documented attacks by killer whales indicates that predation risk to sperm 

whales is low. New hypotheses have been developed on how predation by killer whales has 

influenced marine mammal populations, including sperm whales (Springer et al. 2003; Mizroch 

and Rice 2006). However, while evidence indicates that predation by killer whales has been, and 

is still, a source of natural mortality for sperm whales (Pitman et al. 2001), the extent of impact 

on sperm whale populations is expected to be small based on the fact that few observations have 

occurred. Sperm whale calves are subject to predation by killer whales (Arnbom et al. 1987) and 

possibly large sharks (Best et al. 1984). Sperm whales are also “harassed” by pilot whales 

(Globicephala spp.) and false killer whales (Pseudorca crassidens), but most “attacks” by these 

species do not result in the death of sperm whales (Palacios and Mate 1996; Weller et al. 1996). 

Fighting also occurs between adult male sperm whales (Caldwell et al. 1966; Best 1979; Kato 

1984; Clarke and Paliza 1988; Whitehead 1993). 

Entire schools of sperm whales occasionally strand, but the causes of this phenomenon are 

uncertain (Rice 1989). In fact, the causes of standings of cetaceans in general are not well 

known. However, there is some evidence that sperm whale strandings may be linked to celestial 

cycles, although the precise mechanisms are not clear. Lunar cycles appear to influence 

strandings, possibly as a result of the effects that light levels have on the vertical migration of 

their prey species (Wright 2005). Solar cycles also seem to play a role, possibly by creating 

variations in the Earth’s magnetic field (Vanselow and Ricklefs 2005). 

Little is known about the role of disease in determining sperm whale natural mortality rates 

(Lambertsen 1997). Only two naturally occurring diseases that are likely to be lethal have been 

identified in sperm whales: myocardial infarction associated with coronary atherosclerosis and 

gastric ulceration associated with nematode infection (Lambertsen 1997). Recently, Moore and 

Early (2005) identified a type of cumulative bone necrosis in sperm whales that might be caused 

by the formation of nitrogen bubbles following deep dives and subsequent ascents, essentially 

decompression sickness, or what is called the “bends” in humans. 

D.7 Abundance and Trends 

Whitehead (2002) estimated current sperm whale abundance to be approximately 300,000–

450,000 worldwide. Although his estimates are based on extrapolating surveyed areas to 

unsurveyed areas, without a systematic survey design, these are probably the best available and 

most current estimates of global sperm whale abundance. Using Whitehead’s methods, 
December 2010 I-12 NMFS 

abundance in the Atlantic Ocean is approximately 90,000–134,000 sperm whales. Assuming 

that the population is growing at about 1.1%/year1, Whitehead also estimated that the global 

population is at about 32% of historical numbers. Since the Atlantic kills from 1940–1970 were 

less extreme than those in the Pacific (i.e., much less intensive whaling in the North Atlantic 

during this time than in the Pacific and Southern Oceans), the current status in the Atlantic is 

likely better than the global estimate (of 32%). 

Researchers have provided estimates of small populations of sperm whales within a relatively 

narrow portion of their range. All estimates from sighting surveys are negatively biased due to 

the long submergence times of sperm whales (i.e., dives lasting up to 2 hours). Furthermore, the 

bias associated with a given estimate can be highly variable, depending on the survey platform. 

Barlow and Sexton (1996) concluded that availability bias for ship surveys may be relatively 

small because of the substantial distance at which sperm whale blows can be detected. 

Abundance estimates from aerial surveys, in contrast, could be low by a factor of three to eight 

(Barlow 1994). 

The most extensive sperm whale surveys were shipboard surveys conducted in the western and 

central North Atlantic, during the period 1966–69, which provided a very crude estimate of 

approximately 22,000 sperm whales in the area bounded by 10–70°N and 20–80°W (Mitchell 

1972). 

Currently, the best estimate for the eastern coast of the United States (western North Atlantic) is 

4,804 (CV=0.38) based upon two vessel surveys and an aerial survey conducted during the 

summer of 2004; northern U.S. Atlantic is 2,697 (CV=0.57), and southern U.S. Atlantic is 2,197 

(CV=0.47) (Waring et al. 2009). This joint estimate is considered best because together these 

two surveys have the most complete coverage of the species’ habitat. These estimates were not 

corrected for dive time, and thus are likely downwardly biased and an underestimate of actual 

abundance (Waring et al. 2009). 

The estimate pertains to waters from Florida to the Gulf of Maine within the U.S. Exclusive 

Economic Zone (EEZ) and Canadian portions of the Gulf of Maine, but does not include the 

Nova Scotian shelf and Gulf of St. Lawrence. Thus, it does not apply to the entire range of 

sperm whales in the western North Atlantic, which extends across the Scotian Shelf and into the 

Labrador Sea and Davis Strait (Reeves and Whitehead 1997). The density of sperm whales 

along the U.S. east coast (17.04 per 1000 km2

) is the highest reported in a recent survey of sperm 

whale densities worldwide (Whitehead 2002). Shipboard surveys in the northern Gulf of Mexico 

between 1991 and 1995 resulted in estimates of 530 (CV=0.31) (Waring et al. 1997) and 442 

(CV=0.36) sperm whales (Jefferson 1996). More recent vessel surveys conducted during 2003–

2004 resulted in a combined estimate of 1,665 (CV=0.20) (Mullin 2007) for the oceanic northern 

Gulf of Mexico (Mullin and Fulling 2004). Although some surveys correct for missed animals, 

the survey estimates for the Gulf of Mexico are negatively biased, as they do not account for the 

 

1

 From Whitehead (2002): Maximum rate of increase: best r = 1.1%; reasonable range 0.7 to 1.5%. The population parameters 

used by the IWC (1982) suggest r = 0.9% for a population with stable age distribution, but these include very uncertain, and 

probably overestimated, mortality rates, and no changes with age in either fecundity or adult mortality. It may be more realistic 

to use the well-established mortality schedule of killer whales (Olesiuk et al. 1990) and an age-specific pregnancy rate taken from 

the data presented by Best et al. (1984; pregnancy rate for mature females = 0.257 – 0.0038 × Age in years), in which case the 

annual rate of increase with stable age distribution is 1.1% yr–1.
December 2010 I-13 NMFS 

long submergence time of sperm whales. Furthermore, the bias associated with a given estimate 

can be highly variable, depending on the survey platform. 

Sperm whales are rare in deep Atlantic waters offshore from Iceland and Norway south to the 

Iberian Peninsula, and east into the Mediterranean Sea. When observed, sperm whales are 

mainly seen around Iceland and off western Norway (Andenes), the west coast of Portugal, the 

north coast of Spain, and the Azores. In coastal North European waters, sperm whales are 

mainly reported from July to December. Estimates of sperm whale abundance from surveys in 

the eastern North Atlantic were 2,500 (CV=0.27) in July 1988 (Øien 1990). In the central North 

Atlantic, vessel surveys in June–August 1987, yielded abundance estimates of 4,925 (CV=0.16) 

and 902 (CV=0.45) sperm whales in Icelandic and Faroese waters, respectively (Gunnlaugsson 

and Sigurjønsson 1990). 

Best (1983) claimed that 19th century whalers took “a disproportionately large number” of 

sperm whales in the North Atlantic relative to other ocean basins. Thus, “if signs of 

overexploitation by the primitive fishery are to be detected, these might be most obvious in this 

region” (Best 1983). On the other hand, for most of the 20th century, sperm whales in the North 

Atlantic Ocean were subjected to much less intensive whaling than those in the North Pacific and 

Southern Oceans. Moreover, post-World War II whaling for sperm whales in the North Atlantic 

occurred primarily in areas where females were either absent or substantially less available than 

males (Avila de Melo and Martin 1985). Thus, one could argue that if signs of recovery from 

historical overexploitation were to be detected, they would most likely be found in the North 

Atlantic. No time series of survey data is available to address questions of population trend in 

the North Atlantic in a meaningful way, but several other types of analyses have been at least 

suggestive of trends. Length frequency data on catches at Iceland suggest that males larger than 

35 ft (10.5 m) and mature females in the North Atlantic declined progressively between 1905 and 

1979, with the greatest decline occurring in males from the 1940s onward (Hiby and Harwood 

1981). 

Trends in length frequency of males in the catches at Madeira and the Azores have been 

interpreted as suggesting (1) that the population of large, reproductively-active males at the 

Azores was over-exploited in the 1940s and 1950s, but was recovering by the 1970s; and (2) that 

this component of the population remained depleted at Madeira from the 1960s until the hunt’s 

closure there in 1981 (Avila de Melo and Martin 1985). 

Analyses of temporal trends in sperm whale strandings in the North Sea and British Isles have 

been interpreted as suggesting an increase in the whale population since the 1970s (Smeenk 

1997). However, Goold et al. (2002) reported that stranding of sperm whales in the North 

Atlantic have been increasing at a rate higher than would be expected from a simple increase in 

sperm whale population size alone. It is possible that the increased strandings frequency could 

be related to fishery bycatch (whales having drowned in gear) or to decreased individual health 

as a result of chemical contamination (Evans 1997). 

Although there is no complete abundance estimate for the Mediterranean Sea, estimates in 

smaller studies together with information on distribution and frequency of sightings were used to 

infer that there are fewer than 2,500 mature adults. Gannier et al. (2002) reported the highest 
December 2010 I-14 NMFS 

encounter rates in the northwestern portions of the Mediterranean, especially near the Gulf of 

Lions, and in eastern coastal areas of the Ionian Sea, especially off the Greek Islands. Estimated 

abundance for the Ionian Sea in 2003, based on surveys combining visual and acoustic 

techniques, was 66 individuals (with 95% lognormal confidence limits 28–156) (Lewis et al. 

2006). No sperm whales were observed on-transect during a survey of the Strait of Sicily (Lewis 

et al. 2006). These results are consistent with the number of photo-identified sperm whales 

along the Hellenic Trench (see below). Preliminary results from a survey of a large portion of 

the western basin (from Gibraltar to Sicily and bounded on the north by a line from the Balearics 

east to Sardinia) in Summer 2003 indicate a sperm whale detection rate roughly eight times that 

in the Ionian Sea (T. Lewis, IFAW, pers. comm.). This suggests that sperm whale numbers are 

significantly higher in the western basin than in the Ionian Sea, but still are likely to be only in 

the low to mid hundreds. Gannier et al. (2002) provided sperm whale visual and acoustic 

encounter rates for a large portion of the Mediterranean Sea, however, no absolute abundance 

estimates can be derived from their data. About 1500 individuals have been photo-identified in 

the Mediterranean Sea during the last decade (NAMSC 2004). 

E. Life History–Pacific Ocean Population 

E.1 Population Structure 

Stock structure in the North Pacific was a focus of intense discussion in the IWC Scientific 

Committee during the 1970s, a time when sperm whales were being heavily exploited by 

Japanese and Soviet pelagic whalers (IWC 1980). Masaki (1970) used tagging results, blood 

types, catch distributions, sighting patterns, and size compositions to establish the concept of 

three stocks: one west of 170°E (Asian stock), one between 180° and 160°W (mixed or Central 

stock), and one east of 150°W (American stock) (Tillman 1977). Ohsumi and Masaki (1977) 

emphasized that the “mixing” area in the central North Pacific was used primarily by males, and 

they proposed a two-stock scheme (east and west) for females, while retaining the previous 

three-stock scheme for males. 

Two attempts have been made to analyze historical whaling and tag-return data for insights about 

population separation in the North Pacific. Bannister and Mitchell (1980) evaluated Townsend’s 

(1935) monthly plots of catch positions and Maury’s (1852) whale charts showing effortcorrected indices of whale distribution. Both sets of documents were based on 19th century 

American whaling logbook records. The Maury and Townsend depictions were judged to be 

consistent with Masaki’s (1970) hypothesis of three reasonably well-defined populations. 

Kasuya and Miyashita (1988) evaluated biological, bio-chemical, oceanographic, whaling, 

tagging, and sighting data, and concluded that there were three populations, but with boundaries 

different from those suggested by earlier authors. Their analysis suggested that the eastern North 

Pacific (or American) population is widely distributed north of 20°N, with breeding schools 

circulating between Mexican waters in the southeast, the historical whaling grounds centered 

around the Hawaiian Islands, the Alaskan Gyre, and waters on the south side of the Aleutian 

Chain. The boundaries for this population are approximately the Aleutians in the north, the 

North American coast in the east, and a line connecting 52°30’N, 175°E and 20°N, 160°W. 

Adult males of this population tend to be segregated longitudinally (toward the west) rather than 

latitudinally (toward the north) from the females and juveniles. For the western North Pacific 

population, Kasuya and Miyashita (1988) proposed northwestern and southwestern populations 
December 2010 I-15 NMFS 

with the boundary shifting seasonally (Donovan 1991). 

In U.S. waters, NMFS recognizes three MMPA stocks in U.S. EEZ waters in the Pacific—

California/Oregon/Washington, Hawaii, and Alaska stocks (Carretta et al. 2009). Sperm whales 

in the eastern tropical Pacific are thought to belong to another population. Tag returns indicate 

that whales move between southern California and British Columbia (Rice 1974) and therefore, 

suggest that the California/Oregon/Washington population is separate from the Hawaiian 

population. However, Mizroch (pers. comm. 2009) indicates that there is likely no stock 

separation in the North Pacific based on Discovery Mark data and the northward movements of 

those whales currently separated into the Hawaii stock. Currently, studies of population 

structure using modern methods have not yet been completed for North Pacific sperm whales; 

therefore, any current designation of stocks or management units must be viewed as preliminary 

(Taylor and Dizon 1996). 

Mesnick et al. (1999a; unpublished data) addressed the question of population structure among 

sperm whales in the North Pacific using a data set of over 500 samples collected from 84 social 

groups and a custom-written program to control for the biases of relatedness among individuals 

sampled within groups (B.L. Taylor pers. comm. 2008). The authors analyzed variation in 

mtDNA and nuclear (microsatellite) loci and found significant north to south subdivision 

between samples collected in the California Current and samples collected to the south (between 

the Gulf of California and waters off central and northern South America and the Galapagos) and 

little east-west structure throughout the rest of the North Pacific. Estimates of population 

structure using all individuals (including relatives), or using only one individual per group, 

showed positive (more structure) and negative (less structure) biases, respectively, illustrating 

the need for factoring social structure into population level studies. Rendell et al. (2005, 2006) 

and Mesnick et al. (2008) addressed the question of cultural philopatry by examining mtDNA 

variation among vocal clans of sperm whales using samples from 194 individuals from 30 social 

groups belonging to one of three vocal clans. Both hierarchical Analysis of Molecular Variance 

and partial Mantel tests showed greater genetic subdivision among vocal clans than putative 

populations based on geography (Chile/Peru, Galapagos/Ecuador, and the Southwest Pacific). 

Currently, efforts are underway to define North Pacific stock structure based on 300 samples 

collected throughout the northeastern, southeastern, and central North Pacific using mtDNA and 

nuclear markers which, for the first time, will include the use of single nucleotide 

polymorphisms or SNPs to improve the power to detect structure (Mesnick et al. 1999a; S. L. 

Mesnick, pers. comm. 2008). 

Rice (1977), Wade and Gerrodette (1993), and Dufault and Whitehead (1995) also suggested that 

a separate equatorial Pacific sperm whale population exists. Rendell and Whitehead (2003) 

determined that in the South Pacific, female sperm whales appeared quite clearly structured into 

sympatric cultural clans, each with a distinctive dialect. Photo-identification matches and 

genetic data indicate movement between the Gulf of California and the Galapagos Islands, which 

includes movement across the equator (Jaquet et al. 2003). In all likelihood, at least the females 

and immatures are resident in these tropical and subtropical waters year-round. Genetic data 

indicate that these animals differ from those found off coastal California (Mesnick et al.

1999a,b). Photo-identification studies off the Galapagos Islands and mainland Ecuador and 

North Peru indicate that there may not be geographical separation between Galapagos and 
December 2010 I-16 NMFS 

Ecuador/ North Peru whales as previously indicated (Dufault and Whitehead 1995), as recent 

photo identification information shows several matches between the Galapagos and 

Ecuador/Peru and also some to Chile, although the genetics has yet to be verified. 

E.2 Distribution and Habitat Use 

The known distribution of sperm whales in the North Pacific Ocean can be attributed to whaling 

records, shipboard surveys, and acoustic detections using various recordings. The northern limit 

of adult male sperm whales in the North Pacific Ocean is estimated to extend from Cape Navarin 

Russia, to the Pribilof Islands in the northeastern Bering Sea (Berzin and Rovnin 1966). Females 

and juveniles generally range no further north than about 50–51°N in the southern Gulf of 

Alaska (Berzin and Rovnin 1966). 

Whaling records from the 19th century show that the primary whaling grounds for sperm whales 

were: (l) the Panama, Galapagos, and Offshore grounds in the eastern tropical Pacific; (2) the 

“On-the-Line Ground,” an almost continuous equatorial belt extending a few degrees north and 

south of the Equator in the central Pacific; (3) the Hawaiian Ground centered between 

approximately 20°N and 35°N; (4) areas off Baja California and mainland Mexico; (5) the Japan 

Ground (28–35°N, 150–179°E); (6) the Coast of Japan Ground (34–40°N, 142–149°E); and (7) 

the Bonin Islands Ground southeast of southern Japan (Townsend 1935). The more northern 

grounds were visited mainly in summer and fall, while the equatorial areas afforded 

opportunities for sperm whaling during other seasons, and in some cases, year-round. Sperm 

whales, including females and young males, were abundant on the whaling grounds up to 200 

miles offshore from Vancouver Island and the Queen Charlotte Islands, British Columbia from 

spring through fall (Pike and MacAskie 1969). Although Townsend’s (1935) charts show little 

evidence of sperm whales in the Gulf of Alaska and around the Aleutians, modern shore and 

pelagic whalers took adult males regularly in summer in deep offshore waters of the eastern 

Aleutians and Kodiak Island (Reeves et al. 1985). Sperm whale calls have been detected yearround in the Gulf of Alaska (Mellinger et al. 2004). Discovery Mark data from the days of 

commercial whaling (260 recoveries with location data) show extensive movements of both 

males and females from U.S. and Canadian coastal waters into the Gulf of Alaska and Bering 

Sea and the coast of Japan Ground and Bonin Islands Ground (Omura and Ohsumi 1964; Ivashin 

and Rovnin 1967; Ohsumi and Masaki 1975; Wada 1980; Kasuya and Miyashita 1988, Mizroch, 

pers. comm. 2008). Rice (AFSC-NMML, retired, pers. comm. in Angliss and Allen 2009) 

marked 176 sperm whales during U.S. survey cruises from 1962–1970, mostly between 32° and 

36°N off the California coast. Seven of those marked whales were observed in locations ranging 

from offshore California, Oregon, and British Columbia waters to the western Gulf of Alaska. A 

whale marked by Canadian researchers moved from near Vancouver Island, British Columbia to 

the Aleutian Islands near Adak. A whale marked by Japanese researchers moved from the 

Bering Sea just north of the Aleutians to waters off Vancouver Island, British Columbia 

(Mizroch pers. comm. 2009). Based on these data, there appear to be movements along the U.S. 

west coast into the Gulf of Alaska and Bering Sea/Aleutian Islands region. Large concentrations 

of breeding schools were reported by modern pelagic whalers along a line from 38°N, 142°W to 

45°N, 135°W, thence northwestward to 50°N, 138°W and westward to 52°N, 148°W (Berzin 

1972). The largest concentrations were centered around 50°N, 138°W and in a strip from 42°N, 

140°W to 50°N, 154°W. Large numbers of females were observed along 41°N latitude (Berzin 

1972). Of the nearly 60,000 sperm whales killed in the North Pacific above 50°N, 
December 2010 I-17 NMFS 

approximately 57,000 were males (Mizroch and Rice 2006 appendix). 

A vessel survey south of the eastern Aleutians found sperm whales in waters 4,000–5,000 m 

deep, either over the Aleutian Abyssal Plain or north of the Aleutian Trench over deep basins 

(Forney and Brownell 1997). Sperm whales have also been heard year-round on remote acoustic 

recorders in the Gulf of Alaska, but the number of sperm whale detections was approximately 

twice as high in summer compared to winter (Mellinger et al. 2004). 

Sperm whales are present in all months off California (Dohl et al. 1983; Barlow 1995; Forney et 

al. 1995), but they reach peak abundance from April through mid-June and again from the end of 

August through mid-November (Rice 1974). They are also present off Oregon and Washington 

in all seasons except mid-winter (Dec.–Feb.) (Green et al. 1992). Figure 1 illustrates the location 

of sperm whales seen during NMFS’ Southwest Fisheries Science Center surveys in the eastern 

North Pacific from 1986 through 2005. 

Figure 2. Location of sperm whales (b) seen on Southwest Fisheries Science Center surveys 

in the eastern North Pacific (1986–2005). Fine lines represent track lines surveyed during 

those years. 
December 2010 I-18 NMFS 

Whitehead et al. (1998) used acoustic dialects, fluke markings, and genetics (mtDNA 

haplotypes) to test for geography-based population structure of sperm whales in the South 

Pacific. This study found such structure to be weak in comparison to other non-geographically 

defined structures, but it is suggested that, if applied more intensively and on a larger geographic 

scale, this method could help elucidate the possible existence of a process of population 

differentiation in sperm whales. While latitudinal movements of mature males are believed to be 

seasonal (Best 1979), there is little evidence for this and seasonal components of female 

movement are even less clear (Whitehead 2003). While the following conclusions about sperm 

whales’ movements derived in the Whitehead et al. (2008) study refer only to the tropical 

Pacific, they are consistent with some data from other oceans using other methods (Kasuya and 

Miyashita 1988; Best 1979). Results of Whitehead et al. (2008) indicated that social units and 

groups of females/immature animals in the tropical Pacific adapted their movements over a range 

of temporal and spatial scales to the distribution of resources (Whitehead et al. 2008). In 

addition, Whitehead et al. (2008) suggested home ranges spanning 2000 km that may be related 

to the amount of habitat that an individual or social unit can keep track of, although occasional 

long-distance movements by a few individuals spanned about 4000 km. 

E.3 Feeding and Prey Selection 

See summary in Section D.3. 

E.4 Competition 

Sperm whales are known to interact with longline fisheries in many parts of the world, including 

the Gulf of Alaska where they reportedly take fish from gear set along the ocean bottom to catch 

sablefish (Anoplopoma fimbria) (Rice 1989) and halibut (Hippoglossus stenolepis) (Hill et al.

1997). Direct action taken by fishermen to protect their catch and gear from depredation by 

sperm whales could result in serious injury or mortality of the whales. In seeking to explain 

trends in North Pacific sperm whale populations, Kasuya (1991) referred to the possibilities of 

“competition for food resources among the males” and competition with trawl fisheries. As 

discussed in Section D.4, it is exceedingly difficult to evaluate the role of competition as a 

causative factor in population abundance and trends for large, wide-ranging cetaceans that feed 

on a variety of types of prey. 

E.5 Reproduction 

No differences in the basic reproductive biology of sperm whales in the North Pacific and North 

Atlantic are known or suspected, so, in general, the summary in Section D.5 applies here as well. 

One important consideration, however, is that the numbers of female sperm whales killed in the 

North Pacific by modern Japanese and Soviet whalers were greatly under-reported. Therefore, 

the killing of large breeding males in this ocean basin may not have reduced the pregnancy rate 

as much as previously believed. In other words, the reduction in number of whales may be due 

as much to the loss of potential mothers, as to the scarcity of potential fathers. 

E.6 Natural Mortality 

No differences in the natural mortality of sperm whales in the North Pacific and North Atlantic 
December 2010 I-19 NMFS 

are known (see summary in Section D.6). However, the relatively greater abundance of killer 

whales in the eastern North Pacific compared to the western North Atlantic (if indeed, this 

supposition is correct) could indicate that sperm whales are at greater risk of predation in the 

Pacific. 

E.7 Abundance and Trends 

The density of sperm whales (individuals per 1000 km2

) has been estimated for five large study 

areas in the North Pacific: 1.36 in the eastern tropical Pacific (Wade and Gerrodette 1993, as 

corrected by Whitehead 2002); 1.16 in the western North Pacific (Kato and Miyashita 1998, as 

corrected by Whitehead 2002); 1.7 off the U.S. West Coast (Barlow and Forney 2007); 3.4 to 4.2 

in the eastern temperate Pacific (Barlow and Taylor 2005); and 2.82 in the Hawaiian EEZ 

(Barlow 2006). Whitehead (2002) estimated current sperm whale abundance to be 

approximately 300,000–450,000 worldwide. Although his estimates are based on extrapolating 

surveyed areas to unsurveyed areas, without a systematic survey design, these are probably the 

best available and most current estimates of global sperm whale abundance. Abundance in the 

Pacific is approximately 152,000–226,000 using Whitehead’s methods. Assuming that the 

population is growing at about 1.1%/year2

, Whitehead also estimated that the global population 

is at about 32% of historical numbers. Since the Pacific kills from 1940–1970 were most 

extreme in the Pacific (hunting was not uniform across sperm whale habitats; the Atlantic was 

exploited before the Pacific and Indian Ocean areas and thus during this time period, more 

hunting of sperm whales was occurring in the Pacific Ocean than in the Atlantic Ocean), the 

current status there is likely worse than the global level (of 32%). 

Rice (1989) provided a crude estimate of 1,260,000 for the total pre-exploitation abundance of 

sperm whales in the North Pacific. Rice’s estimates for the North Pacific exceed the current 

worldwide abundance estimate for sperm whales (300,000–450,000; Whitehead 2002). 

According to Hill et al. (1997), “recent information indicates that these estimates are positively 

biased.” No further explanation was provided by these authors. Barlow et al. (1997) refer to the 

same set of estimates (Gosho et al. 1984) and dismiss them as based on a discredited catch-perunit-effort method. 

Wade and Gerrodette (1993) estimated that there were 22,700 (CV=0.224) sperm whales in the 

eastern tropical Pacific. These whales are thought to belong to a different population from those 

off California, Oregon, Washington, and northward. Barlow and Gerrodette (1996) estimated 

that there were 1,231 (CV=0.39; 1.5 per 1000 km2

) in California coastal waters (within 300 

nautical miles of shore) during summer and fall 1991–93, and Barlow (1997) estimated about 

1,200 (1,191, CV=0.22) within the same distance off California, Oregon, and Washington in 

1996. All of the foregoing estimates were based on line-transect ship surveys. Aerial surveys in 

California produced an estimate of 892 sperm whales (CV=0.99) during winter and spring 

 

2

 From Whitehead (2002): Maximum rate of increase: best r = 1.1%; reasonable range 0.7 to 1.5%. The population parameters 

used by the IWC (1982) suggest r = 0.9% for a population with stable age distribution, but these include very uncertain, and 

probably overestimated, mortality rates, and no changes with age in either fecundity or adult mortality. It may be more realistic 

to use the well-established mortality schedule of killer whales (Olesiuk et al. 1990) and an age-specific pregnancy rate taken from 

the data presented by Best et al. (1984; pregnancy rate for mature females = 0.257 – 0.0038 × Age in years), in which case the 

annual rate of increase with stable age distribution is 1.1% yr–1.
December 2010 I-20 NMFS 

(Forney et al. 1995), and this would need to be adjusted upward by 3 to 8 times to account for 

diving whales and provide a closer approximation to the true abundance (Barlow et al. 1997). 

In the eastern North Pacific, a shipboard line-transect survey for sperm whales, using combined 

visual and acoustic methods, was conducted in a 7.8 million km2

 area between the west coast of 

the continental United States and Hawaii in March–June 1997 (Barlow and Taylor 2005). The 

acoustic and sighting data were analyzed separately, yielding estimates of 32,100 (CV=0.36) and 

26,300 (CV=0.81), respectively, and the two estimates were not significantly different (Barlow 

and Taylor 2005). Barlow (2006) estimated sperm whale abundance in the U.S. EEZ waters 

surrounding Hawaii as 6,900 (CV=0.81). There are no available estimates for sperm whales in 

Alaskan waters and no recent estimates of abundance for the entire North Pacific. 

 In South Pacific waters, Childerhouse et al. (1995) determined, using photo-identification and 

an “open” mark-re-capture model, that between 60 and 180 (no CV) male sperm whales occur 

off Kaikoura, New Zealand each winter. In the equatorial Pacific, the total population of sperm 

whales between the Galapagos and Ecuador and North Peru was estimated at 3,891 (95% C.I. 

2,600–5,300) (Whitehead et al. 1992a,b). 

F. Life History-Indian Ocean Population 

F.1 Population Structure 

In the western Indian Ocean, there is evidence that concentrations of mixed female/immature 

whale groups exist south of the Seychelles (James and Soundararajan, 1979; Kasuya and Wada 

1991; (Kahn et al. 1993; Eyre 1995; James 1979). In the central Indian Ocean, concentrations of 

sperm whales have been recorded to the north of St. Paul and Amsterdam Islands in the austral 

summer (Gosho et al. 1984). 

F.2 Distribution and Habitat Use 

See Atlantic and Pacific sections. The Indian Ocean Sanctuary was created in 1979, under 

Article v(l)(c) of the International Whaling Convention for the Regulation of Whaling, and all 

commercial whaling was prohibited within its boundaries. This boundary extends from the 

Antarctic continent north to 55°S and from 20°E to 130°E. 

F.3 Feeding and Prey Selection 

See Atlantic Ocean section. 

F.4 Competition 

See Atlantic and Pacific Oceans sections. 

F.5 Reproduction 

See Atlantic and Pacific Oceans sections. 
December 2010 I-21 NMFS 

F.6 Natural Mortality 

See Atlantic and Pacific Oceans sections. 

F.7 Abundance and Trends 

No estimate of density, abundance or trends are available based on surveys in the Indian Ocean. 

Whitehead (2002) estimated current sperm whale abundance to be approximately 300,000–

450,000 worldwide. Although his estimates are based on extrapolating surveyed areas to 

unsurveyed areas, without a systematic survey design, these are probably the best available and 

most current estimates of global sperm whale abundance. If we use Whitehead’s methods, then 

abundance in the Indian Ocean is approximately 62,000–92,000 sperm whales. Assuming that 

the population is growing at about 1.1%/year3

 (in Whitehead 2002), Whitehead also estimated 

that the global population is at about 32% of historical numbers. 

G. Threats 

A threat is defined as any factor that could represent an impediment to recovery. In this recovery 

plan all threats, those that are natural and those that are human-related, are considered. The 

rankings were developed relative to each other, and put into one of four categories: high, 

medium, low, and unknown (i.e., further research is needed to determine whether it falls into 

high, medium, or low). Relative Impact to Recovery, which is defined in the last column in the 

threats table (Table 1) and at the end of each subsection, is a combination of the severity 

(magnitude, scope, and relative frequency with which the threat is expected to occur) and 

uncertainty of information for each. There are different types of uncertainty relating to threats. 

For example, there may be uncertainty about the extent to which something affects sperm whales 

(e.g., ship strikes); whether a factor affects sperm whales negatively or positively (e.g., climate 

change); or how a factor affects sperm whales (e.g., anthropogenic noise). Therefore, how 

severity and uncertainty interact (to produce Relative Impact to Recovery ranking) is unique by 

situation. Threats to sperm whales are summarized in Table 1. 

G.1 Fishery Interactions – LOW 

The vulnerability of sperm whales to incidental capture in fishing gear, especially gillnets set in 

deep water for pelagic fish (e.g., sharks, billfish, and tuna) and bottom-set longline gear, is well 

documented (Di Natale and Notarbartolo di Sciara 1994; Haase and Felix 1994; Felix et al. 1997; 

Hill et al. 1999; Straley et al. 2005; Warner et al. 2005). Sperm whales may break through or 

carry away fishing gear. Whales carrying gear may die at a later time due to trailing fishing gear, 

become debilitated or seriously injured, or have normal functions impaired, but with no evidence 

of the incident recorded. Sperm whales may also become entangled while attempting to 

depredate (described in detail in following sections) fish off fishing gear. Thus, it is possible that 

the increased strandings frequency in the Atlantic noted in Section D.7 could be related to fishery 

 

3

 From Whitehead (2002): Maximum rate of increase: best r = 1.1%; reasonable range 0.7 to 1.5%. The population parameters 

used by the IWC (1982) suggest r = 0.9% for a population with stable age distribution, but these include very uncertain, and 

probably overestimated, mortality rates, and no changes with age in either fecundity or adult mortality. It may be more realistic 

to use the well-established mortality schedule of killer whales (Olesiuk et al. 1990) and an age-specific pregnancy rate taken from 

the data presented by Best et al. (1984; pregnancy rate for mature females = 0.257 – 0.0038 × Age in years), in which case the 

annual rate of increase with stable age distribution is 1.1% yr–1.
December 2010 I-22 NMFS 

bycatch (whales having drowned in gear) (Evans 1997). Direct action taken by fishermen to 

protect their catch and gear from depredation by sperm whales could result in serious injuries or 

mortality. The ranking of the threat posed by the incidental capture of animals by global gillnet 

and longline fishing practices to sperm whale recovery was based on the assertion that although 

there is low severity and medium uncertainty with regard to impacts to individual animals, the 

impact to the recovery of sperm whale populations due to these fishing practices is considered 

low (Table 1). 

G.1.1 Atlantic Ocean/Mediterranean Sea – LOW 

In U.S. east-coast waters, bycatch of sperm whales has been documented in the pelagic drift 

gillnet fishery, which targeted primarily swordfish and tuna (Waring et al. 1997). In 1990, one 

whale was found entangled and was released in “injured” condition on Georges Bank. In June 

1995, one sperm whale was entangled with gear “in/around several body parts,” then released 

injured from a pelagic drift gillnet haul located on the shelf edge on Georges Bank. In addition 

to pelagic gear, in August 1993, a dead sperm whale, with longline gear wound tightly around 

the jaw, was found floating about 20 miles off Mt. Desert Rock, Maine. In October 1994, one 

sperm whale was successfully disentangled from a fine-mesh gillnet in Birch Harbor, Maine. 

There was one recorded death by entanglement in longline gear in the Caribbean (Northridge 

1996). The pelagic drift gillnet fishery closed in 1997 and the use of drift gillnets prohibited in 

1999. In May 1997, a sperm whale entangled in a net with three buoys trailing was sighted 130 

nm northwest of Bermuda, but no information on the status of that animal was provided. 

There have been no recent interactions between sperm whales and commercial fishing gear in the 

Gulf of Mexico (Waring et al. 2005). It is possible that some mortality and injury occurs in 

offshore fisheries without being documented, such as that resulting from “ghost fishing” by lost 

or discarded gear, but the level is unknown. During 2001–2005, human-caused mortality was 

estimated at 0.2 sperm whales per year (0.0 sperm whales per year from fisheries and 0.2. from 

ship strikes) off the east coast of the U.S. (Waring et al. 2009). 

In the North Atlantic, depredation has been recorded in waters around Norway, the southern 

coast of Greenland and the Davis Strait between Newfoundland and Greenland in fisheries 

targeting Greenland halibut (Reinhardtius hippoglossoides), Atlantic halibut (Hippoglossus 

hippoglosuss), Atlantic cod (Gadus morhua) and Greenland cod (Gadus ogac) (Dyb 2006; Nils 

Oien and Paul Winger, pers. comm. in Mesnick et al. 2008). In the Flemish Cap region, 

Karpouzli and Leaper (2004) recorded interactions with deep-water trawlers, where sperm 

whales appeared during hauling operations targeting Greenland halibut, and one case of 

entanglement in the trawl was reported. Between 2001 and 2005, no sperm whales were known 

to be killed due to fishery interactions in the U.S. Gulf of Mexico (Waring et al. 2009). 

In the Southern Atlantic Ocean interactions with sperm whales involve demersal longline 

fisheries for Patagonian toothfish (Dissostichus eleginoides). There are records of depredation or 

possible depredation occurring at several locations (Falkland, South Georgia) (CCAMLR 1994; 

Crespo et al. 1997; Nolan and Liddle 2000; Northridge 1996; Purves et al. 2004). In the 

Falkland Islands (Nolan and Liddle 2000; Yates and Brickle 2007) and in the Crozet Islands 

(Jerome Maison, pers. comm. in Mesnick et al. 2008) aggressive competition between sperm and 

killer whales for a spot at the hauling station of longliners was reported. Entanglements in 

longline fishing gear have been observed in South Georgia (Purves et al. 2004) and the Falklands 
December 2010 I-23 NMFS 

Islands (Helen Otley, pers. comm. in Mesnick et al. 2008). The threat posed by demersal 

longline fisheries was ranked as low based on the assertion that there is low uncertainty with 

regard to the extent the fishing practice may have on sperm whales and that the severity of the 

threat to the overall population was low (Table 1). 

Such results indicate that current fishing practices pose a low threat to the recovery of sperm 

whale populations in the Atlantic Ocean. However, levels of mortality and injury due to 

entanglement in lost or discarded gear and the number of cases of entanglement in fisheries that 

were not reported are unknown. The threat posed by pelagic drift gillnet fishing was ranked as 

low based on the assertion that there is low uncertainty with regard to the extent the fishing 

practice may have on sperm whales and that the severity of the threat to the overall population 

was low (Table 1). 

The Mediterranean Sea is an exception to this threat being considered low in severity. Should 

this population be later considered separately from the Atlantic Ocean basin, sperm whale 

entanglement is known to be a high risk factor in the swordfish drift gillnet fishery. The primary 

indication that this population is likely to have declined substantially is based on a reduced 

stranding rate where most strandings indicated entanglement mortality. Although the fishery is 

now illegal, fisheries entanglements continue. 

G.1.2 Pacific Ocean – LOW 

The offshore drift gillnet fishery targeting swordfish and sharks off Oregon, California, and Baja 

California (Mexico) is a recognized threat to sperm whales. While the California/Oregon drift 

gillnet fishery killed/seriously injured several sperm whales in the 1990s, since the creation of a 

leatherback sea turtle (Dermochelys coriacea) conservation area was implemented in 2001 off 

central California and Oregon (66 FR 44549), no sperm whales have been observed taken in this 

fishery. No estimates of mortality/serious injury are available for the Mexican drift gillnet 

fisheries (Carretta et al. 2009). Palacios and Gerrodette (1996) noted that sperm whales are at 

least occasionally killed in artisanal gillnet fisheries targeting sharks and large pelagic fishes off 

the Pacific coasts of northwestern South America, Central America, and Mexico. One sperm 

whale has been reported entangled in a longline fishery near Hawaii (Carretta et al. 2006), but 

that animal freed itself and was not considered to be seriously injured (Forney 2004). One sperm 

whale stranded dead in 2004 with 5 to 6-inch mesh nylon netting found in its stomach and two 

sperm whales stranded dead in 2008 with a variety of netting in their stomachs (U.S. Department 

of Commerce 2009, J. Cordaro, NMFS-SWR, pers. comm., 2009). The fishery source of those 

nets is unknown, but is currently being analyzed to determine the type and source (country/area). 

Mean annual takes for these “unknown” fisheries are based on 2002–2006 data (Carretta and 

Chivers 2004; Carretta et al. 2005a, 2005b; Carretta and Enriquez 2006, 2007). This results in 

an average estimate of 0.2 (CV = not available) sperm whale deaths per year attributed to all 

fisheries. The threat posed by the drift gillnet fishery was ranked as low based on the assertion 

that there is a low uncertainty with regard to the extent of impact the fishing practice may have 

on sperm whales and that the severity of the threat to the overall population was low (Table 1). 

 

In the North Pacific, longline depredation is a localized phenomenon, occurring mainly in the 

central and eastern Gulf of Alaska, occasionally in the western Gulf of Alaska and Aleutian 

Islands, and absent in the Bering Sea (Sigler et al. 2008). In this region, depredation occurs in 
December 2010 I-24 NMFS 

the sablefish (black cod) (Anoplopoma fimbria) and Pacific halibut fishery (Hippoglossus 

stenolepis) (Hill et al. 1999; Straley et al. 2005; Sigler et al. 2008). Investigations have been 

conducted to document rates of depredation, to understand how sperm whales manage to find 

vessels and remove fish from the gear, and to quantify the amount of prey removed and record 

the frequency of resulting mortality or serious injury due to entanglement. For instance, in 2006, 

the “Symposium on Fisheries Depredation by Killer and Sperm Whales: Behavioural Insights, 

Behavioural Solutions,” was held in British Columbia. Reports of depredation were first noted 

in 1978, in the Gulf of Alaska, and from 1989–2003, 38 surveyed stations recorded sperm whale 

predation on longline catch (Angliss and Outlaw 2005). However, from 1998 to 2004, neither 

sperm whale presence nor depredation rate increased significantly (Sigler et al. 2008). In 

collaboration with fishermen, research using genetic, acoustic, and fishing behavior studies has 

been conducted in the Sitka area to gain insight into what may attract sperm whales to longlining 

activity (Sigler et al. 2003; Straley et al. 2005). Preliminary analyses found that during a typical 

encounter when sperm whales are present during the haul, about 3%–6% of the catch was 

estimated to be removed, but sometimes over 50% of the catch has been lost by individual 

fishermen. As the frequency of depredation events increases, there are growing concerns about 

the potential for sperm whale entanglements and the prospect of growing economic losses. In 

Alaska there are reports of fishermen throwing seal bombs in the water and yelling at the whales 

when they depredate their gear. Reports of fishermen shooting whales with guns and harpoons 

in the artisanal fishery off Southeast Chile represent potentially fatal threats provoked by 

frustration with reduced catches due to sperm whale depredation (González and Olivarría 2002). 

Based on information documented from 1999–2003 (observer data), one sperm whale was 

observed with trailing gear from the Gulf of Alaska sablefish longline fishery, however, from 

2001–2005, there have been no observed serious injuries or mortalities in federally observed 

Alaska fisheries (Angliss and Outlaw 2007). However, in 2006, there were three observed 

serious injuries in the Gulf of Alaska sablefish longline fishery, which extrapolates to 10 

estimated serious injuries for that fishery for that year. Total estimated total annual takes is 2.01 

(CV=0.49) animals (Angliss and Allen 2009). 

The threat by North Pacific fishing practices in Alaska from the sablefish fishery to sperm whale 

recovery was ranked as low since only a small proportion of the population, when compared to 

the global population, depredates the sablefish fishery in Alaska. The severity and uncertainty of 

this threat are ranked as low. 

The average 5-year estimate within the Hawaiian Islands of annual mortality and serious injury is 

zero (between 1998–2002). Since 2001, the Hawaii-based long line fishery has undergone a 

series of regulatory changes, primarily to protect sea turtles, but the potential impacts of these 

regulatory changes on the rate of sperm whale interaction in unknown. The Hawaii-based 

longline fishery was ranked as low since few whales have interacted with these fisheries and the 

severity and uncertainty of these interactions is low (the one animal that was observed caught in 

longline gear was apparently able to free itself and not considered seriously injured) (Forney 

2004). 

Sperm whales may become entangled in fishing gear (recorded most often in demersal longline 

gear) while attempting to depredate fish off of the gear (Warner et al. 2005). Southern Pacific 
December 2010 I-25 NMFS 

Ocean interactions involve demersal longline fisheries for Patagonian toothfish (Dissostichus 

eleginoides). There are records of depredation or possible depredation occurring in Chile 

(Oporto and Brieva 1994; Ashford et al. 1996; González 2001; González et al. 2001; Olivarría 

2002; Hucke-Gaete et al. 2004). In Chile (Hucke-Gaete et al. 2004), aggressive competition 

between sperm and killer whales for a spot at the hauling station of longliners were reported. 

Entanglements in longline fishing gear have been observed in Chile (Ashford et al. 1996). 

Although the magnitude of these interactions is infrequently documented there are reports of 

sperm whales that have been shot by guns or harpoons and the use of explosives to keep animals 

away from fishing gear (González 2001). In addition, Haase and Felix (1994) recorded two 

instances in which sperm whales were killed after becoming trapped in tuna purse-seine nets off 

Ecuador. The ranking of the threat posed by the incidental capture of animals by these fishing 

practices to sperm whale recovery was listed under the global population/stock, reference G.1 

(Table 1). 

G.1.3 Indian Ocean – UNKNOWN 

Indian Ocean interactions with fishing gear involve demersal longline fisheries for Patagonian 

toothfish. There are records of depredation or possible depredation occurring at several locations 

(Crozet, and Kerguelen Islands; Capdeville 1997; CCAMLR 1994). In Crozet Island aggressive 

competition between sperm and killer whales for a spot at the hauling station of longliners were 

reported (S. Mesnick, pers. comm. 2006). Deepwater gillnets are still prevalent in the Indian 

Ocean and there is risk for entanglements with whales. 

The threat by Indian Ocean fishing practices to sperm whale recovery was ranked as unknown 

because of the high uncertainty with regard to the extent of impact the fishing practices may have 

on sperm whales and the unknown severity of the threat to the overall population. 

G.2 Anthropogenic Noise – UNKNOWN 

Humans have introduced sound intentionally and unintentionally into the marine environment for 

underwater communication, navigation, and research. Noise exposure can result in a multitude 

of impacts, ranging from those causing little or no impact to those being potentially severe, 

depending on level and on various other factors. Response to noise varies due to many factors, 

including type and characteristics of the noise source, distance between the source and the 

receptor, receptor characteristics (e.g., sensitivity, behavioral context, age, sex, and previous 

experience with sound source) and time of the day or season. Noise may be intermittent or 

continuous, steady or impulsive, and may be generated by stationary or transient sources. As one 

of the potential stressors to marine mammal populations, noise may seriously disrupt marine 

mammal communication, navigational ability, and social patterns. Marine mammals use sound 

to communicate, navigate, locate prey, and sense their environment. Both anthropogenic and 

natural sounds may cause interference with these functions. 

The effects of anthropogenic noise are difficult to ascertain and research on this topic is ongoing. 

The possible impacts of the various sources of anthropogenic noise, described below, have not 

all been well studied on sperm whales. The threat occurs at an unknown severity and there is a 

high level of uncertainty associated with the evidence described below. Thus, the relative impact 

of anthropogenic noise to the recovery of sperm whales is ranked as unknown (Table 1). 
December 2010 I-26 NMFS 

Types of Noise

Ambient and Discrete Sources 

Ambient or background noise levels are an important consideration in assessing acoustic 

impacts. Natural (e.g., wind, biologics) and anthropogenic sources contribute significantly to 

ambient noise levels as a whole (i.e., composite of all sources together) (Wenz 1962). These 

sound sources can occur locally or contribute from afar, like distant shipping (Curtis et al. 1999; 

Andrew et al. 2002; McDonald et al. 2006; McDonald et al. 2008). The ambient noise level of 

an environment can be quite complicated and vary from location to location (deep versus shallow 

water), from day to day, within a day, and/or from season to season. For example, the amount of 

noise from shipping can be correlated to amount of traffic (e.g., major shipping lanes are louder 

than other areas outside shipping lanes; Hatch et al. 2008). In addition to describing the ambient 

acoustic environment, sound can be described as discrete sources (e.g., individual seismic vessel, 

individual tactical sonar, individual ship). More information on sound produced by discrete 

sources is provided later in this section. 

Hearing Damage or Impairment 

The potential effects of continuous or impulse noise sources on sperm whales are of particular 

concern. Intense sound transmissions in the marine environment (i.e., explosives) may impact 

sperm whales by causing damage to body tissue or gross damage to ears, causing a permanent 

threshold shift (PTS) or a temporary threshold shift (TTS), if the animal is in close range of a 

sound source or exposed for a long duration. Additionally, an animal’s detection threshold may 

be masked by noise that is at frequencies similar to those of biologically important signals, such 

as mating calls. 

Masking 

An animal’s detection threshold may be masked by noise that is at frequencies similar to those of 

biologically important signals, such as mating calls. Masking, the obscuring of sounds of 

interest by interfering sources (generally at similar frequencies), occurs when noise interferes 

with a marine animal’s ability to hear a sound of interest. Marine mammals use acoustic signals 

for a variety of purposes, which differ among species, but include communication between 

individuals, navigation, foraging, reproduction, and learning about their environment (Erbe and 

Farmer 2000; Tyack 2000). “Auditory Interference,” or masking, generally occurs when the 

interfering noise is louder than, and of a similar frequency to, the auditory signal received by the 

animal. Masking these acoustic signals can disturb the behavior of individual animals, groups of 

animals, or entire populations. 

The size of this “zone of masking” of a marine mammal is highly variable, and depends on many 

factors that affect the received levels of the background noise and the sound signal (Richardson 

et al. 1995; Foote et al. 2004). Masking is influenced by the amount of time that the noise is 

present, as well as the spectral characteristics of the noise source (i.e., overlap in time, space, and 

frequency characteristics between noise and receiver). There are still many uncertainties 

regarding how masking affects marine mammals. For example, it is not known how loud 
December 2010 I-27 NMFS 

acoustic signals must be for animals to recognize or respond to another animal’s vocalizations 

(NRC 2003). It is also unknown if animals listen/respond to all the sounds they can hear or can 

be selective about what they will listen to. Richardson et al. (1995) argued that the maximum 

radius of influence of an industrial noise (including broadband low frequency sound 

transmission) on a marine mammal, is the distance from the source to the point at which the 

noise can barely be heard. This range is determined by either the hearing sensitivity of the 

animal or the background noise level present. Masking of industrial noise is likely to affect 

some species’ ability to detect communication calls and natural sounds (i.e., surf noise, prey 

noise, etc.; Richardson et al. 1995). 

Animals may try to minimize masking by changing their behavior. These behavior changes may 

include producing more calls, producing longer calls, or shifting the frequency of the calls. For 

example, it has been demonstrated that mysticetes, like the North Atlantic right whale (Parks et 

al. 2007; Parks et al. 2009) and blue whale (Di Iorio and Clark 2009) alter their vocalizations 

(call parameters or timing of calls) in response to background noise levels. 

The echolocation calls of toothed whales are subject to masking by high frequency sound. 

Human data indicate low frequency sound can mask high frequency sounds (i.e., upward 

masking). Studies on captive odontocetes (not sperm whales) (Au et al. 1974, 1985; Au 1993) 

indicate that some species may use various processes to reduce masking effects (e.g., 

adjustments in echolocation call intensity or frequency as a function of background noise 

conditions). There is also evidence that the directional hearing abilities of odontocetes are useful 

in reducing masking at the high frequencies used for echolocation, but not at the low-moderate 

frequencies used for communication (Zaitseva et al. 1980). 

There are still many uncertainties regarding how masking affects marine mammals, including 

sperm whales. The potential impacts that masking may have on individual survival, the 

behaviors marine mammals may exhibit to avoid masking, and the energetic costs of changing 

behavior to reduce masking, are poorly understood. 

Behavioral Response 

Behavioral reactions can vary not only among individuals but also for a given individual, 

depending on previous experience with a sound source, hearing sensitivity, sex, age, 

reproductive status, geographic location, season, health, social behavior, or context. The severity 

of the response can also vary depending on characteristics of the sound source (e.g., whether it is 

moving or stationary, number of sound sources) and/or the surrounding environment (e.g., how 

close to shore, region where animals may be unable to avoid exposure, propagation 

characteristics the area either enhancing or reducing exposure) (Richardson et al. 1995; NRC 

2003, 2005). As one of the potential stressors to marine mammal populations, noise and acoustic 

influences may seriously disrupt marine mammal communication, navigational ability, and social 

patterns. 

Most observations of behavioral responses of marine mammals to noise have been limited to 

short-term behavioral responses, which included the cessation of feeding, resting, or social 

interactions. 
December 2010 I-28 NMFS 

Relationships between specific sound sources, or anthropogenic sound in general, and the 

responses of marine mammals to those sources are still subject to scientific investigation, but no 

clear patterns have emerged (see Southall et al. 2007 for a review). Animals may adapt by 

altering vocalizations, but interruption of normal vocalizing behavior or other behaviors could be 

acutely changed for a period of time or slightly modified, which could have efficiency and 

energetic consequences4

. Sensitization (increased behavioral or physiological responsiveness 

over time) to noise could also exacerbate other effects, and habituation (decreased behavioral 

responsiveness over time) to chronic noise could cause animals to remain close to noise sources. 

Sound transmissions could also displace animals from areas for a short or long time period. 

Noise may also reduce the availability of prey, or increase vulnerability to other hazards, fishing 

gear, predation, etc. (Richardson et al. 1995). 

It is important to recognize the difficulty of measuring behavior in free-ranging whales. The 

cumulative effects of habitat degradation are difficult to define and almost impossible to 

evaluate. Additionally, there is a lack of information on how short-term behavioral responses to 

noise translate into long-term or population-level effects (Wartzok et al. 2004; NRC 2003, 2005). 

Responses of sperm whales to anthropogenic noises probably depend on the age and sex of 

animals being exposed, as well as other factors. There is evidence that many individuals respond 

to certain sound sources, provided the received level is high enough to evoke a response, while 

other individuals do not. Studies mentioned in the previous section on Masking suggest that the 

behavioral responses of sperm whales to anthropogenic noises are highly variable, but do not 

appear to result in the death or injury of individual whales or result in reductions in the fitness of 

individuals involved. For more specific information on potential impacts of noise associated 

with vessel traffic, oil and gas exploration, and military activities, see sections below. 

G.2.1 Ship Noise – UNKNOWN 

Sound emitted from large vessels, particularly in the course of transit, is a principal source of 

noise in the ocean today, primarily due to the properties of sound emitted by cargo vessels. Ship 

propulsion and electricity generation engines, engine gearing, compressors, bilge and ballast 

pumps, as well as hydrodynamic flow surrounding a ship’s hull and any hull protrusions and 

vessel speed contribute to a large vessels’ noise emission into the marine environment. Propdriven vessels also generate higher frequency noise through cavitations, which accounts for 

approximately 85% or more of the noise emitted by a large vessel. Larger vessels tend to 

generate lower frequency sounds and are louder (Polefka 2004). 

Surface shipping is the most widespread source of anthropogenic, low frequency (0 to 1,000 Hz) 

noise in the oceans (Simmonds and Hutchinson 1996). Ross (1976) estimated that between 1950 

and 1975, shipping had caused a rise in ambient noise levels of 10 dB. He predicted that this 

would increase by another 5 dB by the beginning of the 21st century. The National Research 

Council (2003) estimated that the background ocean noise level at 100 Hz has been increasing by 

about 1.5 dB per decade since the advent of propeller-driven ships and others have estimated that 

the increase in background ocean noise is as much as 3 dB per decade in the Pacific (Andrew et 

 

4

 Tyack (2008) speaks to the costs associated with marine mammals adjusting their vocalizations to compensate with noise in 

their environment. In birds, energetic costs have been reported with singing louder (Oberweger and Goller 2001). 
December 2010 I-29 NMFS 

al. 2002; McDonald et al. 2006, 2008). At this point, the severity of the threat of ship noise to 

sperm whales is unknown and uncertainty of the threat is high. Therefore, the relative impact to 

recovery of sperm whales due to this threat is ranked as unknown (Table 1). 

Other Miscellaneous Sound Sources 

There is some evidence of disruptions of sperm whale clicking and behavior from exposure to 

pingers (Watkins and Schevill 1975), the Heard Island Feasibility Test (Bowles et al. 1994), and 

the Acoustic Thermometry of Ocean Climate (ATOC) at Pioneer Seamount off Half Moon Bay, 

California (Costa et al. 1998). Sperm whales have been observed to frequently stop echolocating 

in the presence of underwater pulses made by echosounders, such as pingers, at 6 to 13 kHz 

(Watkins and Schevill 1975). Goold (1999) reported six sperm whales that were driven through 

a narrow channel using ship noise, echosounder, and fishfinder emissions from a flotilla of 10 

vessels. They also stop vocalizing for brief periods when codas are being produced by other 

individuals, perhaps because they can hear better when not vocalizing themselves (Goold and 

Jones 1995). 

G.2.2 Oil and Gas Exploration– UNKNOWN 

Drilling for oil and gas generally produces low-frequency sounds with strong tonal components. 

There are few recent studies on the noise from conventional drilling platforms. Recorded noise 

from an early study of one drilling platform and three combined drilling production platforms 

found that noise was so weak it was almost undetectable alongside the platform at Beaufort scale 

sea states of three or above. The strongest tones were at very low frequencies near 5 Hz 

(Richardson et al. 1995). 

Oil and gas exploration, including seismic surveys, typically operate with marine mammal 

observers as part of required mitigation measures. There have been no reported seismic-related 

or industry ship-related mortalities or injuries to sperm whales in areas where marine mammal 

observers are present, such as the Gulf of Mexico. However, the severity of this threat is 

unknown and the uncertainty of this threat is high. Therefore, the relative impact to recovery of 

sperm whales due to this threat is ranked as unknown (Table 1). 

Geophysical and Other Exploration 

A variety of devices and technologies exist which introduce energy into the water for purposes of 

geophysical research, bottom profiling, and depth determination. They are often characterized as 

high-resolution or low-resolution systems. Low-resolution systems such as 2-D and 3-D seismic 

surveys, put appreciable sound energy into the water and operate at low frequencies. 

Published reports identify instances in which sperm whales may have responded to an acoustic 

source and other instances in which they did not appear to respond behaviorally when exposed to 

seismic surveys. Sperm whales in the Gulf of Mexico apparently moved away, possibly by 50+ 

km, when seismic surveys began (Mate et al. 1994; Davis et al. 1995). However, Davis et al. 

(2000) noted that sighting frequency did not differ significantly among the different acoustic 

levels examined in the northern Gulf of Mexico, contrary to what Mate et al. (1994) reported. In 

one DTAG deployment in the northern Gulf of Mexico, researchers documented that the tagged 
December 2010 I-30 NMFS 

whale moved away from an operating seismic vessel once the seismic pulses were received at the 

tag at roughly 137 dB re 1 Pa (Johnson and Miller 2002). Preliminary data from an 

experimental study of sperm whale reactions to seismic surveys in the Gulf of Mexico and a 

study of the movements of sperm whales with satellite-linked tags in relation to seismic surveys 

show that during two controlled exposure experiments in which sperm whales were exposed to 

seismic pulses at received levels up to 148 dB re 1 Pa, the whales did not avoid the vessel or 

change their feeding efficiency (NRC 2003). Miller et al. (2009) found similar results, from 

eight sperm whales exposed to airgun arrays in the Gulf of Mexico that did not exhibit avoidance 

reactions to the airguns, but suggest the animals were affected at ranges beyond those currently 

regulated, due to more subtle effects on their foraging behavior. Some sperm whales in the 

Indian Ocean appeared to react similarly (i.e., by ceasing to vocalize) to the airgun pulses from a 

seismic vessel more than 300 km away and to the low-frequency sounds transmitted during the 

pre-ATOC “Heard Island Feasibility Test” (Bowles et al. 1994). Stone (2003) summarized the 

responses of marine mammals to seismic surveys off the United Kingdom and found that sperm 

whales showed no noticeable avoidance response. Although the sample size is small (4 whales 

in 2 experiments), the results are consistent with those off northern Norway (described below). 

Weir (2008) recently reported that sperm whales encounter rates were similar when airguns were 

firing compared to when they were off, as well as no incidences of overtly observable responses 

to airgun sound. 

Captive odontocetes (bottlenose dolphin and beluga whale) exhibited changes in behavior when 

exposed to a seismic watergun (Finneran et al. 2002). Behavioral changes typically involved 

what appeared to be deliberate attempts to avoid the location of the exposure site during 

subsequent tests or vocalizations after exposure, which began at ~187 dB 1 Parms for the beluga 

whale and 207 dB 1 Parms for the bottlenose dolphin. The relevance of these data to freeranging odontocetes is uncertain. In the wild, cetaceans sometimes avoid sound sources well 

before they are exposed to the levels listed above, and reactions in the wild may be more subtle 

than those described during captive studies. 

 

A recent study offshore of northern Norway indicated that sperm whales continued to call when 

exposed to pulses from a distant seismic vessel. Received levels of the seismic pulses were up to 

146 dB re 1 Pa peak-to-peak (Madsen et al. 2002). Similarly, a study conducted off Nova 

Scotia that analyzed recordings of sperm whale sounds at various distances from an active 

seismic program did not detect any obvious changes in the distribution or behavior of sperm 

whales (McCall Howard 1999). Seismic work off Angola found no difference in encounter rates 

of sperm whales or obvious behavioral changes due to air gun activity (Weir et al. 2001). Recent 

data from vessel-based monitoring programs in United Kingdom waters suggest that sperm 

whales in that area may have exhibited some changes in behavior in the presence of operating 

seismic vessels) (Stone 1997, 1998, 2000, 2001, 2003), but the compilation and analysis of the 

data led the author to conclude that seismic surveys did not result in observable effects to sperm 

whales (Stone 2003). However, there may have been adverse effects that this study did not 

detect, due to the difficulty of making surface observations for a species that spend relatively less 

time at the surface (Stone 2003). Nonetheless, the results from these surveys from the programs 

in United Kingdom waters are similar to previously mentioned studies and seem to show that 

some sperm whales tolerate seismic surveys. 
December 2010 I-31 NMFS 

Very little systematic information is available regarding the reactions of toothed whales to 

impulsive noises, like seismic pulses. Most of the energy in seismic pulses is at low frequencies 

(<125 Hz), where the auditory systems of small and medium-sized toothed whales are not very 

sensitive. However, some energy in seismic pulses at higher frequencies has been recorded 

(Madsen et al. 2006). Seismic pulses are strong enough to be detectable to small-to-moderate 

sized odontocetes many miles away, although avoidance reactions by these animals may be 

limited to considerably small distances (Richardson and WÜrsig 1997; Goold and Fish 1998). 

Thus, more information is needed regarding the effect of impulsive sound on toothed whales, and 

particularly on the specific pulse levels that may cause behavioral or other reactions. Some 

species may become silent (i.e., sperm whale) and/or move away from some sources of strong 

impulsive sounds, but the reactions vary depending on the species and their activities. In the 

presence of abundant food or during sexual encounters, toothed whales sometimes are extremely 

tolerant of noise pulses. There is currently no evidence of long-term changes in behavior or 

distribution as a result of occasional exposure to pulsed acoustic stimuli. Furthermore, because 

of sperm whales’ apparent role as important predators of mesopelagic squid and fish, changes in 

their abundance could affect the distribution and abundance of other marine species. 

Explosives 

Studies identify instances in which sperm whales did not respond (by altering behavior or click 

rate) to anthropogenic or impulse sounds such as the use of explosives. Sperm whales did not 

alter their vocal activity when exposed to levels of 173 dB re 1 Pa (peak equivalent root mean 

square) from impulsive sounds produced by 1 g TNT detonators (Madsen and Mohl 2000). 

Liquefied Natural Gas 

In recent years, many Liquefied Natural Gas (LNG) facilities have been proposed worldwide. 

The noise generated from construction and operation activities could affect marine mammals 

located within the vicinity of the project site. In addition, any increase in vessel traffic resulting 

from construction or operation of a LNG facility could negatively impact marine mammals 

migrating through the area. For more information on vessel impacts, see section G.3. 

G.2.3 Military Sonar and Explosives – UNKNOWN 

Military training activities by the U.S. Navy and the navies of other countries regularly occur in 

the Atlantic (including the Gulf of Mexico and Mediterranean Sea), Indian, and Pacific Oceans. 

These activities include anti-submarine warfare exercises, surface warfare exercises, anti-surface 

mine warfare exercises, missile exercises, sinking exercises, and aerial combat exercises. In 

addition to these training activities, the U.S. Navy conducts ship shock trials, which involve 

detonations of high explosive charges, and operates several permanent and temporary (portable) 

undersea warfare training ranges that employ acoustic sensors. 

These activities introduce a variety of sounds into the marine environment, but most studies have 

focused on the potential effects of active sonar, which has been associated with several marine 

mammal stranding events. The U.S. Navy employs several low-frequency (<1,000 Hz), midfrequency (1,000–10,000 Hz), and high-frequency (>10,000 Hz) active sonar systems. The U.S. 

Navy employs several mid-frequency sonar systems that range from large systems mounted on 
December 2010 I-32 NMFS 

the hulls of ships (e.g., AN/SQS-53 and -56), to smaller systems that are deployed from 

helicopters and fixed-wing aircraft, sonobuoys, and torpedoes. The primary low-frequency sonar 

active sonar system is the Surveillance Towed Array Sensor System Low Frequency Active 

(SURTASS LFA) sonar system, which produces loud signals in the 100–500 Hz range, and has 

operated in the western and central Pacific Ocean. These sonar systems can produce loud sounds 

at frequencies of between 1 and 10 kHz and higher (Evans and England 2001; U.S. Department 

of the Navy 2008). 

For decades, sperm whales have been exposed to sounds associated with these training activities 

in waters off the Atlantic Coast (including portions of the Gulf of Mexico), off Southern 

California, in waters off the main Hawaiian Islands, the Mariana Islands, and off the coasts of 

Washington, Oregon, and Alaska. This pattern of exposure is likely to continue into the 

foreseeable future. What is largely unknown is how sperm whales respond to this type of 

exposure and what the consequences of that exposure could be on the longevity and reproductive 

success of sperm whales. 

Although no audiograms are available for sperm whales, they are expected to have good, high 

frequency hearing because their inner ear resembles that of most dolphins, and appears tailored 

for ultrasonic (>20 kHz) reception (Ketten 1994). The only data on the hearing range of sperm 

whales are evoked potentials5

 from a stranded neonate, which suggest that neonatal sperm 

whales respond to sounds from 2.5 to 60 kHz. Sperm whales vocalize in high- and midfrequency ranges; most of the energy of sperm whales clicks is concentrated at 2 to 4 kHz and 10 

to 16 kHz. Other studies indicate sperm whales’ wide-band clicks contain energy between 0.1 

and 20 kHz (Weilgart and Whitehead 1993, Goold and Jones 1995). Ridgway and Carder (2001) 

measured low-frequency, high amplitude clicks with peak frequencies at 500 Hz to 3 kHz from a 

neonate sperm whale. Based on the limited information on their hearing sensitivities and 

assuming that their vocalizations provide some insight into their hearing, sperm whales would be 

expected to hear high- and mid-frequency sounds, but would have limited sensitivity to lowfrequency sounds. 

Sperm whales have been reported to have reacted to military sonar, apparently produced by a 

submarine, by dispersing from social aggregations, moving away from the sound source, 

remaining relatively silent and becoming difficult to approach (Watkins et al. 1985). Captive 

bottlenose dolphins and a white whale exhibited changes in behavior when exposed to 1 sec 

pulsed sounds at frequencies similar to those emitted by multi-beam sonar that is used in 

geophysical surveys (Ridgway et al. 1997, Schlundt et al. 2000), and to shorter broadband pulsed 

signals (Finneran et al. 2000, 2002). Behavioral changes typically involved what appeared to be 

deliberate attempts to avoid the sound exposure or to avoid the location of the exposure site 

during subsequent tests (Schlundt et al. 2000, Finneran et al. 2002). Dolphins exposed to 1-sec 

intense tones exhibited short-term changes in behavior above received sound levels of 178 to 193 

dB re 1 Pa rms and belugas did so at received levels of 180 to 196 dB and above. Received 

levels necessary to elicit such reactions to shorter pulses were higher (Finneran et al. 2000, 

2002). Test animals sometimes vocalized after exposure to pulsed, mid-frequency sound from a 

watergun (Finneran et al. 2002). In some instances, animals exhibited aggressive behavior 

 

5 An evoked potential is a test to evaluate the electrical activity of brain waves. 
December 2010 I-33 NMFS 

toward the test apparatus (Ridgway et al. 1997, Schlundt et al. 2000). The relevance of these 

data to free-ranging odontocetes is uncertain. In the wild, cetaceans sometimes avoid sound 

sources well before they are exposed to the levels listed above, and reactions in the wild may be 

more subtle than those described by Ridgway et al. (1997) and Schlundt et al. (2000). 

There is some evidence of disruptions of clicking and behavior from sonars (Goold 1999, 

Watkins and Scheville1975, Watkins et al. 1985), pingers (Watkins and Scheville 1975), the 

Heard Island Feasability Test (Bowles et al. 1994), and the Acoustic Thermometry of Ocean 

Climate (Costa et al.1998). Sperm whales have been observed to frequently stop echolocating in 

the presence of underwater pulses made by echosounders (Watkins and Scheville 1975). Goold 

(1999) reported six sperm whales that were driven through a narrow channel using ship noise, 

echosounder, and fishfinder emissions from a flotilla of 10 vessels. Watkins and Scheville 

(1975) showed that sperm whales interrupted click production in response to pinger (6 to 13 

kHz) sounds. They also stopped vocalizing for brief periods when codas were being produced 

by other individuals, perhaps because they can hear better when not vocalizing themselves 

(Goold and Jones 1995). 

Other studies identify instances in which sperm whales did not respond to anthropogenic sounds. 

Sperm whales did not alter their vocal activity when exposed to levels of 173 dB re 1 Pa from 

impulsive sounds produced by 1 g TNT detonators (Madsen and Mohl 2000). Richardson et al.

(1995) citing a personal communication with J. Gordon suggested that sperm whales in the 

Mediterranean Sea continued calling when exposed to frequent and strong military sonar signals. 

When Andre et al. (1997) exposed sperm whales to a variety of sounds to determine what sounds 

may be used to scare whales out of the path of vessels, sperm whales were observed to have 

startle reactions to 10 kHz pulses (180 db re 1 Pa at the source), but not to the other sources 

played to them. 

Published reports suggest that sperm whales might respond to sounds produced by seismic 

surveys in some instances and ignore the sounds in other instances. Mate et al. (1994) reported 

an opportunistic observation of the number of sperm whales to have decreased in an area after 

the start of airgun seismic testing. However, Davis et al. (2000) noted that sighting frequency 

did not differ significantly among the different acoustic levels they examined in the northern 

Gulf of Mexico, contrary to what Mate et al. (1994) reported. In one DTAG deployment in the 

northern Gulf of Mexico on July 28, 2001, the tagged sperm whale moved away from an 

operating seismic vessel once the seismic pulses were received at the tag at roughly 137 dB re 1 

Pa (Johnson and Miller 2002). Sperm whales may also have responded to seismic airgun 

sounds by ceasing to call during some (but not all) times when seismic pulses were received 

from an airgun array >300 km away (Bowles et al. 1994). 

A recent study offshore of northern Norway indicated that sperm whales continued to call when 

exposed to pulses from a distant seismic vessel. Received levels of the seismic pulses were up to 

146 dB re 1 Pa peak-to-peak (Madsen et al. 2002). Similarly, a study conducted off Nova 

Scotia that analyzed recordings of sperm whale sounds at various distances from an active 

seismic program did not detect any obvious changes in the distribution or behavior of sperm 

whales (McCall Howard 1999). Recent data from vessel-based monitoring programs in United 

Kingdom waters suggest that sperm whales in that area may have exhibited some changes in 
December 2010 I-34 NMFS 

behavior in the presence of operating seismic vessels (Stone 1997, 1998, 2000, 2001, 2003). 

However, the compilation and analysis of the data led the author to conclude that seismic surveys 

did not result in observable effects to sperm whales (Stone 2003). The results from these waters 

seem to show that some sperm whales tolerate seismic surveys. 

During two controlled exposure experiments in the Gulf of Mexico, four sperm whales were 

exposed to seismic pulses (300 Hz and 3 kHz) at received levels up to 147 dB re 1 Pa (rms). 

The sperm whales did were not reported to have avoided the vessel or to have changed their 

feeding efficiency (Madsen et al. 2006, Jochens et al. 2008). Although the sample size is small 

(4 whales in 2 experiments), the results are consistent with those off northern Norway. 

Captive bottlenose dolphins and a beluga whale exhibited changes in behavior when exposed to 

1 second pulsed sounds at frequencies similar to those emitted by tactical sonar (Ridgway et al.

1997; Schlundt et al. 2000). In this case, behavioral changes typically involved what appeared to 

be deliberate attempts to avoid the sound exposure or to avoid the location of the exposure site 

during subsequent tests (Schlundt et al. 2000). 

Underwater detonations associated with military training activities range from large high 

explosives such as those associated sinking exercises or ship shock trials, to missile exercises, 

gunnery exercises, mine warfare, disposal of unexploded ordnance, and grenades. Detonations 

produce shock waves and sound fields of varying size. Animals that occur close to a large 

detonation might be killed or seriously injured; animals that are further away might suffer lesser 

injury (i.e., tympanic membrane rupture, or slight to extensive lung injury); while animals that 

are even further away might experience physiological stress responses or behavioral disturbance 

whose severity depends on their distance from the detonation. 

Various measures are being developed to prevent sperm whales from being exposed to active 

sonar transmissions or underwater detonations. For example, the SURTASS LFA sonar system 

employs a high-frequency active sonar that allows the U.S. Navy to detect large and most small 

cetaceans and shut down sonar transmissions until whales have moved away from the sonar 

source; tests of this sonar system suggest that it detects more than 96 percent of the whales that 

occur within 1 kilometer of the sonar system. As another example, the suite of monitoring 

protocols the U.S. Navy developed during the ship shock trial on the U.S.S. Winston Churchill 

were effective at preventing fin whales, other cetaceans, and sea turtles from being exposed to 

the shock wave associated with those detonations. Other measures are being developed and 

tested to reduce the probability of exposing sperm whales and other cetaceans to active sonar 

transmissions and shock waves of underwater detonations. 

The relatively large spatial scale, frequency, duration, and diverse nature of these training 

activities in areas in which sperm whales also occur suggests that these activities have the 

potential to adversely affect sperm whales. However, the severity of the effect of military sonar 

and detonations on sperm whales and the effectiveness of measures that avoid any adverse 

effects remains largely unknown and the uncertainty of our knowledge is high. Therefore, the 

relative impact to recovery of sperm whales due to this threat is ranked as unknown (Table 1). 
December 2010 I-35 NMFS 

G.3 Vessel Interactions 

G.3.1 Ship Strikes – UNKNOWN BUT POTENTIALLY LOW

Laist et al. (2001), Jensen and Silber (2004), Vanderlaan and Taggart (2007), and Van 

Waerebeek and Leaper (2008) compiled information available worldwide regarding documented 

collisions between ships and large whales (baleen whales and sperm whales). Of 292 recorded 

strikes contained in the Jensen and Silber database (2004), 17 were of sperm whales. 

Sperm whales spend long periods (typically up to 10 minutes) “rafting” and socializing at the 

surface between deep dives (Jaquet et al. 1998; Whitehead 2003). This could make them 

vulnerable to ship strikes. There were also instances in which sperm whales approached vessels 

too closely and were cut by the propellers. Within specified areas of U.S. waters in the Atlantic, 

NMFS has established ship speed restrictions, mandatory ship reporting systems, recommended 

routes, and an extensive sighting advisory system to protect right whales. While these measures 

were designed to protect right whales specifically, they are expected to also reduce the risk of 

ship strikes to other marine mammals, including sperm whales (NMFS 2008a). 

Reports of ships colliding with sperm whales are said to be “frequent” in the Canary Islands, 

where ship traffic is heavy and the local density of sperm whales relatively high (André et al.

1997). André et al. (1997) in Laist et al. (2001), reports a case in the Canary Islands in which a 

high speed ferry collided with and killed a sperm whale while traveling at 45 knots. 

One of nine sperm whales found stranded on the north coast of the Gulf of Mexico between 1987 

and 1994 had “deep, parallel cuts posterior to the dorsal ridge that were believed to be caused by 

the propeller of a large vessel” (Waring et al. 1997). In May 1994, a ship-struck sperm whale 

was observed south of Nova Scotia (Reeves and Whitehead 1997) and in May 2000, a merchant 

shop reported a strike in Block Canyon (off the central east coast of the U.S.) (Waring et al.

2009). In the spring, Block Canyon is a major pathway for sperm whales entering southern New 

England continental shelf waters in pursuit of squid (CETAP 1982; Scott and Sadove 1997). 

From 2001–2003 one stranded sperm whale was reported struck by a naval vessel, and another 

whale was reported struck by a merchant vessel near Rhode Island (Waring et al. 2005). During 

2001–2005, mortality from ship strikes off the east coast of the U.S. was estimated at 0.2 sperm 

whales per year (Waring et al. 2009). Due to the sperm whale’s offshore distribution, it is likely 

that mortality and injury from ship strikes off the east coast of North America are documented 

less often than they occur (i.e., they are less likely to drift to shore and strand than some other 

species). 

More than 6% (7) of 111 sperm whales stranded in Italy (1986–1999) and Greece (1982–2001) 

had died after being struck by a vessel, and 6% of 51 photo-identified individuals (39 in Greece 

and 22 in Italy) bore wounds or scars that were clearly caused by a collision (Pesante et al.

2002). 

Two whales described as “possibly sperm whales” are known to have died in U.S. waters in 1990 

after being struck by vessels (Barlow et al. 1997). In 2005, two sperm whales were struck by a 

ship, but it is not known if these ship strikes resulted in a mortality or injury (U.S. Department of 

Commerce 2009). In 2007 a sperm whale calf was struck and killed off of Florence, Oregon 
December 2010 I-36 NMFS 

(U.S. Department of Commerce 2007). There were 14 unidentified whales struck by ships in 

California from 1982–2008 (California Marine Mammal Stranding Network Database, U.S. 

Department of Commerce 2009). While there have been some reports of sperm whales struck by 

ships, it does not appear that ship strikes are a significant threat to sperm whales (Whitehead 

2003). However, quantifying the effects of ship strikes in the U.S. is not possible, at this time. 

The possible impact of ship strikes on recovery of sperm whale populations is not well 

understood. Carcasses that do not drift ashore may go unreported, and those that do strand may 

show no obvious signs of having been struck by a ship. Because many ship strikes go unreported 

or undetected for various reasons and the offshore distribution of sperm whales may make ship 

strikes less detectable than for other species, the estimates of serious injury or mortality should 

be considered minimum estimates. The threat occurs at a medium severity and there is a 

medium level of uncertainty associated with the evidence above. While the number of sperm 

whale ship strikes is likely greater than those reported, the relative impact of this threat to 

recovery of the population is not considered significant. Thus, the relative impact to recovery of 

sperm whales due to ship strikes is ranked as unknown but potentially low (Table 1). 

G.3.2 Disturbance from Whale Watching and Other Vessels – LOW 

Several investigators reported behavioral responses to close approaches by vessels suggesting 

that individual whales might experience a stress response (Watkins et al. 1981; Baker et al.

1983; Malme et al. 1983; Bauer 1986; Bauer and Herman 1986; Baker and Herman 1987; 

Richardson et al. 1995; Jahoda et al. 2003). Others suggest that there is mounting evidence that 

wild animals respond to human disturbance in the same way that they respond to predators 

(Harrington and Veitch 1992; Lima 1998; Gill and Sutherland 2000; Gill et al. 2001; Frid and 

Dill 2002; Beale and Monaghan 2004; Romero 2004). These responses have been associated 

with the abandonment of sites (Bartholomew Jr., 1949; Allen 1991; Sutherland and Crockford 

1993), reduced reproductive success (Giese 1996; Müllner et al. 2004), and the death of 

individual animals (from expending energy and thus compromising their survival) (Feare 1976; 

Daan et al. 1996). 

With regard to sperm whales’ behavioral responses to tour vessels, Richter et al. (2006) found 

that sperm whales in Kaikoura, New Zealand respond to whale-watching activities with small 

changes in ventilation and vocalization patterns. These changes may not be of biological 

importance; however, compared to resident whales, transients, which receive less whalewatching effort, respond differently, and usually more strongly to whale-watching boats. This 

appears to be consistent with Gordon et al. (1992) who also examined the effects of whalewatching and approaching boats off the coast of Kaikoura, New Zealand on sperm whales’ 

behavior and found that sperm whales spent less time at the surface and adjusted their breathing 

intervals and acoustic behavior. The results suggest that sperm whales adjusted their diving and 

acoustic behavior to the whale-watching boats, but also that with frequent exposure, whales 

become increasingly tolerant of the vessels’ presence. Playback experiments were conducted in 

the Canary Islands using sounds expected to be aversive and to drive sperm whales away from a 

ferry route. One interpretation of the results was that sperm whales have a high tolerance for 

certain kinds of noise (André et al. 1997). A recent preliminary analysis of acoustical data from 

the northern Gulf of Mexico also indicates that sperm whales are, in some cases, affected by the 

passing of vessels, with fewer clicks and fewer whales detected afterwards (Loup et al. 2005). It 
December 2010 I-37 NMFS 

is not known if this reflects a change in sound-producing behavior, or the physical movement of 

whales away from the source. Interestingly, similar changes were observed, when the data were 

analyzed for the effects of a passing tropical storm (Newcomb et al. 2004). When Andre et al. 

(1997) exposed sperm whales to a variety of sounds to determine what sounds may be used to 

scare whales out of the path of vessels, sperm whales were observed to have startle reactions to 

10 kHz pulses (180 dB re 1 Pa at the source), but not to the other sources played to them. 

The potential for injury or disturbance to cetaceans from military ships is also a concern. NMFS 

conducted an assessment in its Biological Opinion on Rim of the Pacific (RIMPAC) exercises, 

focusing on ship traffic and mid-frequency sonar, and concluded that sperm whales in the action 

area were likely to respond to ship traffic associated with the maneuvers (NMFS 2008b). 

Sperm whales are not often seen from whale-watching vessels (either because the vessels are not 

located in areas where sperm whales are typically found or the vessels are disruptive and the 

sperm whales avoid them) on the east coast of the United States and Canada, and the potential 

for disturbance to sperm whales by such vessels is probably low. Based on this information, the 

threat occurs at a low severity and there is a medium level of uncertainty. Thus, the relative 

impact to recovery of sperm whales due to disturbance from vessels and tourism is ranked as low 

(Table 1). 

G.4 Contaminants and Pollutants – UNKNOWN 

A dramatic increase in the rate of sperm whale strandings in western Europe since the early 

1980s has raised concern that pollution may be implicated (Goold et al. 2002). Although the 

tissues of some of the stranded whales have been analyzed thoroughly for a wide range of 

contaminants, and detailed pathological examinations have been carried out on some of the 

whales, no clear link between contamination and stranding has been found (Jacques and 

Lambertsen 1997). Levels of mercury, cadmium, and certain organochlorines in these whales’ 

tissues, however, were high enough to cause concern about toxicity and other possibly indirect 

and less obvious effects (Bouquegneau et al. 1997; Law et al. 1997). 

A potential human-caused source of mortality is from accumulation of stable pollutants (e.g., 

polychlorobiphenyls (PCBs)), chlorinated pesticides (DDT, DDE, dieldrin, etc.), polycyclic 

aromatic hydrocarbons (PAHs), and heavy metals in long lived, high -trophic level animals. 

(NMFS 2005a). Holsbeek et al. (1999) analyzed tissue samples obtained from 21 sperm whales 

that mass-stranded in the North Sea in 1994/1995. Their results indicated that mercury, PCB, 

DDE, and PAH levels were low and similar to levels reported for other marine mammals. 

However, cadmium levels were high, and double the reported levels in North Pacific sperm 

whales. While these strandings were not attributable to contaminant burdens, Holsbeek et al. 

(1999) do suggest that the stable pollutants might affect the health or behavior of North Atlantic 

sperm whales. 

Levels of organochlorine contaminants in sperm whales that stranded dead off northwestern 

Spain were intermediate between the levels found in fin whales (Balaenoptera physalus) and 

small odontocetes in the same region (Aguilar 1983). Also, the levels in females were 

consistently higher than those in males, a finding contrary to the typical findings in cetaceans. 

Placental and milk transfer from mothers to their young normally results in a net lowering of 
December 2010 I-38 NMFS 

contaminant burdens in adult females. Given that male and female sperm whales are 

geographically separated during much of the year, it is possible that males feed in less polluted 

waters or perhaps on less contaminated prey than females. 

Japanese scientists have investigated the hypothesis that sperm whales provide a medium for 

transporting radioactive cobalt (and other artificial radionuclides) from the deep seabed to 

surface waters. Umezu et al. (1984) showed that 60Co bio-accumulates in sperm whales (from 

their diet that includes mesopelagic cephalopods). The authors proposed that 60Co is dispersed in 

surface waters when the whales defecate there. The implications for the overall health of sperm 

whales were not considered. 

In a review of organochlorine and metal pollutants in marine mammals from Central and South 

America, Borrell and Aguilar (1999) note that organochlorine levels in marine mammals (based 

on studies of franciscana dolphins (Pontoporia blainvillei) from Argentina and spotted dolphins 

(Stenella attenuata) from the eastern tropical Pacific) suggest low levels of exposure compared 

to other regions of the world. Indeed, although data are extremely scarce, concentrations of 

organochlorines in the tropical and equatorial fringe of the northern hemisphere and throughout 

the southern hemisphere are low or extremely low in marine mammals, and organochlorine 

concentrations in marine mammals off South America, South Africa and Australia are invariably 

low (Aguilar et al. 2002). The lowest organochlorine concentrations are found in the polar 

regions of both hemispheres. However, due to the systematic long-term transfer of airborne 

pollutants from warmer to colder regions, it is expected that the Arctic and, to a lesser extent, the 

Antarctic will become major sinks for organochlorines in the future, warranting long-term 

monitoring of polar regions (Aguilar et al. 2002). 

The highest concentrations of organochlorines found in marine mammals are in the 

Mediterranean Sea. High concentrations of organochlorines in marine mammals also occur, 

although to a lesser extent, along the Pacific coast of the U.S. and generally in other midlatitudes in the northern hemisphere (Aguilar et al. 2002). Fossi et al. (2003) state that 

concentrations in the Mediterranean could have an effect on reproductive rates of sperm whales, 

warranting further study (Fossi et al. 2003). 

Recently, Ocean Alliance, Inc. completed a five-year research voyage to collect baseline data on 

contaminants in the oceans. The team collected 955 sperm whale biopsy samples in 18 regions 

across the globe, with the goal of using sperm whales as global indicators of ocean 

contamination. The study will analyze levels of PCBs, DDT, and hexachlorobenzene (HCB) in 

samples collected. Analysis of toxic metals contained in the samples revealed high levels of 

aluminum in all samples, with more significant levels in the Atlantic and Indian Oceans than in 

the Pacific Ocean or Mediterranean Sea. The range of chromium levels found in the sperm 

whale samples was much higher than previously reported for wildlife, and was higher in the 

Pacific and Indian Oceans than in the Atlantic Ocean or Mediterranean Sea. Previous to this 

study, aluminum and chromium were not considered to be major health concerns. Mercury and 

selenium were detected in the samples, but mercury levels were not considered to be toxic to the 

whales. Also detected in the samples were lead and cadmium (Ocean Alliance 2010). 
December 2010 I-39 NMFS 

Oil Spills 

Oil spills that occur while sperm whales are present could result in skin contact with the oil, 

ingestion of oil, respiratory distress from hydrocarbon vapors, contaminated food sources, and 

displacement from feeding areas (Geraci 1990). Actual impacts would depend on the extent and 

duration of contact, and the characteristics (age) of the oil. Most likely, the effects of oil would 

be irritation to the respiratory membranes and absorption of hydrocarbons into the bloodstream 

(Geraci 1990). If a marine mammal was present in the immediate area of fresh oil, it is possible 

that it could inhale enough vapors to affect its health. Inhalation of petroleum vapors can cause 

pneumonia in humans and animals due to large amounts of foreign material (vapors) entering the 

lungs (Lipscomb et al. 1994). Contaminated food sources and displacement from feeding areas 

also may occur as a result of an oil spill. Long term ingestion of pollutants, including oil 

residues, could affect reproductive success, but data is lacking to determine how oil may fit into 

this scheme for sperm whales. 

Little is known about the possible long-term and trans-generational effects of exposure of sperm 

whales to pollutants. It is not known if high levels of heavy metals, persistent organic pollutants 

such as PCBs, and organochlorines found in prey species accumulate with age and are 

transferred through nursing, as demonstrated in other marine mammals, such as killer whales. It 

is also not known if exposure to oil from an oil spill will have a detrimental effect on sperm 

whales. 

In general, the threat from contaminants and pollutants occurs at an unknown severity and there 

is a high level of uncertainty. Thus, the relative impact to recovery of sperm whales due to 

contaminants and pollution is ranked as unknown (Table 1). However, this ranking may need to 

be revised if future data indicate reproductive rates are indeed impacted by exposed to 

contaminants or pollution. For instance, we may obtain new information based on the 2010 Gulf 

of Mexico oil spill that leads us to reevaluate threats from contaminants in general. 

G.5 Disease – LOW 

Disease presumably plays a role in natural mortality of sperm whales, but little is known. While 

serological studies on North Pacific and North Atlantic sperm whales indicate that these whales 

are carriers of and infected by calciviruses and papillomavirus (Smith and Latham 1978; 

Lambertsen et al. 1987), only two naturally occurring diseases that are likely to be lethal have 

been identified in sperm whales: myocardial infarction associated with coronary atherosclerosis, 

and gastric ulceration associated with nematode infection (Lambertsen 1997). The potential for 

parasitism to have a population level effect on sperm whales is largely unknown. Although 

parasites may have little effect on otherwise healthy animals, effects could become significant if 

combined with other stressors. Pollutants such as PCBs are known to suppress immune system 

function in some marine mammals, but there is considerable uncertainty in applying this 

knowledge to estimate how pollutants might increase disease susceptibility (Marine Mammal 

Commission 1999). Currently, there is no evidence of an increased level of disease in sperm 

whales, so the severity of this threat is considered to be low. However, given the potential but 

unknown effect of pollutants on immune suppression, the uncertainty in this determination is 

considered to be medium. Thus, the relative impact to recovery of sperm whales due to disease 

is ranked as low (Table 1). 
December 2010 I-40 NMFS 

G.6 Injury from Marine Debris – LOW 

Harmful marine debris consists of plastic garbage washed or blown from land into the sea, 

fishing gear lost or abandoned by recreational and commercial fishers, and solid nonbiodegradable floating materials (such as plastics) disposed of by ships at sea. Examples of 

plastic materials are bags, bottles, strapping bands, sheeting, synthetic ropes, synthetic fishing 

nets, floats, fiberglass, piping, insulation, paints, and adhesives. Marine species confuse plastic 

bags, rubber, balloons, and confectionery wrappers with prey and ingest them. The debris 

usually causes a physical blockage in the digestive system, leading to serious internal injuries. 

The bottom-feeding habit of sperm whales, which might involve a suction mechanism (as 

suggested by observations of apparently healthy sperm whales with deformed or broken jaws), 

indicates that they do ingest marine debris (Lambertsen 1997). The consequences can be 

debilitating and even fatal. In 1989, a necropsy on a stranded sperm whale carcass indicated that 

its death was caused by a stomach obstruction following accidental ingestion of plastic bags and 

sheets in the Lavezzi Islands of the Tyrrhenian Sea (Viale et al. 1992). In addition, one of 32 

sperm whales examined for pathology in Iceland had a lethal illness thought to have been caused 

by the complete obstruction of the gut with plastic marine debris (Lambertsen 1990). 

Observational studies cannot fully evaluate the potential for entanglement because many 

entangled animals may die at sea and thus not be seen or reported. Although instances of 

stomach obstruction caused by marine debris have been documented in sperm whales, these are 

few and it is not believed to be a major threat to the species, thus the severity of this threat is 

ranked as low. However, given the potential but unknown effect of entanglement and ingestion 

of marine debris on sperm whales, the uncertainty in this determination is considered to be 

medium. Thus, the relative impact to recovery of sperm whales due to marine debris is ranked as 

low (Table 1). 

G.7 Research – LOW 

Sperm whales have been the subject of field studies for decades. The primary objective of many 

of these studies has generally been monitoring populations to gather data for behavioral and 

ecological studies. Existing permits authorize investigators to make close approaches of 

endangered whales for photographic identification, behavioral observations, passive acoustic 

recording, aerial photogrammetry, and underwater observations. Reported responses of gray 

whales to research activities ranged from no visible responses to short-term behavioral 

responses; however, the consequences of these levels of close approaches on the population 

ecology of listed species remains unknown (Moore and Clarke 2002). Research on sperm 

whales is likely to continue and increase in the future, especially oceanographic surveys, 

collection of genetic information, photographic studies, and acoustic studies. 

The effects of research not directly associated with sperm whales are addressed in other 

subsections of the threats section of this Recovery Plan, such as vessel interactions, 

anthropogenic noise, contaminants and pollutants, oil and gas exploration and other industrial 

activities, and military sonar and explosives. 

Research activities could result in disturbance, but are closely monitored and evaluated in an 
December 2010 I-41 NMFS 

attempt to minimize any impacts of research necessary for the recovery of sperm whales. 

Specifically, the National Environmental Policy Act requires the development of environmental 

impact statements to assess the potential impact of a project on protected species, and ESA and 

MMPA permits are required for any incidental take of sperm whales. The threat occurs at a low 

severity and a medium level of uncertainty, as the potential does exist for unobserved mortality 

to occur following the completion of research activities. Thus, the relative impact to recovery of 

sperm whales due to this threat is ranked as low (Table 1). 

G.8 Predation and Natural Mortality – LOW 

Sperm whale calves are subject to predation by killer whales (Arnbom et al. 1987) and possibly 

large sharks (Best et al. 1984). However, other age classes are also targeted, as an observation 

off the coast of California showed a prolonged and sustained attack by killer whales on a pod of 

sperm whales, mainly juveniles and females, resulting in the severe wounding and death of some 

of the individuals (Pitman and Chivers 1998). Recently, Moore and Early (2005) identified a 

type of cumulative bone necrosis in sperm whales that might be caused by the formation of 

nitrogen bubbles following deep dives and subsequent ascents that could be attributed to 

avoidance of some type of threat. Large sharks are sometimes observed around sperm whales, 

particularly when newborn calves are present, and scars from shark bites have been observed on 

calves (Best et al. 1984). Sperm whale remains have been found in the stomachs of sharks, but 

these were probably from eating carcasses rather than preying on live animals (Rice 1989). 

There are also reports of pilot whales (Globicephala spp.) and false killer whales (Pseudorca 

crassidens) harassing and attacking sperm whales (Palacios and Mate 1996; Weller et al. 1996). 

In none of these cases were there fatalities, although pieces of flesh were observed in the water 

after the false killer whale incident, suggesting that this species may cause some of the marks 

and scars seen on sperm whales’ bodies (Palacios and Mate 1996). 

The potential impact of predation by killer whales on the dynamics of the North Pacific marine 

ecosystem over the last several decades has received substantial attention within the scientific 

community in recent years. Information on killer whale abundance, diet, and movements has 

increased, and new hypotheses have been developed within the scientific community on how 

predation by killer whales has influenced the dynamics of marine mammal populations. 

Evidence indicates that predation by killer whales has been, and still is, a source of natural 

mortality for sperm whales: however, the extent of natural mortality and predation is not known, 

as few observations have occurred. Thus, the relative impact to recovery from predation and 

natural mortality is ranked as low, based on low severity and medium uncertainty (Table 1). 

G.9 Direct Harvest – LOW 

Direct harvest was the main cause of the initial depletion of sperm whales and other large 

whales. The IWC’s moratorium on commercial whaling has largely mitigated this threat, 

however, the possibility of resumed whaling remains and has the potential to affect sperm whale 

populations. The principal products driving the commercial hunt for sperm whales were sperm 

oil and spermaceti. The latter is a semi-liquid waxy oil found only in the head of the sperm and 

some other toothed whales (Norris and Harvey 1972; Rice 1989). Sperm oil, taken from the 

bodies of sperm whales, has special lubricant properties, and the spermaceti was originally 

prized for use in candle-making and illumination. Ambergris (a perfume fixative found 
December 2010 I-42 NMFS 

occasionally in the lower intestines of male sperm whales; Gilmore 1969; Berzin 1972) and tooth 

ivory were also valuable byproducts of sperm whales. Sperm whale skin was used as low-grade 

leather in the Soviet Union (Berzin 1972). Having declined in the late 19th and early 20th 

centuries due to the increasing availability of petroleum for lubrication and lamp fuel, the 

demand for sperm oil and spermaceti greatly expanded after World War II as it was used in the 

manufacture of cosmetics and soaps and as machine oil (Berzin 1972; Rice 1989). Only in a few 

areas where coastal whaling has been conducted, notably in certain parts of Japan (Beary 1979; 

Brownell and Omura 1980), the West Indies (Price 1985), and Indonesia (Barnes 1991), has the 

meat of sperm whales been used regularly for human consumption. 

On a global scale, the exploitation of sperm whales can be regarded in terms of two main eras—

1) the open-boat, sailing-vessel, hand-harpooning period from about 1715 to 1925; and 2) the 

modern period from about 1910 to the early 1980s (Best et al. 1984). 

The total take of sperm whales worldwide between 1800 and 1909 has been estimated as close to 

700,000 and between 1910 and 1973, as close to 605,000 (Best et al. 1984). There is evidence of 

large-scale mis-reporting of whaling data from Soviet factory ships (Yablokov 1994; Zemsky et 

al. 1995). Kasuya (1998) also reported that post-war catch statistics from Japanese shore-based 

whaling also provided inaccurate data. It is clear that previously reported totals and sex ratios 

for North Pacific sperm whale catches are inaccurate, and it seems likely that the officially 

reported data from other areas will prove to be equally unreliable. 

The IWC’s moratorium on commercial whaling for sperm whales throughout the North Atlantic 

and North Pacific has been in place for two decades, and it has almost certainly had a positive 

effect on the species’ recovery. There is currently no legal commercial whaling for sperm 

whales by IWC member nations party to the moratorium. The ongoing threat of commercial 

whaling was one of the primary factors in the decision to add the sperm whale to the list of 

Endangered and Threatened Wildlife. This threat is not likely to recur on a more than local scale 

in the foreseeable future. However, it is important to recognize that whaling for sperm whales in 

the North Pacific was widespread and intensive as recently as the 1970s, and that the scale of 

removals was much larger than indicated in official whaling statistics. The ramifications of this 

recent whaling are uncertain, but give cause for concern. 

Two nations whose activities are relevant to sperm whale conservation in the North Atlantic have 

withdrawn their membership in the IWC, Canada in 1982 and Iceland in 1992. Norway6

 and 

Iceland have formally objected to the IWC ban on commercial whaling and are therefore under 

no obligation to refrain from hunting, but neither country has expressed interest in taking sperm 

whales. Whalers from the Azores and Madeira (both part of Portugal, not an IWC member), 

would not be legally bound by the IWC’s current moratorium on commercial whaling. Future 

terms in the IWC Schedule under which commercial whaling could be resumed would also not 

apply to whalers from these states. There is no evidence that whaling will resume in the 

 

6

 In 1982, the IWC adopted a temporary moratorium on the commercial whaling of all whale species, effective from 1986. 

Norway formally reserved its position on the moratorium, but nevertheless introduced a temporary ban on minke whaling 

pending more reliable information on the state of stocks. The Norwegian government unilaterally decided to resume whaling in 

1993. Norway’s legal right to hunt minke whales is not disputed, as Norway reserved its position on the temporary moratorium 

when it was adopted by the IWC. 
December 2010 I-43 NMFS 

Portuguese islands of the Azores and Madeira, even though Portugal remains outside any 

regulatory body. Canada has continued to ban whaling for the large baleen whales (except the 

bowhead, Balaena mysticetus) in its territorial waters under domestic regulations, and a 

resumption of sperm whaling in Canada is unlikely in the near future. Iceland has not resumed 

its hunting of fin, minke, sei (Balaenoptera borealis), or sperm whales at the time of this writing. 

Shore-based artisanal whaling in the West Indies may result in the killing of a few sperm whales 

in some years (Price 1985; Reeves 1988), but there is no reason to expect an immediate 

expansion in effort or increase in take there. 

As mentioned previously in the Reproduction section of this Recovery Plan, selective killing of 

large males by whalers could have had the residual effect of reducing reproductive rates 

(Whitehead et al. 1997) and the maximal rate of increase in reproduction is very low, perhaps no 

more than one or two percent per year. No new information is available regarding the direct 

harvest of sperm whales. Although historical whaling activities were responsible for the 

depletion of sperm whales worldwide, they are now hunted only by Japan and in small numbers 

(the 2008 program proposed the taking of 10 sperm whales in the western North Pacific), and 

therefore, the threat of overutilization by direct harvest is currently low. However, if the IWC’s 

moratorium on commercial whaling was ended, direct harvest could again become a threat to 

sperm whales, so direct harvest was addressed in this plan. The relative impact of direct harvest 

to recovery of sperm whales was ranked as low (Table 1). 

G.9.1 Direct Harvest – Atlantic Ocean/Mediterranean Sea 

The hunting of sperm whales began in New England in the early 1700s and spread by midcentury throughout the North Atlantic Ocean (Starbuck 1878). No detailed, comprehensive 

record has been compiled of the number of sperm whales taken, but the total kill by the multinational sailing-vessel, open-boat hunt, including whales lost at sea after being killed or mortally 

wounded, would likely have been in the hundreds of thousands. Roughly 3,600 were taken 

(secured) by American pelagic whalers from 1900–1925 in the North Atlantic (including the 

Gulf of Mexico and Caribbean Sea) (Anon. 1981b). 

In contrast, the record of kills by modern whalers (including the whalers at shore stations in the 

Azores and Madeira who continued using open-boat, hand-harpoon whaling techniques until the 

stations closed in the 1980s) is nearly complete. An attempted compilation of all catches in the 

North Atlantic north of 20°N from 1905 onward, gave totals of 28,728 males and 9,507 females 

taken (Anon. 198la). 

In the eastern and central North Atlantic (as far west as Iceland), nearly 30,000 sperm whales 

were killed between 1893 and 1975 (Jonsgård 1977). More than 16,500 of these were taken at 

the Azores between 1933 and 1975. The open-boat hunt for sperm whales at the Azores 

operated continuously from the 1830s to the 1980s, with a highest single-year catch of more than 

700 animals (Clarke 1954; Martin and Avila de Melo 1983; Avila de Melo and Martin 1985). 

Sperm whale hunting took place at Madeira from 1941 (Avila de Melo and Martin 1985) to 1981 

(Klinowska 1991). Shore-based whalers from Portugal, Spain, and northwest Africa took close 

to 7,500 sperm whales between 1921 and 1980 (Sanpera and Aguilar 1992). 

The exploitation of sperm whales in the western North Atlantic during the 20th century was 
December 2010 I-44 NMFS 

comparatively low. It must be borne in mind, however, that pelagic whaling by sailing-ship 

whalers continued until the 1920s (Townsend 1935; Clarke 1954; Hegarty 1959), and their 

catches, many of which were made in the whaling grounds off the American coast (Reeves, 

unpublished data), have not been included in most statistical compilations. Canadian whalers 

based in Labrador and Newfoundland took about 424 sperm whales between 1904 and 1972, all 

of them males (Mitchell and Kozicki 1984). A total of 109 sperm whales, all males, were taken 

off Blandford, Nova Scotia, between 1964 and 1972 (Mitchell 1975; Mitchell and Kozicki 1984). 

Reported kills in Davis Strait (off West Greenland), including both land-based and pelagic 

whaling, totaled 147 from 1924 to 1972 (Kapel 1979). Greenlanders consider sperm whale flesh 

unfit for human consumption and only poor-quality dog food. Sperm whales have been taken in 

small numbers in the West Indies by whalers using hand-harpoon, open-boat techniques (Price 

1985; Reeves 1988). 

G.9.2 Direct Harvest – Pacific Ocean 

The American pelagic sperm whale hunt reached North Pacific waters in the first quarter of the 

19th century and remained active there for approximately a century (Starbuck 1878; Hegarty 

1959; Best 1983). European whalers also hunted for sperm whales in the North Pacific through 

at least the first third of the 19th century, but then gave way to the American whalers (Stackpole 

1972; Best 1983). Shore-based whaling stations that became established following the advent of 

steam power and the invention of the exploding grenade harpoon, took sperm whales in Alaska 

(Reeves et al. 1985), British Columbia (Pike and MacAskie 1969), Washington (Scheffer and 

Slipp 1948), and California (Rice 1974; Clapham et al. 1997), as well as Japan, the Kuril Islands, 

and Kamchatka in the western North Pacific (Berzin 1972; Ohsumi 1980). Pelagic whaling for 

North Pacific sperm whales by factory ship operations began in the Soviet Union in 1932 and in 

Japan, soon after World War II. Peak annual catches by modern whaling before the war were 

less than 2,000, but after the war they reached more than 16,000 in 1968 (Ohsumi 1980). 

According to Ohsumi (1980), approximately 269,000 sperm whales were taken by modern 

whalers in the North Pacific between 1910 and 1976 (but see below regarding under-reporting 

and mis-reporting of catch data). From 1968 to 1972, the whaling fleets moved further south and 

took large catches of sperm whales in the whaling grounds along the Subarctic Boundary (ca. 

42°N). By 1973, there were almost no whale catches north of 50°N. There was a peak in sperm 

whale catches in 1969. Mizroch and Rice (2006) noted that whale catches from 1946 to 1967 

showed a high density of sperm whale catches in the traditional whaling areas through 1967, and 

then from 1968 to 1987, sperm whale catches shifted much farther south, starting in 1968. There 

were no sperm whale catches in most of the areas north of 50°N after 1967. Based on official 

statistics after 1947, the overall male-to-female ratio in the catches was about 3 to 1 (however, 

see below). 

Data presented by Kasuya (1998) indicate large-scale manipulation of the post-war catch 

statistics in Japanese shore-based whaling, including not only the falsification of body lengths of 

under-sized whales and the under-reporting of catches, but also the deliberate listing of females 

as males. Soviet mis-reporting is also known to have occurred on a massive scale (Yablokov 

1994; Zemsky et al. 1995). Brownell et al. (1998) estimated that the true catch of sperm whales 

by the USSR between 1949 and 1971 (the year before the IWC’s international observer scheme 

came into effect) was about 180,000, or some 60% higher than was officially reported. 

Moreover, these authors surmised that the scale of under-reporting was much greater for females 
December 2010 I-45 NMFS 

than for males, about 1.3 versus 9.6 times, respectively. It is clear that previously reported totals 

and sex ratios for North Pacific sperm whale catches are wrong. 

The NMFS 2007 Stock Assessment Report states: “...a total of at least 436,000 sperm whales 

were taken between 1800 and the end of commercial whaling for this species in 1987. Of this 

grand total, an estimated 33,842 were taken by Soviet and Japanese pelagic whaling operations 

in the eastern North Pacific from the longitude of Hawaii to the U.S. West coast, between 1961 

and 1976 (Allen 1980, IWC statistical Areas II and III), and 965 were reported taken in land-base 

U.S. West coast whaling operations between 1947 and 1971 (Ohsumi 1980). In addition, 13 

sperm whales were taken by shore whaling stations in California between 1919 and 1926 

(Clapham et al. 1997). Some of the whales taken during the whaling era were certainly from a 

population or populations that occur within Hawaiian waters” (Carretta et al. 2007). 

It has been suggested that the large 20th century catches of sperm whales in the North Pacific not 

only further reduced the population below its pre-exploitation level and (possibly) reduced 

pregnancy rates by reducing the number of breeding males (Whitehead 1987), but also may have 

1) increased mortality within family units because key individuals were lost, making groups less 

able to defend themselves against killer whales and less adept at tracking resources; and 2) 

affected social structure, forcing depleted or fragmented pods to coalesce and form groups of 

mixed maternal lineages (Richard et al. 1996). 

G.9.3 Direct Harvest – Indian Ocean 

The Indian Ocean sperm whale populations were almost exterminated from areas such as the 

Seychelles back in the 19th Century by Yankee whalers, and by the latter half of the 20th 

Century, modern whaling had brought all large whale species to the point of near biological 

collapse. It was recently revealed that illegal whaling activity by the Soviets in Omani waters in 

the 1960s, devastated the humpback, Bryde’s (Balaenoptera edeni), and sperm whale 

populations. At that time, most Indian Ocean populations of large whales had been devastated 

by commercial whaling activities. In the 1970s, the Soviet fleets continued to reduce sperm 

whale populations that were not protected by the ban on factory ship whaling north of 40 degrees 

south latitude. The widespread slaughter included thousands of females and family groups 

together with juveniles. This widespread whaling likely destroyed intact social groups of sperm 

whales in the area. Gradual reductions and restrictions were implemented leading up to the 

global moratorium. Whaling by factory ships ended in 1980. 

A proposal by the Republic of the Seychelles at the 1979 meeting of the IWC was adopted, 

creating the Indian Ocean Sanctuary (IWC 1980). This Sanctuary consists of those waters of the 

Northern Hemisphere from the coast of Africa east to 100°E (including the Red and Arabian 

Seas and the Gulf of Oman) and those waters of the Southern Hemisphere between 20°E and 

130°E from the equator to 55°S. The Indian Ocean Sanctuary offers protection from commercial 

whaling to the great whales (IWC 1980), including sperm whales.

The Southern Ocean, consisting of most of the area south of 40o

S latitude, was declared a whale 

sanctuary by the IWC in 1994 under a proposal by France. The main argument in favor of the 

Southern Ocean Sanctuary was to protect the Indian Ocean’s whales when they migrated south to 

feed in Antarctic waters. Japan continues to whale in the Southern Ocean Sanctuary for 
December 2010 I-46 NMFS 

scientific purposes, mainly for minke whales (Balaenoptera acutorostrata). Some of these 

whales are believed to migrate north into the Indian Ocean in winter. 

For most countries, the declaration of the Indian and Southern Ocean Sanctuary has begun a new 

era in cetacean studies and has since stimulated a great deal of research in this least known of the 

three large oceans. 

G.10 Competition for Resources – LOW 

The prey species taken by sperm whales are also taken by other cetaceans. Thus, competitive 

interactions are possible; however, there is no basis for assuming that competition for food 

among these cetacean species is a factor in determining their population trend and abundance. 

Fishery-caused reductions in prey resources could also have an influence on sperm whale 

abundance. The effect on sperm whales’ foraging efficiency resulting from disruption of large 

prey aggregations due to commercial fishing is not well known. Commercial removal of prey 

species may have a limited effect on sperm whales, particularly if a large biomass remains 

unharvested and accessible. Furthermore, the disruption of large aggregations of prey into 

multiple smaller aggregations by fishing activity could enhance sperm whale foraging success. 

The species-specific duration and degree of prey disruption due to commercial harvest are also 

unknown and it is not known what impact switching to alternate prey may have on sperm 

whales. Other threats that could be confounded with fisheries are environmental variability and 

inter-specific competition. Research is needed to reduce these uncertainties. The severity of this 

threat was ranked as low and the uncertainty was ranked as medium, thus the relative impact to 

recovery of sperm whales due to this threat is ranked as low (Table 1). 

G.11 Loss of Prey Base Due to Climate and Ecosystem Change – UNKNOWN

Although the future consequences of climate and ecosystem change are not understood, it is 

possible that sperm whale prey bases may be affected. 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 

productivity in the North Pacific (Quinn and Neibauer 1995; Mackas et al. 1998) and other 

oceans could be affected by changes in the environment. 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 Climate Change 2007). The 

potential impacts of climate and oceanographic change on sperm whales will likely affect habitat 

availability and food availability. Site selection for whale migration, feeding, and breeding for 

sperm whales, may be influenced by factors such as ocean currents and water temperature. 

There is some evidence from Pacific equatorial waters that sperm whale feeding success and, in 

turn, calf production rates are negatively affected by increases in sea surface temperature (Smith 

and Whitehead 1993; Whitehead 1997). This could mean that global climate change will reduce 

the productivity of at least some sperm whale populations (Whitehead 1997). Any changes in 

these factors could render currently used habitat areas unsuitable. Changes to climate and 

oceanographic processes may also lead to decreased productivity, different patterns of prey 

distribution, and changes in prey availability. Such changes could affect sperm whales that are 

dependent on those affected prey. 
December 2010 I-47 NMFS 

The feeding range of sperm whales is likely one of the greatest of any species on earth, and 

consequently, it is likely that the sperm whale may be more resilient to climate change, should it 

affect prey, than a species with a narrower range. The severity of the threat posed by 

environmental variability to sperm whale recovery was ranked as unknown due to the 

oceanographic and atmospheric conditions that have changed over the last several decades, and 

the uncertainty was ranked as high due to the unknown potential impacts of climate and 

ecosystem change on sperm whale recovery and regime shifts on sperm whale prey; therefore the 

relative impact to recovery was ranked as unknown (Table 1). 

G.12 Cable Laying – LOW 

Heezen (1957) documented marine mammal entanglement in submarine cables based on data 

from the late 1800s to 1955. All identified specimens were sperm whales. The author concluded 

that the sperm whales became entangled in extremely slack or looped cables while foraging 

along the seafloor. No instance of marine mammal entanglement in submarine cables has been 

documented since the 1950s (STARS 2002). Plow marks, possibly made by sperm whales 

bottom feeding, also suggest sperm whales are foraging in areas where cables are placed, and 

could potentially become entangled in underwater cables; however, improved route selection and 

burial technologies have reduced the threat of entanglement by minimizing looping in cables. 

The severity of this threat was ranked as low and the uncertainty was ranked as low, thus the 

relative impact to recovery of sperm whales due to this threat is ranked as low (Table 1). 
The following table provides a visual synopsis

December 2010 I-48 NMFS 

 of the text regarding threats to sperm whales, the sources of these threats, and

populations that are affected (where information is available). For each threat, the table describes the severity, including the magnitude, scope, and relative frequency with which the threat is expected to occur; the uncertainty of information or effects; and the 

relative impact to recovery, which is a combination of the severity and uncertainty of each threat. The rankings were developed relative to each other, and put into one of four categories: high, medium, low, and unknown (further research is needed to determine 

whether it falls into high, medium, or low). Ranking assignments were determined by an expert panel with contributions from 

reviewers. Table 1. Sperm whale threats analysis table. 

Reference 

Ocean 

Basin/ 

Population 

Threat Source 

Severity 

(Unknown, Low, 

Med., High)

Uncertainty 

(Unknown, Low, 

Med., High)

Relative Impacts 

to Recovery 

(Unknown, Low, 

Med., High)

Fishery Interactions: 

G.1 All Injury or mortality 

from gillnet gear entanglement 

Gillnet gear Low Medium Low 

G.1 All Injury or mortality 

from longline gear entanglement 

Longline gear Low Medium Low 

G.1.1 Atlantic – 

North 

Injury or mortality from pelagic drift gillnet 

Pelagic drift gillnet fishery 

Low7 Low Low 

G.1.1 Atlantic – 

Northern Gulf of Mexico 

Injury or mortality from longline gear and entanglement 

Demersal longline fishery 

Low Low Low 

G.1.2 Pacific – 

CA/OR/WA 

Injury or mortality from drift gillnet entanglement 

CA/OR thresher shark/swordfish gillnet (> 14 in. mesh) 

Low Low Low 

7 Sperm whale entanglement is known to be a high risk factor in the swordfish drift gillnet fishery in the Mediterranean Sea, but this threat is considered “low 

severity” for the Atlantic as a whole. 
December 2010 I-49 NMFS 

Reference 

Ocean 

Basin/ 

Population 

Threat Source 

Severity 

(Unknown, Low, 

Med., High)

Uncertainty 

(Unknown, Low, 

Med., High)

Relative Impacts 

to Recovery 

(Unknown, Low, 

Med., High)

G.1.2 Pacific – HI Injury or mortality 

from longline gear and entanglement 

Hawaii-based longline fishery 

Low Low Low 

G.1.2 Pacific – 

North 

Injury or mortality from longline gear and entanglement 

AK Gulf of Alaska sablefish longline 

Low Low Low 

G.1.3 Indian 

Ocean 

Injury or mortality from longline and gillnet fishing gear entanglement 

Demersal longline and gillnet fisheries 

Unknown High Unknown 

G.2 Anthropogenic Noise: G.2.1 All Ship Noise Ships Unknown High Unknown G.2.2 All Oil and Gas 

Exploration Activities 

Seismic surveys, noise from construction and operation of oil exploration work, LNG facilities 

Unknown High Unknown 

G.2.3 All Military Sonar and 

Explosives 

Ship shock trials, low and mid-frequency sonar 

Unknown High Unknown 

G.3 Vessel Interactions: G.3.1 All Ship Strikes Areas of high vessel 

traffic and/or high speed vessel traffic 

Medium Medium Unknown but 

Potentially Low 

G.3.2 All Disturbance from 

Whale Watching and Other Vessels 

Whale watching and military vessels 

Low Medium Low 

G.4 All Contaminants and 

Pollutants 

Heavy metals, PCBs, organochlorines, oil spills 

Unknown High Unknown 
December 2010 I-50 NMFS 

Reference 

Ocean 

Basin/ 

Population 

Threat Source 

Severity 

(Unknown, Low, 

Med., High)

Uncertainty 

(Unknown, Low, 

Med., High)

Relative Impacts 

to Recovery 

(Unknown, Low, 

Med., High)

G.5 All Disease Parasites, myocardial 

infarction, other vectors 

Low Medium Low 

G.6 All Injury from Marine 

Debris 

Plastic garbage from land, lost/abandoned fishing gear, nonbiodegradable garbage from ships 

Low Medium Low 

G.7 All Disturbance due to 

Research 

Oceanographic surveys and genetic, photographic, and acoustic studies 

Low Medium Low 

G.8 All Predation and Natural 

Mortality 

Killer whales, sharks, bone necrosis 

Low Medium Low 

G.9 All Direct Harvest Japanese scientific 

whaling; West Indies artisanal whaling; illegal whaling 

Low Medium Low 

G.10 All Competition for 

Resources 

Other whales, human fisheries 

Low Medium Low 

G.11 All Loss of Prey Base due 

to Climate and Ecosystem Change or Shifts in Habitat 

Climate and Ecosystem Change 

Unknown High Unknown 

G.12 All Cable Laying Submarine cable Low Low Low 
December 2010 I-51 NMFS 

H. Conservation Measures 

Although minimum size limits of 38 feet for male and 35 feet for female sperm whales were 

imposed in the first regulations of the IWC, commercial whaling for this species was essentially 

unregulated until 1970, when quotas were introduced in the North Pacific Ocean (IWC 1971). 

Quotas were introduced in the Southern Ocean in 1971. Soon thereafter, catch limits were set 

separately for males and females. No catch limits were placed on sperm whales in the North 

Atlantic until 1977. 

 

The IWC accorded sperm whales complete protection from commercial whaling by member 

states beginning with the 1981/82 pelagic fishing season and the 1986 coastal fishing season 

(IWC 1982). Japan formally objected to this whaling ban and continued its shore-based hunt 

through the 1987 season, after which its objection was withdrawn and this hunt ceased (IWC 

1989). Currently, Japan takes a small number of sperm whales each year under an IWC 

exemption for scientific research. Norway and Iceland have formally objected to the IWC ban 

on commercial whaling and are therefore free to resume hunting sperm whales under IWC rules, 

but neither country has expressed an interest in taking sperm whales. Although commercial in 

nature, sperm whale hunting at the Azores and Madeira in the North Atlantic was exempt from 

IWC regulation because Portugal, which owned these islands, was not a member of the IWC. 

Shore-based whaling continued at the Azores until the 1980s. 

In U.S. waters, sperm whales are currently protected under both the ESA and the MMPA. The 

species is classified as Vulnerable in the World Conservation Union (known as the IUCN) Red 

List of Threatened Animals, meaning that it is “facing a high risk of extinction in the wild in the 

medium-term future” (Baillie and Groombridge 1996). The criterion used for this classification 

was that the aggregate world population of the species had been reduced by at least 20% over the 

last three generations (i.e., since the first half of the 20th century, a sperm whale generation 

being at least 20 years). The sperm whale is also listed in Appendix I of the Convention on 

International Trade in Endangered Species of Wild Fauna and Flora (known as CITES). The 

CITES clarification is intended to ensure that no commercial trade of sperm whale products 

occurs across international borders. 

 
December 2010 I-52 NMFS 

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December 2010 II-1 NMFS 

II. RECOVERY STRATEGY 

The primary purpose of this Recovery Plan is to identify and take actions that will minimize or 

eliminate effects of human activities that are detrimental to the recovery of sperm whale 

populations. Immediate objectives are to identify factors that may be limiting 

abundance/recovery/ productivity, and cite actions necessary to allow the populations to 

increase. The main threats to sperm whale populations include collisions with vessels, direct 

harvest, and possibly competition for resources, loss of prey base due to climate change, and 

disturbance from anthropogenic noise. Other potential (but likely low impact) threats include 

entanglement in fishing gear, habitat degradation, disturbance from vessels and tourism, 

contaminants and pollutants, disease, disturbance due to research, predation and natural 

mortality, and cable laying (see Table 1) . 

The original direct threat to sperm whales was addressed by the IWC’s whaling moratorium, and 

an important element in the strategy to protect sperm whale populations is to continue the 

effective international regulation of whaling. 

Another important component of this recovery program is to determine population structure of 

the species and population discreteness. This would be a first step in estimating population size, 

monitoring trends in abundance, and enabling an assessment of the species throughout its range. 

Because sperm whales move freely across international borders, it would be unreasonable to 

confine recovery efforts to U.S. waters, and this Recovery Plan stresses the importance of a 

multinational approach to management. This Recovery Plan recognizes the limits imposed by 

the national nature of protective legislation. As demonstrated by work on humpback whales 

(Structure of Populations, Levels of Abundance and Status of Humpbacks (SPLASH) 

(Calambokidis et al. 2008) and the Year of the North Atlantic Humpback (YONAH)) involving a 

number of researchers from different countries (Palsbøll et al. 1997; Smith et al. 1999), 

considerably more information is gathered for management of whale populations when research 

is conducted on the basis of biological, rather than political, divisions and through multilateral 

cooperation. Ideally, both research and conservation should be undertaken at oceanic rather than 

national levels. 

Although not an explicit goal, this Recovery Plan is also expected to help achieve the MMPA’s 

purpose of maintaining marine mammal populations at optimum sustainable levels. 

 
December 2010 II-2 NMFS 

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December 2010 III-1 NMFS 

III. RECOVERY GOALS, OBJECTIVES, AND CRITERIA 

A. Goals 

The goal of this Plan is to promote recovery of sperm whale populations to levels at which it 

becomes appropriate to “downlist” them from endangered to threatened status, and ultimately to 

“de-list,” or remove them from the list of Endangered and Threatened Wildlife and Plants, under 

the provisions of the ESA. The ESA defines an “endangered species” as “any species which is in 

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

is defined as “any species which is likely to become an endangered species within the 

foreseeable future throughout all or a significant portion of its range.” 

B. Objectives and Criteria 

The two main objectives for sperm whale recovery are to 1) achieve sufficient and viable 

populations in all ocean basins, and 2) ensure significant threats are addressed. Likewise, 

recovery criteria take two forms: 1) those that reflect the status of the species itself and 2) those 

that indicate effective management or elimination of threats. The former criterion may explicitly 

state a certain risk of extinction as a threshold for downlisting or delisting and uses models based 

on at least abundance and trends in abundance to assess whether this threshold has been reached. 

Since sperm whales are currently globally listed, all ocean basins where sperm whales occur 

would need to meet these criteria. 

Guidance on appropriate levels of risk for down-listing and de-listing decisions was developed in 

a workshop for large cetaceans (Angliss et al. 2002). This guidance was employed in the North 

Atlantic Right Whale Recovery Plan criteria (NMFS 2005b) and is also appropriate here. The 

following framework was suggested: 

 A large cetacean species shall no longer be considered endangered when, given current 

and projected conditions, the probability of quasi-extinction is less than 1% in 100 years; 

 A large cetacean species shall no longer be considered threatened when, given current 

and projected conditions, the probability of becoming endangered is less than 10% in a 

period of time no shorter than 10 years and no longer than 25 years (in the case of the 

sperm whale the period of 25 years is considered necessary given imprecise abundance 

estimates); 

 Recurrence of threats that brought the species to the point that warranted listing and 

current threats to the species have been addressed. 

B.1 Downlisting Objectives and Criteria 

Objective 1: Achieve sufficient and viable populations in all ocean basins. 

Criterion: 

Given current and projected threats and environmental conditions, the sperm whale population in 

each ocean basin in which it occurs (Atlantic Ocean/Mediterranean Sea, Pacific Ocean, and 

Indian Ocean) satisfies the risk analysis standard for threatened status (has no more than a 1% 

chance of extinction in 100 years) and the global population has at least 1,500 mature, 
December 2010 III-2 NMFS 

reproductive individuals (consisting of at least 250 mature females and at least 250 mature males 

in each ocean basin). Mature is defined as the number of individuals known, estimated, or 

inferred to be capable of reproduction. Any factors or circumstances that are thought to 

substantially contribute to a real risk of extinction that cannot be incorporated into a Population 

Viability Analysis will be carefully considered before downlisting takes place. 

Objective 2: Ensure significant threats are addressed. 

Criteria: 

Factors that may limit population growth (i.e., those that are identified in the threats analysis 

under relative impact to recovery as high or medium or unknown) have been identified and are 

being or have been addressed to the extent that they allow for continued growth of populations. 

Specifically, the factors in 4(a)(l) of the ESA are being or have been addressed as follows: 

Factor A: The present or threatened destruction, modification, or curtailment of a 

species’ habitat or range. 

 

o Effects of reduced prey abundance due to climate change continue to be investigated and 

action is being taken to address the issue, as necessary. 

o Effects of anthropogenic noise continue to be investigated and actions taken to minimize 

potential effects, as necessary. 

o Competition with fisheries for resources is being addressed through fishery management 

plans and other measures. 

o Effects of oil spills and contaminants are determined to not affect the potential for 

 continued growth or maintenance of sperm whale populations. 

Factor B: Overutilization for commercial, recreational, or educational purposes. 

o Management measures are in place to ensure that any direct harvest (commercial, 

subsistence, and scientific) is at a sustainable level. 

Factor C: Disease or Predation. 

There are no criteria for this factor because there are no data to indicate that disease or 

predation are threats. 

Factor D: The inadequacy of existing regulatory mechanisms. 

o Ship collisions continue to be investigated and actions taken to minimize potential 

effects, as necessary. 

Direct harvest is addressed under Factor B. 

Factor E: Other natural or manmade factors affecting its continued existence. 

No other factors are known to be limiting the recovery of sperm whales. 
December 2010 III-3 NMFS 

B.2 Delisting Objectives and Criteria 

Objective 1: Achieve sufficient and viable populations in all ocean basins 

Criterion: 

Given current and projected threats and environmental conditions, the sperm whale population in 

each ocean basin in which it occurs (Atlantic Ocean/Mediterranean Sea, Pacific Ocean, and 

Indian Ocean) satisfies the risk analysis standard for unlisted status (has less than a 10% 

probability of becoming endangered (has more than a 1% chance of extinction in 100 years) in 

20 years). Any factors or circumstances that are thought to substantially contribute to a real risk 

of extinction that cannot be incorporated into a Population Viability Analysis will be carefully 

considered before delisting takes place. 

Objective 2: Ensure significant threats are addressed 

Criteria: 

Factors that may limit population growth (those that are identified in the threats analysis as high 

or medium or unknown) have been identified and are being or have been addressed to the extent 

that they allow for continued growth of populations. Specifically, the factors in 4(a)(l) of the 

ESA are being or have been addressed as follows: 

Factor A: The present or threatened destruction, modification, or curtailment of a 

species’ habitat or range. 

o Effects of reduced prey abundance due to climate change have continued to be 

investigated and any necessary action being taken to address the issue are shown to be 

effective or this is no longer believed to be a threat. 

o Effects of anthropogenic noise have continued to be investigated and actions being taken 

to address the issue are shown to be effective or this is no longer believed to be a threat. 

Competition with fisheries for resources continues to be addressed through fishery 

management plans and other measures or is no longer believed to be a threat. 

o Effects of oil spills and contaminants are determined to not affect the potential for 

continued growth or maintenance of the sperm whale population and actions taken or 

having been taken to minimize potential effects have been proven effective. 

Factor B: Overutilization for commercial, recreational, or educational purposes. 

o Management measures are in place that ensure that any direct harvest (commercial, 

subsistence, and scientific) is at a sustainable level. 

Factor C: Disease or Predation. 

There are no criteria for this factor because there are no data to indicate that disease or 

predation are threats. 

 
December 2010 III-4 NMFS 

Factor D: The inadequacy of existing regulatory mechanisms. 

 

o Ship collisions have been investigated and action being taken to address the issue are 

shown to be effective or this is no longer believed to be a threat.

Direct harvest is addressed under Factor B. 

Factor E: Other natural or manmade factors affecting its continued existence. 

 

No other factors are known to be threats. 
December 2010 IV-1 NMFS 

IV. RECOVERY PROGRAM 

A. Recovery Action Outline 

Items in this outline are not in order of priority. Priorities are identified in the Implementation 

Schedule following this section. 

 

1.0 Coordinate State, Federal, and International Actions to Implement Recovery 

Actions and Maintain International Regulation of Whaling for Sperm Whales. 

2.0 Develop and Apply Methods to Estimate Population Size and Monitor Trends in 

Abundance. 

2.1 Determine the best methods for assessing sperm whale status and trends. 

2.2 Conduct surveys to estimate abundance and monitor trends in sperm whale 

populations worldwide.

2.2.1 Continue to estimate abundance and monitor trends in the Atlantic Ocean, 

Gulf of Mexico, and Pacific Ocean. 

2.2.2 Estimate abundance and monitor trends in the Indian Ocean and 

Mediterranean Sea. 

3.0 Determine Population Discreteness and Population Structure of Sperm Whales. 

3.1 Support existing studies and initiate new studies to investigate population 

discreteness and population structure of sperm whales using genetic analyses. 

3.1.1 Continue to collect biopsy samples off the Atlantic, Gulf of Mexico, and 

Pacific coasts of North America. 

3.1.2 Collaborate with foreign agencies and researchers to obtain sufficient 

samples at the ocean basin scale. 

3.1.3 Perform genetic analyses on preserved samples from whales killed by the 

whaling industry in the past. 

3.2 Assess daily and seasonal movements and inter-area exchange using telemetry 

and photo-identification. 

 

 3.2.1 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Atlantic Ocean/Mediterranean Sea. 

 3.2.2 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Pacific Ocean. 
December 2010 IV-2 NMFS 

3.2.3 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Indian Ocean. 

3.2.4 Establish and maintain a central repository for sperm whale photographs. 

3.3 Support ongoing studies and initiate new studies to investigate social structure 

and how it influences population structure.

4.0 Conduct Risk Analyses 

4.1 Conduct risk analyses for the Atlantic Ocean /Mediterranean Sea.

4.2 Conduct risk analyses for the Pacific Ocean. 

4.3 Conduct risk analyses for the Indian Ocean.

5.0 Identify, Characterize, Protect, and Monitor Habitat Important to Sperm Whale 

Populations in U.S. Waters and Elsewhere. 

5.1 Characterize sperm whale habitat. 

5.1.1 Conduct research to characterize sperm whale habitat in the Atlantic 

Ocean. 

5.1.2 Conduct research to characterize sperm whale habitat in the Pacific Ocean. 

5.1.3 Conduct research to characterize sperm whale habitat in the Indian Ocean 

and Mediterranean Sea. 

5.2 Monitor important habitat features and sperm whale use patterns to assess 

potentially detrimental shifts in these features that might reflect disturbance or 

degradation of habitat.

5.3 Promote actions to protect important habitat in U.S. waters.

5.4 Promote actions to define, identify, and protect important habitat in foreign or 

international waters.

5.5 Improve knowledge of sperm whale feeding ecology.

5.6 Investigate the impacts of climate change on sperm whales and seek strategies to 

reduce those impacts found to be detrimental to sperm whales and their habitat. 

5.6.1 Conduct studies and perform analyses to assess the effects of climate 

change on the distribution, behavior, reproduction, and productivity of sperm 

whales. 
December 2010 IV-3 NMFS 

5.6.2 Seek strategies to reduce any detrimental impacts of climate change on 

sperm whales and their prey and habitats (identified in action 5.6.1). 

6.0 Investigate Causes of and Reduce the Frequency and Severity of Human-caused 

Injury and Mortality. 

6.1 Investigate and reduce injury and mortality caused by fisheries and fishing 

equipment and reduce depredation. 

6.1.1 Conduct a systematic review of data on sperm whale interactions with 

fishing operations. 

 

6.1.2 Promote studies that investigate the ingestion of fishing gear (and the 

target species/bait) by sperm whales and develop methods to reduce sperm whale 

ingestion of fishing gear. 

6.1.3 Investigate the development of a system to non-lethally deter sperm 

whales from fishing gear. 

6.1.4 Conduct studies of gear modifications that reduce the likelihood of 

entanglement and depredation, mitigate the effects of entanglements, and enhance 

the possibility of disentanglement. Determine whether measures to reduce 

entanglement and depredation are effective. 

6.1.5 Develop and implement schemes to reduce the rate at which gear is lost, 

and improve the reporting of lost gear, in conjunction with studies in 6.1.2, 6.1.3, 

6.1.4, and 6.1.6. 

6.1.6 Continue to review, evaluate, and act upon reports from fishermen and 

fishery observers of fishery interactions with sperm whales. 

6.2 Investigate and reduce mortality and serious injury from vessel collisions.

6.2.1 Identify areas where concentrations of sperm whales coincide with 

significant levels of maritime traffic. 

6.2.2 Identify specific areas where recorded ship strikes of sperm whales have 

occurred (for example, the Canary Islands) and conduct studies to identify 

ecosystem-based traits that could support an assemblage of predictive tools. 

6.2.3 Once areas in 5.0 and 6.2.1 are identified, and in conjunction with 

information derived and resulting predictive tools from 6.2.2, conduct analyses of 

shipping routes and important sperm whale habitat areas to determine the risk of 

ship collisions with sperm whales. 
December 2010 IV-4 NMFS 

6.2.4 Develop a system to encourage, collect, and appropriately analyze 

opportunistic sightings of sperm whales from fishing vessels, whale-watching 

vessels, charter vessels, etc. 

6.2.5 Work with mariners, the shipping industry, and appropriate state, federal, 

and international agencies to develop and implement regionally-based measures 

to reduce the threat of ship strikes. Assess the effectiveness of ship strike 

measures and adjust, as necessary. 

6.2.6 Explore possible mechanisms to encourage vessels that have struck a 

whale to report the incident.

6.3 Conduct studies of environmental pollution that may affect sperm whale 

populations and their prey. 

6.3.1 Identify areas where concentrations of sperm whales coincide with 

significant levels of pollution (including marine debris). 

6.3.2 Conduct studies on individual health and body condition as they may be 

related to accumulated contaminants. 

6.3.3 Take steps to minimize adverse effects from pollutants, if necessary. 

7.0 Determine and Minimize Any Detrimental Effects of Anthropogenic Noise in the 

Oceans. 

7.1 Conduct studies to assess the effects of anthropogenic noise on the distribution, 

behavior, and productivity of sperm whales. 

7.2 Take steps to minimize anthropogenic noises that are found to be potentially 

detrimental to sperm whales.

8.0 Maximize Efforts to Acquire Scientific Information from Dead, Stranded, and 

Entangled Sperm Whales.

8.1 Respond effectively to strandings of sperm whales in U.S. waters. 

8.1.1 Continue and improve programs to maximize data collected from 

necropsy of sperm whale carcasses. 

8.1.2 Maintain and review, and if needed improve, the system for reporting 

dead, stranded, or entangled sperm whales. 

8.1.3 Improve, or as necessary, develop and implement protocols for securing 

and retrieving stranded (on land) or floating (at sea) sperm whale carcasses. 
December 2010 IV-5 NMFS 

8.2 Review, analyze, and summarize data on stranded sperm whales on an annual 

basis. 

8.3 Develop protocols for handling live-stranded sperm whales.

8.4 Establish reliable sources of funding for rescue, necropsy, tissue collection, and 

analysis efforts.

9.0 Develop Post-delisting Monitoring Plan. 

B. Recovery Action Narrative 

1.0 Coordinate State, Federal, and International Actions to Implement Recovery 

Actions and Maintain International Regulation of Whaling for Sperm Whales. 

A coordinated approach to the tasks described in this Recovery Plan would greatly facilitate their 

completion. The establishment of a team charged with coordinating state and federal 

implementation efforts, and with pursuing international cooperative efforts, is highly desirable. 

Liaison efforts between the team and the lead agency would be the responsibility of the 

designated individual from the latter body. 

Cooperate with the IWC (and other relevant international bodies or agreements) to ensure that 

any resumption of commercial whaling on sperm whales is prosecuted on a sustainable basis and 

that all whaling activity is conducted within the purview of the IWC (i.e., there is no “pirate” 

whaling). 

The international regulation of whaling is vital to recovery efforts. This is particularly true for 

sperm whales because of their wide distribution, far-ranging movements, and high commercial 

value. The IWC’s Revised Management Procedure was developed for use with baleen whale 

populations and has yet to be adapted for toothed whales. Therefore, even if the resumption of 

carefully managed exploitation of sperm whales were to be justified on the basis of relatively 

large and productive populations in particular areas, the lack of an agreed upon international 

scheme for monitoring and regulating the take would preclude the U.S. government from 

supporting such a presumption. Pending results of studies outlined under 3.0, below, it is 

precautionary to assume that sperm whale populations in U.S. North Atlantic and North Pacific 

waters range into international waters and into waters under the jurisdictions of other countries. 

Therefore, an international regime for managing any directed exploitation is essential. This 

imperative applies equally to the issue of international trade in sperm whale products (e.g., under 

CITES). 

2.0 Develop and Apply Methods to Estimate Population Size and Monitor Trends in 

Abundance. 

Assessment of the recovery status of sperm whales requires reliable estimates of abundance and 

information on trends. The complexity of the sperm whale’s migratory behavior, involving 

major differences between sex and age classes; its proclivity for deep, prolonged dives; and its 
December 2010 IV-6 NMFS 

extremely wide geographic distribution, make population size estimation particularly 

challenging. Various methods have been used for sperm whales, including population modeling 

based on whaling data, acoustic and visual shipboard surveys, and visual aerial surveys. Markrecapture estimation from photographic or genetic (biopsy) data is another approach that 

deserves consideration. More developmental work is needed to evaluate and compare 

methodologies. 

2.1 Determine the best methods for assessing sperm whale status and trends. 

Considerable effort has been made to gather information on sperm whales in the North 

Atlantic and North Pacific, but very little in the Indian Ocean. An assessment of the level 

and distribution of survey efforts required to achieve optimal assessment results for the 

three ocean basins is essential to ensure that the entire population of sperm whales is 

surveyed and that field work is as efficient and cost-effective as possible. This may be 

achieved through a workshop or other means. 

2.2 Conduct surveys to estimate abundance and monitor trends in sperm whale 

populations worldwide.

Broad international participation, including support from governments, and researchers 

from other countries should be supported. Sperm whale abundance should be estimated 

at least once every three years (depending on results of the workshop recommendations 

in 2.1). Population modeling should be conducted to assess status, trends, abundance, 

and vital rates, including reproduction and survivorship. As necessary, the development 

and implementation of other programs (i.e., improved assessment techniques, alternative 

analysis methods identified) necessary for population monitoring should be supported. 

2.2.1 Continue to estimate abundance and monitor trends in the Atlantic Ocean, 

Gulf of Mexico, and Pacific Ocean. 

Initial survey efforts in the western North Atlantic and Gulf of Mexico (Waring et 

al. 1997) and the eastern North Pacific (Barlow et al. 1997; Barlow and Taylor 

2005) provide a baseline for population assessment. These programs should be 

continued and expanded geographically and perhaps temporally, with surveys 

designed explicitly to provide indices of sperm whale population abundance and 

trends. 

2.2.2 Estimate abundance and monitor trends in the Indian Ocean and 

Mediterranean Sea. 

For meaningful estimates of entire populations, it will be necessary to conduct 

cooperative surveys with foreign scientists in non-U.S. waters. Findings from the 

population structure studies outlined under item 3.0 will be needed for meaningful 

interpretation of survey results. Because of the relatively long generation time of 

sperm whales, and the time scales on which environmental factors affecting their 

distribution and abundance may operate, programs to monitor trends in their 
December 2010 IV-7 NMFS 

populations must involve long-term commitments and extended periods of shipbased surveys on large research vessels. A primary goal should be to foster an 

international collaboration and cooperation in the study and protection of the 

worldwide population of sperm whales. It is likely than within the next five 

years, autonomous acoustic buoys can be developed to estimate sperm whale 

abundance and trends and as a result, costs to accomplish this objective could be 

reduced considerably. Other potential cost savings include combining this 

objective with other large ship-based research projects in the same area and other 

objectives listed in this Recovery Plan.8

 

3.0 Determine Population Discreteness and Population Structure of Sperm Whales. 

Existing knowledge of the population structure of sperm whales is insufficient, and a more 

comprehensive understanding is essential for determining populations status and trends and 

developing strategies to promote recovery.. In addition, in 1996, NMFS and FWS published the 

Policy Regarding the Recognition of Distinct Vertebrate Population Segments (DPS) (61 FR 

4722). This policy interpreted the term “DPS” for the purposes of listing and delisting and 

reclassifying vertebrates under the ESA. It is possible that sperm whales could be more 

appropriately listed as DPSs, which would require an evaluation of discreteness and significance 

among populations. 

To the maximum extent possible, data should be collected in such a way that comparisons with 

historical data are practicable. It may be necessary to develop calibration methods so that results 

of studies, using new or recent techniques, can be compared with those obtained using more 

traditional ones. Analyses should be directed at examining trends over time, and attempts should 

be made to correlate observed changes in sperm whale populations with physical, biological, or 

human-induced changes in the environment. Data collected through any research outlined in this 

Recovery Plan should be analyzed and reported in a timely manner. Reports should be 

thoroughly referenced and follow standards of organization to facilitate comparison with other 

reports. As much as possible, data should be presented in peer-reviewed journals and other open 

publications to ensure that research programs benefit from regular peer scrutiny. Models of 

sperm whale movement (3.2 below) are necessary to understand population structure, both 

genetically (3.1 below) and socially (3.3 below), and to manage the effects of human activities 

on this species (Dufault et al. 1999; Whitehead et al. 2008). NMFS proposes three interrelated 

research initiatives to assess population structure described in detail below: the first, 3.1, uses 

genetic analysis to determine population structure and discreteness; the second, 3.2, uses 

telemetry and photo-identification to assess movement; and the third 3.3, investigates the 

complex social structure of sperm whales. 

 

8

 In the Implementation Schedule, the daily cost of an ocean class University-National Oceanographic Laboratory System 

(UNOLS) ship was estimated to be about $35K per day. This estimate does not account for inflation factors such as fuel costs. It 

was also assumed that the cost of the ship would mainly be split between Actions 3.1, 3.2, 2.2, and 5.1. These actions were 

assumed to be split in the following proportions for ship time: Action 3.2 at 80%, Action 5.1 at 15%, and Actions 3.1 and 3.2 

totaling 5%. The task duration was rounded up to the nearest 6 or 12 month period for ease of estimating costs. Action 3.2 

represents the total cost for the ship time. Other actions items where ship time may be necessary are also included in the total 

cost, but the proportion of ship time that would be used was less than what is reported here for action items 3.1, 3.2, 2.2, and 5.1 

and thus, those specific actions are not discussed in detail.
December 2010 IV-8 NMFS 

3.1 Support existing studies and initiate new studies to investigate population 

discreteness and population structure of sperm whales using genetic analyses. 

Initial investigations of genetic population structure of sperm whales, based on 

mitochondrial DNA, indicated genetic relatedness within groups but relatively little 

geographic structure (Dillon 1996; Lyrholm and Gyllensten 1998). The suggestion of 

low genetic differentiation should not be accepted without first exploring other types of 

analyses and interpreting the results within a demographic, behavioral, morphological, or 

comparative context (Baker and Palumbi 1997; Whitehead and Mesnick 2003a,b). As 

discussed by Taylor and Dizon (1996), until analyses with sufficient power are applied, 

the precautionary assumption should be that structuring exists, and reasonable provisional 

management units should be recognized on the basis of catch history, sighting 

distribution, and other data. Preliminary investigations of calving seasonality suggest, for 

example, that the sperm whales in the Gulf of California, Mexico, are on a different 

schedule from those in the California Current system (B.L. Taylor, pers. comm. 2006). 

Moreover, the year-round presence of sperm whales in some areas (e.g., northern Gulf of 

Mexico) suggests that there may be “resident” populations in certain productive coastal 

areas. 

Over the past decade, several additional authors have investigated population structure in 

sperm whales using sequence variation within the mitochondrial control region DNA 

(mtDNA) and/or polymorphic nuclear loci (microsatellites). In general, results tend to 

find low genetic differentiation among ocean basins and little evidence of subdivision 

within ocean basins, with the exception of some isolated basins such as the 

Mediterranean and Gulf of Mexico (Dillon 1996; Lyrholm and Gyllensten 1998; Mesnick 

et al. 1999a,b; Bond 1999; Lyrholm et al. 1999; Engelhaupt 2004). However, several 

problems hinder these studies, such as low sample sizes, low mtDNA haplotypic 

diversity, and social structure, which alone and together reduce the power to detect 

population structure. A priori definition of strata is problematic and hypotheses of 

structure may be based on geographic, oceanographic, ecologic, and cultural designations 

(Whitehead and Mesnick 2003a,b). Informative models may also be based on historical 

calving grounds, contaminant measures, and scarring patterns. To address the potential 

bias due to relatedness within groups, novel analytical approaches are needed. Although 

it will be more difficult to obtain samples of sufficient size, population structure in males 

will be particularly interesting to address in comparison to the pattern of structure in 

females (Bond 1999). 

The low mtDNA diversity in sperm whales requires that studies using this marker have 

large sample sizes. Mesnick et al. (2005) compiled over 2,473 tissue samples and 1,038 

mtDNA sequences. While sufficient sampling exists to get a rough idea of scale, sample 

gaps remain large, particularly in the North Atlantic, Western Pacific, Indian Ocean, and 

southern hemisphere. This compilation is remarkable for its low diversity: 24 variable 

sites defined 28 haplotypes worldwide. The three most common haploytpes (“a,” “b,” 

and “c”) comprise 82% of the total; 39% are “a”. Several hypotheses for the lack of 

diversity have been proposed (Lyrholm et al. 1996; Amos 1999; Whitehead 1999; 

Tiedemann and Milinkovitch 1999; Hyde et al. 2001). 
December 2010 IV-9 NMFS 

3.1.1 Continue to collect biopsy samples off the Atlantic, Gulf of Mexico, and 

Pacific coasts of North America. 

Sperm whales are found in sufficient densities off the Atlantic, Gulf of Mexico, 

and Pacific coasts of North America, thereby making biopsy sampling at sea an 

efficient way of supplementing tissue samples obtained from stranded whales. 

Such sampling should be routinely integrated into sighting surveys, regardless of 

whether these are dedicated sperm whale surveys or surveys for other species. 

3.1.2 Collaborate with foreign agencies and researchers to obtain sufficient 

samples at the ocean basin scale. 

Collaborative efforts with foreign agencies and researchers will probably be 

necessary to obtain sufficient samples at the appropriate geographic scale (ocean 

basin). Standard sampling protocols and analytical procedures should be used to 

ensure that results are conclusive. All biopsy samples should be preserved in such 

a way that the accompanying blubber can be used for contaminant analyses (item 

6.4.1). A central repository for sperm whale tissue samples would facilitate 

research. 

3.1.3 Perform genetic analyses on preserved samples from whales killed by the 

whaling industry in the past. 

A parallel initiative should be undertaken to ensure that preserved samples from 

whales killed by the whaling industry in the past are made available for genetic 

analyses, and that maximum use be made of these samples to elucidate 

population-identity issues. A very large sample of sperm whale tissues, including 

specimens from the eastern, central, and North Pacific, exists in Japan. These 

tissues were collected routinely as Japanese vessels hunted sperm whales in the 

1960s to early 1980s throughout the North Pacific. 

3.2 Assess daily and seasonal movements and inter-area exchange, using telemetry 

and photo-identification. 

Telemetry studies using satellite-linked and VHP radio tags are needed to investigate 

patterns and ranges of daily, seasonal, and longer-term movements of individual sperm 

whales. Exchange rates between populations might also be addressed to some degree by 

telemetry studies such as those currently being conducted under the SWSS program in 

the Gulf of Mexico (Jochens and Biggs 2004). Photo-identification of sperm whales, 

primarily by reference to features of the trailing edges of their flukes, has been used for 

population studies in several parts of the world (e.g., Whitehead and Gordon 1986; 

Arnbom 1987; Dufault and Whitehead 1995; Jaquet et al. 2003). Opportunistic efforts to 

photo-document sightings could contribute to knowledge of individual animal 

movements and residency times. For example, Jaquet et al. (2003) documented the 

movement of 7 sperm whales from the Galapagos Islands to the Gulf of California. 
December 2010 IV-10 NMFS 

3.2.1 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Atlantic Ocean/Mediterranean Sea. 

 3.2.2 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Pacific Ocean. 

3.2.3 Continue/conduct telemetry and photo-identification studies of sperm 

whales in the Indian Ocean. 

3.2.4 Establish and maintain a central repository for sperm whale photographs. 

A single, central repository for sperm whale fluke (and other) photographs, and a 

system for curating and analyzing them, should be established. Photographs 

should be supplemented whenever possible by tissue samples (whether sloughed 

skin or biopsies), for DNA fingerprinting (Amos and Hoelzel 1990). 

3.3 Support ongoing studies and initiate new studies to investigate social structure 

and how it influences population structure.

Whitehead et al. (1998) used acoustic dialects, fluke markings, and genetics (mtDNA 

haplotypes) to test for geography-based population structure of sperm whales in the South 

Pacific. Although no such structure was found, the approach used by those authors, if 

applied more intensively and on a larger geographic scale, could help elucidate the 

process of population differentiation (or lack of differentiation) in sperm whales. 

Rendell et al. (2005) and Mesnick et al. (2008) examined mtDNA variation among vocal 

clans of sperm whales from social groups sampled from three broad areas of the Pacific 

(Chile/Peru, Galapagos/Ecuador, and the Southwest Pacific). The authors found that 

acoustic dialect showed greater genetic structure than geography, and that coda dialects 

could be especially significant as they directly describe an apparently important type of 

non-geographical population structure. As noted above, to address the potential bias due 

to relatedness within groups, novel analytical approaches are needed. Sperm whales have 

a complex social structure with the observed “groups” of females and immatures being 

temporary associations between more stable social “units” and with breeding males 

roving between female groups, although important elements of the mating system are 

also unknown (Christal and Whitehead 2001; Whitehead 2003). At present, there is no 

known genetic evidence of a strictly or largely matrilineal unit or group of sperm whales. 

Rather, genetic results suggest that groups of female and immature sperm whales 

generally contain more than one matriline, as indicated by the presence of multiple 

mtDNA haploytpes. Both “groups” and “units” contain clusters of closely related 

animals, but some individuals have no close relations. These results are consistent across 

50+ groups sampled at sea and in strandings in four different ocean basins (Richard et al.

1996; Christal 1998; Bond 1999; Lyrholm et al. 1999; Mesnick 2001; Mesnick et al.

2003; Engelhaupt 2004). Groups from areas without a significant whaling history (e.g., 

the western North Atlantic) will be particularly valuable in addressing whether the nonmatrilineal structure is an artifact of removal by commercial whaling. Less is known 

about relatedness among males. Analyses of stranded groups of subadult males find 
December 2010 IV-11 NMFS 

predominantly unrelated individuals. However, there were cases for half-siblings within 

each of the two groups (Bond 1999; Engelhaupt 2004). 

4.0 Conduct Risk Analyses 

Risk analyses incorporate known and projected risks into a population projection. Given the 

large uncertainties in abundance and population growth rate for sperm whales, such uncertainties 

should also be directly incorporated into population projections. The output will be the 

probability of extinction over time for use in the down and delisting criteria. A workshop may 

be needed to address this. 

4.1 Conduct risk analyses for Atlantic Ocean /Mediterranean Sea.

Conduct simulations to estimate risk of extinction. Required data are minimum 

abundance estimates for a significant portion of the range together with estimates on 

trends in abundance. 

4.2 Conduct risk analyses for the Pacific Ocean.

Conduct simulations to estimate risk of extinction. Required data are minimum 

abundance estimates for a significant portion of the range together with estimates on 

trends in abundance. 

4.3 Conduct risk analyses for the Indian Ocean.

Conduct simulations to estimate risk of extinction. Required data are minimum 

abundance estimates for a significant portion of the range together with estimates on 

trends in abundance. No data currently exist for a risk analysis (e.g., minimum 

abundance estimates and trends) so the analysis is anticipated to occur at a much later 

date than for the Atlantic and Pacific Oceans and Mediterranean Sea. 

5.0 Identify, Characterize, Protect, and Monitor Habitat Important to Sperm Whale 

Populations in U.S. Waters and Elsewhere. 

Identifying important habitat and reducing direct and indirect threats to sperm whale habitat is 

integral to recovery. Important habitat may or may not qualify as critical habitat under the ESA. 

Information is needed on environmental factors that influence sperm whale distribution. In 

addition, adequate protective measures are needed to reduce or eliminate human-related impacts 

to sperm whale habitat. 

5.1 Characterize sperm whale habitat.

Areas where sperm whales are consistently seen and heard are assumed to be important to 

their survival. Areas used infrequently or for short periods may also be linked to 

population fitness. Compile or collect relevant physical, chemical, biological, 

meteorological, fishery, and other data to characterize features of important habitats and 
December 2010 IV-12 NMFS 

potential sources of human-caused destruction and degradation of what are determined to 

be important areas for sperm whales. Habitat characterization also involves, among other 

things, descriptions of prey types, densities, and abundances, and of associated 

oceanographic and hydrographic features. Inter-annual variability in habitat 

characteristics, and in sperm whale habitat use, is an important component of habitat 

characterization. Researchers in many different areas have begun to explore the 

correlations between sperm whale occurrence and habitat features (Waring et al. 1993; 

Jaquet and Whitehead 1996; Jaquet et al. 1996, 1998; Davis et al. 1998; Hooker et al.

1998), but more research is needed to define rigorously and specifically, the 

environmental features that make an area important to sperm whales. A predictive 

framework for identifying potentially important sperm whale habitat would be a useful 

management tool. Some areas are known to be important habitat while others may be 

discovered during survey work discussed in sections 2.0 and 3.0, above. Only with 

information on the ecological needs of the species will managers be able to provide 

necessary protections. 

5.1.1 Conduct research to characterize sperm whale habitat in the Atlantic 

Ocean. 

There has recently been extensive work on the movements and habitat use of 

sperm whales in the Northern Gulf of Mexico, by the SWSS. These studies 

include habitat cruises, physical oceanographic analysis, and long term satellite 

tag deployments. Several satellite tags have operated for over 12 months and 

indicate movements generally along the shelf break (700–1000 m depth) 

throughout the Gulf of Mexico, with some animals using deeper oceanic waters. 

Satellite tag deployments also have indicated large scale movements of 

individuals out of the Gulf of Mexico. The SWSS research provided detailed 

information on the habitat preferences and population structure of Gulf of Mexico 

sperm whales (Jochens and Biggs 2004; Jochens et al. 2008). 

5.1.2 Conduct research to characterize sperm whale habitat in the Pacific Ocean. 

While there have been many studies on sperm whale distribution in the Pacific 

Ocean, more work is needed on characterizing habitat in this ocean. 

5.1.3 Conduct research to characterize sperm whale habitat in the Indian Ocean 

and Mediterranean Sea. 

More research is needed on characterizing sperm whale habitat in the Indian 

Ocean and in the Mediterranean Sea. 

5.2 Monitor important habitat features and sperm whale use patterns to assess 

potentially detrimental shifts in these features that might reflect disturbance or 

degradation of habitat.

After baseline data are obtained and analyzed, ongoing studies should be done to 
December 2010 IV-13 NMFS 

determine if shifts are occurring in essential habitat components. Sperm whale habitat 

should be assessed periodically through surveys and GIS analysis. Shifts in distribution 

or habitat use should be analyzed as potentially resulting from anthropogenic sources of 

habitat degradation or disturbance. If shifts are detected and are linked to human 

activities, actions may be taken to modify the activity to reduce or eliminate the cause. 

5.3 Promote actions to protect important habitat in U.S. waters.

Support efforts to collect and compile data on habitat use patterns for the sperm whale 

population in U.S. waters. Once 5.1 and 5.2 are determined, mitigate for actions that 

may disturb or degrade important habitat. Validate those areas where sperm whales are 

thought to occur and determine if those areas are important areas warranting habitat 

protection. 

5.4 Promote actions to define, identify, and protect important habitat in foreign or 

international waters.

Sperm whale range is transboundary. Collaborative efforts should be made with foreign 

governments to protect sperm whale habitat within their EEZ’s, and to join multi-national 

efforts on behalf of marine habitat protection. International efforts to collect and compile 

data on habitat use patterns for the sperm whale population should be supported. Actions 

that have impacts on sperm whales should be mitigated, and the U.S. should support and 

endorse such efforts. Validation of those areas where sperm whales are thought to occur 

and protection of those areas that are determined as important areas warranting habitat 

protection should be supported. Due to the very wide-ranging movements of individual 

sperm whales (demonstrated by tag returns) and the species’ extensive distribution in 

both the North Pacific and North Atlantic, international initiatives to reduce pollution 

(see 6.4) and protect resources on the high seas may be key to the long-term conservation 

of sperm whale populations. 

5.5 Improve knowledge of sperm whale feeding ecology.

Improved knowledge of sperm whale feeding ecology would be useful for evaluating or 

predicting interactions with fisheries. Directed studies of sperm whale feeding ecology 

are especially challenging. The whales are usually distributed far offshore (at least in 

areas where the shelf is wide) and feed at considerable depth on cephalopod species 

which are themselves difficult to sample and study. Most of what is known about sperm 

whale feeding has come from examinations of stomach contents of killed whales. 

Innovative approaches to studying sperm whale feeding ecology should be encouraged. 

For example, Whitehead et al. (1989) and Smith and Whitehead (1993) used observed 

defecation rate as an index of “feeding success” in sperm whales near the Galapagos and 

related this index to oceanographic conditions. In a separate study, Jaquet et al. (1996) 

compared 19th century sperm whale distribution in the tropical Pacific (based on whaling 

catch positions) to satellite-derived pigments. They found that chlorophyll concentration 

was a good indicator of sperm whale distribution, regardless of spatial scale. Stable 

isotope tracers in blubber fatty acids have been used to study the diets of other cetacean 
December 2010 IV-14 NMFS 

species (e.g., Ostrom et al. 1993; Abend and Smith 1995, 1997) and sperm whales in the 

Gulf of Mexico, North and South Pacific, and Atlantic (Santos et al. 2002; Ruiz-Cooley 

et al. 2006; Gomez-Villota 2007; Marcoux et al. 2007) and these should be augmented 

with additional biopsy samples collected (see 3.1.1). It is expected that this objective 

could be accomplished in conjunction with surveys conducted to achieve actions 3.2 and 

5.1, and thus reduce costs. 

5.6 Investigate the impacts of climate change on sperm whales and seek strategies to 

reduce these impacts. 

5.6.1 Conduct studies and perform analyses to assess the effects of climate 

change on the distribution, behavior, and productivity of sperm whales. 

In addition to the information collected in 5.1, 5.2, and 5.5, improved knowledge 

of the effects of climate change on sperm whale feeding ecology and habitat use 

would be informative for evaluating or predicting shifts in prey abundance or 

distribution caused by climatic fluctuations. Investigating the degree of overlap 

between distributions of different species, the environmental factors influencing 

their distributions, and the effect of spatial scale on the significance of different 

environmental predictors should be supported to improve knowledge on the 

potential effects of climate change on sperm whales. Although the natural 

absorption of carbon dioxide (CO2) by the world’s oceans helps mitigate the 

climatic effects of anthropogenic emissions of CO2, it is believed that the 

resulting decrease in pH will have negative consequences. While the full 

ecological consequences of these changes are not known, organisms, such as 

sperm whales, may suffer adverse effects, either directly as reproductive or 

physiological effects or indirectly through negative impacts on their food 

resources. 

5.6.2 Seek strategies to reduce any detrimental impacts of climate change on 

sperm whales and their prey and habitats (identified in action 5.6.1). 

Strategies developed through international efforts to mitigate and minimize the 

effects of climate change should be followed for the benefit of sperm whales as 

well as other ecosystem components. 

6.0 Investigate Causes and Reduce the Frequency and Severity of Human-caused Injury 

and Mortality. 

Known or suspected causes of anthropogenic mortality and injury in sperm whales include vessel 

strikes, ingestion of marine debris, and entanglement in fishing gear or debris. Studies of the 

circumstances leading to collisions with ships and entanglement in fishing gear are required 

before appropriate measures can be developed to reduce the impacts on sperm whales. Available 

evidence does not indicate that shipping-related and fishery-related mortality is affecting 

recovery in U.S. waters, although it is not known what negative effects, if any, observed sublethal impacts may have on sperm whales (Loup et al. 2005). Nevertheless, given the usually 
December 2010 IV-15 NMFS 

offshore distribution of sperm whales, geographical expansion of existing observational effort 

would be necessary to achieve a comprehensive understanding of the frequency of ship strikes 

and entanglements. Studies to quantify the volume and type of ship traffic, fisheries, and 

pollution in areas known to be important to sperm whales would provide a useful perspective on 

the potential seriousness of these threats. 

6.1 Investigate and reduce injury and mortality caused by fisheries and fishing 

equipment and reduce depredation. 

6.1.1 Conduct a systematic review of data on sperm whale interactions with 

fishing operations. 

 In the Atlantic Ocean, the threat posed by pelagic drift gillnet and longline 

fishing was ranked as low, however sperm whale entanglement is known to be a 

high risk factor in the swordfish drift gillnet fishery in the Mediterranean Sea and 

thus further research is needed in this area. There is high uncertainty about threat 

by Indian Ocean fishing practices to sperm whale recovery, and more information 

about fishing interactions in this region is needed. A thorough understanding of 

where sperm whales and fishing gear coincide will help guide management efforts 

to reduce the threat of entanglement and depredation. 

After a systematic review, it should be possible to make a preliminary evaluation 

of what types of fisheries and fishing gear pose the greatest risk to sperm whales 

and the nature of the interaction. Data from areas outside U.S. waters could be 

useful for strengthening inferences and extrapolations. 

 

6.1.2 Promote studies that investigate the ingestion of fishing gear (and the 

target species/bait) by sperm whales and develop methods to reduce sperm whale 

ingestion of fishing gear. 

On-going collaborative projects in Alaska are investigating the extent and 

etiology of depredation (Sigler et al. 2003; Straley et al. 2005). Data from 

fisheries surveys as well as in-depth investigations with acoustic monitoring will 

document the scope and dynamics of the interactions and be valuable for 

developing a deterrence system before serious injuries and mortalities occur. 

6.1.3 Investigate the development of a system to non-lethally deter sperm 

whales from fishing gear. 

6.1.4 Conduct studies of gear modifications that reduce the likelihood of 

entanglement and depredation, mitigate the effects of entanglements, and enhance 

the possibility of disentanglement. Determine whether measures to reduce 

entanglement and depredation are effective. 

Current and ongoing research on possible modifications to fishing gear that 

facilitate an entangled whale freeing itself once entangled should be continued. 

These studies might include assessing the potential use of biodegradable lines, 
December 2010 IV-16 NMFS 

studying ways to reduce the number and length of vertical lines in the water 

column, designing breakaway lines for heavy gear, and researching acoustic 

deterrents. 

6.1.5 Develop and implement schemes to reduce the rate at which fishing gear is 

lost, and improve the reporting of lost gear, in conjunction with studies in 6.1.2, 

6.1.3, 6.1.4, and 6.1.6. 

6.1.6 Continue to review, evaluate, and act upon reports from fishermen and 

fishery observers of fishery interactions with sperm whales. 

6.2 Investigate and reduce mortality and serious injury from vessel collisions.

6.2.1 Identify areas where concentrations of sperm whales coincide with 

significant levels of maritime traffic. 

The possible impacts of ship strikes on recovery of sperm whale populations are 

not well understood. While relatively rare, there are reports of ships colliding 

with sperm whales in the Atlantic Ocean, Pacific Ocean, Gulf of Mexico and 

Mediterranean, and while there are no reports of collisions in the Indian Ocean, 

they likely occur there as well. Many ship strikes go unreported or undetected 

and the offshore distribution of sperm whales may make ship strikes less 

detectable than for other species, thus the estimates of serious injury or mortality 

should be considered minimum estimates. Studies are needed to identify areas 

where high ship traffic densities and sperm whale densities overlap to assist with 

management efforts to reduce the occurrence of ship strikes. 

6.2.2 Identify specific areas where recorded ship strikes of sperm whales have 

occurred (for example, the Canary Islands) and conduct studies to identify 

ecosystem-based traits that could support an assemblage of predictive tools. 

Building upon information compiled in action 6.2.1, the above would assist in the 

determination of when sperm whales may be present, why sperm whales are 

present in the area at that time, and whether the presence of ships alters the 

ecosystem in such a way that sperm whales become more susceptible to a strike. 

It is expected that this objective could be accomplished in conjunction with 

surveys conducted to achieve actions 3.2, 5.1, and 5.5, and thus reduce costs. 

6.2.3 Once areas in 5.0 and 6.2.1 are identified, and in conjunction with 

information derived and resulting predictive tools from 6.2.2, conduct analyses of 

shipping routes and important sperm whale habitat areas to determine the risk of 

ship collisions with sperm whales. 

6.2.4 Develop a system to encourage, collect, and appropriately analyze 

opportunistic sightings of sperm whales from fishing vessels, whale-watching 

vessels, charter vessels, etc. 
December 2010 IV-17 NMFS 

6.2.5 Work with mariners, the shipping industry, and appropriate State, Federal, 

and International agencies to develop and implement regionally-based measures 

to reduce the threat of ship strikes. Assess the effectiveness of ship strike 

measures and adjust, as necessary. 

The practicality and effectiveness of options to reduce ship strikes, should be 

assessed. Methods and measures developed for other endangered whales (e.g., 

right whales) should be considered for their possible application to sperm whales. 

6.2.6 Explore possible mechanisms to encourage vessels that have struck a 

whale to report the incident.

6.3 Conduct studies of environmental pollution that may affect sperm whale 

populations and their prey. 

The inconclusive, but troublesome, nature of studies related to contaminants in sperm 

(and other toothed) whales makes it difficult to develop (and justify) measures to reduce 

their risks of exposure. Research is needed on the long-term and trans-generational 

effects of various contaminants on the whales and on their prey. Research should be 

extended to include studies of metabolic pathways and the influence on contaminant 

burdens of sex, reproductive condition, and geographic origin. 

6.3.1 Identify areas where concentrations of sperm whales coincide with 

significant levels of pollution (including marine debris). 

In a review of organochlorine and metal pollutants in marine mammals from 

Central and South America, Borrell and Aguilar (1999) note that organochlorine 

levels in marine mammals suggest low levels of exposure compared to other 

regions of the world. Although data are extremely scarce, concentrations of 

organochlorines in the tropical and equatorial fringe of the northern hemisphere 

and throughout the southern hemisphere are low or extremely low in marine 

mammals, and organochlorine concentrations in marine mammals off South 

America, South Africa and Australia are invariably low (Aguilar et al. 2002). The 

highest concentrations of organochlorines found in marine mammals are in the 

Mediterranean Sea. High concentrations of organochlorines in marine mammals 

also occur, although to a lesser extent, along the Pacific coast of the U.S. and 

generally in other mid-latitudes in the northern hemisphere (Aguilar et al. 2002). 

6.3.2 Conduct studies on individual health and body condition as they may be 

related to accumulated contaminants. 

Biopsy samples collected under items 3.1.1 and 3.1.2 (above) will be usable for 

some of this work. The Ocean Alliance collected over 900 sperm whale biopsy 

samples during the five-year, round-the-world voyage of the RV Odyssey, and 

plans analyzed many of these samples for organochlorines and heavy metals. 
December 2010 IV-18 NMFS 

Related studies of pollution sources and transport processes are necessary to 

provide the basis for management measures. 

6.3.3 Take steps to minimize adverse effects from pollutants, if necessary. 

If studies indicate that contaminants in the marine environment are adversely 

affecting sperm whales, steps should be taken to reduce the sources of such 

contaminants. 

7.0 Determine and Minimize Any Detrimental Effects of Anthropogenic Noise in the 

Oceans. 

Sperm whales are among the cetaceans likely to be sensitive to disturbance by loud or unfamiliar 

noise. Their deep-ocean distribution and far-ranging movements put them in potential conflict 

with a wide array of human activities, including mineral exploration and exploitation (e.g., 

seismic surveys), military maneuvers, and research using acoustic methods. It is therefore 

important to understand and mitigate the effects of anthropogenic noise on these animals. 

7.1 Conduct studies to assess the effects of anthropogenic noise on the distribution, 

behavior, and productivity of sperm whales.

As discussed in section G.2, some research has addressed questions about the effects of 

noise on sperm whales, and little of this work has been conclusive in regard to the 

biological significance of observed effects. Studies are needed to assess potential adverse 

effects of underwater noise (including ship noise) on sperm whales, including, but not 

limited to, disturbance of intraspecific communication, disruption of vital functions 

mediated by sound, distributional shifts, and stress from chronic or frequent exposure to 

loud sound. Noise sources studied should include, but not be limited to, industrial and 

shipping activities, oceanographic experiments, military related activities, and other 

human activities. 

7.2 Take steps to minimize anthropogenic noises that are found to be potentially 

detrimental to sperm whales. 

If studies of the kind mentioned in item 7.1 indicates that particular types of underwater 

noise have adverse effects on sperm whales (either by masking their sounds or by 

damaging their auditory organ systems), or add physiological stress to their lives, 

implement appropriate regulatory measures on sources of the threat. 

8.0 Maximize Efforts to Acquire Scientific Information from Dead, Stranded, and 

Entangled Sperm Whales.

Assessment of the causes and frequency of mortality (either natural or human-caused) is 

important to understanding population dynamics and the threats that may impede the recovery of 

sperm whale populations. However, discovery of a carcass under circumstances allowing it to be 
December 2010 IV-19 NMFS 

examined in a timely and rigorous manner is a relatively rare event. Accordingly, efforts to 

detect and investigate sperm whale deaths should be as efficient as possible. 

8.1 Respond effectively to strandings of sperm whales in U.S. waters. 

8.1.1 Continue and improve programs to maximize data collected from 

necropsy of sperm whale carcasses. 

Each sperm whale carcass represents an opportunity for scientific investigation of 

the cause of death, as well as addressing other questions related to the biology of 

the species. Delays in attempts to secure or examine a carcass can result in the 

loss of valuable data, or even of the carcass itself. The Stranding Network 

coordinator should work with appropriate agencies, organizations, and individuals 

to ensure that, when a sperm whale carcass is reported and secured: (i) a necropsy 

is performed as rapidly and as thoroughly as possible by qualified individuals to 

gather information regarding the cause of death; (ii) samples are taken and 

properly preserved for studies of genetics, toxicology, and pathology; and (iii) 

funding is available to notify and transport appropriate experts to the site rapidly 

and to distribute tissue samples to appropriate locations for analysis or storage. In 

addition, the coordinator should work with stranding networks and the scientific 

community, to develop and maintain lists of tissue samples requested by qualified 

individuals and agencies, and ensure that these samples are collected routinely 

from each carcass and stored in appropriate locations or distributed to appropriate 

researchers. 

8.1.2 Maintain and review, and if needed improve, the system for reporting 

dead, stranded, or entangled sperm whales. 

8.1.3 Improve, or as necessary, develop and implement protocols for securing 

and retrieving stranded (on land) or floating (at sea) sperm whale carcasses. 

The detection and reporting of dead sperm whales, whether stranded or floating at 

sea, need to be encouraged. The Large Whale Recovery Program coordinator and 

the National Marine Mammal Stranding Network coordinator, should continue 

working with representatives of local, state, and federal agencies, private 

organizations, academic institutions, and regional and national stranding 

networks, to facilitate efficient observer coverage and information exchange. In 

areas where protocols do not exist, they should be developed. The 

responsibilities of all relevant agencies, organizations, and individuals should be 

clearly defined. 

Sperm whales may die at sea and not be detected or reported. Mariners, including 

Navy and Coast Guard personnel, commercial and recreational boaters, and 

fishermen might observe carcasses at sea, but not recognize the importance of 

their observation. Mariners should be educated about the importance of reporting 

carcasses so that as much information as possible can be collected from them. 
December 2010 IV-20 NMFS 

8.2 Review, analyze, and summarize data on stranded sperm whales on an annual 

basis. 

Current and complete data on stranding events and the data derived from them is essential 

to developing protective measures. Summaries should include, but not be limited to, 

assessments of the cause of death and, where applicable, the types of fishing gear, if 

fishing operations resulted in the death of the animal. 

8.3 Develop protocols for handling live-stranded sperm whales.

Disentanglement readiness, contingencies, and programs are essential. When feasible, 

and with maximum regard for human safety, efforts should be made to free entangled 

whales. Therefore, clearly defined strategies should be in place. Disentanglement 

response teams should be trained and efforts to expand disentanglement response should 

be considered to ensure coverage is adequate. Studies of possible advances of 

disentanglement gear should be conducted to improve disentanglement efforts. 

Rehabilitation of live-stranded sperm whales may be feasible in very limited 

circumstances. Attempting and effecting rehabilitation requires advanced planning 

including decisions regarding appropriate facilities, logistics, and equipment to be used. 

These are likely regionally specific and should be developed in advance with 

responsibilities clearly defined. 

8.4 Establish reliable sources of funding for rescue, necropsy, tissue collection, and 

analysis efforts.

As noted, collection of information from sperm whale carcasses is essential to recovery 

efforts. Therefore, identifying and committing predictable sources of funding for 

completing these tasks is also critical. 

9.0 Develop Post-delisting Monitoring Plan.

After populations have been identified, determined to be stable or increasing, and threats 

controlled, a monitoring plan should be developed to ensure that sperm whales do not revert in 

abundance, or become subject to new threats that cause adverse effects. Normally, this 

monitoring plan will be a scaled-down version of the monitoring conducted prior to delisting, 

and will continue for a minimum of 1.5 generations, although it may be continued for longer. 
December 2010 V-1 NMFS 

V. IMPLEMENTATION SCHEDULE 

The implementation schedule that follows is used to estimate costs to direct and monitor 

implementation and completion of recovery tasks set forth in this Recovery Plan. It is a guide 

for meeting recovery goals outlined in this Recovery Plan. The Implementation Schedule 

indicates the action numbers, action descriptions, action priorities, duration of the action, the 

parties responsible for the actions, and estimated costs. Parties with authority, responsibility, or 

expressed interest to implement a specific recovery action are identified in the Implementation 

Schedule. 

Priorities in column 3 of the implementation schedule are assigned as follows: 

Priority 1 – An action that must be taken to prevent extinction or to identify those actions 

necessary to prevent extinction. 

Priority 2 – An action that must be taken to prevent a significant decline in population numbers 

or habitat quality, or to prevent other significant negative trends short of extinction. 

Priority 3 – All other actions necessary to provide for full recovery of the species. 

This implementation schedule accords priorities to individual tasks to specify their importance in 

the recovery effort. It should be noted that even the highest-priority tasks within a plan are not 

given a Priority 1 ranking unless they are actions necessary to prevent extinction or to identify 

those actions necessary to prevent extinction. 

Each action is listed under that section which best describes the intent of that action. However, a 

single action may have multiple consequences. For instance, many of the actions described in 

Action 5 (Identify, Characterize, Protect, and Monitor Habitat Important to Sperm Whale 

Populations in U.S. Waters and Elsewhere.) also have an impact on the threats identified in 

Action 6 (Investigate Causes and Reduce the Frequency and Severity of Human-caused Injury 

and Mortality) as important habitat areas may coincide with areas with significant human 

influences. While this is of little consequence to the overall goal of recovering sperm whales, 

readers should note that because actions are linked, the total cost of achieving the single action 

will include the cost of actions completed in other sections. Hence, while the total cost of 

recovery described in the Implementation Schedule reflects the cost of recovering the species, 

individual actions, or the costs of completing the goals of individual actions, may be understated 

when actions are viewed in isolation. Funding is estimated in accordance with the number of 

years necessary to complete the task once implementation has begun. The provision of cost 

estimates does not mean to imply that appropriate levels of funding will necessarily be available 

for all sperm whale recovery tasks. In addition, the listing party in the Implementation Schedule 

does not require the identified party to implement the action(s) or to secure funding for 

implementing the action(s). The cost of actions within each category is assigned to the 

subsection of that action which encompasses those described under that subsection (i.e., costs in 

subsection 6.1 include those costs incurred in actions 6.1.1, 6.1.2, 6.1.3, 6.1.4, and 6.1.5). For 

each, sub-totals are given as a whole in bold italics. Some costs are listed as discrete (e.g., 5 

years) and some are until time to recovery (i.e., “TBD” and “Ongoing”). Thus, “TBD” and 

“ongoing” were treated equally and both were assumed to equal the time to recovery for cost 
December 2010 V-2 NMFS 

purposes (2024 for Atlantic Ocean/Mediterranean Sea and Pacific Ocean and 2034 for the Indian 

Ocean) and costs that were discrete, were calculated for that discrete time period. 

DISCLAIMER 

The Implementation Schedule that follows outlines actions and estimated costs for the recovery 

program for the sperm whale, as set forth in this Recovery Plan. It is a guide for meeting the 

recovery goals outlined in this Recovery Plan. This schedule indicates action numbers, action 

descriptions, action priorities, duration of actions, the parties responsible for actions (either 

funding or carrying out), and estimated costs. Parties with authority, responsibility, or expressed 

interest to implement a specific recovery action are identified in the Implementation Schedule. 

The listing of a party in the Implementation Schedule does not require the identified party to 

implement the action(s) or to secure funding for implementing the action(s). 

Current NMFS practice is to conduct multi-species marine mammal surveys. The estimates for 

survey costs in this implementation table reflect the cost to conduct sperm whale specific 

research, and therefore are the estimated upper limit. 
Table 2. Sperm Whale Implementation Schedule by Fiscal Year 

December 2010 V-3 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

 1.0 Coordinate State, Federal, and 

International Actions to Implement Recovery Actions and Maintain International Regulation of Whaling for Sperm Whales. 

2 Ongoing NMFS, IWC, 

Department of State (DOS) 

300 300 300 300 300 4,000 5,500 

TOTAL 1 300 300 300 300 300 4,000 5,500  2.0 Develop and Apply Methods to 

Estimate Population Size and Monitor Trends in Abundance. 

2.1 Determine the best methods for 

assessing sperm whale status and trends. 

2 1 NMFS, 

International Partners 

30 30 

2.2 See text for explanation of cost. Costs include 2.2 sub-actions 

Conduct surveys to estimate abundance and monitor trends worldwide. 

2 One 

survey10

NMFS, International Partners 

9 Few actions are expected to be undertaken in the first five fiscal years of this plan. 10 Using two ships for approximately 4.5 months/year. The task duration was rounded up to the nearest 6 or 12 month period for ease of estimating costs. Task Duration is 

one survey and for the Atlantic Ocean, one survey is expected to last 4.6 years. Rounding the value up to coincide with the nearest 6th or 12th month, the total annual cost is 

the total cost in thousands of a sperm-whale specific survey ($43,990), divided by 5 years = $8,798. For the Pacific Ocean, one survey is expected to last 3.4 years. 

Rounding the value up to coincide with the nearest 6th or 12th month, the total annual cost is the total cost in thousands of a sperm-whale specific survey ($32,160), divided 

by 3.5 years = $9,189. For the Indian Ocean, one survey is expected to last 2.8 years. Rounding the value up to coincide with the nearest 6th or 12th month, the total annual 

cost is the total cost in thousands of a sperm-whale specific survey ($27,490), divided by 3 years = $9,163. 
December 2010 V-4 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

2.2.1 Continue to estimate abundance 

and monitor trends in the Atlantic Ocean, Gulf of Mexico, and Pacific Ocean. 

2 One survey 

(see footnote 9) 

NMFS, International Partners 

 76,150 76,150 

2.2.2 Estimate abundance and monitor 

trends in the Indian Ocean. 

2 One survey 

(see footnote 9) 

NMFS, International Partners 

 27,490 27,490 

TOTAL 2 30 n/a n/a n/a n/a 103,640 103,670 3.0 Determine Population 

Discreteness and Population Structure of Sperm Whales. 

3.1 See text for explanation of cost. Costs include 3.1 sub-actions. 

Support existing studies and initiate new studies to investigate population discreteness and population structure of sperm whales using genetic analyses. 

2 5 NMFS, IWC, 

International Partners 

 2,500 2,500 

3.1.1 Continue to collect biopsy samples 

off the Atlantic, Gulf of Mexico, and Pacific coasts of North America. 

2 5 NMFS 

3.1.2 Collaborate with foreign agencies 

and researchers to obtain sufficient samples at the ocean basin scale. 

2 5 NMFS, IWC, 

International Partners 

3.1.3 Perform genetic analyses on 

preserved samples from whales killed by the whaling industry in the past. 

2 5 NMFS, IWC, 

International Partners 
December 2010 V-5 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

3.2 See text for explanation of cost. Costs include 3.2 sub-actions. 

Assess daily and seasonal movements and inter-area exchange using telemetry and photo-identification. 

2 5 NMFS, 

International Partners 

3.2.1 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Atlantic Ocean/Mediterranean Sea. 

2 5 NMFS, 

International Partners 

 1,000 1,000 

3.2.2 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Pacific Ocean. 

2 5 NMFS 1,000 1,000 

3.2.3 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Indian Ocean. 

2 5 NMFS, 

International Partners 

 500 500 

3.2.4 Establish and maintain a central 

repository for sperm whale photographs. 

3 Ongoing NMFS 

3.3 Support ongoing studies and 

initiate new studies to investigate social structure and how it influences population structure. 

2 10 NMFS, 

International Partners 

 2,500 2,500 

TOTAL 3 7,500 7,500  4.0 Conduct Risk Analyses. 4.1 Conduct risk analyses for the

Atlantic Ocean/ Mediterranean Sea. 

2 2 NMFS, 

International Partners 

 200 200 

4.2 Conduct risk analyses for the

Pacific Ocean. 

2 2 NMFS 200 200 

4.3 Conduct risk analyses for the

Indian Ocean. 

2 2 NMFS, 

International Partners 

 200 200 
December 2010 V-6 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

TOTAL 4 n/a n/a n/a n/a n/a 600 600 5.0 Identify, Characterize, Protect, 

and Monitor Habitat Important to Sperm Whale Populations in U.S. Waters and Elsewhere. 

5.1 See text for explanation of cost 

Characterize sperm whale habitat. 2 10 NMFS, 

International Partners 

5.1.1 Conduct research to characterize 

sperm whale habitat in the Atlantic Ocean. 

2 10 NMFS 5,000 5,000 

5.1.2 Conduct research to characterize 

sperm whale habitat in the Pacific Ocean. 

2 10 NMFS 5,000 5,000 

5.1.3 Conduct research to characterize 

sperm whale habitat in the Indian Ocean and Mediterranean Sea. 

2 10 NMFS, 

International Partners 

 5,000 5,000 

5.2 See 5.1 for costs 

Monitor important habitat features and sperm whale use patterns to assess potentially detrimental shifts in these features that might reflect disturbance or degradation of habitat. 

2 Ongoing NMFS, 

International Partners 

5.3 Promote actions to protect 

important habitat in U.S. waters. 

3 Ongoing NMFS, NOS * * * * * * 

5.4 Promote actions to define, identify, 

and protect important habitat in foreign or international waters. 

3 Ongoing NMFS, DOS, 

International Partners 

* * * * * * 

5.5 Improve knowledge of sperm 

whale feeding ecology. 

2 10 NMFS 4,000 4,000 
December 2010 V-7 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

5.6 Conduct research and perform 

analyses to understand the impacts of climate change on sperm whales and seek strategies to reduce these impacts. 

2 TBD TBD TBD TBD TBD TBD TBD TBD TBD 

5.6.1 Conduct studies and perform 

analyses to assess the effects of climate change on the distribution, behavior, and productivity of sperm whales. 

2 TBD TBD TBD TBD TBD TBD TBD TBD TBD 

5.6.2 Seek strategies to reduce any 

detrimental impacts of climate change on sperm whales and their prey and habitats (identified in action 5.6.1). 

2 TBD TBD TBD TBD TBD TBD TBD TBD TBD 

TOTAL 5 19,000 19,000 6.0 Investigate Causes and Reduce 

the Frequency and Severity of Human-caused Injury and Mortality.

6.1 Costs include 6.1 sub-actions 

Investigate and reduce injury and mortality caused by fisheries and fishing equipment and reduce depredation. 

2 5 NMFS, USCG, 

NOS 

 13,750 13,750 

6.1.1 Conduct a systematic review of 

data on sperm whale interactions with fishing operations. 

3 TBD NMFS, 

International Partners 

6.1.2 Promote studies that investigate the 

ingestion of fishing gear (and the target species/bait) by sperm whales and develop methods to reduce ingestion of fishing gear. 

2 TBD TBD 

6.1.3 Investigate the development of a 

system to non-lethally deter sperm whales from fishing gear. 

2 TBD TBD 
December 2010 V-8 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

6.1.4 Conduct studies of gear 

modifications that reduce the likelihood of entanglement and depredation, mitigate effects of entanglements, and enhance possibility of disentanglement. Determine whether measures to reduce entanglements and depredation are effective. 

2 TBD TBD 

6.1.5 Develop and implement schemes 

to reduce the rate at which gear is lost, and improve the reporting of lost gear, in conjunction with studies in 6.1.2, 6.1.3, 6.1.4, and 6.1.6. 

3 TBD TBD 

6.1.6 Continue to review, evaluate, and 

act upon reports from fishermen and fishery observers of fishery interactions with sperm whales. 

2 Ongoing NMFS, States, 

USCG 

* * * * * * 

6.2 Costs include 6.2 sub-actions 

Investigate and reduce mortality and serious injury from vessel collisions. 

2 5 NMFS, USCG, 

States 

 11,250 11,250 

6.2.1 In conjunction with 3.2, 5.1, and 5.5. 

Identify areas where concentrations of sperm whales coincide with significant levels of maritime traffic. 

2 5 NMFS 
December 2010 V-9 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

6.2.2 Identify specific areas where 

recorded ship strikes of sperm whales have occurred (for example, the Canary Islands) and conduct studies to identify ecosystem-based traits that could support an assemblage of predictive tools. 

2 10 NMFS, NOS, 

DOS, States, International Partners 

6.2.3 Once areas in 5.0 and 6.2.1 are 

identified, and in conjunction with information derived and resulting predictive tools from 6.2.2, conduct analyses of shipping routes and important sperm whale habitat areas to determine the risk of ship collisions with sperm whales. 

2 TBD NMFS, DOS, 

International Partners 

6.2.4 Develop a system to encourage, 

collect, and appropriately analyze opportunistic sightings of sperm whales from fishing vessels, whale-watching vessels, charter vessels, etc. 

3 TBD NMFS, NOS, 

USCG, International Partners 

6.2.5 Work with mariners, the shipping 

industry, and appropriate state, federal, and international agencies to develop and implement regionally-based measures to reduce the threat of ship strikes. Assess effectiveness of ship strike measures and adjust, as necessary. 

2 TBD NMFS, USCG, 

NOS 

6.2.6 Explore possible mechanisms to 

encourage vessels that have struck a whale to report the incident. 

3 Ongoing NMFS, NOS, 

USCG, International Partners 
December 2010 V-10 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

6.3 Conduct studies of environmental 

pollution that may affect sperm whale populations and their prey. 

3 5 EPA, NMFS 3,000 3,000 

6.3.1 See 6.3 and 8.1 for costs 

Conduct studies on individual health and body condition as they may be related to accumulated contaminants. 

3 Ongoing NMFS, NOS, 

States, International Partners 

6.3.2 See 6.3 for costs 

Take steps to minimize adverse effects from pollutants, if necessary. 

3 TBD TBD 

TOTAL 6 28,000 28,000  7.0 Determine and Minimize Any 

Detrimental Effects of Anthropogenic Noise in the Oceans. 

7.1 Conduct studies to assess the 

effects of anthropogenic noise on 

the distribution, behavior, and productivity of sperm whales. 

2 5 NMFS, U.S. 

Navy (USN), Bureau of Ocean Energy Management, Regulation, and Enforcement, Int’l Partners 

 7,000 7,000 

7.2 Take steps to minimize 

anthropogenic noises that are found to be potentially detrimental to sperm whales.

3 TBD NMFS, Army 

Corps of Engineers, USN, USCG, Bureau of Ocean Energy Management, Regulation, and Enforcement 

TBD TBD TBD TBD TBD TBD TBD 

TOTAL 7 7,000 7,000 
December 2010 V-11 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Potentially 

Involved 

Cost Estimates by FY 

(thousands of dollars) 

FY11 FY12 FY13 FY14 FY15 FY16 +9

Total/yr. 

x Task 

Duration 

 8.0 Maximize Efforts to Acquire 

Scientific Information from Dead, Stranded, and Entangled Sperm Whales. 

8.1 Respond effectively to strandings 

of sperm whales in U.S. waters. 

3 Ongoing NMFS, NOS, 

States 

180 180 180 180 180 1,800 2,700 

8.1.1 See 8.1 for costs 

Continue and improve programs to maximize data collected from necropsy of sperm whale carcasses. 

3 Ongoing NMFS * * * * * * 

8.1.2 Maintain and review, and if needed 

improve, the system for reporting dead, stranded, or entangled sperm whales. 

3 Ongoing NMFS, States * * * * * * * 

8.1.3 Improve, or as necessary, develop 

and implement protocols for securing and retrieving stranded (on land) or floating (at sea) sperm whale carcasses. 

3 1 NMFS, NOS, 

States 

* * * * * * * 

8.2 Review, analyze, and summarize 

data on stranded sperm whales on an annual basis. 

3 Ongoing NMFS, NOS, 

States 

* * * * * * * 

8.3 Develop protocols for handling 

live-stranded sperm whales.

2 1 NMFS 4 4 

8.4 Establish reliable sources of 

funding for rescue, necropsy, tissue collection, and analysis efforts. 

2 Ongoing NMFS * * * * * * * 

TOTAL 8 180 184 180 180 180 1,800 2,704 9.0 Develop Post-delisting Monitoring 

Plan. 

2 TBD NMFS * * * * * * 

TOTAL 9 * * * * * * TOTAL Overall 

510 484 480 480 480 171,540 173,974 

*No cost associated, NMFS staff time
Table 3. Sperm Whale Implementation Schedule by Ocean Basin 

December 2010 V-12 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

 1.0 Coordinate State, Federal, and 

International Actions to Implement Recovery Actions and Maintain International Regulation of Whaling for Sperm Whales. 

2 Ongoing NMFS, IWC, 

Department of State (DOS) 

100 100 100 300 5,500 

TOTAL 1 100 100 100 300 5,500 2.0 Develop and Apply Methods to 

Estimate Population Size and Monitor Trends in Abundance. 

2.1 Determine the best methods for 

assessing sperm whale status and trends. 

2 1 NMFS, 

International Partners 

 30 30 

2.2 See text for explanation of cost. Costs include 2.2 sub-actions 

Conduct surveys to estimate abundance and monitor trends in sperm whale populations worldwide. 

2 One 

survey11

NMFS, International Partners 

43,99012 32,16013 27,49014 103,640 103,640 

11 Using two ships for approximately 4.5 months/year. The task duration was rounded up to the nearest 6 or 12 month period for ease of estimating costs. 12 In this case, the Task Duration is one survey and for the Atlantic Ocean, one survey is expected to last 4.6 years. Rounding the value up to coincide with the nearest 6th or 

12th month, the total annual cost is the total cost in thousands of a sperm-whale specific survey ($43,990), divided by 5 years which is $8,798. 

13 In this case, the Task Duration is one survey and for the Pacific Ocean, one survey is expected to last 3.4 years. Rounding the value up to coincide with the nearest 6th or 

12th month, the total annual cost is the total cost in thousands of a sperm-whale specific survey ($32,160), divided by 3.5 years which is $9,189. 

14 In this case, the Task Duration is one survey and for the Indian Ocean, one survey is expected to last 2.8 years. Rounding the value up to coincide with the nearest 6th or 

12th month, the total annual cost is the total cost in thousands of a sperm-whale specific survey ($27,490), divided by 3 years which is $9,163. 
December 2010 V-13 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

2.2.1 Continue to estimate abundance and 

monitor trends in sperm whale populations in the Atlantic Ocean, Gulf of Mexico, and Pacific Ocean. 

2 One survey 

(see footnote 12) 

NMFS, International Partners 

2.2.2 Estimate abundance and monitor 

trends in sperm whale populations in the Indian Ocean and Mediterranean Sea. 

2 One survey 

(see footnote 12) 

NMFS, International Partners 

TOTAL 2 43,990 32,160 27,490 103,670 103,670 3.0 Determine Population Discreteness 

and Population Structure of Sperm Whales. 

3.1 See text for explanation of cost. Costs include 3.1 sub-actions. 

Support existing studies and initiate new studies to investigate population discreteness and population structure of sperm whales using genetic analyses. 

2 5 NMFS, IWC, 

International Partners 

200 200 100 500 2,500 

3.1.1 Continue to collect biopsy samples 

off the Atlantic, Gulf of Mexico, and Pacific coasts of North America. 

2 5 NMFS 

3.1.2 Collaborate with foreign agencies 

and researchers to obtain sufficient samples at the ocean basin scale. 

2 5 NMFS, IWC, 

International Partners 

3.1.3 Perform genetic analyses on 

preserved samples from whales killed by the whaling industry in the past. 

2 5 NMFS, IWC, 

International Partners 
December 2010 V-14 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

3.2 See text for explanation of cost. Costs include 3.2 sub-actions. 

Assess daily and seasonal movements and inter-area exchange using telemetry and photoidentification. 

2 5 NMFS, 

International Partners 

200 200 100 500 2,500 

3.2.1 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Atlantic Ocean/Mediterranean Sea. 

2 5 NMFS, 

International Partners 

3.2.2 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Pacific Ocean. 

2 5 NMFS 

3.2.3 Continue/conduct telemetry and 

photo-identification studies of sperm whales in the Indian Ocean. 

2 5 NMFS, 

International Partners 

3.2.4 Establish and maintain a central 

repository for sperm whale photographs. 

3 Ongoing NMFS 

3.3 Support ongoing studies and initiate 

new studies to investigate social structure and how it influences population structure. 

2 10 NMFS, 

International Partners 

100 100 50 250 2,500 

TOTAL 3 500 500 250 1,250 7,500  4.0 Conduct Risk Analyses. 4.1 Conduct risk analyses for the

Atlantic Ocean/ Mediterranean Sea . 

2 2 NMFS, 

International Partners 

100 100 200 

4.2 Conduct risk analyses for the Pacific 

Ocean. 

2 2 NMFS 100 100 200 

4.3 Conduct risk analyses for the Indian 

Ocean. 

2 2 NMFS, 

International Partners 

 100 100 200 
December 2010 V-15 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

TOTAL 4 100 100 100 300 600 5.0 Identify, Characterize, Protect, and 

Monitor Habitat Important to Sperm Whale Populations in U.S. Waters and Elsewhere. 

5.1 See text for explanation of cost 

Characterize sperm whale habitat. 2 10 NMFS, 

International Partners 

5.1.1 Conduct research to characterize 

sperm whale habitat in the Atlantic Ocean. 

2 10 NMFS 500 500 5,000 

5.1.2 Conduct research to characterize 

sperm whale habitat in the Pacific Ocean. 

2 10 NMFS 500 500 5,000 

5.1.3 Conduct research to characterize 

sperm whale habitat in the Indian Ocean and Mediterranean Sea. 

2 10 NMFS, 

International Partners 

 500 500 5,000 

5.2 See 5.1 for costs 

Monitor important habitat features and sperm whale use patterns to assess potentially detrimental shifts in these features that might reflect disturbance or degradation of habitat. 

2 Ongoing NMFS, 

International Partners 

5.3 Promote actions to protect important 

habitat in U.S. waters. 

3 Ongoing NMFS, NOS * * * * 

5.4 Promote actions to define, identify, 

and protect important habitat in foreign or international waters. 

3 Ongoing NMFS, DOS, 

International Partners 

* * * * * 

5.5 Improve knowledge of sperm whale 

feeding ecology. 

2 10 NMFS 150 150 100 400 4,000 

5.6 Investigate the impacts of climate 

change on sperm whales and seek strategies to reduce these impacts. 

2 TBD TBD TBD TBD TBD TBD TBD 
December 2010 V-16 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

5.6.1 Conduct studies and perform 

analyses to assess the effects of climate change on the distribution, behavior, and productivity of sperm whales. 

2 TBD TBD TBD TBD TBD TBD TBD 

5.6.2 Seek strategies to reduce any 

detrimental impacts of climate change on sperm whales and their prey and habitats (identified in action 5.6.1). 

2 TBD TBD TBD TBD TBD TBD TBD 

TOTAL 5 650 650 600 1,900 19,000 6.0 Investigate Causes and Reduce the 

Frequency and Severity of Humancaused Injury and Mortality.

6.1 Costs include 6.1 subactions 

Investigate and reduce injury and mortality caused by fisheries and fishing equipment and reduce depredation. 

2 5 NMFS, USCG, 

NOS 

500 1,500 750 2,750 13,750 

6.1.1 Conduct a systematic review of data 

on sperm whale interactions with fishing operations. 

2 TBD NMFS, 

International Partners 

6.1.2 Promote studies that investigate the 

ingestion of fishing gear by sperm whales and develop methods to reduce ingestion of fishing gear. 

2 TBD TBD 

6.1.3 Investigate the development of a 

system to non-lethally deter sperm whales from fishing gear. 

2 TBD TBD 
December 2010 V-17 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

6.1.4 Conduct studies of gear 

modifications that reduce the likelihood of entanglement and depredation, mitigate effects of entanglements, and enhance possibility of disentanglement. Determine whether measures to reduce entanglements and depredation are effective. 

2 TBD TBD 

6.1.5 Develop and implement schemes to 

reduce the rate at which gear is lost, and improve the reporting of lost gear, in conjunction with studies in 6.1.2, 6.1.3, 6.1.4, and 6.1.6. 

2 TBD TBD 

6.1.6 Continue to review, evaluate, and act 

upon reports from fishermen and fishery observers of fishery interactions with sperm whales. 

2 Ongoing NMFS, States, 

USCG 

* * TBD * * 

6.2 Costs include 6.3 subactions 

Investigate and reduce mortality and serious injury from vessel collisions. 

2 5 NMFS, States, 

USCG 

750 750 750 2,250 11,250 

6.2.1 Identify areas where concentrations 

of sperm whales coincide with significant levels of maritime traffic. 

2 5 NMFS 

6.2.2 In conjunction with 3.2, 5.1, and 5.5. 

Identify specific areas where recorded ship strikes of sperm whales have occurred (for example, the Canary Islands) and conduct studies to identify ecosystem-based traits that could support an assemblage of predictive tools. 

2 10 NMFS, NOS, 

DOS, States, International Partners 
December 2010 V-18 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

6.2.3 Once areas in 5.0 and 6.1.2 are 

identified, and in conjunction with information derived and resulting predictive tools from 6.3.1, conduct analyses of shipping routes and important sperm whale habitat areas to determine the risk of ship collisions with sperm whales. 

2 TBD NMFS, DOS, 

International Partners 

6.2.4 Develop a system to encourage, 

collect, and appropriately analyze opportunistic sightings of sperm whales from fishing vessels, whalewatching vessels, charter vessels, etc. 

3 TBD NMFS, NOS, 

USCG, International Partners 

6.2.5 Work with mariners, the shipping 

industry, and appropriate state, federal, and international agencies to develop and implement regionallybased measures to reduce the threat of ship strikes. Assess effectiveness of ship strike measures and adjust, as necessary. 

2 TBD NMFS, NOS, 

USCG, 

6.2.6 Explore possible mechanisms to 

encourage vessels that have struck a whale to report the incident. 

3 Ongoing NMFS, NOS, 

USCG, International Partners 

6.3 Conduct studies of environmental 

pollution that may affect sperm whale populations and their prey. 

3 5 EPA, NMFS 250 250 100 600 3,000 

6.3.1 Identify areas where concentrations 

of sperm whales coincide with significant levels of pollution (including marine debris). 

2 5 NMFS 
December 2010 V-19 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

6.3.2 See 6.3 and 8.1 for costs 

Conduct studies on individual health and body condition as they may be related to accumulated contaminants. 

3 Ongoing NMFS, NOS, 

States, International Partners 

6.3.3 See 6.3 for costs 

Take steps to minimize adverse effects from pollutants. 

3 TBD TBD 

TOTAL 6 1,500 2,500 1,600 5,600 28,000  7.0 Determine and Minimize Any 

Detrimental Effects of Anthropogenic Noise in the Oceans. 

7.1 Conduct studies to assess the effects 

of anthropogenic noise on the distribution, behavior, and productivity of sperm whales. 

2 5 NMFS, U.S. Navy 

(USN), Bureau of Ocean Energy Management, Regulation, and Enforcement, Int’l Partners 

500 500 400 1,400 7,000 

7.2 Take steps to minimize 

anthropogenic noises that are found to be potentially detrimental to sperm whales.

3 TBD NMFS, Army 

Corps of Engineers, USN, USCG, Bureau of Ocean Energy Management, Regulation, and Enforcement 

TBD TBD TBD TBD TBD 

TOTAL 7 500 500 400 1,400 7,000  8.0 Maximize Efforts to Acquire 

Scientific Information from Dead, Stranded, and Entangled Sperm Whales. 

8.1 Respond effectively to strandings of 

sperm whales in U.S. waters. 

3 Ongoing NMFS, NOS, 

States 

90 90 180 2,700 
December 2010 V-20 NMFS 

Action 

Number Action Description Priority 

Task 

Duration 

(years) 

Agencies/ 

Organizations 

Involved/ 

Potentially 

Involved 

Cost Estimates by Ocean Basin 

(thousands of dollars) 

Atlantic 

Ocean 

(2025) 

Pacific 

Ocean 

(2025) 

Indian 

Ocean 

(2035) 

Total 

Total/yr. x 

Task 

Duration 

8.1.1 See 8.1 for costs 

Continue and improve programs to maximize data collected from necropsy of sperm whale carcasses. 

3 Ongoing NMFS 

8.1.2 Maintain and review, and if needed 

improve, the system for reporting dead, stranded, or entangled sperm whales. 

3 Ongoing NMFS, States * * TBD * * 

8.1.3 Improve, or as necessary, develop 

and implement protocols for securing and retrieving stranded (on land) or floating (at sea) sperm whale carcasses. 

3 1 NMFS, NOS, 

States 

* * TBD * * 

8.2 Review, analyze, and summarize data 

on stranded sperm whales on an annual basis. 

3 Ongoing NMFS, NOS, 

States 

* * * * * 

8.3 Develop protocols for handling livestranded sperm whales. 2 1 NMFS 2 2 TBD 4 4 8.4 Establish reliable sources of funding 

for rescue, necropsy, tissue collection, and analysis efforts. 

2 Ongoing NMFS * * TBD * * 

TOTAL 8 92 92 184 2,704 9.0 Develop Post-delisting Monitoring 

Plan. 

2 TBD NMFS * * * * 

TOTAL 9 * * * * 

*No cost associated, NMFS staff time
December 2010 V-21 NMFS 

Table 4. Estimated Cost of Action Items Listed as Priority 1, Priority 2, and Priority 3 

in the Table 2 (in thousands of dollars). 

ACTION ITEMS LISTED AS: TOTAL COST

PRIORITY 1 0

PRIORITY 2 168,274

PRIORITY 3 5,700

NOTE: The cost above does not reflect task duration (e.g., 5 years) rather all costs were estimated until time to 

recovery for all three ocean basins (15 years for the Atlantic Ocean/Mediterranean Sea and Pacific Ocean (2025) and 

25 years for the Indian Ocean (2035)).

Table 5. Estimated Cost of Action Items by Ocean Basin in Table 2 (in thousands of 

dollars). 

Year Action 

1 

Action 

2 

Action 

3 

Action 

4 

Action 

5 

Action 

6 

Action 

7 

Action 

8 

Action 

9 Total1

Atlantic 

(2025) 1,500 43,990 3,000 200 6,500 7,500 2,500 1,352 * 66,542 

Pacific 

(2025) 1,500 32,160 3,000 200 6,500 12,500 2,500 1,352 * 59,712 

Indian 

(2035) 2,500 27,490 1,500 200 6,000 8,000 2,000 47,690 

Total for 

Task 

Duration 

5,500 103,6702

 7,500 600 19,000 28,000 7,000 2,704 * 173,974 

NOTE: The cost above does not reflect task duration (e.g., 5 years) rather all costs were estimated until time to recovery for 

each ocean basin (15 years for the Atlantic Ocean/Mediterranean Sea and Pacific Ocean (2025) and 25 years for the Indian 

Ocean (2035)). 

1 Total reflects cost of recovery for ocean basin. 2

 Total reflects an additional cost of $30K that is not specific to one ocean basin. 

* No cost associated, NMFS staff time. 

 
December 2010 V-22 NMFS 

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December 2010 VI-1 NMFS 

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