OCS Study 

MMS 2007-033 

 

Cooperative Research to Study 

Dive Patterns of Sperm Whales 

in the Atlantic Ocean 

U.S. Department of the Interior

Minerals Management Service 

Gulf of Mexico OCS Region 
U.S. Department of the Interior

Minerals Management Service 

Gulf of Mexico OCS Region 

OCS Study 

MMS 2007-033 

Cooperative Research to Study 

Dive Patterns of Sperm Whales 

in the Atlantic Ocean 

Editors 

Debra Palka 

National Marine Fisheries Service 

Woods Hole, Massachusetts 

Mark Johnson 

Woods Hole Oceanographic Institution 

Woods Hole, Massachusetts 

Prepared under Interagency Agreement 

RU98-15958 

by 

National Marine Fisheries Service 

Northeast Fisheries Service Center 

Woods Hole, Massachusetts 02543 

Published by 

New Orleans

May 2007 
iii 

DISCLAIMER 

This report was prepared under an interagency agreement between the Minerals Management Service 

(MMS) and the National Marine Fisheries Service. This report has been technically reviewed by the 

MMS, and it has been approved for publication. Approval does not signify that the contents necessarily 

reflect the views and policies of the MMS, nor does mention of trade names or commercial products 

constitute endorsement or recommendation for use. It is, however, exempt from review and compliance 

with the MMS editorial standards. 

REPORT AVAILABILITY 

Extra copies of this report may be obtained from the Public Information Office (Mail Stop 5034) at the 

following address: 

U.S. Department of the Interior 

Minerals Management Service 

Gulf of Mexico OCS Region 

Public Information Office (MS 5034) 

1201 Elmwood Park Boulevard 

New Orleans, Louisiana 70123-2394 

Telephone: (504) 736-2519 or 

 1-800-200-GULF 

CITATION 

Suggested citation: 

Palka, D. and M. Johnson, eds. 2007. Cooperative research to study dive patterns of sperm whales in the 

Atlantic Ocean. U.S. Dept. of the Interior, Minerals Management Service, Gulf of Mexico OCS 

Region, New Orleans, LA. OCS Study MMS 2007-033. 49 pp. 

CONTRIBUTING AUTHORS 

Stephanie Watwood – Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 

Peter Madsen – Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 

Natacha Aguilar de Soto – University of La Laguna, Tenerife, Spain 

Maria Elena Quero – Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 

Peter Tyack – Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 

Gordon Waring – National Marine Fisheries Service, Woods Hole, Massachusetts 

Jay O’Reilly – National Marine Fisheries Service, Naragansett, Rhode Island 

ACKNOWLEDGMENTS 

Thanks are extended to Kira Barton, Dan Englehaupt, Matt Grund, Wayne Hoggard, Tom Hurst, Alex 

Shorter, Walter Zimmer, Fred Wenzel, Stacy DeRuiter, Susan Rocca, Carol Fairfield, Anna Nowsek, 

Gina Reppucci, Irene Briga, and the crew of the R/V Delaware who were essential to the collection and 

integration of these data. 
EXECUTIVE SUMMARY 

The National Marine Fisheries Service (NMFS) is required to produce stock assessments for all 

marine mammal stocks within the U.S. Exclusive Economic Zone. The Minerals Management Service 

(MMS) is evaluating potential environmental impacts of offshore oil and gas activities on marine 

mammals. Both agencies have a need for similar information on sperm whales and this is the basis for the 

cooperative research outlined here. This study, conducted in July 2003, has started a baseline of linetransect, photo-identification, oceanographic and genetic data for the Atlantic sperm whale. Compared 

with the Delta region in the Gulf of Mexico, parts of the Atlantic Ocean may serve as a control population 

of sperm whales with little exposure to sounds of oil and gas related activities. 

A total of 12 sperm whales were tagged during the four-week, July 2003 cruise yielding a substantial 

data set spanning both deep foraging and socializing from 9 of the 12 tagged animals. These tag 

recordings represent the first acquisition of sound and movement data from sperm whales in the North 

Atlantic. Visual and acoustic surveys were performed whenever weather permitted throughout the cruise 

and visual focal follows were made when tags were deployed. Complimentary data products included 

physical oceanographic measurements and skin and fecal samples from tagged and neighboring whales. 

The tag data set from the cruise has been examined using techniques developed on the Sperm Whale 

Seismic Study (SWSS) program to parameterize foraging and social behaviors. The data set has also 

been integrated into a combined data set covering the Gulf of Mexico, North Atlantic and Mediterranean 

seas to enable comparative analyses. We found that the North Atlantic whales follow a foraging and 

socializing cycle similar to the Gulf of Mexico whales but dive significantly deeper to forage. Foraging 

largely occurs at 500-1,100 m but a small amount of food may be taken in water as shallow as 300 m. A 

wide range of codas was produced but even fairly closely located groups appeared to prefer distinct 

codas. 

An unusually high rate of breaching, possibly associated with tag attachment, limited the longevity of 

the tag attachment. The maximum attachment duration of six hours in this Atlantic Ocean study 

compares unfavorably with 16 hours in the Gulf of Mexico and Mediterranean. The unknown reason for 

why there were few long attachments may reduce the number of future successful tagging events from 

whales in the Atlantic. Breaching, possibly associated with tag attachment, has been observed in other 

areas, and those breaching rates varied from year to year. So, perhaps this first year in the Atlantic is just 

on the high side of the inter-annual variability. Further work is needed to address this. In addition, there 

are areas in the Atlantic, such as off Virginia, where there are, at times, a substantial amount of low 

frequency impulsive sounds from underwater explosions in Navy test ranges. Such times and areas 

should not be considered as a future controlled exposure study area. 

Acoustic data could potentially be used in two ways to improve the sperm whale abundance 

estimates. One way is to utilize both visual and passive acoustic detections to estimate the abundance. A 

new project to advance development of such methods was recently funded. The visual and acoustic data 

collected during the Search Mode in this cruise will be used as a test case. 

Another way acoustic data could be used to improve visual line-transect abundance estimates is to use 

the dive time pattern data collected on the acoustic tag (DTAG) in surfacing-based line-transect analysis 

methods. If we assume the tagged animals are representative of the dive patterns of the Atlantic 

population, then there is a 27% (CV=0.46) chance that a single sperm whale is at the surface to be able to 

be detected by a visual sighting team. A simple implementation of using these dive data is to estimate 

total abundance of sperm whales as a function of (i) the abundance using standard visual line-transect 

methods, assuming this is an abundance estimate of surface animals and (ii) the percentage of time whales 

are at the surface using the tag data. Using this over-simplified method the dive time corrected total 

abundance of sperm whales would then be 14,922 (CV=0.60), which is about 3.5 times greater than the 

standard visual abundance estimate. However, this abundance estimate is biased upwards due to the facts 

that the standard abundance estimate is based on detection of groups of whales, where groups are usually 

greater than one, while the probability of a whale being at the surface using the tag data is based on 

singleton whales, and individual sperm whales do not dive totally independent of the other animals in its 

group. Thus, surface-based, not group-based, line-transect analysis methods are required to properly 

account for the confounding facts. These methods are explained in this report and are under development, 

thus results are not currently available. 

Another objective of this and the SWSS cruises is to address the question “Do sperm whales have 

preferred habitats that can be defined physiologically and/or with oceanographically?” One way to 

v 
address this is to model the distribution and abundance of the sperm whales with respect to physical and 

biological parameters, such as water depth, bottom slope, sea-surface temperature, salinity at the surface, 

mixed layer depth, surface color (primary productivity), and distribution and abundance of other trophic 

levels (such as that obtained from bongo samples). Such a model can also include nuisance variables, 

such as Beaufort sea state, which affects the sightability of the whales, but probably does not affect the 

actual distribution of the whales. To start this process, five-day composites from the middle of the cruise 

of sea surface temperature (SST) and chlorophyll-a (chl-a) using satellite pictures were produced and the 

sightings were overlaid. Interestingly, sperm whales appear to be present in more diverse combinations 

of SST and chl-a than many of the other cetacean species detected during this cruise. This could imply 

that sperm whales are not cueing in on these two parameters, like some other species do. Or, sperm 

whales are generalists and so can utilize a variety of habitats or perhaps sperm whales are not cueing in 

ocean surface factors but are cueing on ocean bottom factors. More data are needed to address this. 

Because this cruise concentrated on putting tags on sperm whales and not investigating many type of 

potential habitats, this cruise surveyed a limited number of types of potential habitats. However, the 

NEFSC conducted a large scale line transect abundance survey in 1998 and is currently conducting one 

during the summer of 2004. The plan is to merge the line transect data of the 1998, 2003, and 2004 

surveys to investigate habitat preferences of sperm whales in the Atlantic. Stepwise selection of 

Generalized Additive Models (GAM) will be used to define a model that uses physical and biological 

parameters to describe the sperm whale habitat. To start this modeling exercise, the 1998 data were used 

to model the distribution and abundance of sperm whales in five nautical mile sections of the track line. 

The stepwise GAM determined depth and an interaction between two groups of plankton species (groups 

2 and 3) were the best predictors for sperm whale distribution and abundance, where depth was the most 

influential factor. Sperm whales were inversely related to Plankton group 3, which are species generally 

associated with warm core rings. Sperm whales were positively related to Plankton group 2, which are 

species most often associated with cooler waters, such as those on the outside edge of a ring or in between 

warm core rings. Thus, these GAM results can be interpreted as Atlantic sperm whales are most 

commonly found in waters approximately 2000 meters deep, when those waters are cool, like those found 

on the outside or in between warm core rings. 

vi 
TABLE OF CONTENTS 

Page

LIST OF FIGURES .....................................................................................................................................ix

LIST OF TABLES.......................................................................................................................................xi

1. INTRODUCTION ..................................................................................................................................1

2. FIELD METHODS.................................................................................................................................2

2.1 DTAG .........................................................................................................................................2

2.2 Visual and Acoustic Data Acquisition ........................................................................................3

2.3 Tagging Method..........................................................................................................................3

2.4 Environmental Data Acquisition.................................................................................................4

2.5 Photo-identification (Photo-ID) Data Acquisition......................................................................4

2.6 Diet and Foraging Success Data Acquisition..............................................................................4

3. CRUISE SUMMARY.............................................................................................................................5

4. DATA SUMMARY..............................................................................................................................10

4.1 DTAG Data...............................................................................................................................10

4.2 Permit Data/Close Observations from RHIB............................................................................10

4.3 Visual Data................................................................................................................................10

4.4 Acoustic Data............................................................................................................................11

4.5 Skin and Fecal Samples ............................................................................................................11

4.6 CTD Data ..................................................................................................................................11

4.7 Environmental and Ship Location Data ....................................................................................11

5. DATA ANALYSES AND RESULTS..................................................................................................13

5.1 Tag Data....................................................................................................................................13

5.1.1 Dive Behavior ............................................................................................................13

5.1.2 Foraging Behavior......................................................................................................15

5.1.3 Social Behavior ..........................................................................................................24

5.2 Dive Time Correction for Abundance Estimates......................................................................31

5.2.1 Visual and Passive Acoustic Data ..............................................................................31

5.2.2 Visual and Acoustic Tag Data .........................................................................................32

5.3 Habitat Preferences...................................................................................................................33

6. LITERATURE CITED .........................................................................................................................40

vii 
LIST OF FIGURES 

Page

Figure 1. DTAG deployed on a sperm whale in the North Atlantic.......................................................2

Figure 2. Acoustic survey track lines for the R/V Delaware cruise........................................................8

Figure 3. Visual survey and focal follow tracklines for the R/V Delaware cruise. ................................9

Figure 4. Example of a visual observation chart produced by the SACLANT-WHOI system............12

Figure 5. Typical elements in a normal dive profile.............................................................................14

Figure 6. Average normalized foraging dive profile for sperm whales in the Gulf of Mexico, 

Atlantic, and Mediterranean..................................................................................................17

Figure 7. Dive profile indicating sound events for sw03_197a............................................................18

Figure 8. Dive profile indicating sound events for sw03_201b. ..........................................................19

Figure 9. Dive profile indicating sound events for sw03_202a............................................................20

Figure 10. Dive profile indicating sound events for sw03_202b. ..........................................................21

Figure 11. Dive profile indicating sound events for sw03_206c............................................................22

Figure 12. Dive profile indicating sound events for sw03_207a............................................................23

Figure 13. Depth occurrence of codas normalized by dive depth produced by tagged sperm whales 

in the Gulf of Mexico, the Atlantic, and the Mediterranean. ................................................25

Figure 14. Depth occurrence of codas normalized by dive depth produced by untagged sperm 

whales in the Gulf of Mexico, the Atlantic, and the Mediterranean. ....................................26

Figure 15. Average number of codas produced and heard per animal per descent in the Gulf of 

Mexico, Atlantic, and Mediterranean....................................................................................27

Figure 16. Average number of codas produced and heard per animal per ascent in the Gulf of 

Mexico, Atlantic, and Mediterranean....................................................................................28

Figure 17. Average number of codas produced and heard per animal per inter-dive interval in the 

Gulf of Mexico, Atlantic, and Mediterranean.......................................................................29

Figure 18. Average number of codas produced and heard per animal per surface interval in the Gulf 

of Mexico, Atlantic, and Mediterranean. ..............................................................................30

Figure 19. Distribution of sperm whales seen during 2003 cruise overlaid on a 5-day composite of 

the sea surface temperature (SST) from the middle of the cruise. ........................................35

Figure 20. Distribution of sperm whales seen during 2003 cruise overlaid on a 5-day composite 

from the middle of the cruise of the chlorophyll-a as measured from SeaWiFS. .................36

Figure 21. Distribution of cetaceans with respect to sea surface temperature (SST) and 

Chlorophyll-a (CHLOR-A) for all species detected during Survey Mode. ..........................38

Figure 22. Results of applying Generalize Additive Modeling (GAM) techniques to model the 

abundance and distribution of sperm whales using water depth and the abundance of 

Plankton Group 2 and Plankton Group 3. .............................................................................39

Figure 23. Location of sperm whale sightings (+) with respect to the shelf edge, two warm core 

rings, and levels of abundance of Plankton Group 2 and 3 (the taller the bar, the more 

plankton of that group there are at the locations of the sperm whale sightings. ...................39

ix 
LIST OF TABLES 

Page

Table 1. Number of Groups and Animals Detected during Survey Mode............................................6

Table 2. DTAG Data Sets for the R/V Delaware Cruise, North Atlantic, July 2003............................7

Table 3. Dives Recorded by DTAG during the R/V Delaware Cruise................................................15

Table 4. Average Duration (in minutes) and Depth (in meters) of Dive Features (defined in 

Figure 5) from Animals Tagged in the North Atlantic, Gulf of Mexico, and 

Mediterranean .......................................................................................................................15

Table 5. Regular Clicks and Creaks Recorded by DTAGs on Atlantic Sperm Whales......................16

Table 6. Codas Recorded on DTAGs during the R/V Delaware Cruise .............................................24

Table 7. Numbers of Different Types of Codas Produced by the Tagged or Focal Whale (F) and 

Non-focal Whales (NF) in the Atlantic for Three of Four Tags Containing Codas..............31

xi 
1. INTRODUCTION 

The National Marine Fisheries Service (NMFS) is required to produce stock assessments for all 

marine mammal stocks within the U.S. Exclusive Economic Zone. The Minerals Management Service 

(MMS) is evaluating potential environmental impacts of offshore oil and gas activities on marine 

mammals. Both agencies have a need for similar information on sperm whales and this is the basis for the 

cooperative research outlined here. 

To contribute to information needs of both agencies, the Sperm Whale Seismic Study (SWSS) 

program research started in 2000 to address the following questions regarding sperm whales in the Gulf of 

Mexico: 

1. What are the sources and levels of anthropogenic noise? 

2. What are the effects of anthropogenic noise (e.g., seismic activity) on the 

distribution, behavior, and vocalization patterns of sperm whales? 

3. What is the stock status of sperm whales that inhabit the Gulf of Mexico compared to 

the adjacent Atlantic Ocean and Caribbean Sea? 

4. Will surveys using both acoustic and visual methods improve (change) the NMFS’ 

absolute abundance estimates of sperm whales in U.S. waters? 

5. Is the social structure of sperm whales in the Gulf of Mexico similar or different 

compared to sperm whales in other parts of the world? 

6. How do sperm whales spatially use the Gulf of Mexico? Are there specific feeding, 

breeding, socializing, and resting areas? How do these areas relate to offshore oil and 

gas activities? 

7. Do sperm whales have preferred habitats that can be defined physiographically 

and/or oceanographically? 

The knowledge and techniques developed during the Gulf of Mexico 2000-2003 studies were built on 

to collect data to address questions 2 to 5, and 7. This study centered on a cruise onboard the NOAA R/V 

Delaware in July 2003. This study has started a baseline of line-transect, photo-identification, 

oceanographic and genetic data for the Atlantic sperm whale. Compared to the Delta region in the Gulf 

of Mexico, parts of the Atlantic Ocean may serve as a control population of sperm whales with little 

exposure to sounds of oil and gas related activities. 

During the cruise, scientists from NMFS and Woods Hole Oceanographic Institution (WHOI) 

simultaneously conducted line-transect marine mammal visual, passive acoustic, oceanographic, and 

plankton surveys. Satellite data on ocean color and sea surface temperature were also collected. When 

concentrations of sperm whales were located, DTAGs were placed on the sperm whales to continuously 

record the acoustic stimulus impinging on the sperm whale, hydrostatic pressure, water temperature, and 

the animal’s pitch, roll, and compass heading. When animals were tagged, photographs were taken for 

photo-id studies, biopsy and skin samples were collected for genetic analyses, and visual behavioral 

studies were conducted. Additional chlorophyll-a and oceanographic data were also collected. 

The R/V Delaware study was designed to start collecting data to address the following questions 

posed by the Gulf of Mexico SWSS project. Behavioral pattern data from the Atlantic Ocean could be 

compared to behavioral pattern data of sperm whales that are around oil and gas platforms in the Gulf of 

Mexico (Question 2). Dive-time data could be used to reduce the availability bias of previous and future 

abundance estimates of Atlantic sperm whales (Question 4). Visual and acoustic data could be used to 

develop methods to utilize both visual and acoustic detections to improve abundance estimates of sperm 

whales (Question 4). Genetic data could be used to improve the stock structure knowledge of Atlantic 

sperm whales and could be compared to Gulf of Mexico sperm whales (Question 3). Behavioral data 

could be used to learn about the social structure of Atlantic sperm whales and could be compared to the 

social structure of Gulf of Mexico sperm whales (Question 5). The integration of the line transect, 

plankton, DTAG, and oceanographic data could be used to model the preferred habitat of the Atlantic 

1 
sperm whales, which could then be compared to the preferences of the Gulf of Mexico sperm whales 

(Question 7). 

2. FIELD METHODS 

The data collection systems and methodologies used for the DTAG component of the Atlantic R/V 

Delaware cruise were based on those developed for the Gulf of Mexico SWSS ’02 and ’03 cruises, details 

are below. 

2.1 DTAG 

In 1999, the DTAG was developed by WHOI investigators using ONR and WHOI endowments 

(Johnson and Tyack 2003). This non-invasive tag records the sounds heard, and made by the tagged 

whale together with its depth and orientation (i.e., pitch, roll, and heading), in a synchronized fashion 

throughout the dive cycle. The tag records data digitally for between 10 and 24 hours, depending on 

sampling rate, with enough resolution to track individual fluke strokes and is sensitive enough to record 

sounds from distant whales and ships. A new version of the DTAG, called DTAG-2, was used in the R/V 

Delaware cruise and in the SWSS’03 cruise preceding it. This device has more recording capacity and a 

higher audio sampling rate and resolution than the original version. It is also one half the size and weight 

(300g in air). The improved recording capacity is achieved using a loss-less compression algorithm to 

increase the storage efficiency of the audio data. This algorithm gives a consistent compression factor of 

between 3 and 4 (i.e., the effective memory capacity is 3-4 times the nominal value). With the 3GByte 

memories used on the 2003 DTAG-2s, it is possible to record 96 kHz, 16 bit audio for over 16 hours. The 

sensitivity of the DTAGs used in the SWSS’03 and R/V Delaware cruises was approximately -193 dB re 

μPa (pp) (this is also the clipping level or loudest sound level accurately recorded by the tag). 

The DTAG is housed in a plastic fairing and is attached to the whale with a set of four small suction 

cups. The tag has a low profile on the whale (Figure 1) to minimize the risk of tag removal by conspecific 

rubbing. The tag has been successfully deployed on more than 60 sperm whales, 25 pilot whales and 5 

beaked whales, with deployment durations of up to 30 hours. In the SWSS’03 cruise in the Gulf of 

Mexico immediately prior to the R/V Delaware cruise, tag attachments of up to 17 hours with an 8 hour 

average were achieved with the new tag. The tag has a VHF beacon which broadcasts a signal in the 2m 

band (148-150 MHz) every second for tracking and recovery of the tag. Data is off-loaded from the tag 

via an infra-red interface. The tag battery can be recharged while data is off-loading maximizing the 

availability of the device. 

Figure 1. DTAG deployed on a sperm whale in the North Atlantic. 

2 
2.2 VISUAL AND ACOUSTIC DATA ACQUISITION

Continuous visual and acoustic observation was critical not only to locate and close on sperm whales 

but also to provide a context for the data collected by the DTAG. Visual observations while following a 

tagged whale (i.e., during a focal follow) provided a surface track for the tagged whale and anchored the 

movement data collected on the DTAG into a geographic frame. Visual and acoustic observations were 

also used to define the group size and distance between whales, important data for understanding the 

social behavior of the tagged whale. Acoustic tracking was also essential to stay with a tagged whale 

overnight or during bad weather. 

During the search phase of operations (Survey mode), sperm whales were located using visual and 

acoustic techniques. Visual observers (two teams of three people each rotating every two hours) scanned 

for whales using 25x150 powered ‘Big-Eye’ binoculars while steaming at 4-6 knots and using standard 

line transect protocols. Weather permitting, visual surveying was conducted from sunrise (6 am) to 

sunset (8 pm). The Visual Team recorded range and relative bearing to whales, group size, initial cue, 

behavior and direction the group was swimming in. The visual and acoustics data were entered into 

logging software that was also interfaced with the ship’s navigation network to precisely locate each 

observation. Real-time displays of all the visual and acoustic contacts were maintained in both the 

acoustics laboratory and on the flying bridge to help the two teams communicate. The software for this 

system was developed cooperatively by WHOI and SACLANTCEN NATO Undersea Research Center in 

La Spezia, Italy and was managed by Marilena Quero of WHOI. 

The WHOI-supplied three-element hydrophone array was built for the SWSS program and deployed 

from the R/V Delaware as a streaming array (i.e., without a depressor) using a mechanical capstan. 

Acoustic observers (three observers rotating on a four-hour schedule 24-hours a day) detected and located 

sperm whales by listening for their vocalizations on a towed hydrophone array. During Survey mode, the 

acoustic environment was recorded for one minute every ten minutes. In addition, a log of acoustic 

events was updated every five minutes. These data included who was monitoring the equipment, what 

type of survey mode the observers were in, and the presence and magnitude of the following: sperm 

whale-like clicks, high and low frequency whistles, clicks, bursts, ship noise, sonar-like sounds, or none 

of the above. Thus, the acoustic data were used not only to detect clicks of sperm whales, but also to 

monitor dolphins, and ship noise. Two software systems were used in parallel for acoustic tracking. The 

first, Rainbow Click from the International Fund for Animal Welfare (IFAW), provided reliable bearing 

estimates for distant sperm whales. The other program, developed by Walter Zimmer of the 

SACLANTCEN NATO Undersea Research Center was most effective for close whales and was used 

during focal follows. Sound from the array was recorded continuously on an Alesis hard-drive recorder at 

a sampling-rate of 48 kHz while tracking and 96 kHz during focal follows. Acoustic observations were 

logged using custom software also developed by Zimmer. Sound samples were acquired digitally using 

Logger software from IFAW. 

Once whales were detected, Survey mode ended and Tracking mode started. At this time, the R/V 

Delaware was steered toward the whales, and the Visual and Acoustic Teams, following protocols 

developed under SWSS, provided directions to the tag boat, monitored sperm whale activity in the area 

and recorded behavioral observations of any target species. The Acoustic Team monitored the diving 

sperm whales to assist in determining where and when a diving animal would come up to the surface. 

2.3 TAGGING METHOD

Approaches to large whales were conducted under authority of the Marine Mammal and Endangered 

Species Scientific Permit #917, and CITES Permit # US 789250 issued to NOAA/Northeast Fisheries 

Science Center. Tagging was conducted under authority of the Marine Mammal and Endangered Species 

Scientific Permit #981-1707-00 issued to Dr. Peter Tyack of WHOI. Once whales were located and the 

R/V Delaware moved close to the animals, a WHOI provided 24′ rigid-hulled inflatable boat (RHIB) was 

deployed with a 3- or 4-person tagging team to attach DTAGs to whales. The tag boat was a fiberglasshulled Novurania, called the Balena. The Balena was captained by Wayne Hoggard from 

NMFS/Southeast Fisheries Science Center, an expert boat operator with experience of approaching sperm 

whales gained during the MMS-funded 2000-2001 Sperm Whale Acoustic Monitoring Program 

(SWAMP) trials. The Balena has two counter-rotating 4-stroke Yamaha 110 hp outboard motors. The 

Balena was stowed on the aft deck of the R/V Delaware and lowered over the starboard side using the 

3 
main crane. On the RHIB, a directional hydrophone was used to locate and close on sperm whales. 

Visual and acoustic observers on the research vessel supported the tagging effort by providing surfacing 

positions and acoustic bearings of whales to the RHIB team. A 46’ cantilevered pole, made of carbon 

fiber, was used to deliver the tag allowing the approach vessel to remain well behind the flukes of the 

target animal. Visual and acoustic observations from the nearby R/V Delaware recorded the social and 

geographical context of the whales’ behavior, before, during, and after tagging. After attaching a tag, the 

length of the whale was measured using photogrammetry and photographs of the fluke and other 

distinguishing features were taken for photo-identification. Whether a tag was attached or not, no more 

than three approaches were made to any individual or tight group of whales, in keeping with the 

requirements of the Permit issued to Peter Tyack. After each approach, the whale’s surfacing location was 

inspected to search for feces or skin, and a data sheet was filled out detailing the position, approach 

number and response of the whale. Once a whale was tagged and photographed, the RHIB either returned 

to the R/V Delaware or attempted to tag another whale. No more than three whales were tagged at a time. 

2.4 ENVIRONMENTAL DATA ACQUISITION

Environmental data were collected continuously from the ship’s thermo-salinograph and other 

instrumentation. The data included time, position, wind direction and speed, and the ship’s course, 

bearing and speed. CTD’s were deployed periodically. In addition, water samples were collected during 

the CTD cast to be used to calibrate the CTD. 

Satellite sensors (AVHRR, GOES, SeaWiFS, MODIS, QuikSCAT) provided high resolution synoptic 

views of the near surface oceanic ecosystem, depicting areas of surface chlorophyll concentrations, 

upwelling-downwelling features, turbidity, nutrient enrichment, surface temperature and winds, and 

principal circulation forces all of which are closely linked to ocean productivity. Before, during and after 

the survey, such satellite data were collected, and processed. During the survey the satellite data were 

emailed to the ship from the NMFS Narragansett Lab.

2.5 PHOTO-IDENTIFICATION (PHOTO-ID) DATA ACQUISITION

Photo-ID was conducted from the RHIB. The animals were approached to at least 100 m, preferably 

30 m, to photograph the underside of the whale’s flukes as they were lifted out of the water prior to a 

dive. Digital cameras and color slide film 35 mm autofocus, autoadvance cameras with a 200-300 zoom 

lens were used. Photographs were also taken opportunistically from the R/V Delaware. A photographer 

was on the R/V Delaware during all operations to photograph/video flukes, when possible. 

Between groups of animals “blank” shots were taken as reference points. Rolls of film were labeled 

with a number that was also written on a film sheet. Film sheets contained the following information for 

each photograph: date, position, frame number, time, part of whale photographed, number of whales and 

photographer’s initials. 

Color slide film was professionally developed and each slide was evaluated based on: focus, percent 

of the slide the fluke comprises, tilt of the fluke, exposure, orientation and percent of area of fluke in the 

photograph. Slides were given a “Q value” representing zero for non-identification and 5 for absolute 

certainty of identification. Slides will be examined for matches and whales that do not match whales in 

the catalog will be given a new number. 

In addition to the slides for photo-ID, a digital video camera was used to record behavior of sperm 

whales at the surface and to capture images of the sperm whale flukes. 

2.6 DIET AND FORAGING SUCCESS DATA ACQUISITION

Because of physiological constraints associated with diving deeply, sperm whales that defecated at 

the surface provided an opportunity, through collecting and analyzing fecal material, to study the diet of 

living sperm whales. Whenever possible fecal material left at the surface were collected to study the diet 

of sperm whales. 

4 
3. CRUISE SUMMARY 

Leg 1. Gear was loaded onto the R/V Delaware on July 7, 2003. We left Woods Hole, MA on July 

8th at 2pm and steamed to Hydrographer Canyon on the southern edge of Georges Bank. At 6am on July 

9 we were in our study area and the tag boat was deployed to calibrate and check all the equipment and 

computer programs. By 10am, everything was checked out and surveying started. During Leg 1, the area 

covered included waters on the southern edge of Georges Bank between Hydrographer and Munson 

Canyons (Figure 1). Surveying, tracking and tagging continued until 2pm on July 17, at which time we 

started steaming back to Woods Hole, MA to refuel the ship and change personnel. We arrived at Woods 

Hole, MA at 10am on July 18th. 

Leg 2. We departed Woods Hole at 11:30am on July 19th. Arrived at the new study area, Block 

Canyon, at 10pm on July 19th, at which time acoustic surveying commenced. The study area during Leg 

2 was in two separate areas: around Hudson Canyon (off of New Jersey), and on the shelf edge/Gulf 

Stream off Norfolk, Virginia (Figure 1). Surveying, tracking and tagging continued until 11:30am on July 

31, at which time we started to steam for home. We arrived at Woods Hole at 6am, and removing the 

gear from the ship by about 1pm. 

Good weather conditions, preferably less than 12 knots of wind with swells less than 2 feet, were 

required to safely deploy/retrieve the tag boat and put tags on the sperm whales. Unfortunately, these 

conditions are not common in the Atlantic and this survey was no exception. Of the 21 days allocated to 

this project where we were not transiting, only 10 days had weather conditions sufficient to attempt 

tagging animals. This percentage of good weather days is slightly less than that typical seen in these 

offshore Atlantic waters. A summary of time expenditure on the cruise is given below. 

Total cruise days 26 

Comprising: Survey only (winds > 12 knots) 11 

Successful tagging 6 

In-transit or dock-side 5 

Good weather but no sperm whales 1 

Unsuccessful tagging 3 

Considering that on many of the bad weather days sperm whales were located and tracked by the R/V 

Delaware, the encounter rate of sperm whales was excellent. 

A summary of the tracklines covered by acoustic watches and where sperm whales were heard is 

shown in Figure 2. Acoustic watches were manned for nearly 24 hours per day at sea. The acoustic data 

collection effort operated well. The array that was used throughout the experiment performed well. 

The tag boat, Balena, was stowed on the aft deck of the R/V Delaware and lowered over the starboard 

side using the main crane. The tight fit of the Balena on the deck made deployment challenging; however, 

there were no incidents during deployment or operation of the small boat. 

The visual team worked for over 55 hours during Survey Mode and for about 155 hours during 

Tracking Mode. The visual data collection effort operated well throughout the cruise with the results 

summarized in Figure 3. During Tracking Mode, 205 surfacings of 292 animals were recorded. Note, 

these animals were not identified to individuals or individual groups; many of the individuals and groups 

were recorded multiple times. During Survey Mode, 92 cetacean groups consisting of 1139 individuals 

were detected (Table 1). 

A total of 12 tags (Table 2) were attached to sperm whales within the 10 days that had suitable 

conditions to tag whales. On 6 of the 10 suitable days we were successful in finding and tagging sperm 

whales. Overall, we found the sperm whales straightforward to approach—comparable to the most 

successful year in the Gulf of Mexico. Twenty-four approaches to sperm whales and 14 tag attempts 

resulted in the delivery of 12 tags. Three approaches to pilot whales resulted in no tag attempts and no 

tagged pilot whales. On half of the days that were suitable for tagging (10 days) we delivered two or 

more tags. 

5 
Table 1. 

 

Number of Groups and Animals Detected during Survey Mode 

Number of Species Groups Animals 

Balaenoptera physalus 15 19 

Balaenoptera sp. 2 2 

Delphinus delphis 8 419 

Globicephala sp. 3 58 

Grampus griseus 7 56 

Megaptera novaengliae 1 1 

Orcinus orca 3 15 

Physeter macrocephalus 13 15 

Stenella coeruleoalba 4 171 

Tursiops truncatus 13 221 

Tursiops truncatus offshore 1 15 

Undetermined cetacean 2 2 

Undetermined dolphin 13 134 

Undetermined large whale 7 11 

Total 92 1139 

Nighttime recoveries of tags were achieved fairly efficiently from the R/V Delaware although, at 

times, this required the acoustic array be winched in. 

With two exceptions, the attachment durations were fairly short (1.0-6.4 hours, see Table 2). This 

was, in part, due to a large number of breaches: 4 out of 12 tagged whales breached, in most cases ending 

the attachment. Similar high breaching rates were seen on the SWAMP’01 trial in the Gulf of Mexico, 

whereas in other years in the Gulf of Mexico, few breaches were seen. It is not yet clear whether the 

breaches were in response to the tag. 

Within 33.6 hours for which a whale carried a tag, we received 27.2 hours of recorded data (Table 2). 

The difference in the carry time and record time is due to one tag that was attached but the battery failed 

so no data were collected. Three tags failed to yield a dataset: one tag was not recovered, a second tag had 

a battery failure and so did not record, and the third tag fell off the sperm whale when it breached nearly 

immediately after the tag was attached. The battery failure problem had been identified and rectified in a 

slightly modified design. 

Despite the short attachments, we sampled each of the usual behavioral modes of sperm whales: 

foraging dives, socializing, resting, and traveling. A set of 18 deep dives provides a strong initial baseline 

for estimates of foraging success and energy expenditure using metrics developed in the SWAMP and 

SWSS programs. Two of the tagged animals stayed near the surface for the entire carry time, thus, 

displaying typical resting behaviors and so having no full deep dives (Table 2). In addition to sperm 

whale vocalizations, the tags recorded sounds from other nearby odontocetes including pilot whales, 

bottlenose dolphins and spotted dolphins. The sounds of passing vessels and explosions from a distant 

naval exercise were also collected. 

Environmental data were collected continuously from the ship’s thermo-salinograph and other 

instrumentation. Eleven CTD’s were deployed while the ship traveled at 2-3 knots when the acoustic 

array was also deployed. The ship must continue to move to keep the acoustic array near the surface. 

More CTD’s would have been deployed if we had realized earlier that the ship could be traveling, have 

the array out, and still deploy a CTD. No bongos were deployed. On nearly a daily basic, Dr. Jay 

O’Reilly from the NMFS Narragansett Lab emailed to the ship sea surface temperature and chlorophyll 

maps. These were very useful to help find new potential concentrations of sperm whales and to help 

interpret the distribution and abundance of sperm whales that we did detect. 

6 
No biopsies were attempted from the tag boat. Three biopsies were attempted from the bow of the 

R/V Delaware to get a sample of bow riding dolphins. No samples were obtained. 

A high percentage (75%) of tags yielded skin samples (Table 2) and these will be analyzed for gender 

and to assess the relatedness of the study whales with those in the Gulf of Mexico. Fecal samples were 

collected from two of the animals that were tagged (Table 2). 

Overall we found the study area to be an exceptionally good site for sperm whale tagging. However 

the potential for poor weather and the unknown reason for why there were few long attachments may 

reduce the number of future successful tagging events. Also, if this area is to be considered a “control” 

for the Gulf of Mexico, then future Atlantic tagging should not be done in the Virginia area were there are 

frequent naval exercises that may pre-expose the population to impulsive sounds. At least during this 

survey, the southern Georges Bank region had many sperm whales and no Naval exercises that made 

impulsive sounds. 

Table 2. 

 

DTAG Data Sets for the R/V Delaware Cruise, North Atlantic, July 2003 

(Carry time indicates the amount of time that a tag is on a whale. 

Record time indicates the amount of time that dive data were 

successfully recorded. Number of full deep dives indicates the number 

of dives that exceeded 50 feet depth.) 

Date Time ID Tag 

id 

Record time / 

carry time 

(hours) 

# of 

full 

deep 

dives 

Sampling 

Rate, kHz 

Skin/ 

Fecal 

sample 

Comments 

7/16/03 10:44:17 sw197a 202 2.1 / 2.1 2 96 S 

7/16/03 12:01:41 sw197b 209 2.4 / 2.4 2 96 S Breached off 

7/20/03 11:42:10 sw201a 202 3.7 / 3.7 0 96 S Breached off 

7/20/03 15:15:13 sw201b 207 3.2 / 3.2 2 96 - 

7/21/03 12:10:59 sw202a 202 1.0 / 1.0 1 96 S Breached off 

7/21/03 12:55:43 sw202b 209 2.0 / 2.0 0 96 S 

7/25/03 11:59:02 sw206a 202 3.8 / 3.8 4 96 S 

7/25/03 - sw206b 205 0 / 6.3 - 96 F Battery failure 

7/25/03 13:12:45 sw206c 209 2.6 / 2.6 3 96 S 

7/26/03 11:28:00 sw207a 202 6.4 / 6.4 4 96 S 

7/26/03 - sw207b 209 0 / ? - 96 S,F Lost at sea 

7/31/03 - sw212a 13 0 / 0 0 32 - Breached off 

7 
• Acoustic effort 

• Acoustic detections of sperm 

Figure 2. Acoustic survey track lines for the R/V Delaware cruise. 

8 
Figure 3. Visual survey and focal follow tracklines for the R/V Delaware cruise. 

9 
4. DATA SUMMARY 

As shown in Table 2, a total of 12 DTAGs were deployed which yielded nine data sets of dive 

patterns. In addition, shipboard acoustic recordings and visual sightings of cetaceans were also collected. 

A full copy of all data was provided to NEFSC at the end of the cruise for archiving. The procedure for 

quality assurance, archiving and handling each data source is described below. 

4.1 DTAG DATA

The tag data comprises two streams: the audio recording and the sensor stream. Sound from the tag is 

archived to a sequence of audio files in WAV format. The sampling rate for all tags except sw212a was 

96kHz and the resolution was 16 bits (Table 2). The data in the WAV files corresponds to the raw analog 

acquisition: a magnitude of 32,768 corresponds to a full-scale input on the analog-to-digital converter. 

The frequency range of the audio acquisition was from about 100Hz to 46kHz with a flat response from 

400Hz to 45kHz. The format for audio data as stored on the tag contains a built-in quality check with 

regularly spaced repeated samples and cyclic-redundancy error checking. The sensor data from the tag are 

archived in a sequence of 12-channel WAV format files. Each channel corresponds to a physical sensor 

channel, namely: accelerometer x, y, and z axes, magnetometer x, y and z axes, depth, temperature, and 

four variables related to engineering variables within the tag. The sampling rate of each sensor channel is 

50Hz. The raw tag data are archived on CDs in WHOI’s marine mammal center managed by Research 

Assistant Amanda Hansen. The large WAV files are available on hard drives or can be regenerated from 

the raw data files on any PC. Sensor data are analyzed as described in Johnson and Tyack (2003), which 

also describes methods for quality assurance. Acoustic records are completely audited to produce a 

catalog of sounds produced by the tagged whale as well as other natural and man-made sounds recorded 

by the tag. 

4.2 PERMIT DATA/CLOSE OBSERVATIONS FROM RHIB 

During close approaches of the RHIB to whales, a range of data is collected for permit compliance, 

and for sizing and identifying individuals. These data include tagging location, reaction of the whale to 

tagging, tag placement, videogrammetry, and fluke identification photography. Visual observations are 

recorded on data sheets. Data sheets are copied while in the field for archival and a copy is maintained in 

the WHOI marine mammal laboratory. Video recordings are streamed into a computer using FireWire 

and back-ups made on CD. Fluke-shots and other images are extracted as high-quality bit-map images 

and contributed to local identification catalogues where they exist. A description of each whale approach 

is generated for Permit reporting purposes. 

4.3 VISUAL DATA

The SACLANT-WHOI visual data collection system acquires ship location and heading at onesecond intervals and stores this along with visual observations in a Microsoft Access format database. The 

visual observation data include the range and bearing from the ship to a whale and the aspect (i.e., the 

heading) of the whale. These data are used to produce a surface track of focal whales (see, for example, 

Figure 4) and to correct the dead-reckoned track derived from the tag data. Other visual data recorded 

include the species location and number of other species as well as the environmental conditions. 

Locations of whales sighted through the Big-Eye binoculars are determined from their relative bearing 

and reticle distance. The standard algorithm is used to convert reticles to distance in meters, based on the 

height from the water-line to the binoculars. The visual database is checked daily during the cruise to 

ensure that group ID’s are correct, and that focal whales were correctly identified. The database is 

archived on CDs held at the WHOI marine mammal lab. After the cruise, surfacing locations of whales 

are plotted in MATLAB or Arcview and integrated with positions of the observation-boat. 

10 
4.4 ACOUSTIC DATA

Acoustic data comprise recordings made on the Alesis recorders, audio samples taken with Logger, 

and observations recorded with AcLogger. The recordings were backed up using external hard drives and 

these copies are maintained in the WHOI marine mammal lab. The start and end time of each recording is 

listed on a data sheet and the disks are sampled to check the recording quality. The AcLogger database 

was stored in Microsoft Access format and, during the cruise, was periodically archived to CD. A final 

copy is kept in the WHOI marine mammal lab. The acoustic recordings are used in after-the-fact data 

analysis for passive tracking and to link acoustic activity to sounds recorded on the tag. 

4.5 SKIN AND FECAL SAMPLES

Feces and sloughed skin material were occasionally collected during close approaches to whales 

using a dip-net. Skin was also sometimes found on the DTAG suction cups after tag recovery. 

Anticipating this, the suction cups are sterilized before each deployment. The location and ID of the 

animal from which the material was collected are recorded on data sheets. A total of nine skin samples 

and two fecal samples were collected from tags or during tagging on the R/V Delaware cruise. Skin 

samples were stored in vials of DMSO during the cruise and then split for analysis by two separate 

laboratories. One set of samples was sent to Dan Englehaupt at the University of Durham to determine 

gender and relatedness. Dan has processed samples collected with DTAGs from the Gulf of Mexico and 

the Mediterranean and will examine relatedness of the North Atlantic whales with these populations. The 

other set of samples will be analyzed at the NMFS laboratories to compare against samples from previous 

biopsy efforts in the North Atlantic. For samples with substantial material, excess material will be added 

to a library of genetic material maintained by NMFS. Fecal samples were first checked for skin that was 

removed and handled as above. Filtered fecal material was frozen and then taken by NEFSC for analysis. 

4.6 CTD DATA

Eleven CTD casts were deployed during this cruise. During each cast the depth, salinity, and 

temperature were recorded continuously as the CTD was lowered to 200m or to near the bottom, 

whichever was shallower. These data were recorded on a ship’s computer in real-time as the CTD was 

deployed. After the deployment the data were checked, printed, and a backup copy was made. After the 

cruise, these data were processed, checked, and then archived by NEFSC staff in the Oceanography 

Branch. The data are available on line after they pass QC tests. 

4.7 ENVIRONMENTAL AND SHIP LOCATION DATA

Environmental and ship location data are continuously collected 24-hours a day. Data fields include 

time, location, wind speed and direction, depth, chlorophyll-a, and barometric pressure. At the end of 

each cruise these data are routinely archived at the NEFSC. 

11 
Figure 4. Example of a visual observation chart produced by the SACLANT-WHOI system. 

12 
5. DATA ANALYSES AND RESULTS 

5.1 TAG DATA

Analysis of the tag and supporting data proceeds in two phases. The first phase consists of low level 

auditing of the data. In this phase, the sensor data are calibrated based on laboratory and field calibration 

values and checked for quality. The data from the orientation sensors (magnetometer and accelerometer) 

must also be corrected for the tag position on the whale that is estimated from visual sightings of whale 

aspect (i.e., compass heading) during surfacings as well as photographs and video taken from the tag boat. 

The tag position is then refined iteratively in order to maximize the consistency of the data. This 

technique, developed under the SWSS program, takes advantage of the fact that, in normal diving 

behavior, a sperm whale has a zero mean pitch and roll while at the surface and does not roll during the 

initial few seconds of a steep (i.e., non-social) dive. This method can also be used to detect a change in 

placement of the tag that could occur due to sliding. The end result is an accurate time series of the whale 

orientation parameterized by the Euler angles pitch, roll, and yaw. The accelerometer used to determine 

pitch and roll is inherently sensitive to sudden changes of movement as well as orientation and these give 

rise to an error in the orientation estimate. Fortunately the occasional episodes with strong dynamics due 

to sharp acceleration or turning can be readily identified in the data and flagged as inaccurate. The final 

step in the sensor data preparation is to combine the visual tracks with the DTAG pitch and roll time 

series to produce a dead-reckoned 3-dimensional track of the whale. 

The initial processing of the audio data from the tag involves careful listening of the entire recording 

by expert listeners. A data sheet is used to record every vocalization from the tagged whale and other 

nearby whales as well as sounds from movement, vessels etc. Key features are entered into a database. 

These include creaks (fast click sequences associated with foraging, also referred to as buzzes), codas 

(stereotypical click sequences associated with socializing), and the start and end of regular clicking in 

each dive. The audio data are also inspected for echoes from the sea floor to determine the depth of the 

whale relative to the bottom. 

The second phase of data analysis is to examine the meta-data products produced in the first phase 

(described above) to determine behavioral states, estimate foraging efficiency, look for evidence of 

foraging specialization, and to examine social interactions. The same low-level processing has also been 

performed for tag data acquired during the SWSS and Mediterranean studies. The resulting meta-data has 

a well-defined format facilitating comparisons between data sets and so the analytic value of the North 

Atlantic tag data will extend well beyond the time frame of the current project. 

We are in the process of preparing a paper based on the North Atlantic data and present here an 

overview of the two main behavioral states represented in the data: foraging and socializing. 

The following are key definitions. “Foraging dives” are defined as a deep, typically U- or V-shaped 

dive (Figure 5). “Foraging dive series” are foraging dives separated by an “inter-dive interval”, defined 

as a brief time near the surface (Figure 5). Foraging dive series are separated by “surface intervals”, 

defined as an extended near-surface period (Figure 5). Foraging dives consist of an “ascent” and 

“descent” phase (Figure 5). The descent is the period of time from where the whale left the surface until 

the pitch first became positive (whale was no longer oriented downward). The ascent started when the 

whale was last oriented downward (pitch#0) and ended when the whale reached the surface. 

5.1.1 Dive Behavior 

The North Atlantic tags recorded sequences of deep and shallow dives, similar to those observed 

elsewhere. Table 3 summarizes the dive parameters (as defined in Figure 5) of the tagged animals from 

the North Atlantic. The dive times and descent/ascent rates are typical of sperm whales in other study 

areas (Table 4). Dive depths were on average deeper than in the Gulf of Mexico: four of seven deepdiving whales in the North Atlantic dove below 1000m with a deepest dive depth of 1186m. This is more 

similar to the diving behavior recorded from isolated large males in the Mediterranean, where dives to 

1250m have been recorded. According to published bathymetry, the water depth at the North Atlantic 

tagging locations was between 1500m and 3000m. No bottom echoes have been found in the tag audio 

data indicating that the whales were at least 500m above the bottom and suggesting that the tagged whales 

were foraging in the mid-water column, like those in the Mediterranean deep water. In contrast, whales 

tagged in the Gulf of Mexico and in the Gulf of Genova in the Mediterranean often dove close to the 

13 
bottom that was at a depth of between 600 and 1000m, so there were bottom echoes on these tag audio 

data. 

The tag audio recording was typical of that recorded in the Gulf of Mexico. Deep dives contained 

regular clicking with interspersed creaks while codas were common in shallow dives and during the nearsurface portions of deep dives. The following sections describe the occurrence of sounds in these two dive 

classes in more detail. 

Figure 5. Typical elements in a normal dive profile. 

14 
Table 3. 

Dives Recorded by DTAG during the R/V Delaware Cruise 

Whale # Full dives Dive duration

(min) 

Surface time

(min) 

Descent rate

(m/sec) 

Ascent rate 

(m/sec) 

Max depth 

(m) 

197A 2 53 

50 

26 1.3 

1.1 

1.5 

1.2 

720 

821 

197B 2 42 

40 

73 1.0 

1.1 

1.2 

1.0 

816 

986 

201A 0 - 221 - - 49 

201B 2 55 

55 

72 1.3 

1.2 

1.4 

1.2 

970 

1186 

202A 1 39 21 1.1 1.5 920 

202B 0 - 120 - - 17 

206A 4 41 

42 

40 

39 

39 1.3 

1.1 

1.4 

0.9 

1.3 

2.2 

1.7 

2.0 

952 

942 

927 

1016 

206C 3 47 

43 

43 

31 0.9 

1.6 

1.0 

1.4 

1.3 

1.6 

976 

947 

1040 

207A 4 45 

43 

46 

41 

194 1.2 

1.1 

0.9 

1.3 

1.4 

1.4 

1.7 

1.1 

891 

915 

1013 

871 

Table 4. 

Average Duration (in minutes) and Depth (in meters) of Dive Features (defined in Figure 5) 

from Animals Tagged in the North Atlantic, Gulf of Mexico, and Mediterranean 

Average Duration (min) 

Area Foraging Dive 

Total Descent Ascent 

Inter-Dive 

Interval 

Surface 

Interval 

North Atlantic 44.6 24.4 20.2 7.1 70.0 

Gulf of Mexico 44.7 22.2 22.4 8.2 63.7 

Mediterranean 40.3 24.4 19.3 9.7 57.5 

Average Depth (m) 

Area Maximum Depth 

of Foraging Dives 

Inter-Dive 

Interval 

Surface 

Interval 

North Atlantic 933.9 1.15 5.6 

Gulf of Mexico 638.7 0.45 4.6 

Mediterranean 797.3 0.34 4.9 

5.1.2 Foraging Behavior 

Table 5 lists the key acoustic features of the deep foraging dives recorded in the North Atlantic. 

Regular clicks started at depths typically seen in other areas, but some animals kept clicking on the ascent 

(see especially sw03_201b), which had not commonly been documented before. Looking at the depth 

distribution of whales from the three study sites, shown in Figure 6, it appears that the North Atlantic 

whales spend comparatively less time at the maximum dive depths and rather more at intermediate 

15 
depths. This is in agreement with the observation that the North Atlantic profiles are somewhat more Vshaped than those seen elsewhere. Some example dive profiles are shown in Figures 7 to 12 with acoustic 

features superimposed. Creaks also occur over a much broader depth range than that documented in the 

other study sites. Although the majority of creaks still occur near the base of the dive, the occasional 

shallow creaks and continued clicking through the ascent may indicate opportunistic foraging at shallower 

depths perhaps taking advantage of dispersed layers of prey. This represents a point of difference as 

compared to the Gulf of Mexico and Mediterranean data in which foraging appears to be limited to the 

base of the dive or to several distinct deep layers. Sperm whales, although primarily teutophagus, are 

known to also eat fish. In future work, we plan to examine fisheries information for the North Atlantic to 

identify possible meso-pelagic prey species. 

Table 5. 

 

Regular Clicks and Creaks Recorded by DTAGs on Atlantic Sperm Whales 

Whale Dive Regular clicks start 

(m) 

Regular clicks stop 

(m) # Creaks/dive Creak depth 

197A 1 

2 

130 

147 

527 

508 

20 

17 

537-720 

636-803 

197B 1 

2 

154 

130 

640 

587 

8 

7 

653-816 

613-917 

201A 

201B 1 

2 

253 

110 

157 

483 

32 

30 

225-975 

583-1192 

202A 1 340 628 18 598-923 

202B 

206A 1 

2 

370 

225 

483 

652 

23 

29 

589-954 

657-952 

206C 1 

2 

3 

86 

342 

339 

543 

673 

649 

27 

29 

30 

635-986 

675-923 

543-1032 

207A 1 

2 

3 

4 

378 

331 

317 

373 

503 

339 

461 

461 

29 

25 

32 

18 

743-893 

415-918 

501-873 

461-596 

16 
17 

Figure 6. Average normalized foraging dive profile for sperm whales in the Gulf of Mexico, Atlantic, 

and Mediterranean. 
18

Figure 7. Dive profile indicating sound events for sw03_197a.
19

Figure 8. Dive profile indicating sound events for sw03_201b. 
20

Figure 9. Dive profile indicating sound events for sw03_202a. 
21

Figure 10. Dive profile indicating sound events for sw03_202b. 
22

Figure 11. Dive profile indicating sound events for sw03_206c. 
Figure 12. Dive profile indicating sound events for sw03_207a. 

23
5.1.3 Social Behavior 

As shown in Figures 7 to 12, codas (stereotypical click patterns) were often heard near the surface. 

Codas were made both by deep-diving whales during the descent and ascent, and by whales performing 

shallow dives. A number of tag recordings made on the R/V Delaware cruise contained extended periods 

with shallow (<50m) dives and many codas. Codas are considered strong indicators of social behavior 

and were frequently accompanied, in the tag recordings, by sounds from other nearby conspecifics 

(usually also codas) and rubbing sounds from body contact. Out of the nine DTAG recordings, four 

contained codas (Table 6). Although it can be difficult to judge if a particular sound was made by the 

tagged whale or by another whale nearby, codas were identified in two recordings that were 

unambiguously produced by the tagged whale. On average, there were 121 codas on a given tag, with 45 

being assigned to the tagged whale. 

Table 6. 

Codas Recorded on DTAGs during the R/V Delaware Cruise 

Data set Tagged 

whale 

Untagged 

whale 

Unknown 

202A 0 0 29 

202B 0 201 224 

206C 17 20 4 

207A 118 85 4 

Figures 13 and 14 show the depth histogram of coda production in the three study sites divided 

according to whether the coda was produced by the tagged (focal) whale or the untagged (nonfocal) 

whale. Whales in the North Atlantic tended to produce most of their codas in the shallowest part of the 

foraging dive (i.e., at the very beginning and end of the dive). No codas were recorded below 300 m. In 

the Gulf of Mexico, whales tended to produce codas throughout the upper 50% of their foraging dives. 

Most codas were produced above 300 m, although two whales produced codas between 300 m and 400 m. 

Tagged whales in the Mediterranean produced codas at up to 70% of their maximum dive depth, far 

deeper than in the other two regions. Three Mediterranean whales produced codas between 500 m and 

700 m. 

Figure 14 shows the depths at which codas from an untagged whale were recorded by the tag. This 

figure has a similar form to Figure 13, indicating that focal sperm whales tend to produce codas when 

they hear them from other animals and that other animals respond to codas produced by the focal whale. 

Figures 15 to 18 show the average number of codas produced by tagged and untagged whales during 

foraging dive descents (Figure 15), ascents (Figure 16), inter-dive intervals (Figure 17), and surface 

intervals (Figure 18). Although codas were produced and heard during all phases of the dive cycle, by far 

most codas were produced during surface intervals. However animals tend to spend less of their day in the 

surface behavioral mode than in foraging dives, and so the low number of codas produced in each 

foraging dive still represent a significant portion of the total coda count. Codas were rarely produced 

during inter-dive intervals, i.e., between foraging dives. 

24 
25 

Figure 13. Depth occurrence of codas normalized by dive depth produced by tagged sperm whales in 

the Gulf of Mexico, the Atlantic, and the Mediterranean. 
26 

Figure 14. Depth occurrence of codas normalized by dive depth produced by untagged sperm whales 

in the Gulf of Mexico, the Atlantic, and the Mediterranean. 
27 

Figure 15. Average number of codas produced and heard per animal per descent in the Gulf of Mexico, 

Atlantic, and Mediterranean. The box has lines at the lower quartile, median, and upper 

quartile. 
28 

Figure 16. Average number of codas produced and heard per animal per ascent in the Gulf of Mexico, 

Atlantic, and Mediterranean. The box has lines at the lower quartile, median, and upper 

quartile. 
29 

Figure 17. Average number of codas produced and heard per animal per inter-dive interval in the Gulf of Mexico, 

Atlantic, and Mediterranean. The box has lines at the lower quartile, median, and upper quartile. 
30 

Figure 18. Average number of codas produced and heard per animal per surface interval in the Gulf of 

Mexico, Atlantic, and Mediterranean. The box has lines at the lower quartile, median, and upper 

quartile. 

Codas have previously been described as being produced primarily by animals tightly aggregated at 

the surface and during surface intervals. The data presented here demonstrate that codas are produced by 

animals during the descent and ascent portions of foraging dives as well, and are even produced at 

considerable depth (>500 m in the Mediterranean). This suggests that codas may be used generally by 

animals to maintain contact at all times, not just when at the surface. 

The specific pattern of clicks in a coda has long been thought to indicate group allegiance or 

correspond to geographic location. Table 7 lists the numbers of distinct coda types recorded by tags in the 

North Atlantic. Although a wide variety of codas were heard, a majority of codas were of types 1 to 6. 

Nine, eight, and two click codas were common to two or more of the tag recordings, while all other codas 

types were only heard on a single tag recording. Tagged and untagged whales on the same tag recording 

seem to produce similar types of codas but whales tagged on adjacent days in close geographic proximity 

such as 206c and 207a do not seem to use similar coda types. This may reflect a diverse population in the 

North Atlantic or broad repertoire of codas. Work is continuing to compare coda usage between the three 

study sites. 
31 

Table 7. 

 

Numbers of Different Types of Codas Produced by the Tagged or Focal Whale (F) and 

Non-focal Whales (NF) in the Atlantic for Three of Four Tags Containing Codas.

sw03_206c sw03_207a Sw03_202b 

Coda Type F NF F NF F NF 

1+4+1 52 58 

2 26 21 6 

9 2 12 1 16 

2+3+1 26 

8 11 3 1 

5+1 9 3 

10 1 3 

6 2 

1+3+1 1 1 

11 2 

5 1 

2+1 1 

7 1 

4+2 1 

1+4 1 

8+1 1 

1+3+2 1 

1+4+2 1 

2+4+1 1 

10+1 1 

5.2 DIVE TIME CORRECTION FOR ABUNDANCE ESTIMATES

Abundance estimates of sperm whales have commonly been estimated from visual line-transect 

sighting surveys. That is, an observation platform (usually a ship or airplane) traverses a series of transect 

lines, and all detected animals of the target species are recorded, together with the perpendicular distance 

between the location of the group and the transect line. These perpendicular distances are then used to 

estimate the proportion of target animals that were missed within the searched area. Standard line 

transect approaches assume that detection of animals exactly on the transect line are seen with certainty. 

This assumption can be relaxed using multiple observation platforms, such as two teams of visual 

observers on one ship, as is used on abundance surveys conducted by the NEFSC (e.g. Palka 1995). 

However, for species, such as sperm whales, that spend a large percentage of their time below the surface, 

resulting visual abundance estimates even when using the two-team survey methods can still be severely 

under-estimated. Acoustic data could potentially be used in two ways to improve the sperm whale 

abundance estimates. One way is to utilize both visual and passive acoustic detections to estimate the 

abundance. The other way is to use acoustic tag (DTAG) data in surfacing-based analyses of visual line 

transect data. Both ways are discussed below. 

5.2.1 Visual and Passive Acoustic Data 

One approach to estimate abundance from visual surveys when detection on the track line is not 

certain is to combine distance sampling and mark-recapture methods and use multiple observation 

platforms. The most benefit is gained when the two teams use independent detection methods. 
32 

Following this logic, fundamentally, one platform could be the visual observers detecting surfacing sperm 

whales and the other platform could be the passive acoustic observers detecting below-surface vocalizing 

sperm whales. In addition, acoustic platforms are able to collect data in some conditions in which visual 

platforms cannot collect data, such as at night or in bad weather. However, the methodology for 

combining visual and acoustic surveys needs to be developed more fully. Currently, there is a new 

project to advance this method development that was recently funded by the Office of Naval Research. In 

this project the skills of survey specialists (Dr. David Borcher and Dr. Debra Palka), acoustic specialists 

(Dr. Jonathan Gordon, Dr. Doug Gillespie and Dr. Russell Leaper) and statisticians (Dr. Len Thompson) 

are joined to work together to develop the theoretical and practical aspects of this new method. 

Preliminary development of this method focused on visual-acoustic surveys of harbor porpoises (Borchers 

2002). The intent of the new project is to expand these methods to utilize survey data from sperm whales. 

Actual data collected in the field are necessary to develop and test any analytical method. To fill this 

need, the visual and acoustic data collected during this cruise will be helpful. Though the main purpose 

of the cruise was not to conduct an extensive visual-acoustic abundance survey, the data collected during 

the Search Mode can be used as a test case. This new project has just been funded and so work has not 

yet started, but it is expected that the visual-acoustic data collected during the present cruise could be an 

extremely useful test case. 

5.2.2 Visual and Acoustic Tag Data 

Another way acoustic data could be used to improve visual line-transect abundance estimates is to use 

the dive time pattern data collected on the acoustic tag (DTAG) in a surfacing-based line-transect analysis 

method. Surface-based methods differ from conventional line-transect methods in that they involve 

modeling the probability that an individual surfacing of a whale will be at the surface and detected, 

whereas conventional line-transect analysis methods merely involves modeling the probability that a 

whale group will be detected, conditional that it is at the surface. 

A simple implementation of using the dive time pattern data is to estimate total abundance of sperm 

whales that are at and below the surface as a function of: (i) the abundance using standard visual linetransect methods, assuming this is an abundance estimate of surface animals, and (ii) the percentage of 

time whales are at the surface. That is, 

spermyprobabilit surfacetheatarewhales

abundance surfaceat total abundance = Equation 1 

Given the accuracy of the tag data and the fact that it is possible to see cetaceans when they are just 

under the surface, the animals can be assumed to be detectable by a visual sighting team when the tag 

records the animal is at or above 1 m depth. Of the nine animals with tag data, there are examples of 

animals diving deep and other animals making shallow dives. The percentage of time spent at the surface 

for the tagged animals varied from 16% to 50%, with a mean of 0.27 (CV = 0.46). If we assume these 

nine animals are representative of the dive patterns of the population, then there is a 27% (CV=0.46) 

chance that a single sperm whale is at the surface to be able to be detected by a visual sighting team. The 

sperm whale abundance estimated during the last Atlantic abundance survey in 1998 was 4029 with a CV 

of 0.38 (Waring et al. 2004). Using Equation 1, the dive time corrected total abundance of sperm whales 

would then be 14,922 (CV=0.60). However, this abundance estimate is biased upwards. This bias is due 

to the standard abundance estimate being based on detection of groups of whales that are typically greater 

than one and the probability of a whale being at the surface being based on singleton whales. The bias is 

due to the fact that individual sperm whales do not dive totally independent of the other animals in its 

group. During previous abundance surveys, the average group size ranged between two and three, 

however, there were groups of a dozen or so. This method is very simple and should not be considered as 

the best method to obtain the corrected total abundance estimate of a long diving animal. A more precise 

method is described below. 

Surface-based line transect analysis methods, first suggested by Schweder (1977), takes explicit 

account of the fact that sperm whales are only visible when surfacing and can treat all animals separate of 

its group. A surfacing can be regarded as a single event. The surface-based approach then involves the 

estimation of the probability that a single surfacing will be detected, as a function of its location relative 

to the ship and the surfacing patterns of the whales. The conventional line transect detection function 
33 

uses a conditional detection function (p(y)), that is, the probability of a whale at a specific location 

relative to the ship will be seen is conditional on the whale not previously having been seen by that 

platform, where y is the perpendicular distance between the track line and the surfaced animal. The 

surface-based line transect uses an unconditional detection function (q(y)), that is, the probability that the 

surfacing whale is seen and no previous surfacing of that whale had been seen. An explicitly specified set 

of surfacing sequences can be used in the unconditional detection function or it can be assumed the 

surfacing pattern of a whale follows a specific process, typically the Poisson process. Since we have a set 

of surfacing sequences we can avoid assuming a parametric specification of the surfacing model. 

In conventional line transect analyzes, the estimated abundance is: 

Lw N nA2 = Equation 2 

where n is the number of whales sighted, A is the area of the survey region, L is the total length of the 

track line and the effective half-strip width is: 

∫

∞

= 0 )( dyypw Equation 3 

where p(y) = the probability of a whale at a perpendicular distance of y will be seen, conditional on the 

whale not previously having been seen by that platform. 

In the surface-based analysis method, the probability that a whale is at perpendicular distance y from 

the track line will be detected at least once is: 

∫

∞

= 0 yg να ),()/()( dxyxq Equation 4 

where " is the surfacing rate and < is the speed of the ship, x is the forward distance in Cartesian 

coordinates and 

∏ ∑

∞

+=

−

= ⎭

⎬

⎫

⎩

⎨

⎧ = +−

1

1

1

(1),,(),,( ):,

ij

j

k

i k β yxpyxq β yDvxp β Equation 5 

where $ are the parameters of the model for q(x,y), i is the ith surfacing in a long sequence of recorded 

dive times, Dk is the time interval between the kth and the (k+1) surfacing in the dive sequence, and p(x,y)

is the conditional detection function which is the probability that a surfacing of a whale at a given position 

will be seen from a platform, conditional on the whale not being seen previously by that platform. 

If the end of the dive sequence of one animal is reached, the sequence is assumed to move to the next 

animal and then when the last dive of the last animal is reached, the sequence is repeated. The value of 

q(x,y) for a random surfacing at position (x,y) is the average q(x,y)i over the entire sequence. 

There are several options for the functional form of p(x,y). The preferred option is the logistic 

regression method used by Borchers et al. (1998) and Okamura et al. (2003): 

⎟

⎟

⎠

⎞ ⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞ ⎜

⎜

⎝

⎛

⎟

⎟

⎠

⎞ ⎜

⎜

⎝

⎛

∑

∑

∑

 = logit +y + z

 +y + + 1 z

 +y + z

p = z)(y, 1)+i(r r

R

1=r

i1i0

1-

1)+i(r r

R

1=r

i1i0

1)+i(r r

R

1=r

i1i0

i θθθ

θθθ

θθθ

exp

exp

 Equation 6 

However other functions that could be investigated include the r-logx model from Schweder et al. 

(1997) and the product model from Cooke (1997). 

The estimation of abundance using this method is presently underway, so results are not available. 

5.3 HABITAT PREFERENCES

Another objective of this cruise and the SWSS cruises is to address the question, “Do sperm whales 

have preferred habitats that can be defined physiographically and/or oceanographically?” One way to 

address this is to model the distribution and abundance of the sperm whales with respect to physical and 

biological parameters, such as water depth, bottom slope, sea surface temperature, salinity at the surface, 

mixed layer depth, surface color (primary productivity), and distribution and abundance of other trophic 
34 

levels (such as that described from bongo samples). Such a model can also include nuisance variables, 

such as Beaufort sea state, which effects the sightability of the whales, but probably do not effect the 

actual distribution of the whales. 

Before we can create a habitat model, the first step is to gather and process the data. For the 2003 

cruise, satellite pictures of sea surface temperature (SST) and chlorophyll-a (chl-a) were obtained. A 

five-day composite from the middle of the cruise was produced by Dr. Jay O’Reilly of NEFSC at the 

Narragansett Lab in Narragansett, RI. Figures 19 and 20 show the sperm whale sightings overlaid on the 

5-day composite of SST and chl-a, respectively. Such pictures have been produced for all the species 

detected during this cruise, however, due to space, they are not all displayed in this report. To further 

investigate any potential relationship with both SST and chl-a, plots of the locations of cetacean species 

with respect to the SST and chl-a were produced (Figure 21). Interestingly, sperm whales appear to be 

present in the most diverse combinations of SST and chl-a. This could mean they are not cueing in these 

two parameters. Perhaps because the sperm whales are generalists and so they are cueing on ocean 

bottom characteristics, not surface characteristics, like those measured by satellites. 

The second step is to model the sperm whale distribution information. Because this cruise 

concentrated on putting tags on sperm whales and not investigating many type of potential habitats, not 

all types of potential habitats were sampled. However, the NEFSC, Woods Hole conducted a large scale 

line transect abundance survey in 1998 and is currently conducting one during the summer of 2004. The 

plan is to merge the line transect data of the 1998, 2003, and 2004 surveys to investigate habitat 

preferences of sperm whales in the Atlantic. 

Stepwise selection of Generalized Additive Models (GAM) will be used to define a model that uses 

physical and biological parameters to describe the sperm whale habitat. An example of this type of 

analysis is using the 1998 data to model the distribution and abundance of sperm whales in five nautical 

mile sections of the track line with the following potential habitat descriptors: SST, water depth, plankton 

species groups, and Beaufort sea state. The stepwise GAM determined depth and an interaction between 

two groups of plankton species (groups 2 and 3) were the best predictors for sperm whale distribution and 

abundance (Figure 22), where depth was the most influential factor. Locations of sperm whales were 

inversely correlated to the location of Plankton group 3, which are species generally associated with warm 

core rings, and positively correlated with Plankton group 2, which are species most often associated with 

cooler waters, such as those on the outside edge of a ring or in between warm core rings. Thus, these 

GAM results can be interpreted as Atlantic sperm whales are found in waters approximately 2000 meters 

deep, when those waters are cool, like those found on the outside or in between warm core rings (Figure 

23). 

In future analyses using the three years of line transect data, environmental variables such as bottom 

slope, surface salinity, mixed layer depth, and surface chlorophyll-a levels will also be used as potential 

habitat descriptors, in addition to those in the 1998 analyses described above. 
35 

Figure 19. Distribution of sperm whales seen during 2003 cruise overlaid on a 5-day composite of the sea 

surface temperature (SST) from the middle of the cruise. 
36 

Figure 20. Distribution of sperm whales seen during 2003 cruise overlaid on a 5-day composite from the middle of 

the cruise of the chlorophyll-a as measured from SeaWiFS. 
37 

Figure 21. Distribution of cetaceans with respect to sea surface temperature (SST) and Chlorophyll-a 

(CHLOR-A) for all species detected during Survey Mode. 
38 

Figure 22. Results of applying Generalize Additive Modeling (GAM) techniques to model the 

abundance and distribution of sperm whales using water depth and the abundance of 

Plankton Group 2 and Plankton Group 3. 
39 

Figure 23. Location of sperm whale sightings (+) with respect to the shelf edge, two warm core rings, and 

levels of abundance of Plankton Group 2 and 3 (the taller the bar, the more plankton of that group 

there are at the locations of the sperm whale sightings. 
40 

6. LITERATURE CITED 

Borchers, D. 2002. Estimating harbour porpoise abundance in the Gulf of Maine from combined visual 

and acoustic surveys: Method development and exploratory analysis. Research Unit for Wildlife 

Population Assessment Report 003/02. Available from D. Palka at NEFSC, 166 Water St., Woods 

Hole, MA 02543 USA. 

Borchers, D.L., S.T. Buckland, P.W. Goedhart, E.D. Clarke, and S.L. Hedley. 1998. Horvitz-Thompson 

estimators for double-platform line transect surveys. Biometrics, 54:1221-37. 

Cooke, J.G. 1997. An implementation of a surfacing-based approach to abundance estimation of minke 

whales from shipboard surveys. Report of the International Whaling Commission, 47:513-28. 

Johnson, M.P. and P.L. Tyack. 2003. A digital acoustic recording tag for measuring the response of 

whild marine ammals to sound. IEEE Journal of Oceanic Engineeering 28(1):3-12. 

Okamura, H., T. Kitakado, K. Hiramatsu, and M. Mitsuyo. 2003. Abundance estimation of diving 

animals by the double-platform line transect method. Biometrics 59:512-520. 

Palka, D. 1995. Abundance estimate of Gulf of Maine harbor porpoise. Rep. Int. Whal. Commn Special 

Issue 16—The Biology of Phocoenidae. Pp. 28-50. 

Schweder, T. 1977. Point process models for line transect experiments. In: Barba, J.R., F. Brodeau, 

G. Romier, and B. VanCutsem, eds. Recent Developments in Statistics. New York, NY: NorthHolland Publishing Company. Pp. 221-242. 

Schweder, T., H.J. Skaug, X.K. Dimakos, M. Langaas, and N. Øien. 1997. Abundance of northeastern 

Atlantic minke whales, estimates for 1989 and 1995. Rep. int. Whal. Commn 47:453-483. 

Waring, G.T., R.M. Pace, J.M. Quintal, C.P. Fairfield, and K. Maze-Foley, eds. 2004. U.S. Atlantic and 

Gulf of Mexico marine mammal stock assessments—2003. NOAA Technical Memorandum 

NMFS-NE-182. Available at NEFSC, 166 Water St., Woods Hole, MA 02543. 
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