NOAA Technical Memorandum NMFS-NE-202

U. S. DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

National Marine Fisheries Service

Northeast Fisheries Science Center

Woods Hole, Massachusetts

March 2007

Evaluation of Northern Right Whale 

Ship Strike Reduction Measures 

in the Great South Channel

of Massachusetts
184. A Large Marine Ecosystem Approach to Fisheries Management and Sustainability. By Frank J. Gable. August 2004. v + 84 

p., 38 figs., 10 tables. NTIS Access. No. PB2005-101435. [Online publication only.]

185. Revised and Updated Edition of F. Bruce Sanford's 1957 "Planning Your Scientific Research Paper." By Jon A. Gibson. August 

2004. x + 36 p., 5 figs., 12 tables. NTIS Access. No. PB____-______.

186. Essential Fish Habitat Source Document: Silver Hake, Merluccius bilinearis, Life History and Habitat Characteristics. 2nd 

ed. By Meredith C. Lock and David B. Packer. August 2004. v + 68 p., 28 figs., 6 tables. NTIS Access. No. PB2005-101436. [Online 

publication only.]

187. Essential Fish Habitat Source Document: American Plaice, Hippoglossoides platessoides, Life History and Habitat Characteristics. 2nd ed. By Donna L. Johnson. August 2004. vi + 72 p., 23 figs., 6 tables. NTIS Access. No. PB2006-102421. [Online publication 

only.]

188. Northeast Regional Commercial Fishing Input-Output Model, by Scott R. Steinback and Eric M. Thunberg. NTIS Access. No. 

PB2007-104394. April 2006. v + 54 p., 2 figs, 15 tables. [Online publication only.]

189. Essential Fish Habitat Source Document: Sea Scallop, Placopecten magellanicus, Life History and Habitat Characteristics. 

2nd ed. By Deborah R. Hart and Antonie S. Chute. September 2004. v + 21 p., 6 figs., 2 tables. NTIS Access. No. PB2005-104079. 

[Online publication only.]

190. Essential Fish Habitat Source Document: Atlantic Cod, Gadus morhua, Life History and Habitat Characteristics. 2nd ed. By 

R. Gregory Lough. November 2004. vi + 94 p., 27 figs., 5 tables, 1 app. NTIS Access. No. PB2006-101528. [Online publication only.]

191. Essential Fish Habitat Source Document: Northern Shortfin Squid, Illex illecebrosus, Life History and Habitat Characteristics. 

2nd ed. By Lisa C. Hendrickson and Elizabeth M. Holmes. November 2004. v + 36 p., 13 figs., 1 table. NTIS Access. No. PB2005-

101437. [Online publication only.]

192. Essential Fish Habitat Source Document: Atlantic Herring, Clupea harengus, Life History and Habitat Characteristics. 2nd 

ed. By David K. Stevenson and Marcy L. Scott. July 2005. vi + 84 p., 40 figs., 7 tables. NTIS Access. No. PB2005-107567. [Online 

publication only.]

193. Essential Fish Habitat Source Document: Longfin Inshore Squid, Loligo pealeii, Life History and Habitat Characteristics. 2nd 

ed. By Larry D. Jacobson. August 2005. v + 42 p., 20 figs., 1 table. NTIS Access. No. PB2005-110684. [Online publication only.]

194. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments -- 2005. By Gordon T. Waring, Elizabeth Josephson, Carol 

P. Fairfield, and Katherine Maze-Foley, eds. Dana Belden, Timothy V.N. Cole, Lance P. Garrison, Keith D. Mullin, Christopher Orphanides, 

Richard M. Pace III, Debra L. Palka, Marjorie C. Rossman, and Fredrick W. Wenzel, contribs. March 2006. v + 392 p., 45 figs, 79 tables, 

5 app., index. NTIS Access No. PB 2007-104395.

195. A Large Marine Ecosystem Voluntary Environmental Management System Approach to Fisheries Practices. By Frank J. Gable. 

December 2005. v + 84 p., 38 figs., 10 tables. NTIS Access. No. PB____-______.

196. Essential Fish Habitat Source Document: Haddock, Melanogrammus aeglefinus, Life History and Habitat Characteristics. 2nd 

ed. By Jon K.T. Brodziak. December 2005. vi + 64 p., 27 figs., 2 tables. NTIS Access. No. PB2006-103439. [Online publication only.]

197. In preparation by author.

198. Essential Fish Habitat Source Document: Bluefish, Pomatomus saltatrix, Life History and Habitat Characteristics. 2nd ed. By 

Jon K.T. Brodziak. December 2005. vi + 89 p., 48 figs., 5 tables, 1 app. NTIS Access. No. PB2006-103439. [Online publication only.]

199. Distribution and Abundance of Fish Eggs Collected during the GLOBEC Broad-Scale Georges Bank Surveys, 1995-1999. By 

John D. Sibunka, Donna L. Johnson, and Peter L. Berrien. August 2006. iv + 72 p., 28 figs., 1 table. NTIS Access. No. PB____-______. 

[Online publication only.]

200. Essential Fish Habitat Source Document: Black Sea Bass, Centropristis striata, Life History and Habitat Characteristics (2nd 

ed. By Amy F. Drohan, John P. Manderson, and David B. Packer. February 2007. vi + 68 p., 33 figs., 2 tables. NTIS Access No. PB____-

______. [Online publication only.]

201. U.S. Atlantic and Gulf of Mexico Marine Mammal Stock Assessments -- 2006. By Gordon T. Waring, Elizabeth Josephson, Carol 

P. Fairfield, and Katherine Maze-Foley, eds. Dana Belden, Timothy V.N. Cole, Lance P. Garrison, Keith D. Mullin, Christopher Orphanides, 

Richard M. Pace III, Debra L. Palka, Marjorie C. Rossman, and Fredrick W. Wenzel, contribs. March 2007. vi + 378 p., 92 figs, 84 tables, 

5 app., index. NTIS Access No. PB____-______.

Recent Issues in This Series:
U. S. DEPARTMENT OF COMMERCE

Carlos M. Gutierrez, Secretary

National Oceanic and Atmospheric Administration

Vice Admiral Conrad C. Lautenbacher, Jr., USN (ret.), Administrator

National Marine Fisheries Service

William T. Hogarth, Assistant Administrator for Fisheries

Northeast Fisheries Science Center

Woods Hole, Massachusetts

March 2007

This series represents a secondary level of scientific publishing. All issues employ thorough 

internal scientific review; some issues employ external scientific review. Reviews are -- by 

design -- transparent collegial reviews, not anonymous peer reviews. All issues may be 

cited in formal scientific communications.

NOAA Technical Memorandum NMFS-NE-202

Evaluation of Northern Right Whale 

Ship Strike Reduction Measures

in the Great South Channel

of Massachusetts

Richard L. Merrick and Timothy V.N. Cole

National Marine Fisheries Service, 166 Water Street, Woods Hole, MA 02543
Editorial Notes

Species Names: The NEFSC Editorial Office’s policy on the use of species names in all technical communications is

generally to follow the American Fisheries Society’s lists of scientific and common names for fishes (i.e., Robins et al.

1991aa

,bb) mollusks (i.e., Turgeon et al. 1998c), and decapod crustaceans (i.e., Williams et al. 1989d), and to follow the

Society for Marine Mammalogy's guidance on scientific and common names for marine mammals (i.e., Rice 1998e).

Exceptions to this policy occur when there are subsequent compelling revisions in the classifications of species, resulting

in changes in the names of species (e.g., Cooper and Chapleau 1998f, McEachran and Dunn 1998g).

Statistical Terms: The NEFSC Editorial Office’s policy on the use of statistical terms in all technical communications is

generally to follow the International Standards Organization’s handbook of statistical methods (i.e., ISO 1981h

).

Internet Availability: This issue of the NOAA Technical Memorandum NMFS-NE series is being copublished, i.e., as

both a paper and Web document. The Web document, which will be in HTML (and thus searchable) and PDF formats,

can be accessed at: http://www.nefsc.noaa.gov/nefsc/publications/.

a

Robins, C.R. (chair); Bailey, R.M.; Bond, C.E.; Brooker, J.R.; Lachner, E.A.; Lea, R.N.; Scott, W.B. 1991. Common and scientific names

of fishes from the United States and Canada. 5th ed. Amer. Fish. Soc. Spec. Publ. 20; 183 p.

b

Robins, C.R. (chair); Bailey, R.M.; Bond, C.E.; Brooker, J.R.; Lachner, E.A.; Lea, R.N.; Scott, W.B. 1991. World fishes important to

North Americans. Amer. Fish. Soc. Spec. Publ. 21; 243 p.

c

Turgeon, D.D. (chair); Quinn, J.F., Jr.; Bogan, A.E.; Coan, E.V.; Hochberg, F.G.; Lyons, W.G.; Mikkelsen, P.M.; Neves, R.J.; Roper, C.F.E.;

Rosenberg, G.; Roth, B.; Scheltema, A.; Thompson, F.G.; Vecchione, M.; Williams, J.D. 1998. Common and scientific names of aquatic

invertebrates from the United States and Canada: mollusks. 2nd ed. Amer. Fish. Soc. Spec. Publ. 26; 526 p.

d

Williams, A.B. (chair); Abele, L.G.; Felder, D.L.; Hobbs, H.H., Jr.; Manning, R.B.; McLaughlin, P.A.; Pérez Farfante, I. 1989. Common

and scientific names of aquatic invertebrates from the United States and Canada: decapod crustaceans. Amer. Fish. Soc. Spec. Publ. 17;

77 p.

e

Rice, D.W. 1998. Marine mammals of the world: systematics and distribution. Soc. Mar. Mammal. Spec. Publ. 4; 231 p.

f

Cooper, J.A.; Chapleau, F. 1998. Monophyly and interrelationships of the family Pleuronectidae (Pleuronectiformes), with a revised

classification. Fish. Bull. (Washington, DC) 96:686-726.

g

McEachran, J.D.; Dunn, K.A. 1998. Phylogenetic analysis of skates, a morphologically conservative clade of elasmobranchs

(Chondrichthyes: Rajidae). Copeia 1998(2):271-290.

h

ISO [International Organization for Standardization]. 1981. ISO standards handbook 3: statistical methods. 2nd ed. Geneva, Switzerland:

ISO; 449 p.
Page 1

INTRODUCTION

Ship strike mortality remains one of the two primary 

causes for lack of recovery of the North Atlantic population of northern right whales (Eubalaena glacialis; NMFS 

2005; Waring et al. 2006). As a result, NOAA Fisheries 

has developed a series of management measures that seek 

to reduce interactions between ships and whales. Central 

to this approach is the concept that ship strike risks can be 

reduced either by separating vessels and whales or by slowing ships. A series of analyses support this concept (Laist et 

al. 2001; Jensen and Silber 2003; Nichols and Kite-Powell 

2005; Pace and Silber 2005; Vanderlaan and Taggert 2007). 

NOAA Fisheries is now in the position to translate this research into management. Spatial and temporal aspects of 

ship strike mitigation measures were developed through a 

series of meetings within NOAA supported by a variety of 

analyses conducted by the Northeast and Southeast Fisheries 

Science Centers (e.g., Merrick 2005). The latter analyses 

defined a series of Seasonal Management Areas (SMAs) in 

which seasonal speed restrictions would be applied. Three 

SMAs were defined in the Northeast United States (Figure 

1): Cape Cod Bay (January–May), Off Race Point (March 

–April), and Great South Channel (GSC) (April–July). This 

work led to an advanced notice of proposed rule making 

(June 2004; 69 FR 30857) followed by a proposed rule (June 

2006; 71 FR 36299) outlining measures (http://www.nero.

noaa.gov/shipstrike/) to accomplish much of the approach. 

The focus of the rule will be to provide for seasonal speed 

restrictions for vessels of 300 gt or larger (excluding sovereign flag vessels) from Maine to Florida. 

NOAA is also considering other protective measures 

which would need to be adopted by the International Maritime Organization (IMO). These include a narrowing of 

the Boston Traffic Separation Scheme (TSS), and designation of the Great South Channel area as an “Area To Be 

Avoided” (ATBA)1

. In 2006, NOAA and the U.S. Coast 

Guard (USCG) proposed to the IMO that the northern leg 

of the TSS be realigned and narrowed. The IMO agreed to 

implement this proposal on 1 July 2007, in part because of 

the reduction in large whale risk (Merrick 2005). NOAA 

and USCG are now considering a second proposal to the 

IMO which would designate the Great South Channel ATBA 

and possibly narrow the leg of the Boston TSS which passes 

through the Great South Channel. This report evaluates 

the reduction in whale/vessel collision risk of these two 

measures by using whale sighting and vessel track data. A 

simple risk model is built from these two datasets to assess 

the relative likelihood of a whale/vessel collision. 

METHODS

DATA

Whale Sightings

The only recent systematic, broad-scale survey observations in the Gulf of Maine2

 are those from NOAA aerial 

surveys (Cole et al. 2007). Directed surveys for North 

Atlantic right whales were conducted during March–November, 1999–2005 in the area from south of Nantucket, 

MA northward to the Bay of Fundy in Canada, and from the 

New England coast eastward to the Hague Line. Surveys 

were accomplished using one or two high-wing, twin-engine 

fixed wing aircraft. One was a NOAA DeHavilland Twin 

Otter (1999–2005), and the other was a chartered amphibious Grumman Widgeon (1998–2000) or Grumman Goose 

ABSTRACT

Ship strike mortality remains one of the two primary causes for lack of recovery of the North Atlantic population of northern right 

whales (Eubalaena glacialis). As a result, NOAA Fisheries has identified a number of actions to reduce interactions between ships and 

whales. Central to this approach is the concept that ship strike mortality risk can be reduced either by slowing ships or by separating 

vessels and whales. More specifically, in the Great South Channel Seasonal Management Area (GSCSMA) of the southern Gulf of 

Maine, NOAA is considering an April–July requirement that all vessels over 300 gross tons travel no faster than 10 kts. To physically 

separate whales and vessels, NOAA is also considering (a) designating the Great South Channel critical habitat (GSCCH) area as an 

International Maritime Organization (IMO)-approved Area To Be Avoided (ATBA) and (b) narrowing (by 1 nm) the Boston Traffic 

Separation Scheme (TSS). 

We analyzed the risk reduction of right whale ship strikes which could result from the above two proposals by using data on commercial shipping traffic and right whale sightings collected during April–July 1999–2005. During this period, 2,032 right whales were 

observed in the New England Mandatory Ship Reporting System (MSRS) area. Of these whales, 1,594 were sighted within the bounds

of the proposed ATBA, suggesting that such a designation could greatly reduce right whale ship strikes. A narrowing of the TSS by 1 

nm suggests that 77 of the 196 right whales seen in the TSS during April–July 1999–2005 would have been separated from ship traffic. 

We also evaluated ship strike risk by overlaying right whale sightings on vessel tracks. This analysis suggests that during April-July 

there are two areas of the GSCSMA where right whales are at greatest relative risk of ship strike: (a) a diagonal track within the GSCCH 

proceeding northeasterly from the southwest corner of the GSCCH; and (b) that part of the TSS which passes through the GSCCH. 

Implementing an ATBA in the GSCCH area would reduce the relative risk of right whale ship strike in the GSCCH by 63%. Narrowing 

the TSS by 1 nm on the eastern side would reduce the relative risk in the GSCCH by another 11%. Though narrowing the TSS will affect fewer animals than the ATBA, the relative risk per individual whale is much greater in the TSS because of the heavier traffic there. 

Similar reductions in ship strike risk would accrue for fin (Balaenoptera physalus) and humpback (Megaptera novaeangliae) whales in 

both the ATBA and a narrowed TSS.
Page 2

(2001–2003). Surveys were flown at ca. 230 m altitude (310 

m in 2001), and 100 kts (185 km/hr) when visibility was 

good and the Beaufort sea state was 5 or less. Sightings of all 

marine mammals were recorded. Right whale counts used in 

this analysis represent the best final estimate of the number 

of animals at a sighting location. To obtain this estimate, 

after a right whale was sighted, the survey aircraft broke off 

effort and circled the sighting location until the observers 

were confident that all whales had been recorded. This is the 

only situation where “off-watch” observations were included 

in this analysis. This only affected right whale counts; the 

aircraft followed standard line-transect protocols and stayed 

on-effort when all other whale species were seen. 

During 1998–2001, flights were either flown along 

tracklines developed for the South Channel Ocean Productivity Experiment (SCOPEX, Kenney and Wishner 1995) in 

the Great South Channel area, or they were directed toward 

areas of reported or suspected right whale concentrations. 

During 2002–2005, emphasis was placed on uniform coverage of the entire study area. Cole et al. (2007) describes how 

survey coverage was allocated and the results of the effort 

allocation by year. The data used in the analyses conducted 

here have not been corrected for effort or for unobserved animals (i.e., g(0) corrections). We assumed, for this analysis, 

that effort was uniformly distributed throughout the area. As 

such, there may be spatial and temporal bias in the sighting 

locations. Also, the additional “off-watch” effort for right 

whales described above likely provides a reasonable estimate 

of the animals along the track line, even without the g(0) 

correction. However, the actual numbers of other whales 

present are underestimated. 

Vessel Tracks 

In 1998, the United States proposed to the IMO a 

Mandatory Ship Reporting System (MSRS) as a mitigation 

tool for right whale ship strikes. The IMO, the Specialized 

Agency of the United Nations to address international shipping issues, is the competent international body to develop 

guidelines, criteria, and regulations on an international level 

for shipping including approval of a MSRS. The proposed 

MSRS was approved by the IMO later that same year (66 

FR 58066; Silber et al. 2002).

Reporting under the MSRS began on 1 July 1999. All 

commercial vessels 300 gross tons and greater are required 

to report to a shore-based station when they enter two areas 

off the east coast of the United States: one off Massachusetts 

and one off Georgia and Florida. The reporting system off 

Massachusetts (WHALESNORTH) operates year round, 

while the Georgia and Florida system (WHALESSOUTH) 

operates from 15 November to 15 April. Upon entering the 

MSRS, ships report their name, call sign, course, speed, location, destination, and route. A computer server, operated 

under federal contract, handles and stores incoming ship 

reports and sends an automated-return message. Incoming 

reports are text messages that arrive via International Maritime Satellite (INMARSAT) or Telex (Silber et al. 2002). In 

return, a vessel receives an automated message that provides 

the latest information about right whale sightings and avoidance procedures that may prevent a collision.

Incoming ship reports were reviewed by the USCG for 

duplicate or erroneous records and stored in a relational 

database. Florida’s Fish and Wildlife Research Institute 

(FWRI) staff (Ward-Geiger et al. 2005) then extracted records from the database in a format compatible for mapping 

locations within ArcInfo and ArcView. Tracks were either: 

(1) “simple,” where a line was drawn between the point of 

entry into the system and the reported destination; or (2) 

“descriptive,” which included tracks that were generated by 

sequentially linking more than two points along the reported 

route. For simple tracks from ships that reported only the 

name of the destination port, substitute coordinates were 

assigned to complete the track.

To improve the quality of inbound descriptive tracks, 

FWRI staff mapped every route terminus coordinate within 

the MSRS to verify that the end of each track falls within a 

reasonable distance (10-km radius) from the pilot station for 

the reported destination port. When a descriptive track did 

not meet this criterion, the Geographic Information System 

(GIS) completed the track by using the substitute coordinates 

from the appropriate pilot station. 

The validity of each track was assessed based on criteria reported by Silber et al. (2002), and only tracks that met 

these criteria were analyzed. Tracks within each area were 

tallied and mapped to characterize traffic concentrations. 

ANALYSIS

Great South Channel ATBA analysis

Initially, both the entire GSC SMA (Figure 1) and the 

MSRS area were considered as candidate ATBAs. However, 

large areas of the 22,980 km2

 SMA and 23,000 km2 MSRS 

have relatively low densities of either whales or shipping. 

After additional discussion within NOAA, it was determined 

that the area defined by the GSC Critical Habitat provided a 

more appropriate ATBA (Figure 2). This area was truncated 

at the eastern edge of the Boston TSS, so its area (7,450 km2

) 

is somewhat smaller than the original critical habitat area 

(8,360 km2

). Boundaries of the ATBA analyzed were:

 69° 33.6’ W, 41° 44.4’ N 

 68° 31.0’ W, 42° 10.0’ N 

 68° 13.0’ W, 41° 38.0’ N 

 69° 4.2’ W, 41° 1.2’ N 

An index of vessel traffic density was developed from 

ship tracks reported through the northeast MSRS during 

1999–2005 (Ward-Geiger et al. 2005). Because the MSRS 

WHALESNORTH was initiated on 1 July 1999, data from 

WHALESNORTH were processed on a 1 July – 31 June 

cycle. The ATBA that NOAA is considering is seasonal and 
Page 3

would be effective for the months of April through July, so 

data for an “analysis year” represents a re-aggregation of 

the yearly cycle of MSRS data. As an example, 1999/2000 

analysis year includes the months of July 1999, April 2000, 

May 2000 and June 2000. Six years of MSRS data were 

analyzed: 1999/2000 to 2004/2005. Tracks entering the 

TSS north of Cape Cod were excluded. Vessels departing 

from within the MSRS (e.g., Boston) do not report into the 

MSRS, and thus there is underreporting of vessel tracks 

headed southwards in the TSS. 

A spatial query polygon was used to isolate and summarize the annual subsets of tracks within the MSRS boundary, 

GSC critical habitat, and southern leg of the Boston TSS. 

All tracks which intersected the spatial query polygon were 

selected with ArcGIS and converted into a gridded density 

file. This grid was created in ArcInfo Workstation using 

the LineDensity command with the following parameters: 

kernel density interpolation, 2 km search radius (accuracy of 

reported locations is to the nearest minute), and 100 m cell 

size. Grid values represent km of ship track/km2 within the 

relevant polygon. The final grid file of ship track density 

prepared by staff of FWRI for this analysis included a total 

of 761 vessel trips through the GSC Critical Habitat/ATBA 

and 421 northbound trips through the southern leg of the 

Boston TSS for April-July 1999-2005. This is essentially 

the same data reported in Ward-Geiger et al. (2005), but 

updated with information from 2003-2005. 

Right whale sightings were analyzed by using ArcView 

3.2, Spatial Analyst, and ArcGIS/ArcMap 9.2. An index of 

GSC SMA right whale sighting densities was calculated for 

the April–July, 1999–2005 period by using sighting events 

weighted by the number of animals seen in the event. Two 

parameters were used with the ArcView DENSITY function: kernel density interpolation and 100m cell size. Grid 

values represent whales/km2 within the Gulf of Maine aerial 

survey area.

Both the ship track and sightings data were analyzed 

by using a NAD1983 UTM Zone 19N, Transverse Mercator projection.

Finally, we developed a crude risk model to identify areas of highest relative risk for right whale-vessel interactions 

within the MSRS. By using the Spatial Analyst function 

in ArcGIS/ArcMap 9.2 Tool Box, Relative Risk (RR) was 

calculated for subareas (e.g., the ATBA) within the MSRS 

as the normalized product of the right whale and ship track 

density indices:

where

 rwdij = right whale density in cell i in sub area j

 stdij = ship track density in cell i in sub area j

This produced estimates of relative risk (compared to 

the entire MSRS area) for two key subareas: the ATBA and 

the TSS. A side product of the analysis was an estimate of 

RR for each cell within the MSRS area. These results, by 

cell, were binned, contoured, and plotted by four levels of 

relative risk: Minimal (0<RR<0.01), Low (0.01<RR<0.05), 

Medium (0.05<RR<0.25), and High (0.25<RR<1.00), where 

RR=1.00 is the highest risk. Note that Cape Cod Bay was not 

included in this analysis; a separate analysis of ship strike 

risk is provided in Nichols and Kite-Powell (2005). 

Traffic Separation Scheme Analysis

The existing TSS was designed prior to concerns over 

right whale ship strikes. Analyses of the northern leg of the 

Boston TSS showed that a slight rotation of the TSS could 

greatly reduce the likelihood of large whale ship strikes 

(Merrick 2005; D Wiley, Stellwagen Bank NMS, pers. 

comm.). However, the southern leg of the TSS cannot be 

shifted to the west and away from the great densities of right 

whales in the GSC because of the navigational hazards associated with the nearby Davis Bank and Nantucket Shoals. 

The TSS might, nonetheless, be narrowed from the existing 

configuration of 2 nm lanes separated by 1 nm buffer zone 

to 1.5 nm lanes separated by a 1 nm buffer zone. This is 

identical to the width change the IMO approved for the 

northern leg of the TSS. 

We evaluated this proposal in two ways. First, we compared the number of whales sighted within the bounds of 

the existing TSS southern leg to a narrowed configuration. 

ArcView spatial query polygons were used to select the 

number of sightings under both lane configurations. While 

right whales were the focus of this analysis, data are also 

provided on humpback (Megaptera novaeangliae) and fin 

(Balaenoptera physalus) whales. Secondly, the relative risk 

analysis of right whale ship strike in the MSRS discussed 

previously provided information on the location and degree 

of risk in the TSS, as well as in the ATBA. 

RESULTS

During April–July 1999–2005, Northeast Fisheries 

Science Center (NEFSC) surveys in the Gulf of Maine recorded a total of 2,533 right whale sightings (Figure 3). Of 

these sightings, 2,032 of the whales were seen in the MSRS 

area, and 1,594 were seen in the proposed ATBA (Table 1). 

Based on this approach and assuming vessels comply with 

its provision, creation of an ATBA could reduce interactions 

between right whales and vessels within the MSRS area by 

78%. Reductions in vessel interactions with humpback and 

fin whales are also likely (54-58% of the sightings in the 

MSRS were within the ATBA).

Narrowing the TSS lanes from 2 nm to 1.5 nm each, 

while holding the western boundary constant, would further 

reduce the risk of ship strikes. Some 196 right whales were 

sighted within the boundaries of the southern leg of the TSS 

during April–July, 1999–2005. If the TSS was 1 nm nar-
Page 4

rower, 77 (39%) of these whales could have been at least 

temporarily separated from vessel traffic (Table 2). Note 

though that is only 4% of the whales seen in the MSRS area 

during the period. Risk reduction would also be observed 

for humpback and fin whales. 

An alternative approach to evaluating right whale’s ship 

strike risk is to explicitly consider the overlap of right whale 

and vessel traffic densities. Right whale sighting densities 

during April–July, 1999–2005 surveys varied greatly within 

the Gulf of Maine (Figures 3 and 4). Mean density for the 

Gulf of Maine was 0.03 whales/km2

 (sd = 0.13) and ranged 

from 0 to 2.63 whales/km2

. The ATBA encompasses most of 

the medium to high density sighting areas for April-July in 

the Gulf of Maine with the greatest sighting densities found 

in the southwest corner of the GSC Critical Habitat/ATBA 

area (Figure 4). 

Mean period traffic density within the MSRS area for 

April-July, 1999-2005 was 5.62 km of vessel tracks/km2

(sd = 15.88, max = 213.99). An examination of the ship 

tracks with the ATBA (mean = 8.73 km/km2

, sd = 13.30, 

max = 112.5) suggests that the densest vessel traffic within 

the ATBA occurs along a northeastward diagonal from the 

southwest corner (Figure 5). These ATBA traffic densities 

are, however, lower than the traffic density within the TSS 

itself (mean = 44.37 km/km2

, sd = 46.58, max = 188.5). 

Comparing right whale sighting densities (Figure 4) 

and ship track densities (Figure 5) suggests that the highest 

potential for right whale-vessel interactions is along the 

southwest to northeast diagonal of the GSC and in the TSS 

adjacent to the GSC critical habitat area. 

The risk analysis confirms that these areas are the most 

likely locations for right whale-vessel interactions (Figure 

6). Vessel traffic through the ATBA accounts for 63% of 

the relative risk of right whale ship strike within the MSRS 

(even though 78% of the whales seen in the MSRS were 

seen in the ATBA area). While the number of right whales 

potentially interacting with vessels is lower in the TSS than 

in the ATBA, the risk appears to be much higher for the 

whales traveling through the TSS. This is due to the heavier 

vessel traffic through the TSS (44.37 km/km2

) compared to 

the ATBA (8.73 km/km2). The portion of the TSS adjacent 

to the GSC critical habitat area currently accounts for 35% 

of the relative ship strike risk within the MSRS, even though 

only 10% of the MSRS whale observations occurred in the 

TSS. The 1 nm wide swath proposed to be excluded from 

the TSS accounts for 11% of the total risk of right whale 

ship strike in the MSRS, and as such a 1 nm narrowing of 

the TSS is likely to have strong conservation benefits for 

right whales. 

In summary, implementing the ATBA and narrowing the 

TSS by 1 nm would reduce the relative risk of right whale 

ship strike within the MSRS by 74% during April-July (63% 

from the ATBA and 11% from the narrowing of the TSS).

DISCUSSION

Both the ATBA as presented here (aligned with the Great 

South Channel Critical Habitat) and the narrowing of the 

Boston TSS have the potential to greatly reduce the risk of 

ship strike of right whales (and other large whales.) Seventyfour percent of the relative risk of right whale vessel strike 

within the MSRS was in these areas. Together these two 

changes could alleviate most of the right whale ship strike 

risk during April–July in the MSRS area.

The analysis presented here should be viewed as an 

evaluation of relative risk reduction. The absolute risk reduction is difficult to measure for several reasons. First, the 

underlying interaction rate between whales and shipping in 

Table 2. Number of large whales seen in current Boston Traffic Separation Scheme (TSS) and the 1 nm strip proposed to be excluded 

from the TSS, and the percent of animals observed in the 1 nm strip: April–July 1999–2005.

Species 

of whale Original TSS Exclusion Area

Percent of Total 

in Exclusion Area

Right 196 77 39%

Humpback 373 50 13%

Fin 139 28 20%

Total 708 155 22%

Table 1. Number of large whales seen in the Gulf of Maine, Great South Channel Seasonal Management Area, Mandatory Ship Reporting System area, and proposed Area To Be Avoided: April–July 1999–2005.

Species 

of whale

Gulf 

of Maine

Seasonal 

Management 

Area

Mandatory 

Ship Reporting 

System Area

Proposed Area 

To Be 

Avoided

Right 2,533 2,218 2,032 1,594

Humpback 2,046 1,344 1,376 744

Fin 1,445 750 762 444

Total 6,024 4,312 4,170 2,782
Page 5

the Northeast is unknown. As such, absolute risk reduction 

cannot be determined.

Secondly, the observations of whales in the area are only 

approximations of the true numbers of animals present. In 

addition to underestimating the number of animals present, 

there is considerable interannual variability in the temporal 

and spatial distribution of these whales. However, it is clear 

from this analysis and previous studies (e.g., Cetacean and 

Turtle Assessment Program [CETAP 1982; Kenney and 

Winn 1986] and SCOPEX [Kenney and Wishner 1995; Kenney et al. 1995]) that large whales concentrate in the Great 

South Channel in late spring and early summer. 

Finally, the vessel track data used here represent an 

underreporting of the actual traffic, although the only systematic spatial bias in the reporting of commercial vessels 

≥ 300 gt is likely the lack of tracks for vessels heading 

southward along the TSS. Vessels departing from within the 

MSRS are not required to report into the MSRS. However, 

missing tracks elsewhere are likely distributed in proportion 

to reported tracks, so that the spatial pattern of densities is 

most likely correct (Ward-Geiger et al. 2005 for additional 

discussion), but the magnitude is underestimated. We will be 

able to assess this once sufficient data become available from 

the recently implemented Automated Identification System 

(AIS) for vessels. A more significant problem may be the 

lack of data on vessels < 300 gt. These smaller vessels are 

also involved in ship strikes of large whales.

Narrowing the TSS by 1 nm while holding the western 

boundary fixed provides some conservation value, albeit less 

than that provided by the ATBA. More comprehensive protection would be provided by shifting or rotating the entire 

scheme as far westward as possible. For example, a 5 nm 

westward shift combined with the ATBA would result in an 

almost complete separation between whales and north-south 

vessel traffic in the Great South Channel-Georges Bank area. 

However, even the narrowing of the lanes has positive value, 

particularly if the ATBA provision results in the routing of 

additional northbound traffic into the TSS, thereby increasing the ship strike risk in the TSS.

Rerouting vessels around the ATBA, either to the south 

for SW-NE traffic or into the TSS, will eliminate a large 

area of potential interaction that presently exists within the 

Great South Channel. This is true even though individual 

right whales move throughout the SMA during the spring 

and summer and are exposed to vessel traffic at various locations. The predictably high numbers of sightings within 

the ATBA from year to year (Merrick 2005) suggest that the 

residence times in the ATBA are significantly longer than 

elsewhere in the SMA or Gulf of Maine. Thus, even though 

individuals may be seen in more than one area, they spend 

more time in certain areas, and are, therefore, at greater risk 

of vessel interactions in such areas.

ENDNOTES

1. The ATBA proposed will likely be in place annually from 1 

April through 31 July and will encourage all non-sovereign 

flag vessels greater than 300 gross tons to avoid the area.

2. A separate but similar survey was conducted during this same 

time period in Cape Cod Bay by the Provincetown Center 

for Coastal Studies under contract to the State of Massachusetts.

ACKNOWLEDGEMENTS

We gratefully acknowledge two groups for their invaluable assistance. Our thanks to Rene Baumstark and Leslie WardGeiger of Florida’s Fish and Wildlife Research Institute for providing the ship track data for this analysis. Secondly, we 

are indebted to the observers who spent many hours over the water and many more in the office double checking the data, 

including Cynthia Christman, Lisa Conger, Rob DiGiovanni, Peter Duley, Holly Fearnbach, Allison Glass, Brett Hayward, 

Kelly Houle, Brendan Hurley, Amy Knowlton, Brenna Kraus, Keri Lodge, Regina Campbell-Malone, Marilyn Marx, Misty 

Nelson, Misty Niemeyer, Liz Pomfret, Cathy Quinn, Sara Quinn, Amy Renner, Brenda Rone, Cheryl Ryder, Kent Smedbol, 

Alison Stimpert, Christopher Tremblay, Peter Trull, Fred Wenzel, and Monica Zani. We also had the observer services of 

Jon Alberts, Allison Chaillet, G. Childreth, Jason Conner, A. Farak, Tom Fetherston, Andrea Hallett, Brian Hopper, Nate 

Johnson, Juliette Finzi, Glenn Mitchell, Mia Morete, Dave Potter, Janeen Quintal, Marjorie Rossman, Owen Nichols, Amber 

Sobrosky, Rob Stephenson, Jonathan Wendland, and Dave Wiley. Expert piloting was provided by Nancy Ash, Chris Barton, 

Eric Berkowitz, John Bidwell, Nicole Cabana, Bill Clark, B. Cooper, Adam Dunbar, Phil Eastman, Brad Fritzler, Jeff Hagan, 

Phil Hall, T. Hinds, Nickie Lambert, Gregg LaMontagne, Doug MacIntyre, Jason Mansour, Cathy Martin, Kirk McQuown, 

Mark Moran, Mark B. Nelson, Jon Neuhaus, Carl Newman, Wally Pierce, Scott Sandorf, Charlie Smith, Tom Strong, Mark 

Sweeney, Brian Taggart, Bob Thistle, Nick Toth, Kristie Twining, Bob Wallace, Fred Weir, and James Wortham. Thanks 

also to Richard Pace for providing biometric oversight on survey design and valuable input on this manuscript, Debra Palka 

for sharing her survey and programming expertise, and Phil Clapham. We are especially indebted to the U.S. Coast Guard 

Air Station on Cape Cod for the use of their facilities and airframes, as well as their whale sighting and weather reports. 

Finally, thanks to the reviewers (David Gouveia, Lindy Johnson, Fred Serchuk, and Greg Silber) of this paper for the value 

they have added to it. 

This work was funded in part by the U.S. Coast Guard under a Memorandum of Agreement (NEC 2003-021), and was 

conducted using MMPA/ESA Permits 775-1600, 1295, and 917.
Page 6

CeTAP. 1982. A characterization of marine mammals and 

turtles in the mid- and north Atlantic areas of the U.S. 

outer continental shelf. Cetacean and Turtle Assessment 

Program, University of Rhode Island. Final Report 

#AA551-CT8-48 to the Bureau of Land Management, 

Washington DC, 538 p.

Cole T, Gerrior P, Merrick R. 2007. Methodologies and 

preliminary results of the NOAA National Marine 

Fisheries Service aerial survey program for right whales 

(Eubalaena glacialis) in the Northeast U.S., 1998-2006. 

Northeast Fish Sci Cent Ref Doc. 07-02; 11 p.

Jensen AS, Silber GK. 2003. Large whale ship strike 

database. U.S. Dep. Commer. NOAA Tech Memo 

NMFS-F/OPR–25; 37 p.

Kenney RD, Winn HE. 1986. Cetacean high-use habitats of 

the Northeast United States continental shelf. Fish Bull 

(Wash DC) 84:345–357.

Kenney RD, Wishner KF. 1995. The South Channel Ocean 

Productivity Experiment. Cont Shelf Res. 15:373-384.

Kenney RD, Winn HE, Macaulay MC. 1995. Cetaceans 

in the Great South Channel, 1979-1989: right whale 

(Eubalaena glacialis). Cont Shelf Res. 15:385-414.

Laist DW, Knowlton AR, Mead JG, Collet AS, Podesta 

M. 2001. Collisions between ships and whales. Mar 

Mammal Sci. 17(1):35-75.

Merrick RL. 2005. Seasonal management areas to reduce 

ship strikes of northern right whales in the Gulf of Maine. 

Northeast Fish Sci Cent Ref Doc. 05-19; 18 p. 

Nichols OC, Kite-Powell HL. 2005. Analysis of risk to 

North Atlantic right whales (Eubalaena glacialis) 

from shipping traffic in Cape Cod Bay. Unpubl. report. Available at: www.nero.noaa.gov/shipstrike/doc/ 

Publications and Research.htm.

NMFS. 2005. Recovery plan for the North Atlantic right 

whale (Eubalaena glacialis). NMFS, Silver Spring 

MD; 133 p.

Pace RM, Silber GK. 2005. Simple analyses of ship and 

large whale collisions: Does speed kill? [Abstr.; oral 

pres.] Prepared for: Sixteenth Biennial Conference on 

the Biology of Marine Mammals, San Diego CA; Dec. 

12-16, 2005; np.

Silber GK, Ward LI, Clarke R, Schumacher KL, Smith 

AJ. 2002. Ship traffic patterns in right whale critical 

habitat: Year one of the Mandatory Ship Reporting 

System. US Dep Commer NOAA Tech Memo 

NMFS-OPR-20; 25 p. 

Vanderlaan ASM, Taggart CT. 2007. Vessel collisions with 

whales: the probability of lethal injury based on vessel 

speed. Mar Mammal Sci. 23(1):144-156.

Ward-Geiger LI, Silber GK, Baumstark RD, Pulfer TL. 

2005. Characterization of ship traffic in right whale 

critical habitat. Coast Manage. 33:263-278.

Waring GT, Josephson E, Fairfield CP, Maze-Foley K Editors. 2006. U.S. Atlantic and Gulf of Mexico marine 

mammal stock assessments -- 2005. US Dep Commer 

NOAA Tech Memo NMFS-NE-194; 352 p.

REFERENCES CITED
Page

7

Figure 1. Northern right whale seasonal management areas (SMAs) in New England.

Off Race Point SMA

Great South Channel SMA

Cape Cod Bay SMA

70 0 70 140 Miles

N

E W

S

71o 70o 69o 68o 67o

41o

42o

43o
Page 8

Figure 2. Mandatory Ship Reporting System, proposed Area To Be Avoided (ATBA) and Critical Habitat areas.

Mandatory Ship Reporting System Area

Great South Channel ATBA & Critical Habitat

Remainder Great South ChannelCritical Habitat Area

70 0 70 140 Miles

N

E W

S

71o 70o 69o 68o 67o

41o

42o

43o
Page

9

Figure 3. Northern right whale sightings during April–July, 1999–2005 shown with the Great South Channel Seasonal Management Area (SMA) and Area To Be Avoided (ATBA).

Great South Channel SMA Great South Channel ATBA50 fathom contour

Right Whales: 1999-2005

N

E W

S
Page 10

Figure 4. Northern right whale sighting densities (whales/km2) in the Great South Channel during April–July, 1999–2005 shown with the Great South Channel Area To Be Avoided (ATBA) 

and Mandatory Ship Reporting System (MSRS) boundary.

Right Whale density (whales/km2)

Great South Channel ATBAMSRS boundary50 fathom contour0.01 - 0.20.2 - 0.40.4 - 0.60.6 - 0.80.8 - 1.01 - 1.21.2 - 1.41.4 - 1.6>1.6No Data

40 0 40 80 Miles

N

E W

S

70o 69o

42o

41o
Page 11 Figure 5. Mandatory ship reporting system (MSRS) boundaries and densities of ship track (km of ship track/km2) through the potential Great South Channel Area To Be Avoided (ATBA for April–July, 1999–2005.

Vessel Track Density: 1999-2005

Great South Channel ATBAMSRS boundary50 fathom contour0.01 - 1.171.17 - 2.352.35 - 4.694.69 - 7.047.04 - 9.399.39 - 11.7311.73 - 16.4316.43 - 25.8125.81 - 55.1455.14 - 222No Data

40 0 40 80 Miles

N

E W

S

70o 69o

42o

41o
Page 12

Figure 6. Relative risk of right whale interactions with vessel traffic in the Great South Channel Area To Be Avoided (ATBA) and Mandatory Ship Reporting System (MSRS) area during 

April–July, 1999–2005.

Ship Strike Relative Risk

Great South Channel ATBAMSRS boundary50 fathom contourMinimalLowMediumHighNo Data

40 0 40 80 Miles

N

E W

S

70o 69o

42o

41o
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