ACCESS NUMBER: 85186 

STUDY TITLE: Deepwater Program: Cooperative Research on Sperm Whales and 

Their Response to Seismic Exploration in the Gulf of Mexico – (Sperm Whale Seismic 

Study-SWSS) 

REPORT TITLE: Sperm Whale Seismic Study in the Gulf of Mexico: Summary Report, 

2002-2004 

CONTRACT NUMBER: 1435-01-02-CA-85186 

SPONSORING OCS REGION: Gulf of Mexico 

APPLICABLE PLANNING AREAS: Western, Central, and Eastern Gulf of Mexico 

FISCAL YEARS OF PROJECT FUNDING: 2002, 2003, 2004, 2005, 2006, and 2007 

COMPLETION DATE OF REPORT: August 2006 

COSTS: FY 2002 $2,069,017; FY 2003 $1,792,477; FY 2004 $2,280,205; FY 2005 

$2,516,537; FY 2006 $643,149; FY 2007 $0; CUMULATIVE PROJECT COST: 

$9,301,385 (Note: $260,972 of this total was contributed to MMS for SWSS by the 

Industry Research Funders Coalition) 

PROJECT MANAGER: Ann E. Jochens 

AFFILIATION: Texas A&M University 

ADDRESS: Department of Oceanography, 3146 TAMU, College Station, TX 77843-

3146 

PRINCIPAL INVESTIGATORS*: Douglas Biggs, Daniel Engelhaupt, Jonathan Gordon, 

Nathalie Jaquet, Ann Jochens, Mark Johnson, Robert Leben, Bruce Mate, Patrick Miller, 

Joel Ortega-Ortiz, Aaron Thode, Peter Tyack, John Wormuth, and Bernd Würsig 

KEY WORDS: Sperm whale, Physeter macrocephalus, Gulf of Mexico 

BACKGROUND: With oil and gas and related activities moving into the deepwater Gulf 

of Mexico, the Minerals Management Service (MMS), Gulf of Mexico Outer Continental 

Shelf Region, recognizes that such activities may occur in regions frequented by 

deepwater species of cetaceans, particularly the endangered sperm whale (Physeter 

macrocephalus). MMS seeks to expand the existing assessments of sperm whales and 

to improve the understanding of the effects of seismic exploration on sperm whales in 

the Gulf of Mexico (Gulf). At the MMS Information Transfer Meeting in January 2002, 

the geophysical industry through the International Association of Geophysical 

Contractors (IAGC) offered to provide a seismic source vessel as a sound source for 

several weeks of controlled exposure experiments (CEEs) of sperm whales to seismic 

exploration in the Gulf. With this contribution of the IAGC, MMS awarded the 
ACCESS NUMBER: 85186 

Cooperative Agreement for research on sperm whales and their response to seismic 

exploration in the Gulf to a multi-institutional, interdisciplinary research team under the 

program management of Texas A&M University. In the second field year of the study, 

five major oil companies joined with IAGC to form the Industry Research Funders 

Coalition (IRFC) to allow a second summer of contribution of a seismic source vessel 

for CEEs. In field years 3 and 4, IRFC also provided contributions through MMS for 

additional sperm whale research under the Cooperative Agreement. This summary 

presents the main results of the Sperm Whale Seismic Study (SWSS) for 2002-2004 by 

program component. 

OBJECTIVES: The objectives of this study were to (1) establish the normal behavior of 

sperm whales in the northern Gulf, (2) characterize sperm whale habitat use in the 

northern Gulf, and (3) determine possible changes in behavior of sperm whales when 

subjected to man-made noise, particularly from seismic airgun arrays used for offshore 

petroleum exploration and geological monitoring. 

DESCRIPTION: Because sperm whales range widely, the study area essentially 

encompasses the entire Gulf. However, SWSS cruise activities in 2002-2004 were 

focused along the 1000-m isobath in the region off the Mississippi River Delta between 

91°W and 86°W in the range of water depths of 800-1200 m. There were six project 

components. These were to: (1) study the long-term (months to seasonal) movements 

and distributions of sperm whales using satellite-tracked radio telemetry tags (S-tags); 

(2) study the short-term (hours) behavior of sperm whales using digital-recording 

acoustic tags (D-tags) and examine potential changes in behavior of the whales when 

subjected to seismic airgun sounds during controlled exposure experiments (CEEs); (3) 

examine the social behaviors of sperm whale groups using visual and passive acoustic 

observations over periods of days; (4) use biopsy samples to determine the sex of the 

S-tag and D-tag tagged animals and their relatedness to sperm whales from the North 

Atlantic Ocean and Mediterranean Sea; (5) examine diving depths and movements 

using 3-D passive acoustic tracking techniques; and (6) characterize the physical and 

biological oceanographic habitat in which the sperm whales in the Gulf are found. 

Seven field cruises were conducted during the summers of 2002, 2003, and 2004. One 

cruise each summer was in support of S-tag deployments and was aboard the R/V 

Gyre. A cruise in summer 2002 on Gyre and another in summer 2003 on R/V Maurice 

Ewing were in support of D-tag/CEE work. The offshore industry work boat M/V Rylan 

T, with the shallow-water airgun boat M/V Speculator attached to the rear work deck, 

provided an airgun array that was used as the sound source for the 2002 CEEs. The 

seismic survey vessel M/V Kondor Explorer provided the airgun sound source for the 

2003 CEEs. A third cruise in 2003, Whale Survey and Habitat Characterization cruise, 

was conducted from Gyre concurrently with the D-tag/CEE cruise to collect the 

supporting suite of environmental, habitat data. In 2004, the acoustically quiet, 46' 

Hunter sailboat Summer Breeze was used to study the social behavior of sperm whale 

groups. Visual and passive acoustic observations of sperm whales were collected on all 

cruises, as were biopsy samples for genetic observations. Fluke photographs were 

taken for photo-identification, and data from hydrophone arrays were used to study 3-D 
ACCESS NUMBER: 85186 

passive acoustic tracking of sperm whales. Habitat characterization data included 

currents from 153 kHz and 38 kHz acoustic Doppler current profilers; temperature and 

salinity profiles using both conductivity-temperature-depth and expendable 

bathythermograph profilers; continuous, near-surface temperature, salinity, and 

fluorescence/chlorophyll observations; and sea surface height fields and ocean color 

from remote sensing.

SIGNIFICANT CONCLUSIONS: Genetic analyses, coda vocalizations, and population 

structure support the conclusion that sperm whales in the Gulf of Mexico are different 

from other populations. Population size associated with the limited region between 

Mississippi Canyon and DeSoto Canyon about the 1000-m isobath is estimated at 398 

individuals with a range of 253-607. Initial CEE observations seem to suggest that 

neither gross diving behavior nor direction of movement changed for any of the eight 

exposed whales at either the onset of gradual ramp-up at ranges of 7.3 – 12.5 km or 

during full power exposures at ranges of 1.5-12.8 km. This suggests that there is no 

horizontal avoidance of sperm whales in the Gulf to seismic survey activities. Results 

from observing foraging behavior suggest that there is some reduction in foraging 

during airgun exposure. However, additional studies are required to increase the 

sample size to numbers yielding the desired statistical power. 

STUDY RESULTS: Comparisons of mitochondrial DNA and other molecular markers of 

tissue samples from sperm whales in the northern Gulf of Mexico, Mediterranean Sea, 

North Sea, and North Atlantic Ocean reveal a significant genetic differentiation between 

the Gulf population and populations of the other three regions. Preliminary analyses of 

coda vocalizations also suggest there are significant differences in repertoires between 

the Gulf population and the populations of the rest of the Atlantic. The available 

recorded coda vocalizations indicate that the mixed groups in the Gulf belong to an 

acoustic clan that is rarely encountered in other areas and, from this, it is inferred that 

groups from other clans rarely enter the northern Gulf. The population structure also is 

different. The mean group size in the study area is 9-11 individuals, which is about onehalf the size of groups elsewhere. Individual whales are significantly smaller in length 

than what would be expected on the basis of whaling data from the Gulf or lengths in 

the Sea of Cortez. Mature males seem to have either a different behavior or a different 

seasonality to those in other regions as no large breeding males were observed in 2004 

from the sailboat. Groups of females/immatures have a high site fidelity that has not 

been described elsewhere. There is no evidence of long-distance movements as no 

matches were found between the 185 individuals identified in the northern Gulf and the 

~2500 individuals identified in the rest of the Atlantic (North Atlantic and Mediterranean 

Sperm Whale Catalogue). These results indicate a degree of segregation between 

sperm whales in the Gulf and the rest of the Atlantic, likely spanning temporal scales of 

years (absence of matches) to decades (differences in coda repertoire). These results 

suggest that, for management questions, sperm whales in the northern Gulf should be 

treated as a separate population. 

Summer-to-summer variability in intensity and geographic location of Loop Current 

eddies, warm slope eddies, and areas of cyclonic eddy circulation forced striking year-
ACCESS NUMBER: 85186 

to-year differences in the locations along the 1000-m isobath where there was onmargin and off-margin flow and resulted in significant differences in the current structure 

and water properties on the northern slope. The integration of the physical and 

biological data show that, in summers 2002 and 2003, most sperm whales were 

encountered in regions of negative sea surface height anomaly and/or higher-thanaverage surface chlorophyll. This is consistent with the hypothesis that cyclonic eddies, 

which are features of negative sea surface height anomaly and new biological 

production, may support locally richer feeding grounds for sperm whales. In contrast, 

however, only a few of the whale encounters in summer 2004 were in regions of 

negative sea surface height anomaly and/or higher-than-average surface chlorophyll. 

These habitat associations in 2004 are anomalous when compared to the GulfCet II, 

SWAMP, and 2002-2003 SWSS results. In addition to considerable summer-tosummer variability, local oceanographic conditions also changed during the course of a 

single summer, with resultant changes in encounter rates with whales. 

The two D-tag/CEE cruises directly examined the behavior of sperm whales when 

exposed to airgun sounds. The movement and sound-recording D-tag was used to 

record acoustic exposure and foraging behaviors of 8 sperm whales before, during, and 

after 1-2 hr controlled sound exposures of industry-provided airgun arrays in the Gulf in 

2002 and 2003. In 2002, two CEEs were conducted involving 4 subjects. In 2003, three 

CEEs were completed also with a total of 4 subjects. The 8 whales for which these 

CEEs were conducted were exposed to maximum sound levels between 130 and at 

least 162 dBp-p re 1 μPa at ranges of roughly 1.4-12 km from the sound source. 

Neither gross diving behavior nor direction of movement changed for any of the eight 

exposed whales at either the onset of gradual ramp-up at ranges of 7.3-12.5 km or 

during full power exposures at ranges of 1.5-12.8 km. The CEE results, together with 

results from two other independent approaches, do not indicate any horizontal 

avoidance of sperm whales in the Gulf to seismic survey activities. These data do not 

support the assumption that whales swim away from an airgun array as it ramps up or 

approaches the whale at full power. However, there was only limited exposure above 

160 dBp-p re 1 mPa. Further research is required to test for avoidance at higher 

received levels. Gulf sperm whales, at least in the area studied, may have some level 

of acclimation to seismic airgun sounds. Moreover, whales were tagged in a region with 

substantial human activity, so they are not naïve to human-generated sounds. Followon studies in regions not as affected by human activities are needed to address the 

issue of habituation. 

The effects of airguns on the foraging behavior of sperm whales were assessed. The 

whale that was approached most closely prolonged a surface resting bout hours longer 

than typical, but resumed foraging immediately after the airguns ceased. While this 

whale showed no horizontal avoidance, the alteration of diving behavior could be 

considered a vertical avoidance response. Differences of foraging response measures 

between exposure and post-exposure control periods in the remaining 7 exposed 

whales (which made foraging dives during both conditions) were compared to sham 

exposure and post-exposure control periods in 13 unexposed whales. Pitching 

movements generated by swimming motion were 6% lower during exposure (P=0.014). 
ACCESS NUMBER: 85186 

Distinctive echolocation sounds, called buzzes, produced when whales attempt to 

capture prey were 19% lower during the exposure condition, but this effect was not 

statistically significant (P=0.141). Given the low sample size of exposure subjects, a 

Bayesian analysis was conducted to quantify the odds-ratio for whether the data 

support models of increase, decrease, or no change. The result indicates that a 

decrease in buzz rate is 3.6 times more likely than no change given our data; this is a 

Bayes factor considered to be "substantial" or "positive" evidence for an effect. The 

same analysis indicates that a decrease in pitching movement is 2.9 times more likely 

than no change. More research is needed to define the effects of seismic on foraging 

behavior on sperm whales, but this analysis suggests that a 20% decrease in foraging 

attempts at exposure levels ranging from <130 to 162 dBp-p re 1 μPa at distances of 

roughly 1-12 km from the sound source is more likely than no effect. 

STUDY PRODUCTS: Jochens, A., D. Biggs, D. Engelhaupt, J. Gordon, N. Jaquet, M. 

Johnson, R. Leben, B. Mate, P. Miller, J. Ortega-Ortiz, A. Thode, P. Tyack, J. Wormuth, 

and B. Würsig. 2006. Sperm whale seismic study in the Gulf of Mexico; Summary 

Report, 2002-2004. U.S. Dept. of the Interior, Minerals Management Service, Gulf of 

Mexico OCS Region, New Orleans, LA. OCS Study MMS 2006-034. 352 pp. 

Jochens, A.E. and D.C. Biggs, editors. 2004. Sperm whale seismic study in the Gulf of 

Mexico; Annual Report: Year 2. U.S. Dept. of the Interior, Minerals Management 

Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2004-067. 

167 pp. 

Jochens, A.E. and D.C. Biggs, editors. 2003. Sperm whale seismic study in the Gulf of 

Mexico; Annual Report: Year 1. U.S. Dept. of the Interior, Minerals Management 

Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2003-069. 

139 pp. 

*P.I.'s affiliations may be different than that listed for Project Manager. 
ACCESS NUMBER: 85186 

Study area of the Sperm Whale Seismic Study (SWSS), which focused along the 1000-

m isobath of the northern Gulf of Mexico. Bathymetry contours shown are 200, 1000, 

2000, and 3000 m.