Marine Sanctuaries Conservation Series NMSP-07-03

U.S. Department of Commerce 

National Oceanic and Atmospheric Administration

National Ocean Service 

Office of Ocean and Coastal Resource Management 

 A Bioregional Classification of the Continental 

Shelf of Northeastern North America for 

Conservation Analysis and Planning Based on 

Representation 

National Marine Sanctuary Program July 2007 
About the Marine Sanctuaries Conservation Series 

The National Oceanic and Atmospheric Administration’s National Ocean Service (NOS) 

administers the National Marine Sanctuary Program (NMSP). Its mission is to identify, 

designate, protect and manage the ecological, recreational, research, educational, 

historical, and aesthetic resources and qualities of nationally significant coastal and 

marine areas. The existing marine sanctuaries differ widely in their natural and 

historical resources and include nearshore and open ocean areas ranging in size from 

less than one to over 5,000 square miles. Protected habitats include rocky coasts, kelp 

forests, coral reefs, sea grass beds, estuarine habitats, hard and soft bottom habitats, 

segments of whale migration routes, and shipwrecks. 

Because of considerable differences in settings, resources, and threats, each marine 

sanctuary has a tailored management plan. Conservation, education, research, 

monitoring and enforcement programs vary accordingly. The integration of these 

programs is fundamental to marine protected area management. The Marine 

Sanctuaries Conservation Series reflects and supports this integration by providing a 

forum for publication and discussion of the complex issues currently facing the National 

Marine Sanctuary Program. Topics of published reports vary substantially and may

include descriptions of educational programs, discussions on resource management 

issues, and results of scientific research and monitoring projects. The series facilitates 

integration of natural sciences, socioeconomic and cultural sciences, education, and 

policy development to accomplish the diverse needs of NOAA’s resource protection 

mandate. 
A Bioregional Classification for the Continental Shelf of 

Northeastern North America for Conservation Analysis 

and Planning Based on Representation 

Rosamonde R. Cook and Peter J. Auster 

National Undersea Research Center & Department of Marine Sciences 

University of Connecticut, Groton 

Silver Spring, Maryland

July 2007 

U.S. Department of Commerce 

Carlos M. Gutierrez, Secretary 

National Oceanic and Atmospheric Administration 

VADM Conrad C. Lautenbacher, Jr. (USN-ret.) 

Under Secretary of Commerce for Oceans and Atmosphere

National Ocean Service 

John H. Dunnigan, Assistant Administrator 

National Marine Sanctuary Program

Daniel J. Basta, Director 
DISCLAIMER 

Report content does not necessarily reflect the views and policies of the National Marine 

Sanctuary Program or the National Oceanic and Atmospheric Administration, nor does 

the mention of trade names or commercial products constitute endorsement or 

recommendation for use. 

REPORT AVAILABILITY 

Electronic copies of this report may be downloaded from the National Marine Sanctuary 

Program web site at www.sanctuaries.nos.noaa.gov. Hard copies may be available from 

the following address:

National Oceanic and Atmospheric Administration

 National Marine Sanctuary Program

 SSMC4, N/ORM62 

 1305 East-West Highway 

Silver Spring, MD 20910 

COVER 

The continental shelf of northeastern North America (northwest Atlantic Ocean). Image 

was generated from the ETOPO2v2 (2006) database by NOAA NGDC. Source at 

http://www.ngdc.noaa.gov/mgg/image/2minrelief.html. 

SUGGESTED CITATION

Cook, R.R. and P.J. Auster. 2007. A bioregional classification of the continental shelf of 

northeastern North America for conservation analysis and planning based on 

representation. Marine Sanctuaries Conservation Series NMSP-07-03. U.S. Department 

of Commerce, National Oceanic and Atmospheric Administration, National Marine 

Sanctuary Program, Silver Spring, MD. 14 pp. 

CONTACT

Rosamonde R. Cook 

528 Spruce Street 

Riverside, CA 92507 

RosamondeCook@aol.com

951-787-8767 
ABSTRACT 

Understanding how well National Marine Sanctuaries and other marine protected areas 

represent the diversity of species present within and among the biogeographic regions 

where they occur is essential for assessing their conservation value and identifying gaps 

in the protection of biological diversity. One of the first steps in any such assessment

should be the development of clearly defined and scientifically justified planning 

boundaries representing distinct oceanographic conditions and faunal assemblages. Here, 

we propose a set of boundaries for the continental shelf of northeastern North America 

defined by subdivisions of the Eastern Temperate Province, based on a review and 

synthesis (i.e. meta-analysis) of the scientific literature. According to this review, the 

Eastern Temperate Province is generally divided into the Acadian and Virginian

Subprovinces. Broad agreement places the Scotian Shelf, Gulf of Maine, and Bay of 

Fundy within the Acadian Subprovince. The proper association of Georges Bank is less 

clear; some investigators consider it part of the Acadian and others part of the Virginian. 

Disparate perspectives emerge from the analysis of different groups of organisms. 

Further, while some studies suggest a distinction between the Southern New England 

shelf and the rest of the Mid-Atlantic Bight, others describe the region as a broad 

transition zone with no unique characteristics of its own. We suggest there exists

sufficient evidence to consider the Scotian Shelf, Gulf of Maine, Georges Bank, Southern 

New England, and Southern Mid-Atlantic Bight as distinct biogeographic regions from a

conservation planning perspective, and present a set of proposed mapped boundaries. 

KEY WORDS 

biogeography, boundaries, species distributions, physiography, gap analysis
TABLE OF CONTENTS 

Topic Page

Abstract and Key Words......................................................................................... i 

Table of Contents.................................................................................................... ii 

List of Figures and Tables....................................................................................... iii 

Introduction............................................................................................................. 1 

Regional Context .................................................................................................... 1 

 Eastern Temperate Subdivisions ....................................................................... 3 

 Georges Bank and Southern New England........................................................ 5 

Proposed Planning Boundaries ............................................................ 7 

Acknowledgements................................................................................................. 10 

Literature Cited ....................................................................................................... 11 
LIST OF FIGURES 

Figure Number and Title Page

Figure 1 – The Northeast Continental Shelf study area .................................... 2 

Figure 2 – Marine provinces and subprovinces ............................................. 2 

Figure 3 – Bathymetry and major surface currents .......................................... 4 

Figure 4 – Biogeographic regions ............................................................. 8 
INTRODUCTION 

Understanding how well National Marine Sanctuaries and other types of marine 

protected areas represent the diversity of species present within and among the 

biogeographic regions where they occur is essential for assessing their conservation value 

and identifying gaps in the protection of biological diversity (Auster and Shackell 2000, 

Roberts et al. 2003). One of the first steps in any such assessment should be the 

development of a well-defined set of biogeographic boundaries for planning purposes. 

Biogeographic regions are generally defined by stratifying the marine environment

according to a range of oceanographic and biological similarities (Mondor 1997).

However, there is no single method of classification (Longhurst 1998). Delineations 

have been variously based on descriptive analyses of the distribution of particular taxa, 

patterns of endemism, location of persistent oceanographic conditions that limit 

distributions, locations of particular physiographic features, and multivariate analyses of 

selected groups of organisms. Different outcomes have been reached using different 

approaches. Regardless of conflicts arising from disparate approaches and taxonomic

groups, a single set of biogeographic boundaries is necessary for conservation 

assessments, gap analyses, and for linking the efforts of different groups focused on 

meeting conservation goals. Here we propose a set of boundaries for the continental 

shelf of northeastern North America, from the Scotian Shelf off Nova Scotia to Cape 

Hatteras (Figure 1), based on a review and synthesis (a meta-analysis) of the scientific

literature. Use of a single set of boundaries will aid regional analyses focused on the 

conservation value of a wide variety of marine protected areas in this area, including

Stellwagen Bank National Marine Sanctuary (e.g., Recchia 2001). 

REGIONAL CONTEXT 

The Northwest Atlantic Marine Region (Dunbar 1972) extends from Cape

Hatteras along the eastern coast of the United States, northward to Lancaster Sound at the 

north end of Baffin Island, and then westward to the Bering Strait in Alaska. Dunbar 

(1988) proposed three principal second order subdivisions based principally on the 

definition of water masses that included temperature, salinity, origin of water masses,

current and tidal patterns, sea-ice cover, vertical stability of the water column, and 

biological indicators (i.e., species distributions). Zoned north to south, these included the

Polar, Subpolar, and Eastern Temperate provinces. Mondor et al. (1995) further 

subdivided these provinces into ten third order marine biogeographic zones based on the 

identification of marginal seas. These included four Polar subdivisions (Viscount 

Melville Sound, Lancaster Sound, Hudson Strait, and Hudson James Bay), three Subpolar 

subdivisions (North Slope/Beaufort Sea, Labrador Shelf, and Gulf of St. Lawrence), and 

three Eastern Temperate subdivisions (Grand Banks/Scotian Shelf, Acadian, and 

Virginian). We focus here on the Eastern Temperate subdivisions (Figure 2). 

1 
Northeast Channel

Cape Hatteras

Georges Bank

Newfoundland

Grand Banks

Scotian Shelf

Delaware Bay

Hudson Canyon

Great South Channel

Gulf of Maine

Atlantic Ocean

8 0 8 Kilometers

N

W E

S

Inset

Stellwagen Bank

National Marine Sanctuary

Cape Cod

Figure 1. The Northeast Continental Shelf study area. Location names are referred to in 

text. Note the location of Stellwagen Bank National Marine Sanctuary in the western 

Gulf of Maine.

Ba yo fF un d y

900 0 900 Kilometers

N

W E

S

Northeast Temperate Province

Grand Banks/Scotian Shelf

Acadian

Virginian

Carolinian

Warm Temperate Province

Figure 2. Marine provinces and subprovinces of the Northeast Continental Shelf .

2 
Eastern Temperate Subdivisions 

Prior to 1970, three general biogeographic schemes had evolved to characterize 

the northwest Atlantic south to Cape Hatteras (Hazel 1970; based on a review of 17 

papers from 1838 to 1966). Many studies used patterns of mean annual ocean surface

temperature to define the boundaries of biogeographic regions or faunal provinces (e.g., 

Coomans 1962). However, information on geographic patterns in the assemblages of 

organisms was based primarily on inshore faunas. Some authors (including Mondor 

1995) considered the Eastern Temperate (also known as the Boreal or Cold Temperate) 

Province to include the continental shelf from Newfoundland to Cape Hatteras while 

others described a boundary at Cape Cod between the Eastern Temperate and the Warm

Temperate (also known as the Trans-Atlantic) Province to the south. Some classification 

schemes divide the Warm Temperate Province into two subprovinces (i.e., the Virginian, 

from Cape Cod to Cape Hatteras, and the Carolinian, from Cape Hatteras to Cape 

Canaveral). In some cases, the Virginian Subprovince was classified as a transition 

zone, lacking a unique fauna of its own (e.g., Coomans 1962). 

Later studies tended to further subdivide these large regions. Based on his 

definition of water masses, Dunbar (1972) found the Gulf of Maine and Bay of Fundy to

represent a distinct region, what he called the Acadian subdivision of the Eastern 

Temperate Province, with a northern boundary at the Scotian Shelf and a southern 

boundary at Cape Cod. He also described a strong boundary between the Scotian Shelf 

and Georges Bank defined by the Northeast Channel, which reaches depths over 300 m. 

The Virginian subdivision of this province continued south from there. Ingham et al. 

(1982) identified the Gulf of Maine, Georges Bank, Southern New England, and southern 

Mid-Atlantic Bight as separate regions based on distinct bathymetry and circulation 

(Figure 3). Whereas the Gulf of Maine was characterized by a cyclonic gyre and a 

seasonally stratified three layer water mass system over the deep basins, Georges Bank 

was dominated by mixed water with an anticyclonic gyre over the shallower bottom. 

Sherman et al. (1996) compared and contrasted productivity, zooplankton, and 

fish species composition for Georges Bank, Gulf of Maine, Southern New England, and 

the southern Mid-Atlantic Bight, according to the regions described by Ingham et al. 

(1982). All regions were found to differ in patterns of primary productivity, experiencing 

peaks and declines at different times of the year. Dominant zooplankton species changed 

during the year in each region and the dominant species differed. These authors also

described a boundary for fishes at Cape Cod. They noted that most fish species occurring 

between Cape Cod and Cape Hatteras are migrants. About 15% are boreal with principal 

abundances north of Cape Cod; 75% range north of Cape Hatteras only in summer. Most 

inshore-offshore migration also occurs between Cape Cod and Cape Hatteras as most 

species in this region have temperature tolerances that are exceeded by the normal

inshore seasonal temperature cycle. Resident species move offshore and south as inshore 

areas become too cold in winter. The divisions described by Ingham et al. (1982) and 

Sherman et al. (1996) were further supported by Longhurst (1998), based on his analysis 

of the distribution of pelagic primary productivity. 

3 
600 0 600 Kilometers

N

W E

S

50

100

200

Major Currents

Depth (m)

Figure 3. Bathymetry and major surface currents on the Northeast Continental Shelf. 

Theroux and Wigley (1998) compared assemblages of benthic macroinvertebrates in the Gulf of Maine, Georges Bank, Southern New England, and the 

Scotian Shelf, and two subregions below 150 m on the continental slope. Average 

density and biomass of these organisms were substantially higher on Georges Bank and 

in Southern New England than the Gulf of Maine and Scotian Shelf. Theroux and 

Wigley related these differences to variation in mean annual temperature among regions 

(8.6°C for Georges Bank, 5.7°C for the Gulf of Maine, and 4.6°C for the Scotian Shelf), 

and to annual variations in temperature within regions, these being greatest on Georges

Bank and in Southern New England, and less in the Gulf of Maine) and on the Scotian 

Shelf. Variation in temperature is especially important, as density and biomass are 

highest in areas with high annual ranges in temperature, and lowest in areas with low 

annual ranges, although this is probably influenced also by other chemical and physical 

properties of water masses. Theroux and Wigley observed large differences among 

regions in the composition and abundance of major groups of organisms such as 

decapods, holothurians, and bivalves. The Gulf of Maine was distinguished from 

Georges Bank by the presence of small groups of Arctic and Subarctic species that do not 

appear on Georges Bank, and by an absence of many of the tropical and subtropical 

species that do occur on Georges Bank and in Southern New England. 

4 
In agreement with Dunbar (1972), Theroux and Wigley (1998) described a strong 

boundary between Georges Bank and the Scotian Shelf among benthic macroinvertebrates of the continental shelf. They found that even for species that maintain 

breeding populations in other boreal and temperate transition zones, Georges Bank 

represents a distinct entity, with populations differing and separated from those on the 

Scotian Shelf by the deep Northeast Channel, what they referred to as “a formidable

barrier to most benthic and demersal animals”. 

Data on the abundance and distribution of demersal fishes have been collected 

annually in fishery independent trawl surveys by the National Marine Fisheries Service 

since 1963 and by the Canada Department of Fisheries and Oceans since 1970. To 

reduce the chances of biased population estimates, the surveys of both nations divide the 

continental shelf into strata for random sampling, with strata defined by depth and 

temperature (Grosslein 1969, Clark and Brown 1977). Depth strata include four zones: 

27-55 m, 56-110 m, 111-183 m, and > 183 m. Divisions between two strata are made 

down the middle of the Great South Channel. 

Using nine years of trawl survey data (1963-1974), Colvocoresses and Musick 

(1984) demonstrated consistent patterns of composition and distribution among demersal 

fishes with the use of cluster analysis. These included four relatively constant and well 

defined areas of faunal homogeneity in the spring and five more general areas in the fall.

Spring assemblages included: 1) a northern inner shelf group from shore to 68-80 m from

Cape Cod to Delaware Bay; 2) a mid shelf group from Cape Cod to Hudson Canyon in 

deeper waters from 60-80 m to 150 m; 3) a southern mid shelf group from Delaware Bay 

to Cape Hatteras at depths from 60 to 150 m; and 4) an outer shelf group at depths 

exceeding150 m. Their analysis therefore agrees with Theroux and Wigley’s (1998) 

finding of a boundary at 150 m. Fall assemblages occupied similar latitudinal ranges, but

tended to occur in the shallower depths. In particular, the northern mid-shelf group 

occurred at depths between 60 and 90 m, the southern inner and mid shelf group occurred 

only to 60 m, and the outer shelf group occurred from 60-90 m and 150 m. 

Georges Bank and Southern New England 

Work by numerous authors corroborate Cape Cod as a barrier to many species, 

both warm-water and cold-water forms, including ectoprocta, bryozoa (Schopf 1968) 

opistobranch mollusks (Hazel 1970), gammaridean amphipods (Watling 1979), sea stars

(Franz et al. 1981), fishes (Mahon and Sandeman 1985), and benthic macro-invertebrates 

(Wigley and Burns 1971, Williams and Wigley 1977, Theroux and Wigley 1983, 

Theroux and Grosslein 1987, Theroux and Wigley 1998). However, there exists some

ambiguity as to just where the break occurs on the shelf, depending on which biological 

characteristics (e.g., faunal composition, patterns of endemism, and population structure) 

are examined, and whether studies were conducted inshore or offshore. Theroux and 

Grosslein (1987) studied benthic macro-invertebrates in the western North Atlantic, south 

of the Scotia Shelf. They noted that zoogeographers have tended to focus on coastal 

features like Cape Cod, rather than offshore barriers, as ecological boundaries because 

inshore faunas have been studied more extensively. In their analysis, they found that the

5 
large majority of species off Nova Scotia and in the Gulf of Maine consisted of boreal 

forms, whereas Georges Bank had a significant component of temperate transitional or 

Virginian species because of its higher seasonal maximum water temperatures (which

preclude reproduction and/or growth of many subarctic or boreal species). 

Based on these results, Theroux and Grosslein (1987) concluded that much of 

Georges Bank belongs to the Warm Temperate Province, noting “A critical point here is 

that Cape Cod forms the inshore part of this faunal boundary while Georges Bank forms

the offshore part”. They described the American Atlantic Boreal Region (i.e., the Eastern 

Temperate Province) as delimited by 5° and 10° C isotherms (annual mean surface 

temperature). The 10° isotherm cuts across the north-eastern part of Georges Bank. 

Under this scheme, Georges Bank forms an unbroken extension of Southern New 

England with no sharp change in depth or water temperature before the Northeast 

Channel where the steepest gradients in these features occur. 

Briggs (1974) on the other hand, developed a classification system in which 

provinces on the shelf were identified primarily on the basis of endemism. By his

criteria, all of Georges Bank was considered to be part of the Eastern Temperate

Province. This classic work, which modified the earlier classification of Eckman (1953), 

remains the principal authority of marine biogeography the world over. Ingham’s (1982) 

analysis of oceanographic characteristics tends to support Briggs’ conclusions regarding 

Georges Bank, in that he considered this region and the Gulf of Maine to form a coupled 

ecosystem with prominent characteristics distinguishing it from Southern New England. 

Some demersal fish species such as yellowtail flounder (Cadrin 2000) and winter 

flounder (Nitschke et al. 2000) are known to have distinct Southern New England and 

Georges Bank subpopulations. Differing life history parameters and little mixing 

between subpopulations suggests the presence of a strong physical barrier between these 

regions. Using multivariate analysis, Brown et al. (1996) also suggest a break between 

Georges Bank and Southern New England for some species of demersal fishes. They 

analyzed fish assemblages using data from the research trawl survey for the region

between Cape Chidley in northern Canada and Cape Hatteras. Methods included visual 

inspection of distribution maps, Principal Components Analysis, and Cluster Analysis. 

Visual inspection suggested four bank and slope species assemblages occurring at depths 

less than 200 m. These included a northern group extending from the Scotian Shelf to 

Cape Chidley, a south-temperate group from the mid-Atlantic Bight to the Grand Banks,

a southern group from the southern Gulf of Saint Lawrence to Cape Hatteras, and a northtemperate group from Georges Bank (inclusive) to Cape Chidley. The latter group 

exhibited a range limit in the area of the Great South Channel. Principal Components 

Analysis suggested a sole biogeographic boundary in the Grand Banks area, but Cluster

Analysis suggested a break at Cape Cod, with five (of 17) cluster groups occurring 

exclusively south of this region, the others mostly to the north. 

Although Theroux and Wigley (1998) analyzed Georges Bank and Southern New 

England separately, their results suggested a northern boundary for many benthic macroinvertebrate species that extends east across the northern end of the Great South Channel

6 
at depths of 50-100 m and continues along the northern margin of Georges Bank and then 

southeasterly along the western boundary of the Northeast Channel. This boundary 

would separate Georges Bank and Southern New England from the Gulf of Maine but not 

from each other. However, it differs from that described earlier by Theroux and 

Grosslein (1987) in that it does not bisect Georges Bank. 

Proposed Planning Boundaries 

It is often the case that different methods of classification produce different

results. When similar methods are used, different outcomes can arise depending on the 

choice of taxa. However, even for similar methods and taxa, results can vary depending 

on how data are grouped or the spatial extent of the analyses (e.g., Colvocoresses and 

Musick 1983, Brown et al. 1996). Despite the potential for disagreement based on the 

use of different methods and data sets, there appears to be a reasonably strong consensus 

for the existence of five distinct biogeographic regions on the continental shelf of the 

eastern United States and Nova Scotia, including the Scotian Shelf, Gulf of Maine, 

Georges Bank, Southern New England, and southern Mid-Atlantic Bight. Each is 

characterized by a unique combination of oceanographic conditions, physiographic 

features, fish species assemblages, and a wide variety of invertebrate taxa. While most 

studies recognize these five regions as distinct, they differ somewhat in how they group 

them at a broader scale. The boundary at Cape Cod appears to be so strong that some

authorities consider it to be a break between two major provinces, the Eastern Temperate 

and Warm Temperate. Others consider it to be a boundary between subprovinces of the 

Eastern Temperate Province. The distinction is not terribly important from a regional 

conservation perspective because smaller, ecologically distinctive regions within these 

larger areas are clearly apparent. 

The principal area of dispute is Georges Bank. Theroux and his colleagues (e.g., 

Theroux and Wigley 1983, 1998; Theroux and Grosslein 1987) suggest that Georges 

Bank faunas are largely an extension of Southern New England’s, based on mean

maximum sea surface temperatures and the distribution of boreal and southern forms of 

benthic macro-invertebrates. However, other comparisons based on primary and 

secondary productivity, fish species assemblages and population structure, bathymetry 

and circulation, and patterns of endemism (e.g., Ingham et al. 1982, Sherman et al. 1996, 

Longhurst 1998, Briggs 1974, Brown et al. 1996, Colvocoresses and Musick 1984) 

suggest that the two regions are distinct. 

Recognizing finer order divisions would be the most conservative approach for planning 

a system of representative marine protected areas. Capturing representative endemism is 

particularly important for the conservation of biodiversity. The designation of protected 

areas on Georges Bank as well as Southern New England would help ensure that the 

greatest number of species unique to those areas were protected. For this reason, and 

because a number of biogeographic assessments support doing so, we recognize Georges 

Bank as a unique biogegraphic region for planning purposes. Similarly, although some

classifications consider the entire Virginian subprovince a transition zone, we consider 

7 
Southern New England and the southern Mid-Atlantic Bight to be distinct, based on 

evidence provided by Ingham et al. (1982) and Sherman et al. 1996. 

Scotian Shelf

Gulf of Maine

Southern New England

Georges Bank

Southern Mid-Atlantic Bight Atlantic Ocean

600 0 600 Kilometers

N

W E

S

Figure 4. Biogeographic regions for conservation planning on the Northeast Continental 

Shelf 

These five regions correspond in spatial scale with fourth-order subdivisions 

defined by Dunbar (1972). While many individual investigations support the recognition

of distinct bioregions at this scale, relatively few make suggestions about where exactly

to draw boundary lines. This is probably due to the fact that boundaries are rarely sharp 

divisions and can shift somewhat between seasons and over longer time scales. For 

example, the latitudinal position of the point where the Gulf Stream breaks from the 

North American coastline in the vicinity of Cape Hatteras ranges from 30-40 km during 

the year (Hogg and Johns 1995). Nonetheless, it is necessary to draw lines for mapping 

and planning purposes. Based on the information available in this review, we propose the 

following set of boundaries (Figure 4). Precise placement was guided by divisions 

between sampling strata for demersal fishes where other information was not available. 

1. The Scotian Shelf extends from southern Newfoundland to the southern tip of 

Nova Scotia. Following results obtained by Theroux and Wigley (1998) for 

benthic macroinvertebrate assemblages, and lacking any additional information, 

the boundary is set at the 100-meter isobath along the northern edge of the

Northeast Channel, which separates it from the Gulf of Maine. The outer 

boundary of the Scotian shelf follows the 150 m isobath that delineates the shelf 

8 
break per results obtained for benthic macroinvertebrates by Theroux and Wigley 

(1998) and demersal fish species assemblages by Colvocoresses and Musick 

(1984). 

2. The Gulf of Maine, including the Bay of Fundy and the Northeast channel, is 

bound by the Scotian Shelf and Georges Bank at depths of 100 m, following the 

distribution of benthic macroinvertebrate assemblages examined by Theroux and 

Wigley (1998). 

3. Georges Bank is bound in the north by the Northeast Channel, a physical feature 

that separates water masses of the Scotian Shelf and Gulf of Maine (Dunbar 1972) 

and benthic macroinvertebrate assemblages (Theroux and Wigley 1998). The 

northern boundary extends from the Northeast Channel to the Great South 

Channel at depths of 100 m per the distribution of benthic macroinvertebrate 

assemblages (Theroux and Wigley 1998). The southern boundary is defined by 

the 150 m isobath delineating the shelf break following results obtained for 

benthic macroinvertebrates (Theroux and Wigley 1998) and demersal fish species 

assemblages by (Colvocoresses and Musick 1984). 

4. Southern New England extends from the Great South Channel in the north to 

Hudson Canyon in the south and is distinguished by differences in primary and 

secondary productivity, fish species assemblages and population structure, 

bathymetry and circulation, and endemism (e.g., Ingham et al. 1982, Sherman et 

al. 1996, Longhurst 1998, Briggs 1974, Brown et al. 1996, Colvocoresses and 

Musick 1984). 

5. The southern Mid-Atlantic Bight extends from Hudson Canyon in the north, 

following results obtained for demersal fish faunal assemblages by Colvocoresses 

and Musick (1984), to Cape Hatteras in the south. Cape Hatteras is a well known 

biogeographic boundary created by abrupt latitudinal differences in water 

temperature where the south flowing Labrador Current meets the northeast 

movement of the Gulf Stream (Cerame-Vivas and Gray, 1966) 

The ecological and oceanographic distinctiveness of these five regions suggest 

that any network of marine protected areas aimed at conserving biological diversity on 

the northeastern continental shelf include at least one site from each region. Within 

regions, the location and number of sites should be chosen with the aim of representing 

all habitat types. Often, from a purely biological perspective, there exist numerous 

scenarios involving tradeoffs between size and number of sites that can accomplish

similar goals of representation (e.g., Cook and Auster 2005). Representation may be 

redundant where species cross boundaries, but such redundancy can help ensure the 

regional continuation of species and stability of populations impacted by local 

catastrophes. 

Numerous marine protected areas have been established on the eastern continental 

shelf of North America, both in the United States and Canada, providing various types 

9 
and levels of protection to biological organisms. These include year round and seasonal 

fishery closures, which largely protect benthic habitats from disturbance by mobile 

trawling gear, mesh size control areas for protection of juvenile fish, critical habitat 

protection for marine mammals, and others. National Marine Sanctuaries provide 

protection from a wide range of extractive activities, but some currently permit most 

forms of fishing, including the use of fishing gears that alter seafloor habitats. 

Stellwagen Bank National Marine Sanctuary in the western Gulf of Maine is 

currently the only national marine sanctuary within the Eastern Temperate Province of 

the United States. The set of boundaries we propose can be useful to sanctuary 

management in that they define the species pool that should be represented within the 

region. With knowledge of the location and types of protection afforded by the sanctuary 

and other protected areas in the Gulf of Maine, Gap Analysis could be used to identify 

which species and communities (and associated habitats) are in greater need of

representation or protection on a bioregional basis. This information could be used by 

sanctuary management to determine how well protection within the sanctuary meets 

larger regional goals of representation and enhance the level of protection afforded those 

species and communities in need, where the opportunity exists. Such information would 

also be useful for greater coordination among agencies in regional management efforts. 

Finally, fourth order subdivisions of marine biogeographic realms, including 

those proposed in this paper, represent the level at which regional marine planning is 

currently being developed by Parks Canada for Canada’s national system of marine 

protected areas, and by UNESCO’s Man and the Biosphere Program for the United States 

(Agardy 1988, McCormick-Ray et al. 1988). These two national efforts make up the 

northwest Atlantic portion of the IUCN’s Global Representative System of Marine 

Protected Areas program (Kelleher et al. 1995). Using a common set of biogeographic 

boundaries for ongoing conservation analysis and planning efforts will ensure that results 

of various efforts can be compared and contrasted with a high level of ecological 

consistency. 

ACKNOWLEDGEMENTS 

This work was supported by grants from the Conservation Law Foundation, 

Oceana, NOAA’s Undersea Research Program, Stellwagen Bank National Marine 

Sanctuary and the Census of Marine Life Gulf of Maine Program. We thank three 

anonymous referees and Kathy Broughton for comments that improved the quality of the 

manuscript. The views expressed herein are those of the authors and do not necessarily 

reflect the views of the funding agencies. 

10 
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Auster, P.J. and N.L. Shackell, 2000. Marine protected areas for the temperate and boreal 

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biodiversity. Northeastern Naturalist. 7:419-434. 

Briggs, J.C. 1974. Marine Zoogeography. New York, NYT. McGraw-Hill Book Co. 475 pp. 

Brown, S.K., R. Mahon, K.C.T. Zwanenburg, K.R. Buja, L.W. Claflin, R.N. O’Boyle, B. 

Atkinson, M. Sinclair, G. Howell, and M.E. Monaco. 1996. East Coast of North America 

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14 
ONMS CONSERVATION SERIES PUBLICATIONS 

To date, the following reports have been published in the Marine Sanctuaries Conservation Series. All

publications are available on the National Marine Sanctuary Program website

(http://www.sanctuaries.noaa.gov/). 

M/V Wellwood Coral Reef Restoration Monitoring Report, Monitoring Events 2004-2006, Floriday Keys 

National Marine Sanctuary, Monroe Country, Floriday (NMSP-07-02)

Survey report of NOAA Ship McArthur II cruises AR-04-04, AR-05-05 and AR-06-03: Habitat 

classification of side scan sonar imagery in support of deep-sea coral/sponge explorations at the Olympic 

Coast National Marine Sanctuary (NMSP-07-01) 

2002 - 03 Florida Keys National Marine Sanctuary Science Report: An Ecosystem Report Card After Five

Years of Marine Zoning (NMSP-06-12) 

Habitat Mapping Effort at the Olympic Coast National Marine Sanctuary - Current Status and Future Needs 

(NMSP-06-11) 

M/V CONNECTED Coral Reef Restoration Monitoring Report Monitoring Events 2004-2005 Florida Keys 

National Marine Sanctuary Monroe County, Florida (NMSP-06-010)

M/V JACQUELYN L Coral Reef Restoration Monitoring Report Monitoring Events 2004-2005 Florida

Keys National Marine Sanctuary Monroe County, Florida (NMSP-06-09)

M/V WAVE WALKER Coral Reef Restoration Baseline Monitoring Report – 2004 Florida Keys National 

Marine Sanctuary Monroe County, Florida (NMSP-06-08)

Olympic Coast National Marine Sanctuary Habitat Mapping: Survey report and classification of side scan 

sonar data from surveys HMPR-114-2004-02 and HMPR-116-2005-01 (NMSP-07-07)

A Pilot Study of Hogfish (Lachnolaimus maximus Walbaum 1792) Movement in the Conch Reef Research

Only Area (Northern Florida Keys) (NMSP-06-06)

Comments on Hydrographic and Topographic LIDAR Acquisition and Merging with Multibeam Sounding

Data Acquired in the Olympic Coast National Marine Sanctuary (ONMS-06-05)

Conservation Science in NOAA's National Marine Sanctuaries: Description and Recent Accomplishments 

(ONMS-06-04)

Normalization and characterization of multibeam backscatter: Koitlah Point to Point of the Arches, 

Olympic Coast National Marine Sanctuary - Survey HMPR-115-2004-03 (ONMS-06-03)

Developing Alternatives for Optimal Representation of Seafloor Habitats and Associated Communities in

Stellwagen Bank National Marine Sanctuary (ONMS-06-02) 

Benthic Habitat Mapping in the Olympic Coast National Marine Sanctuary (ONMS-06-01) 

Channel Islands Deep Water Monitoring Plan Development Workshop Report (ONMS-05-05) 

Movement of yellowtail snapper (Ocyurus chrysurus Block 1790) and black grouper (Mycteroperca 

bonaci Poey 1860) in the northern Florida Keys National Marine Sanctuary as determined by acoustic

telemetry (MSD-05-4) 

15 
The Impacts of Coastal Protection Structures in California's Monterey Bay National Marine Sanctuary

(MSD-05-3) 

An annotated bibliography of diet studies of fish of the southeast United States and Gray's Reef 

National Marine Sanctuary (MSD-05-2) 

Noise Levels and Sources in the Stellwagen Bank National Marine Sanctuary and the St. Lawrence 

River Estuary (MSD-05-1) 

Biogeographic Analysis of the Tortugas Ecological Reserve (MSD-04-1) 

A Review of the Ecological Effectiveness of Subtidal Marine Reserves in Central California (MSD-04-

2, MSD-04-3) 

Pre-Construction Coral Survey of the M/V Wellwood Grounding Site (MSD-03-1) 

Olympic Coast National Marine Sanctuary: Proceedings of the 1998 Research Workshop, Seattle, 

Washington (MSD-01-04) 

Workshop on Marine Mammal Research & Monitoring in the National Marine Sanctuaries (MSD-01-

03) 

A Review of Marine Zones in the Monterey Bay National Marine Sanctuary (MSD-01-2) 

Distribution and Sighting Frequency of Reef Fishes in the Florida Keys National Marine Sanctuary

(MSD-01-1) 

Flower Garden Banks National Marine Sanctuary: A Rapid Assessment of Coral, Fish, and Algae 

Using the AGRRA Protocol (MSD-00-3) 

The Economic Contribution of Whalewatching to Regional Economies: Perspectives From Two 

National Marine Sanctuaries (MSD-00-2) 

Olympic Coast National Marine Sanctuary Area to be Avoided Education and Monitoring Program

(MSD-00-1)

Multi-species and Multi-interest Management: an Ecosystem Approach to Market Squid (Loligo

opalescens) Harvest in California (MSD-99-1)

16