Vessel Operations in Right Whale Protection 

Areas in 2009 

Gregory K. Silber and Shannon Bettridge 

U.S. Department of Commerce 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

NOAA Technical Memorandum NMFS-OPR-44 

July 2010

Vessel Operations in Right Whale Protection 

Areas in 2009 

Gregory K. Silber and Shannon Bettridge 

Office of Protected Resources 

National Marine Fisheries Service 

1315 East-West Highway 

Silver Spring, MD 20910 

NOAA Technical Memorandum NMFS-OPR-44 

July 2010

U.S. Department of Commerce 

Gary Locke, Secretary 

National Oceanic and Atmospheric Administration 

Jane Lubchenco, Ph.D., Administrator 

 

National Marine Fisheries Service 

Eric C. Schwaab, Assistant Administrator for Fisheries
ii 

Suggested citation:

Silber, G.K., and S. Bettridge. 2010. Vessel operations in right whale protection areas in 

2009. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-OPR-44. 44 p. 

A copy of this report may be obtained from: 

Office of Protected Resources 

NOAA, NMFS, F/PR2 

1315 East-West Highway 

Silver Spring, MD 20910 

Or online at:

http://www.nmfs.noaa.gov/pr 

Acknowledgements

Mr. Kam Chin and Mr. Dave Phinney of the Department of Transportation’s Volpe 

National Transportation Systems Center have been a pleasure to work with on this project 

and their technical expertise is formidable. Ms. Carliane Johnson of SeaJay 

Environmental helped immensely with data processing and in developing procedures for 

data synthesizing. 
iii 

Executive Summary 

One of the greatest threats to the recovery of the highly depleted North Atlantic 

right whale (Eubalaena glacialis) is collisions with ships (or “ship strikes”). The U.S. 

National Oceanic and Atmospheric Administration’s (NOAA) National Marine Fisheries 

Service (NMFS) has taken a number of steps to reduce the threat, including issuing a 

final rule (73 Federal Register 60173, October 2008) that requires vessels >65 feet in 

length to travel at 10 knots or less in certain times and locations (termed “Seasonal 

Management Areas”, or SMA) of right whale occurrence. NMFS also initiated a 

program whereby “Dynamic Management Areas” (DMA) are established in areas in 

which right whales are observed outside SMAs, whereby temporary zones are created 

and vessels are requested (but, not required) to either navigate around the zone or travel 

through it at 10 knots or less. This process allows for management measures that are tied 

directly to the known, but perhaps transitory, presence of right whales, and provides a 

means to establish areas effecting vessel operations that are smaller (in area) and shorter 

(in duration) than seasonal management measures. NMFS is monitoring the effectiveness 

of the restrictions by assessing compliance with the vessel speed limits as well as 

adherence to associated voluntary measures. Automatic Identification System (AIS) 

technologies provide a precise and easily accessible means to do so. 

Originally conceived as a safety of navigation technology, the AIS uses Global 

Positioning System (GPS)-linked, very high frequency (VHF) radio signal that provides 

for ship-to-ship and ship-to-shore information transfer. It transmits the ship’s name, call 

sign, position, dimensions, speed, heading and other information multiple times each 

minute. The AIS signal provides a suite of information, both dynamic (that is unique to a 

particular voyage) and static (that is consistent for a given vessel). Dynamic information 

includes the vessel’s position, speed over ground, course over ground, heading, rate of 

turn, and position accuracy (< or > 10 m) which are determined by continuous GPSlinked updates. Static information includes the vessel’s: name, call sign, type, cargo, and 

its Maritime Mobile Service Identity (MMSI) number. Given the rate at which it provides 

this information, AIS is a precise means to remotely track vessel speeds and other vessel 

operations. 

Our goal here is to provide (a) a characterization of vessel traffic volume, 

patterns, and speeds of vessels transiting SMAs, and (b) an initial assessment of vessel 

adherence to the vessel speed restrictions. This summary is for the period of January 

2009 (the rule was enacted December 2008) through December 2009. We also provide 

an initial characterization of vessel use of DMAs in the same period. 

We gathered information on vessel activity in 10 operational SMAs, and in 18 

DMAs for the period January to December 2009. As set forth in the rulemaking, the 

SMAs we analyzed were effective in: Cape Cod Bay (1 January – 15 May); an area Off 

Race Point, MA (1 March – 30 April); an area in the Great South Channel (1 April – 31 

July); an area extending from mid-coastal Georgia to northern Florida (15 November – 

15 April); and (1 November – 30 April for each of the following) Block Island Sound, 

port entrances of New York City and New Jersey, Philadelphia, PA, Norfolk VA, 

Wilmington, NC, and an area extending from Wilmington, NC to just south of Savannah, 

GA. 
iv 

A total of 39,615 vessel transits were recorded in active SMAs in 2009. Of these, 

10,982 were not applicable to conditions set forth in the Rule or were deemed inaccurate 

and were therefore removed from further analysis. Thus, a total of 28,633 transits were 

analyzed to determine vessel types, vessel speeds, SMA use, and other characteristics of 

these passages. 

The New York-New Jersey port entrance SMA had the greatest number of transits 

(n = 7,651) followed by the North Carolina-Georgia complex and the Norfolk SMAs 

(6,502 and 4,790 transits, respectively). Cargo vessels constituted the majority of ship 

passages in all SMAs, comprising over 50.3 % of all vessel transits, (and excluding the 

“other” vessel type category) followed by tanker vessels (14.9%), and tug-type vessels 

(10.2%). Cargo vessels were strongly represented in the New York-New Jersey, Norfolk 

and North Carolina-Georgia SMAs, with the North Carolina-Georgia complex having the 

highest number of cargo transits of all SMAs. Considering all transits in all active SMAs 

the ratio of foreign flagged to domestic vessels was 1.6:1 

The most common maximum speed represented was 11 knots; and the majority of 

all transits were between 11 and 16 knots. A substantial number of transits were at 

maximum speeds in excess of 16 knots. Aggregate maximum speeds in most SMAs 

exhibited a “bell-curve” with peaks between 10 and 16 knots; while the most highly 

represented maximum speed in nearly all SMAs was 11 - 12 knots. Generally, domestic 

vessels had lower aggregate vessel speeds than did foreign-flagged vessels; foreignflagged vessels tended to travel at 12 knots or greater. Cargo vessels exhibited the 

highest aggregate maximum speeds (with the most traveling in the 15-16 knot range), 

followed by tankers (with peaks in the 11-13 knot range), and aggregate speeds for 

passenger vessels had peaks around 12 knots. Vessels in the “tug, tow, dredge”, and 

“other” categories exhibited peak aggregate speeds around 10 knots. 

In 2009, 18 DMAs were “triggered” by right whale presence, all occurring in 

waters off New England. A total of 1,406 vessel transits occurred in these active DMAs. 

The majority were tankers (n = 521), nearly twice as many as any other vessel category. 

Excluding the “other” category, cargo vessels were the second most common type. The 

distribution of vessel speeds through DMAs is different than the distribution for vessel 

speeds utilized in SMAs (it was not a “bell-shape” as in the SMA speed distributions). In 

DMAs, 11 knots was the most common maximum speed; and there appeared to be a 

higher proportion of vessels traveling 11 knots or less than those vessels traversing 

SMAs. A second peak occurred at 14 knots with a large portion traveling at 13 and 14 

knots; probably reflecting the number of cargo ships and tankers traversing the zones. 

Likely, many tug and barges and “big-tows” (vessels typically traveling at speeds under 

12 knots) have limited options to route around such areas: being largely coastal and 

having specific destinations that require routes through DMAs and therefore opt to travel 

through DMAs; whereas larger, ocean-going vessels on more lengthy routes may have 

the latitude to avoid a particular area. 

It is not clear why “compliance” (defined strictly here as maximum speed <10 

knots) with vessel speed requirements was low. Contributing factors may be a lack of 

public recognition of the rule, disregard for it, or inadequate early enforcement. There 

are almost certainly learning and acquisition phases to a requirement that substantially 
v 

alters standard practices. With regard to “foreign-flagged” vessels and their operators, 

particularly those making infrequent port calls, language barriers or simple lack of 

familiarity with domestic requirements may hamper acquisition of the significance and 

requirements of the rule. Regarding knowledge of the rule, however, NOAA and a suite 

of partners made a concerted effort to notify the public and maritime community about 

the requirements both prior to their enactment and during the periods in which SMAs 

were in effect. Perhaps one significant weakness in efforts to alert mariners is that of 

NOAA’s printed nautical charts which currently do not depict SMAs. There are lessons 

to be learned about the importance of an effective enforcement program, and about 

possible weaknesses in the distribution of various notification outlets, their capacity to 

reach the targeted audience, or the level of their impact in influencing the behavior of 

certain maritime operators. 
vi 

Acronyms and Abbreviations 

AIS Automatic Identification System 

BI Block Island 

CCB Cape Cod Bay 

DMA Dynamic Management Area 

GPS Global Positioning System 

GSC Great South Channel 

IMO International Maritime Organization 

ITU International Telecommunications Union 

MID Maritime Identification Digits 

MMSI Maritime Mobile Service Identity 

MOA Memorandum of Agreement 

MOR Morehead City, South Carolina 

NAIS National Automatic Identification System 

NC-GA Wilmington, North Carolina to Savannah, Georgia 

NEUS Northeast United States 

NY-NJ Port of New York and New Jersey 

NOR Norfolk 

ORP Off Race Point 

PHI Ports of Philadelphia 

SEUS Southeast United States 

SMA Seasonal Management Area 

SOG speed over ground 

SOLAS [International Convention for the] Safety of Life at Sea 

USCG United States Coast Guard 

VHF very high frequency

 
1 

Vessel Operations in Right Whale Protection Areas in 2009 

Introduction 

Perhaps the greatest threat to the 

recovery of the highly depleted North 

Atlantic right whale (Eubalaena 

glacialis) is collisions with ships (or 

“ship strikes”). In response to this 

threat, the U.S. National Oceanic and 

Atmospheric Administration’s (NOAA) 

National Marine Fisheries Service 

(NMFS) has taken a number of steps to 

reduce right whale vulnerability to 

severe ship strikes. One such measure is 

the Final Rule to Implement Speed 

Restrictions to Reduce the Threat of 

Ship Collisions with North Atlantic 

Right Whales (73 Federal Register 

60173, October 2008) that requires 

vessels >65 feet in length to travel at 10 

knots or less in certain areas during right 

whale occurrence (NMFS, 2008a). 

Vessel speed restrictions apply in 

“Seasonal Management Areas” (SMA): 

specific locations and times that coincide 

both with key right whale aggregation 

and migration areas and with port 

entrances and other locations where 

maritime activities are concentrated. In 

this same rule, NMFS also established 

“Dynamic Management Areas” (DMA): 

areas in which right whales are observed 

outside SMAs whereby temporary zones 

are established and vessels are requested 

(but, not required) to either navigate 

around the zone or travel through it at 10 

knots or less. NMFS is monitoring the 

effectiveness of the regulation by 

assessing compliance with the vessel 

speed restrictions as well as adherence to 

associated voluntary measures. 

Automatic Identification System (AIS) 

technologies provide a precise and easily 

accessible means to do so. 

Originally conceived as a safety 

of navigation technology, the AIS uses 

Global Positioning System-linked, very 

high frequency (VHF) radio signal that 

provides for ship-to-ship and ship-toshore information transfer. It transmits 

the ship’s name, call sign, position, 

dimensions, speed, heading and other 

information multiple times each minute. 

Given the rate at which it provides this 

information, AIS is a highly precise, and 

in a number of ways an ideal means to 

remotely track vessel speeds and other 

vessel operations. 

 AIS transponders are required 

on certain vessel types that transit U.S. 

waters. These include: 1) all commercial 

tugs, barges, tow and similar vessels that 

are 26 feet in length or greater; 2) all 

passenger vessels (such as ferries and 

cruise ships) 150 gross tonnage or more; 

and 3) any commercial self-propelled 

vessel that is 65 feet in length or greater, 

which consists of commercial fishing 

vessels, tankers, cargo ships, etc. (33 

CFR 164.46). United States Coast Guard 

(USCG) rulemaking proposed in 

December 2008 would also require AIS 

on any passenger vessel carrying 50 or 

more passengers for hire, regardless of 

length or tonnage; and high speed craft 

(30 knots or greater) that carry 12 

passengers or more, regardless of length 

or tonnage. The USCG is incrementally 

establishing a National Automatic 

Identification System (NAIS) system -- a 

network of shore-based receivers and 
2 

relayers that when completed will 

provide coverage of nearly all U.S. 

coastal waters. 

NMFS Headquarters’ Office of 

Protected Resources has been acquiring 

AIS data feeds from the USCG NAIS. 

Data are downloaded and processed, 

under a Memorandum of Agreement 

(MOA), by the Department of 

Transportation’s Volpe National 

Transportation Systems Center (Volpe 

Center) and provided to NMFS in 

monthly data summaries. Using those 

data, we were able to describe vessel 

traffic volume and operations in the 

SMAs and describe mariner behavior 

with regard to adherence with NOAA’s 

vessel speed restrictions. 

Our goal here is to provide (a) a 

characterization of vessel traffic volume, 

patterns, and speeds of vessels transiting 

SMAs, and (b) an initial assessment of 

vessel adherence to the vessel speed 

restrictions. This summary is for the 

period of January 2009 (the rule was 

enacted December 2008) through 

December 2009. We also provide an 

initial description of vessel use of DMAs 

in 2009. We expect to prepare a more 

comprehensive summary report for a 

longer time series, likely through late 

2010 or early 2011; and we expect to 

prepare periodic summaries (e.g., 

monthly or quarterly) during that period. 

The Automatic Identification System

The U.S. Coast Guard (USCG) 

implemented a vessel safety rule in 2003 

(Title 33 Code of Federal Regulations 

164.461

) that requires all vessels of 65 

 

1 § 164.46 Automatic Identification System (AIS). 

(a) The following vessels must have a properly installed, 

operational, type approved AIS as of the date specified: 

 (1) Self-propelled vessels of 65 feet or more in 

length, other than passenger and fishing vessels, in 

feet (20 meters) or greater and transiting 

U.S. navigable waters to carry AIS. The 

rule codified regulations by the 

International Convention for the Safety 

of Life at Sea (SOLAS), an international 

agreement that specifies minimum 

standards for the construction, 

equipment and operation of ships 

(International Maritime Organization, 

1974). Flag States are responsible for 

ensuring that ships operating under their 

jurisdiction comply with SOLAS 

requirements. Under the Convention, all 

ships of 300 gross tonnage and greater 

engaged in international voyages and 

cargo ships of 500 gross tonnage and 

greater not engaged in international 

voyages and passenger ships irrespective 

of size are required to have AIS. A 

large, undetermined number of vessels 

less than 300 gross tons (and less than 65 

feet) also voluntarily carry AIS 

transmitting capabilities. 

The initial intent of AIS was to 

help ships avoid collisions, as well as 

assist port authorities to better control 

sea traffic. The AIS transponder includes 

a Global Positioning System (GPS) 

receiver and collects static and dynamic 

information and transmits this 

 

commercial service and on an international voyage, not 

later than December 31, 2004. 

 (2) Notwithstanding paragraph (a)(1) of this section, 

the following, self-propelled vessels, that are on an 

international voyage must also comply with SOLAS, as 

amended, Chapter V, regulations 19.2.1.6, 19.2.4, and 

19.2.3.5 or 19.2.5.1 as appropriate (Incorporated by 

reference, see § 164.03): 

 (i) Passenger vessels, of 150 gross tonnage or 

more, not later than July 1, 2003; 

 (ii) Tankers, regardless of tonnage, not later than 

the first safety survey for safety equipment on or after 

July 1, 2003; 

 (iii) Vessels, other than passenger vessels or 

tankers, of 50,000 gross tonnage or more, not later than 

July 1, 2004; and 

 (iv) Vessels, other than passenger vessels or 

tankers, of 300 gross tonnage or more but less than 

50,000 gross tonnage, not later than the first safety 

survey for safety equipment on or after July 1, 2004, but 

no later than December 31, 2004. 
3 

information on two VHF channels 

(frequencies 161.975 MHz and 162.025 

MHz). Other vessels or base stations are 

able to receive this information, process 

it using special software and display the 

location of vessels on a chart plotter or 

on a computer. The data are also 

available in the public domain. One 

searchable database on the Internet that 

offers location information of ships is 

www.marinetracker.com. 

The AIS is capable of handling 

more than 4,500 reports per minute and 

updating as often as every two seconds. 

AIS vessel transponders normally work 

in an autonomous and continuous mode 

with a typical range of coverage of about 

20 nautical miles, but perhaps more in 

certain circumstances. 

A national network of receivers 

is being established by the USCG; and 

NOAA, in cooperation with the USCG 

utilizes data feeds from this system to 

monitor vessel operations, relative to its 

vessel speed restrictions and other ship 

strike reduction measures. 

Methods 

Timing and Locations of Vessel Speed 

Restrictions 

 We gathered information on 

vessel activity in 10 operational SMAs, 

and in 18 DMAs for the period January 

to December 2009. NOAA’s vessel 

speed restrictions went into effect 9 

December 2008 establishing SMAs in 

specific periods and locations 

corresponding to right whale migration, 

feeding, and nursery areas, as well as 

high vessel traffic densities in certain 

port entrances (Tables 1 & 2; Fig. 1) (73 

FR 60173, October 2008) (NMFS, 

2008). As set forth in the rulemaking, 

the SMAs we analyzed were effective: 

1 January – 15 May: Cape Cod Bay 

(CCB); 

1 March – 30 April: an area Off Race 

Point (ORP); 

1 April – 31 July: an area in the Great 

South Channel (GSC); 

1 November – 30 April: 

- Block Island Sound (BI); 

- port entrances of New York 

City (NY); 

- Philadelphia (PHI); 

- Norfolk (NOR); 

- Wilmington, NC; and 

- an area extending from 

Wilmington, NC to just south 

of Savannah, GA (NC-GA); 

and 

15 November – 15 April: an area 

extending from mid-coastal Georgia to 

northern Florida (SEUS). 

Processing Automatic Identification 

System Data 

 

 The monitoring program we 

developed involves a rather substantive 

data set. As noted, vessels’ AIS 

transponders send signals multiple times 

each minute; tens of vessels are moving 

through active SMAs at any given time, 

thousands of transits per month. 

Nonetheless, we wanted to ensure, to the 

extent possible and despite the volume 

of data, that results were summarized in 

ways useful to managers and that we 

were clear in how these data were 

processed. Therefore, we provide detail 
4 

here on data handling and error 

checking. 

Under the conditions of a 

Memorandum of Agreement (MOA), 

dated 10 June, 2009, and in cooperation 

with the USCG, NOAA acquires NAIS 

data via the Volpe Center (Cambridge, 

MA). The Volpe Center obtains AIS 

data directly from the USCG NAIS and 

archives and houses the entire data set at 

its Cambridge, MA facility. The Volpe 

Center provides to NOAA (via a secure 

web site) monthly spreadsheet 

summaries of every vessel transit 

occurring in an active SMA. The Volpe 

Center utilizes a highly customized 

software program it developed over a 

decade ago to handle such data, called 

Transview 32 (or “TV32”). Under the 

MOA, the Volpe Center is also 

providing analysis of the DMA program 

established in conjunction with the final 

rule; NOAA-established recommended 

routes; and an International Maritime 

Organization (IMO)-approved Area To 

Be Avoided. The latter two measures 

will be assessed in subsequent reports. 

Having monthly spreadsheet 

summaries allowed us to organize large 

amounts of data and to readily analyze 

them for various features to characterize 

vessel traffic (e.g., by vessel type, 

country of origin). Each spreadsheet 

line entry represents a unique “transit,” 

that corresponds to a vessel that made a 

single entry and exit within a 

management zone during the time the 

SMA was active. Inbound, outbound, 

and transiting ships occurring in any 

active SMA were analyzed. Vessels 

making multiple transits during the same 

day, or within more than one SMA, were 

also designated by a single spreadsheet 

line. 

The AIS signal provides a suite 

of information, both dynamic (that is 

unique to a particular voyage) and static 

(that is consistent for a given vessel). 

Dynamic information includes the 

vessel’s position, speed over ground, 

course over ground, heading, rate of 

turn, and position accuracy (< or > 10 m) 

which are determined by continuous 

GPS-linked updates. Static information 

includes the vessel’s 

- name, 

- call sign, 

- type, 

- cargo, and 

- Maritime Mobile Service 

Identity (MMSI) number. 

The MMSI is a unique nine digit 

number regulated by the International 

Telecommunications Union (ITU). The 

MMSI is a unique nine digit number 

regulated by the International 

Telecommunications Union (ITU). The 

MMSI format for a vessel is 

M1I2D3X4X5X6X7X8X9 where the first 

three digits represent the Maritime 

Identification Digits (MID) and X is any 

figure from 0 to 9. The MID denotes the 

country or geographical area responsible 

for the identified ship station and ranges 

from 201 to 775. In general, a MID 

beginning with 2 denotes Europe; 3 is 

North America, Central America or the 

Caribbean; 4 is Asia; 5 is Oceana; 6 is 

Africa; 7 is South America; and 8 is for 

regional use. 

Data Handling and Screening

We established three initial data 

screening criteria. We first removed all 

vessels <20 m (65 ft) as these were not 

subject to the conditions of the vessel 

speed restrictions (Table 3). We then 
5 

removed all records identified as 

belonging to sovereign vessels, as they 

are exempt from the speed restrictions 

(described in more detail below). We 

also decided, a priori, to remove from 

analysis transits that were represented by 

<10 AIS position “fixes”, reasoning that 

a small amount of information would 

likely not provide an adequate 

characterization speed and other features 

of these transits. 

Identifying and Correcting Errors in 

the Data 

Although we believe the 

information presented here faithfully 

characterizes vessel activity in these 

areas and times, the AIS data are not 

flawless. This section describes our 

attempts to locate and address 

incomplete records, because we want to 

ensure their accuracy and because these 

data are an assessment of the regulation 

and actions of a significant portion of a 

substantial maritime industry. 

Nonetheless, we believe the vast 

majority of records are accurately sent, 

received, and processed by generally 

highly reliable electronic technologies 

and systems. 

Consisting of a VHF signal, the 

range (distance of reception) of AIS 

transmissions is constrained essentially 

to "line of sight", or tens (or in some 

instances perhaps hundreds) of miles, a 

distance that varies depending on the 

height of the receiving antenna and other 

factors. In addition, the signal may be 

momentarily compromised, or enhanced, 

by local meteorological conditions (e.g., 

electrical storms), atmospheric bounce, 

or other possible interferences (e.g., 

other radio signals), and therefore, 

ranges may vary. 

It is possible that some data are 

inaccurate or absent. Conceivably, this 

could happen as a result of: 

a. Malfunction of the AIS 

transponder of the vessel, 

b. Errors of the Global 

Positioning System (GPS) 

and, 

c. Neglect of the vessel's crew 

to correctly configure the 

information transmitted by 

the AIS transponder such as 

the vessel’s name, type and 

dimensions. 

 Of these, we believe “a”, above, 

is unlikely (although it is possible that a 

vessel failed to carry or use or disabled 

its transponder or it may have 

malfunctioned for some reason; 

however, we have no way of assessing 

this). Although it is possible a vessel’s 

GPS could generate an erroneous 

position or speed, we believe the 

occurrence of “b”, above, to be highly 

unlikely given the reliability of this 

proven international navigational 

network. (Below, we provide a 

description of additional screening to 

remove possible erroneous position fixes 

and speeds.) 

As to “c”, above, some of the 

AIS system is based solely on 

information provided to the unit by its 

operators; therefore, correct 

configuration of the AIS transponders by 

the ship’s crew is important to the 

transmission of accurate information. 

That is, while much information (i.e., 

position, speed, course over ground) 

contained in this data packet is highly 

accurate because it is automatically 

supplied by ship navigation systems 

including GPS, user input attributes (i.e., 

length, draft, vessel type) are subject to 
6 

misinformation due to user input errors 

or lack of proper training and standards. 

It was clear some of the 

information received was not accurate. 

As described in more detail below (in 

the section on “Vessel Length”) this 

occurred most with regard to 

information on vessel dimensions. Such 

records, a relatively small portion of the 

entire sample, were either removed prior 

to further analysis, or the correct 

information was added where possible. 

In quite a few of these cases, we were 

able to use the ship’s name to locate its 

length via Internet searches; and as a 

result were able to re-constitute accurate 

information in the transit record. 

Nonetheless, in a number of cases, we 

were unable to locate such information 

for the vessel and therefore removed 994 

records (2.5% of the total received) from 

further analysis (Table 3). 

 In some instances, we observed 

a particular MMSI number being used 

by more than one vessel. (For example, 

sequences such as 123456789 are fairly 

common.) This may occur for several 

reasons. An operator may enter the 

wrong MSSI number, or if an operator 

enters no MMSI number the AIS 

transponder may automatically enter a 

pre-determined default number. In 

addition, if an AIS transponder is shut 

down or loses its internal configuration 

memory, a default number may be 

entered when the system is re-activated. 

At least one AIS manufacturer uses this 

default system as standard practice. 

 A MMSI number links the 

vessel’s static information (e.g., name, 

call sign) to its dynamic information 

(e.g., speed, location). A problem can 

arise if two vessels being tracked within 

a SMA, or one occurring outside the 

SMA, have the identical MMSI 

numbers. If duplicate MMSI numbers 

are received by the system, each 

subsequent signal from the vessel within 

the SMA will generate a new vessel 

record and track when only one should 

have been recorded. Thus, duplicative 

records and erroneous position locations 

in one or more records for that vessel 

will be generated. 

 

 To correct this situation, a new 

geo-feasibility test capability was added 

to the “Transview” (i.e., TV32) program 

by personnel at the Volpe Center. This 

test determines whether it is feasible for 

a vessel to move from point to point 

within a reasonable time using a 

reasonable speed. When the program 

calculates that a jump is not feasible 

(i.e., two vessels with the same MMSI 

number are being considered as one 

vessel), a side record of the history trail 

is established. As additional position 

reports are received, each is compared 

for validity to the latest position report 

for each side record. As soon as a set of 

points is found to be geo-feasible, the 

new report is associated to that vessel 

track. This can repeat for any number of 

separate tracks of vessels transiting 

through any number of zones. The 

result, for us, is a drastically reduced set 

of transit summaries as each ship’s track 

is verified. Even with the correction, 

there is the possibility that two vessels 

with the same MMSI could cross paths 

or be in close enough proximity to cause 

tracks to swap – a condition that can also 

confound radar tracking systems. 

 

 A second outcome arising from 

duplicate MMSI numbers is a lack of 

assurance in assigning a vessel’s name 

(and other static data) to a string of 
7 

position reports. If the IDs of the AIS 

base stations receiving reports from the 

multiple ships is known, then that could 

help determine an association between 

messages, however, this is generally not 

the case. To address this, incoming 

information was processed to indicate if 

a given vessel being tracked underwent 

numerous “name changes” which would 

indicate a possible duplicate MMSI 

number in the summary record. This is 

not the number of unique names seen for 

the MMSI, but the total number of times 

the name differs from the previously 

received static vessel messages. This 

condition was used as long as the vessel 

is tracked by the system, regardless of 

whether the vessel is within the SMA. 

When the vessel departs the SMA, the 

name change count is written with the 

transit record. This count indicates how 

many name changes had occurred since 

the acquisition of the tracked vessel. 

Although the name associated with a 

transit summary is not guaranteed to be 

correct, but there is an indication when it 

may not be. In those cases in which a 

legitimate record was not certain (here 

termed “too many name changes”) we 

removed it from further analysis; a total 

of 213 records (0.5%) were removed by 

this process (Table 3). 

Finally, a small number of 

records (0.5% of all records analyzed) 

were removed from further analysis 

because the static information could not 

be corrected with a high level of 

certainty (Table 3). For example, the 

system may receive positions for a 

vessel that has not yet transmitted its 

static information. This occurs when a 

static vessel’s information is transmitted 

less frequently than its positions. In this 

case, the MMSI number of the vessel 

will appear in the “vessel name” column 

instead of its name. In the January 2009 

dataset, this occurred 12 times in more 

than 6,000 transits in the raw data. This 

ratio was comparable in the other 

months analyzed. 

Given our detection and removal 

or correction of erroneous information, 

and given the high transmission rates 

(i.e., up to hundreds, and often 

thousands, of individual data points per 

transit), we believe most of these 

potential problems with the data set are 

overcome by the volume of data and 

they provide a reasonable representation 

of vessels transiting SMAs and their 

operations within SMAs. 

Grouping of Vessel Type

Numerous identifiers are used by 

ships to report the type of vessel.2

 In 

such databases, ships are categorized and 

subcategorized to better identify the 

vessel and also its cargo. 

Vessel type categories provided 

by the operator were grouped to 

facilitate our summarization of the data. 

Vessel types coded by the operator as 

“cargo”, “tanker”, and “passenger” 

comprise their own, discrete categories. 

“Tow” and “big tow” boats reflect the 

sizes of the towing vessel based on the 

operator’s judgment, and were combined 

into one group called “tow”. 

Thus, in a number of the graphics 

presented here, we used only the general 

category of “type” to differentiate the 

vessels moving through the SMAs. 

They are: 

Cargo 

Tanker 

 

2

 These codes can be found at 

http://www.navcen.uscg.gov/enav/ais/AIS_Mess

ages_A_Static.htm
8 

Passenger 

Tow 

Pilot 

Tug 

Sovereign3, and 

“Other”. 

Note that in some graphics that 

follow, we present summaries in 

categories that include greater detail 

within a vessel category (e.g., a stand 

alone category for fishing vessels, 

pleasure craft -- otherwise complied in 

the “other” category). The cargo vessel 

category consists of any ship or vessel 

that carries cargo, goods, materials from 

one port to another, including container 

ships, bulk carriers, and general cargo 

ships. The tanker category includes ships 

carrying oil or other liquid products. 

Passenger vessels include large cruise 

ships as well as smaller (often coastal) 

passenger ferries. 

“Other” vessels includes the 

remaining vessels that were listed as: 

fishing, sailing, pleasure, 

dredging, diving, anti-pollution, 

WIG (wing-in-ground), Resol-18 

(ITU Radio Regulations 

Resolution No. 18), HSC (high 

speed craft), reserved, unknown, 

and other. 

 

3 Sovereign vessels was a category of 

our own creation (inasmuch as they are exempt 

from the vessel speed restrictions), and included, 

on occasion, a number of descriptions as entered 

by the AIS operator, such as tanker, fishing, 

dredging, and law enforcement vessels. We 

provide some characterizations of sovereign 

vessel behavior here, but generally, they were 

removed from analysis.

A number of ship types grouped 

within the “other” category are not well 

defined in the literature such as “Resol18” and “WIG” but these comprised 

only a few entries (i.e., generally fewer 

than five) in any given month. 

On occasion, ship operators 

miscoded vessel type information. In 

many of these instances ships that were 

clearly misidentified were coded as 

“other”, such as the Cape Fear Pilot 2

that was coded as a “fishing” vessel 

instead of a pilot vessel. These were not 

corrected in the data set. In some 

records, a default is used by one AIS 

company for their transponders that, if 

not reset by the operators, results in 

“Nauticast” inserted as the vessel name. 

In these cases, the record was removed 

from the dataset. 

In a future iteration of this report, 

further Internet search queries on the 

vessel types is planned to correct much 

of this information and allow for more 

reliable vessel type assessments to be 

conducted. Nonetheless, we believe the 

vast majority is coded correctly, and 

overall characterizations of vessel types 

are a true representation of transiting 

vessel type proportions. 

Vessel Length 

Vessel dimension (length and 

beam) is static information transmitted 

in the AIS signal. We were interested in 

vessel length as a condition for knowing 

whether the vessel was required to 

comply with speed restriction zones, i.e., 

at a length of 65 feet or greater. As 

noted, vessels generally less than 65 feet 

in length are not required to carry AIS 

but some do so for purposes of enhanced 

navigational safety. Although these are 

found in the dataset, they have been 
9 

taken out in the final analysis presented 

here. It is also possible that not all 

sovereign vessels transmit an AIS signal, 

but those that did were removed from 

most information presented here (unless 

otherwise indicated). 

In some cases, the vessel 

dimension information was provided as 

“zero”. Vessels that were listed from 

one to six meters in length (those above 

6 m were generally found to be reliably 

reported) were independently verified 

and required correcting in a relatively 

few cases. For example, some cargo 

ships were incorrectly coded as being 

one meter long. Inaccurately entered 

vessel length information occurred in 

1,007 of 6,371 (or 16%) entries in 

January 2009 representing 103 different 

vessels. The proportion of cases lacking 

vessel length information in January 

2009 is comparable to the proportion 

occurring in all months in 2009. 

In many cases, we were able to 

locate vessel dimensions that were 

incorrect or listed as zero by searching 

on Internet web sites that provide details 

on vessels worldwide. This was usually 

done by searching using a vessel’s name, 

MMSI number, and/or call sign on such 

websites as the USCG Information 

Exchange 

(http://cgmix.uscg.mil/PSIX/PSIXSearch

.aspx), the Federal Communication 

Commission’s Universal Licensing 

System 

(http://wireless2.fcc.gov/UlsApp/UlsSea

rch/searchLicense.jsp), Vessel Tracker 

(http://www.vesseltracker.com/en/Vessel

Archive.html), and Digital Seas 

(http://www.digitalseas.com/vessel_search/vessel_archive.h

tml). In cases in which it was not 

possible to locate the necessary 

information for a vessel, the entry was 

removed to a separate worksheet and not 

used in analysis. 

After the lengths were obtained 

for as many ships as possible, the dataset 

was again sorted and all those found to 

be 19 meters (62.3 feet) or less were 

removed and not analyzed further 

because they are exempt from the rule. 

Thus, all vessels analyzed in this report 

were 20 meters (65.6 feet) or greater in 

length and were presumed to be required 

to comply with the speed zones in the 

SMAs. 

Determining Country of Origin 

AIS data also include country of 

origin information. We were interested 

in analyzing this to, in part, assess 

whether certain segments of the shipping 

industry should be the focus of 

subsequent outreach efforts, and, if so, to 

help direct such efforts. For analytical 

purposes, we divided all vessels into two 

broad categories: domestic and foreign. 

“Domestic” includes vessels registered 

in the United States, including Puerto 

Rico and the U.S. Virgin Islands; 

“Foreign” includes all others. 

As indicated above, the MMSI 

number can be used to determine flag 

country and we used this to separate 

foreign-registered vessels from 

domestic. For the relatively small 

number that had “unknown” information 

with regard to flag country, we used 

MMSI numbers and conducted Internet 

searches to determine country of 

registry. 

Sovereign Vessels

Nearly all sovereign vessels (e.g., 

U.S. Navy, USCG, NOAA, etc.) carry 

AIS transmitting and receiving 
10 

capabilities; however, for national 

security reasons they are neither required 

nor expected to transmit the signal. 

Thus, many sovereign vessel transits 

may be absent from the data set. Since 

sovereign vessels are exempt from the 

speed restrictions, records identified as 

belonging to sovereign vessels were 

removed from further analysis (Table 3). 

Several sort queries were used on the 

dataset to identify sovereign vessels; two 

of the most common methods were by 

the vessel’s name or its type. 

Certain known acronyms of 

governmental entities were used to 

determine sovereignty: CG, CGC, Coast 

Guard, COE, USCG, USCGC, USA, 

USAV, USGOV, USEPA, USNS, USS, 

US Sub, and Warship. Certain vessel 

codes, including MILOPS (military 

operations), SAR (search and rescue), 

and LAW, were used to determine 

sovereign status. Some vessels were 

also coded as “fishing” but were 

determined to be NOAA ships (such as 

the Thomas Jefferson). Other military 

vessels were listed as “tankers” but 

determined to be military based on an 

Internet search on their names (such as 

Big Horn, Kanawha, Leroy Grumman, 

and others). 

It is possible that some sovereign 

vessels were overlooked because they 

were neither clearly coded as such nor 

had a vessel name that easily identified 

them as sovereign. If so, we believe this 

represents a very small, if any, portion of 

the dataset. 

Vessel Speed

Vessel “Speed Over Ground” 

(SOG) is the speed metric used explicitly 

in the vessel speed restriction rule; and 

here we use SOG interchangeably with 

the term “speed”. 

There were some cases in which 

a vessel’s status (as entered by the user) 

indicated a vessel was “anchored”, but 

we obtained position and speed 

information, as supplied by the ship’s 

GPS, that indicated the vessel was 

moving. Therefore, we relied on the 

more accurate GPS-linked vessel 

position, speed, and course indicators. 

We observed vessel SOG as 

provided by AIS transmissions to range 

from 0 to 102 knots. Vessels with speeds 

greater than 100 knots or that included 

speeds of “N/A” were removed from the 

analysis as they clearly are erroneous 

data for a vessel at sea (although some 

craft transmitting AIS signals are 

capable of considerable speeds (e.g., 

high speed ferries) we believe some of 

these in excess of 100 knots may be 

aircraft, some of which also carry AIS 

capabilities). In most cases, this 

represented fewer than ten instances in 

each month’s data. 

We used “maximum SOG” as a 

means to characterize vessel transit 

speeds. As noted elsewhere, there are 

likely a number of ways to characterize a 

particular transit. We explore one later 

in this paper and others are being 

discussed, but for our purposes – 

characterizing adherence to the vessel 

speed restrictions – we regarded this 

metric suitable for these purposes. 
11 

Results and Discussion

 A total of 39,615 vessel transits 

were recorded in active SMAs in 2009 

(Table 4). We assume this is a full 

record of all vessels traveling in active 

SMAs, but we have no way to determine 

if all vessels with AIS carriage 

requirements adhered to those 

requirements. Given, however, AIS’s 

primary function is that of navigational 

safety in low light and poor sea 

conditions it is illogical that vessels 

would not use the system. 

Of these, a total of 10,982 

transits were removed from further 

analysis; including those in which 

vessels were < 20 meters as the vessel 

speed restrictions did not apply to 

vessels of this length (n = 7,020); reports 

related to sovereign vessels (n = 1,370); 

those reports that contained < 10 AIS 

position “fixes” (n = 1,500); records in 

which multiple vessels had the same 

MMSI numbers (or, “name changes” 

here) (n = 213); and those records in 

which the data appeared erroneous for 

other reasons (n = 211) (Table 3). As 

noted above, a number of records did not 

have vessel lengths as entered by the 

AIS operator. In many cases, we were 

able to determine vessel length by 

making Internet searches; nonetheless, 

we could not determine vessel length in 

994 of the records, and they, too, were 

removed from further analysis. 

Some vessel transits fell into 

more than one category for exclusion; 

for example, a vessel could be < 20 

meters in length and have fewer than 10 

AIS position reports and thus could be 

flagged for removal more than once. A 

total of 326 transits were flagged for 

removal under two or more categories, 

therefore 10,982 transits were removed 

from the database (with the removal 

criteria having been met a total of 11,308 

times) (Table 3). Thus, following this 

review and manually checking virtually 

each transit, we analyzed a total of 

28,633 records of vessels traveling 

through operational SMAs in 2009 

(Table 4). 

We therefore regard these 

numbers as minimum, but reliable 

counts of the number of vessel transits. 

By any measure, the number of records 

removed from analysis notwithstanding, 

this is a formidable fleet that traverses 

areas vital to the right whale 

population’s longevity. It appears large 

vessels are nearly ubiquitous throughout 

the range of the species, and a given 

individual may encounter tens of vessels 

each day, hundreds each year. 

Composition of Vessel Traffic within 

SMAs

Overall, the greatest vessel traffic 

volumes were in the NY/NJ, NC-GA 

and NOR SMAs (see Table 1 and the 

“Acronyms and Abbreviations” 

appendix for lists of acronyms for each 

of the SMAs). The NY-NJ SMA had the 

greatest number of transits (n = 7,651) 

followed by the NC-GA complex and 

the NOR SMA (6,502 and 4,790 transits, 

respectively) (Table 5). The number of 

ship using the NY-NJ port complex 

dwarfs the others, despite the fact that 

the NC-GA SMA encompasses a 

number of large ports, including 

Savannah and Charleston; and 

considering the NOR SMA services 

Baltimore, Hampton Roads, and other 

destinations within the Chesapeake Bay. 

The NOR SMA exhibited a relatively 

large number of sovereign and “other” 

vessels due to key military installations 

being located there. The total number of 

transits is likely underrepresented at this 
12 

location based on the assumption that 

some military vessels likely are not 

transmitting. Volume in the MOR SMA 

is, proportionally, much lighter relative 

to the other ports.; however noted an 

increase in the total number of vessels 

transiting the NOR SMA in December 

2009. This resulted from dredging 

activity near or within the SMA, such 

that the number of dredge vessels went 

from three in November to 254 

December. 

Vessel Type

Cargo vessels constituted the 

overwhelming majority of ship passages 

in all SMAs, comprising over 50.3 % of 

all vessel transits, (and not including the 

“other” category, for the moment, were) 

followed by tanker vessels (14.9%), and 

tug-type vessels (10.2%) (Table 5; Fig. 

2). Cargo vessels were strongly 

represented in the NY-NJ, NOR and 

NC-GA SMAs, with the NC-GA 

complex having the highest number of 

cargo transits of all SMAs (Fig. 3). The 

proportion of cargo vessels is also 

substantially greater than other vessel 

types using the SEUS SMA (57.9%). 

Tanker vessels were higher, 

proportionally, in northern SMAs than in 

more southern SMAs. The NC-GA 

complex encompasses the primary ports 

supporting movement of goods to the 

U.S. south, which accounts in part for 

the volume represented here over singleport entrance SMAs. 

Relative to the other SMAs, there 

were proportionally low numbers of 

vessels transiting the ORP, GSC, and 

MOR SMAs. The ORP SMA is active 

for a relatively short period (Table 2) 

which likely accounts for this pattern; 

but, overall, Morehead City appears to 

be one of the smaller ports, in terms of 

volume, inside active SMAs. The 

numbers reflected in the Great South 

Channel SMA is more difficult to 

interpret given it is the largest (in area) 

of all the SMAs and is used by 

international vessels making port calls in 

Boston, New York, and elsewhere. The 

relatively low volume in this area may 

indicate that (a) mariners are responding 

to the Area To Be Avoided established 

in June, 2009 by skirting the area; (b) 

vessels are (more heavily) utilizing the 

Traffic Separation Scheme servicing 

Boston since it lies outside the GSC 

SMA; or (c) relatively higher vessel 

volumes in SMAs other than the GSC is 

indicative of the level of many coastwide (e.g., port-to-port) transits along 

the eastern seaboard, as opposed to 

trans-Atlantic passages. There may be 

an additional compounding factor in this 

SMA, and that is the inherent 

transmission ranges of the AIS signal. 

Given this SMA extends rather far from 

shore, perhaps not all transmissions from 

vessels in the area are being captured. 

(This will likely be a subject of further 

study.) Regardless, this is a key feeding 

aggregation area for right whales, which 

may involve relatively long residency 

times for the whales, and it is be 

fortuitous that the traffic volume may be 

low in this area. 

Tow-type vessels were common 

in the Cape Cod Bay SMA (Fig. 4) 

reflecting the tug-and-barge industry 

utilizing the Cape Cod Canal as well as 

those vessels providing heating oil and 

other materials to Cape Cod 

communities and elsewhere in the 

northeast. These are typically slow 

moving vessels, a fact that is partly 

reflected in slower speeds in this area 

relative to other SMAs where other 

vessel types and higher speeds were 

observed. Also, an intensive outreach 
13 

effort has been ongoing for years 

involving a NOAA/U.S. Army Corps of 

Engineers collaboration whereby vessels 

using the canal are provided information 

on minimizing ship strikes from canal 

vessel traffic officials. 

Vessel Lengths 

Vessel length is another feature 

available from AIS (limited to those with 

AIS carriage requirements and are 

transmitting the signal) to characterize 

vessel traffic in SMAs, and therefore a 

further means to identify industry 

segment recipients for outreach and 

education actions. The majority of SMA 

transits involve large vessels (generally 

considered to be the tankers and cargo 

ships) that range from 100 meters (328 

feet) to 299 meters (981 feet) in length 

(Fig 5). 

Country of Origin

Considering all transits in all 

active SMAs the ratio of foreign flagged 

to domestic vessels was 1.6:1 (Fig. 6). 

This is generally consistent across all 

months except July when only the GSC 

SMA was active in which the ratio was 

5:1. The majority of cargo and tanker 

vessels were foreign-flagged; while all 

tow and nearly all tug and pilot vessels 

were domestic (Fig 7). The highest 

proportion of foreign versus domestic 

vessels occurred in the GSC SMA, 

followed by the ORP SMA perhaps 

reflecting trans-Atlantic passages 

destined for Boston or New York; and 

lowest number of foreign flags relative 

to domestic vessels occurred in the CCB 

and MOR SMAS (Fig 8). Patterns of 

domestic versus foreign-flag SMA 

transits appeared comparable when 

plotted by month (Fig 9). 

Assessment of Vessel Speeds

 There are a number of ways to 

characterize vessel speeds within SMAs. 

As described above, for this analysis, we 

chose to use “maximum speed over 

ground” as one metric of vessel speed. 

This may not be the most accurate way 

to depict speeds used in an entire transit, 

but it was a readily accessible metric, 

and one measure of each transit. More 

nuanced characterizations follow, 

particularly with regard to “compliance” 

with the speed restrictions, and will be 

explored in future analysis. 

Nonetheless, using this metric and for 

the purposes of this report, we provide 

distributions of vessel speed in 

aggregate, by vessel type, and vessel 

speeds in each of the SMAs. The most 

common maximum speed represented 

was 11 knots; and the majority of all 

transits were between 11 and 16 knots 

(Fig. 10). A substantial number of 

transits were at maximum speeds in 

excess of 16 knots. 

We were interested in 

determining if aggregated maximum 

vessel speeds diminished with time as 

awareness of the restrictions increased. 

However, there were not large 

differences in vessel speed distributions 

when compared by months studied (Fig 

11). We observed the greatest number 

of transits with maximum speeds around 

10 knots for the months of January, 

March, April, May, June and July. The 

greatest number of transits for the 

months of February, November and 

December were centered around 11 

knots maximum speed. It is unclear why 

this was observed in February, but the 

trend in the November and December 
14 

records may reflect the SMAs once 

again going into effect. 

Cargo vessels exhibited the 

highest aggregate maximum speeds 

(with the most traveling in the 15-16 

knot range), followed by tankers (with 

peaks in the 11-13 knot range), and 

aggregate speeds for passenger vessels 

had peaks around 12 knots (Fig. 12). 

Vessels in the “tug, tow, dredge”, and 

“other” categories exhibited peak 

aggregate speeds around 10 knots. With 

regard to those in the tug, tow, and 

dredge categories, such vessels travel 

around 10-12 knots routinely and 

regardless of vessel speed restrictions. 

We observed an interesting bimodal 

distribution, around 10 and between 20 -

22 knots, for fishing vessels. This may 

reflect the non-homogenous nature of 

the vessel category; some fishing 

vessels, such as charter fishing 

operations, travel at high speeds to 

minimize transit time to fishing grounds 

and maximize fishing time for 

passengers. Other fishing vessels may 

not be capable of traveling above certain 

speeds, or may not find it economical to 

travel at such speeds. Note, too, that in 

some cases pilot vessels – that are 

capable of relatively high speeds – were 

coded as “fishing” vessels for reasons 

that are not clear to us. 

Generally, domestic vessels had 

lower aggregate vessel speeds than did 

foreign-flagged vessels; foreign-flagged 

vessels tended to travel at 12 knots or 

greater (Fig. 13). 

Aggregate maximum speeds in 

most SMAs exhibited a “bell-curve” 

with peaks between 10 and 16 knots; 

while the most highly represented 

maximum speed in nearly all SMAs was 

11 - 12 knots (Fig. 14). Data expressed 

as aggregate speeds were quite similar 

for the GSC, ORP, BI, PHI, NOR, and 

MOR SMAs, all exhibiting peaks around 

10 to 11 knots maximum speed, and a 

number of these had relatively a large 

number of vessels with maximum speeds 

over 16 knots (Figs. 14 & 15). The 

outliers appear to be the SEUS SMA, 

exhibiting a peak at 12 knots; and the 

NC-GA SMA with the most transits with 

maximum speeds around 14 - 16 knots, 

with a second set of transits with 

maximum speeds of 19 - 21 knots. The 

MOR SMA exhibited a steady increase 

in the number of compliant vessels for 

the months of February and March. This 

is due to the number of fishing and 

dredging vessels recorded in these 

months that were not present in similar 

numbers during the other months. These 

vessels are typically slower moving than 

other vessel types also using these 

waters. 

 The CCB SMA exhibited the 

lowest aggregate vessel speeds, with the 

highest proportion (90%) among the 

SMAs in which maximum speeds were 

<11 knots. This is likely due to the 

proportion of tug-and-barge type vessels 

in the region. As noted, these vessels 

typically travel at slower speeds than 

ocean-going vessels. 

It is not clear why “compliance” 

(defined strictly here as maximum speed 

<10 knots) with these regulations was 

relatively low. Contributing factors may 

be a lack of public recognition of the 

rule, disregard for it, or inadequate early 

enforcement. There are almost certainly 

learning and acquisition phases to a 

requirement that substantially alters 

standard practices. With regard to 

“foreign-flagged” vessels and their 

operators, particularly those making 

infrequent port calls, language barriers 
15 

or simple lack of familiarity with 

domestic requirements may hamper 

acquisition and understanding of the 

significance and requirements of the 

rule. 

With regard to knowledge of the 

rule, however, NOAA and a suite of 

partners made a concerted effort to 

notify the public and maritime 

community about the requirements both 

prior to their enactment and during the 

periods in which SMAs were in effect. 

Such notifications appeared in various 

navigational aids, such as the U.S. Coast 

Pilots, Sailing Directions, USCG Local 

and Broadcast Notices to Mariners; via 

periodic NOAA Weather Radio 

announcements; distribution of 

laminated “compliance guides” and free 

interactive CDs through USCG 

personnel, port captains, and marine 

exchanges; National Weather Buoy and 

other web sites; NOAA shipping 

industry liaisons and NOAA’s Nav 

Managers; e-mail distribution lists; press 

releases; notifications provided directly 

to their members by maritime 

associations (e.g., World Shipping 

Council, the U.S. Chamber of Shipping, 

the Passenger Vessel Association); 

announcements and articles in trade 

journals and periodicals (see, for 

example, Silber and Bettridge, 2009); 

distributions by agencies such as the 

Department of Transportation’s 

Maritime Administration (literally 

thousands of vessels or owners were 

contacted directly); outgoing messages 

of the U.S. east coast right whale 

Mandatory Ship Reporting systems, and 

other means (Bettridge and Silber, 

2008). 

Perhaps one significant weakness 

in efforts to alert mariners is that of 

NOAA’s nautical charts themselves. 

Nautical charts are a key, perhaps the 

most important, navigational aid used 

routinely by every mariner. However, at 

this time, SMAs do not appear on 

NOAA paper charts because the areas 

are not permanent (i.e., seasonal, and set 

to expire in 2013) and due to issues of 

“chart clutter”. 

This study may provide feedback 

about the importance, and components, 

of an effective enforcement program. 

Lessons can be learned, too, about the 

use of various outlets to notify maritime 

interests and whether distribution of 

such notifications is possibly 

incomplete, their capacity to reach the 

targeted audience, or their level of 

impact in influencing the behavior of 

certain maritime operators. 

Characterization of Vessel Tracks

 One of the principal reasons for 

our interest in acquiring and analyzing 

AIS data was to monitor “compliance” 

with the vessel speed regulations. Using 

these data we could determine if, for 

example, compliance changed through 

time; as a result of a particular 

enforcement action; or whether outreach 

or enforcement actions needed to be 

targeted for a particular port or region, or 

segment of the industry. 

 Questions remain as to the most 

desirable way to represent speeds used in 

a vessel’s transit. Characterization may 

be complex and imperfect because, for 

example, a vessel may employ a number 

of speeds on any given transit as a result 

of slowing after entering the SMA, 

slowing to board a pilot, or finding the 

need to increase speed in adverse 

weather conditions. Because a ship may 

use a number of speeds in the course (or 
16 

even a portion) of a given transit, 

providing an “average” speed for the 

duration of the trip may be misleading. 

Use of “maximum speed”, or any of a 

variety of other metrics, may have 

similar pitfalls. 

Ultimately, the means used to 

characterize a voyage will depend on 

one’s objectives. As a first assessment 

of “compliance”, we choose maximum 

speed as the metric reasoning that, 

strictly speaking, any speed (by any 

measure) over 10 knots is a violation of 

the vessel speed restrictions (although 

perhaps not reasonable to enforce at this 

threshold). However, maximum speed 

may represent only a fraction of the 

entire transit, so this measure may 

overestimate the overall speed of a given 

transit and bias upward summaries of 

speeds in all transits. 

Therefore, to further characterize 

mariner behavior within SMAs we 

examined the portion of each transit for 

which speeds were above 10 knots and 

above 12 knots. This approach provides 

a means for examining the 

“egregiousness” of violations of the 

speed restrictions (i.e., was the violator 

exceeding the speed limit for the 

majority of the trip or only a small 

portion?). We assessed the “percent of 

the transit (distance) >10 knots” and 

“percent of the transit (distance) >12 

knots” of each transit. We then 

determined, for each transit, whether 

most of the trip (<50% or >50%) was 

below or above these two speed 

thresholds. Thus, as general measures of 

“compliance”, we provide the 

distribution of vessels traveling (a) 

slower than 10 knots/12 knots for the 

entire transit, (b) those traveling at and 

above 10 knots/12 knots for up to half of 

the transit, and (c) those traveling more 

than half of the transit distance above 10 

knots/12 knots (Fig. 17). 

A preliminary (but, not 

statistical) comparison of speed 

distributions between “maximum” 

speeds and those with a large percentage 

over particular thresholds (Fig. 17) 

suggest that either metric may be a 

reasonable representation of speeds 

utilized, particularly given the goals of 

this study and overall monitoring 

program are (a) determination of number 

and which vessels are in violation of the 

regulation (e.g., over 10 knots at any 

point of the passage), and (b) general 

characterization of speeds to determine 

if compliance improves through time. 

Nonetheless, we anticipate further 

examination and comparison of these 

metrics to identify one or more that best 

represents mariner behavior in SMAs. 

Only 5,584 (or 20% of over 

28,000) records exhibited maximum 

speeds at or below 10 knots for the entire 

transit; 13,800 (49%) were at or under 

12 knots for the duration of the transit 

(Fig. 17). A total of 18,415 (or 64% of 

all records) exhibited maximum speeds 

over 10 or 12 knots for the entire transit. 

However, to the extent that enforcement 

actions, or monitoring efforts for that 

matter, rely on any excessive speed 

above, say, 12 or 13 knots as an 

indicator of “non-compliance”, 

maximum speed still serves as a measure 

of relative adherence to the restrictions. 

Dynamic Management Areas 

Designating Dynamic 

Management Areas (DMA) is a process 

of restricting vessels’ activities in areas 

where right whales occur outside the 

SMAs or in areas encompassed by SMA 

but when they are not in effect. DMAs 
17 

could effectively occur anywhere 

throughout out the range of the species. 

The use of dynamically managed 

areas allows for substantially smaller (in 

area) and shorter (in duration) seasonal 

management measures. It also allows 

for management measures that are tied 

directly to the known, but perhaps 

transitory, presence of right whales. 

When a specific aggregation of right 

whales is sighted, a temporary zone 

around the aggregation is established in 

which speed restrictions applies for 15 

days. However, mariner action is 

voluntary: they are expected, but not 

required, to either avoid the area or 

travel through it at 10 knots or less. 

Zones are in effect for 15 days and 

automatically expire at the end of that 

period. If the whale aggregation persists 

the period may be extended for an 

additional 15 days. 

In 2009, 18 such areas were 

“triggered” by right whale presence 

(Table 6), all occurring in waters off 

New England. We quantified the (a) 

number of vessels, (b) vessel types, and 

(c) speeds of vessels passing through 

each of the DMAs (Table 6; Fig 18). In 

subsequent analysis, we plan to assess 

whether mariners were inclined to avoid 

the areas as opposed to traveling through 

them. 

A total of 1,406 vessels passed 

through the 18 active DMAs. The 

majority were tankers (n = 521), nearly 

twice as many as any other vessel 

category. Excluding the “other” 

category, cargo vessels were the second 

most common type (Table 6). The 

distribution of vessel speeds through 

DMAs (Fig. 18) is different than the 

distribution for vessels traversing SMAs 

(it was not a “bell-shape” as in the SMA 

speed distributions). In DMAs, 11 knots 

was the most common maximum speed; 

and there appeared to be a higher 

proportion of vessels traveling 11 knots 

or less than those vessels traversing 

SMAs. A second peak occurred at 14 

knots with a large portion traveling at 13 

and 14 knots; probably reflecting the 

number of cargo ships and tankers 

traversing the zones. Many tug and 

barges and “big-tows” may have limited 

options in routing around such areas, 

engaging in largely coastal passages and 

having specific destinations that require 

routes through DMAs; whereas larger 

vessels on more lengthy routes may have 

the latitude to route around a particular 

area. 
18 

Literature Cited 

Bettridge, S., and G.K. Silber. 2008. Update on the Untied States’ actions to reduce the 

threat of ship strikes to large whales. Paper provided to the International Whaling 

Commission’s Working Group on Ship Strikes and Presented at the International 

Whaling Commission’s Conservation Committee, Santiago, Chile, 16 June 2008. 

11 pages. Available at: www.nmfs.noaa.gov/pr/shipstrike/. 

International Maritime Organization. 1974. International Convention for the Safety of 

Life at Sea (SOLAS). Adopted 1 November 1974. Available at: 

http://www.imo.org/Conventions/contents.asp?topic_id=257&doc_id=647. 

National Marine Fisheries Service. 2008. Final rule to implement speed restrictions to 

reduce the threat of ship collisions with North Atlantic right whales. 73 FR 

60173; 10 October 2008. Available at: http://www.nmfs.noaa.gov/pr/pdfs/fr/fr73-

60173.pdf. 

Silber, G.K., and S. Bettridge. 2009. New vessel speed regulations for U.S. east coast 

ports. Mariners Weather Log 53 (1):8-9. April 2009. 
19 

Tables and Figures 

Table 1. Dates of active SMAs, number of days analyzed in each, and number of transits 

analyzed in each in 2009. 

Region Acronym Times “Active” Number of 

SMA days 

Number of 

SMA transits

analyzed 

Cape Cod Bay CCB 1 January – 15 May 135 718 

Off Race Point ORP 1 March – 30 April 61 217 

Great South Channel GSC 1 April – 31 July 122 410 

Block Island BI 1 November –30 April 181 1,240

New York NY 1 November – 30 April 181 7,651

Philadelphia PHI 1 November – 30 April 181 3,857

Norfolk NOR 1 November – 30 April 181 4,790

Morehead City MOR 1 November – 30 April 181 475 

North Carolina to 

Georgia 

NC-GA 1 November – 30 April 181 6,502

Southeast U.S. SEUS 15 November – 15 April 152 2,773

TOTAL 5,636 28,633
20 

Table 2. Dates of active SMAs. Shaded cells represent SMA in effect. 

 CCB ORP GSC BI NY/NJ PHI NOR MOR NC-GA SEUS

Jan 

Feb 

Mar 

Apr 

May 

Jun 

Jul 

Aug 

Sept 

Oct 

Nov 

Dec 
21 

Table 3. Records flagged for removal from analysis and the reason for removal.

Month 

2009 

Vessels 

<20 m 

Sovereign 

Vessels 

Too Few 

Total 

Reports 

No 

Vessel 

Length 

Found 

“Name 

Changes” 

Misc. 

Corrupted 

Data 

Total 

January 1,070 153 199 143 17 18 1,600 

February 879 159 193 113 36 24 1404 

March 1,354 460 188 337 40 27 2,406 

April 995 161 593 20 29 27 1825 

May 13 8 4 2 0 2 29 

June 2 9 7 1 1 2 22 

July 4 7 23 0 0 5 39 

November 1,285 202 174 236 50 58 2,005 

December 1,418 211 119 142 40 48 1,978 

Total 7,020 1,370 1,500 994 213 211 11,308 
22 

Table 4. Number of records received, removed, and analyzed in 2009. 

Month 2009 Total Records 

Received 

Total Records 

Removed 

Total Transits 

Analyzed 

January 6,371 1,554 4,817 

February 5,718 1,361 4,357 

March 7,532 2,354 5,178 

April 6,369 1,785 4,584 

May 202 29 173 

June 129 20 109 

July 174 39 135 

November 6,279 1,912 4,367 

December 6,841 1,928 4,913 

TOTAL 39,615 10,982 28,633 
23 

Table 5. Number of transits analyzed, by vessel type, in each of the SMAs in 2009. 

SMA Cargo Tanker Passenger Tow Tug Pilot Other 

CCB 22 65 1 205 380 0 45 ORP 87 71 0 25 23 0 11 GSC 165 132 35 5 0 0 73 BI 400 309 8 118 194 0 211 NY-NJ 3,200 1,562 151 896 1,001 127 714 PHI 1,385 779 138 598 517 21 419 NOR 3,382 285 47 181 224 2 669 Morehead 51 30 3 26 25 0 340 NC-GA 4,116 811 65 176 454 59 821 SEUS 1,606 212 251 278 113 0 313 Total 14,414 4,256 699 2,508 2,931 209 3,616 
24 

Table 6. Dates, locations and vessels transiting active Dynamic Management Areas. 

Event Number Date of Implementation 

#RWs

General 

Location

Boundaries

Total 

Area 

(nm2) 

Days 

in 

Effect 

Cargo Tanker Tow/Big Tow 

E04 1-Jan 

7 Jeffreys Ledge 

43 24 N 42 40 N 069 44 W 070 46 W 1994.1 29 16 46 42 

E05 16-Jan 

3 Race Point 

42 26 N 41 46 N 069 41 W 070 35 W 1602.7 13 26 44 37 

E06 

11-Feb 

6 

Northern Jeffreys Ledge 

43 18 N 42 40 N 069 45 W 070 37 W 1445.5 

14 

7 15 7 

E07 

5 

Southern Jeffreys Ledge 

42 56 N 42 18 N 069 32 N 070 24 W 1454.1 

14 

20 41 2 

E08 

12 

Great South Channel 

42 04 N 41 15 N 069 04 W 070 10 W 2416.2 

14 

18 17 0 

E09 17-Mar 

3 Georges Shoal 

41 45 N 41 05 N 066 50 W 067 43 W 1589.8 11 0 0 0 
25 

Event Number Date of Implementation 

#RWs

General 

Location

Boundaries

Total 

Area 

(nm2) 

Days 

in 

Effect 

Cargo Tanker Tow/Big Tow 

E10 13-Apr 

5 Georges Shoal 

41 51 N 41 09 N 067 05 W 068 01 W 1761.5 12 1 0 0 

E11 12-May 

15 Cashes Ledge 

43 08 N 42 30 N 068 26 W 069 35 W 1923.3 15 6 13 0 

E12 13-May 

3 Jordan Basin 

43 42 N 43 02 N 068 14 W 069 09 W 1599.3 14 15 33 0 

E13 2-Jun 

37 Cashes Ledge 

43 06 N 42 07 N 068 15 W 069 56 W 27 34 49 3 

E14 9-Jul 

3 Cashes Ledge 

43 06 N 42 07 N 068 15 W 069 56 W 13 21 23 0 

E15 2-Sep 

5 Fippenies Ledge 

43 11N 42 31N 068 48W 069 44W 14 3 7 2 

E16 15-Oct 

11 Jeffreys Ledge 

43 21N 42 35N 069 45W 070 48W 27 9 23 28 
26 

Event Number Date of Implementation 

#RWs

General 

Location

Boundaries

Total 

Area 

(nm2) 

Days 

in 

Effect 

Cargo Tanker Tow/Big Tow 

E17 22-Oct 

7 Jordan Basin 

43 50N 43 06N 068 02W 069 02W 41 27 52 8 

E18 27-Oct 

16 Cashes Ledge 

43 24N 42 35N 068 28W 069 36W 2437.1 15 4 11 2 

E19 10-Nov 

30 Jeffreys Ledge 

43 33N 42 32N 069 27W 070 49W 40 18 117 23 

E20 10-Nov 

47 Cashes Ledge 

43 22N 42 21N 068 26W 069 42W 14 7 22 1 

E21 4-Dec 

27 Jordan Basin 

43 47N 42 47N 067 47W 069 23W 15 0 8 0 

Total 232 521 155 
27 

Figure 1. Locations of vessel speed reduction Seasonal Management Areas. 
28 

 

Figure 2. Distribution of vessel types transiting all SMAs in 2009. 
29 

Figure 3. Number of transits in each SMA by vessel type. (Note: CCB, GSC and ORP 

SMAs were collapsed into “NEUS” category for this figure because the numbers of 

transits in each of these SMAs were too small to register on this graph.) 
30 

Figure 4. Number of transits in each SMA by vessel type with cargo vessels removed to 

provide finer detail on other vessel types. (Note: CCB, GSC and ORP SMAs were 

collapsed into “NEUS” category for this figure because the numbers of transits in each of 

these SMAs were too small to register on this graph.) 
31 

Figure 5. Distribution of vessel lengths transiting all SMAs in 2009. 
32 

Figure 6. Proportion of domestic and foreign flag vessels transiting all SMAs in 2009. 
33 

Figure 7. Country of origin by vessel type. 
34 

Figure 8. Proportion of use of each SMA by domestic and foreign flag vessels, 2009. 
35 

Figure 9. Monthly distributions of domestic and foreign vessels, 2009. 
36 

Figure 10. Distribution of vessel speeds, as described by “maximum speed over ground”, used in all SMA transi

32% of transits vessels traveled at or below 10 knots for the entire transit 

68% of transits vessels exceeded 10 knots at some point in the transit 
37 

0

50

100150200250300350400450500550600650700750800850

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28>30

Speed in Knots

Number of Transits

Figure 11. Distribution of vessel speeds, as described by “maximum speed over ground”, used in all SMA transi
38 

0

300600900

1,2001,5001,8002,100

0 2 4 6 8 10 12 14 16 18 20 22 24 26 28>30

Speed in Knots

Number of Transits

Figure 12. Distribution of vessel speeds, as described by “maximum speed over ground”, used in all SMA transivessel type. 
39 

Figure 13. Vessel speed as a function of country of origin. 
40 

Figure 14. Distribution of vessel speeds, as a function of “maximum speed over ground” used in each of the SM
41 

Figure 15. Distribution of vessel speeds, displayed as a percent of the total transit, as a 

function of “maximum speed over ground” used in each of the SMAs. 
42 

Figure 16. Distribution of vessel speeds, displayed as a percent of the total transit, as a 

function of “maximum speed over ground” by vessel type. 
43 

Figure 17. Number of transits in which vessel speed was a) below 10 or 12 knots for the 

entire distance; b) above 10 or 12 knots for 1-50% of the distance; or c) above 10 or 12 

knots for 51-100% of the distance, for all SMAs in 2009. 
44 

Figure 18. Distribution of speeds of vessels traveling through Dynamic Management 

Areas.