Summaries of the findings of the 2020 Condition Report

The summaries below suggest that water quality in the sanctuary is fairly good, but habitat, living resources, and maritime heritage resources continue to be impacted in various ways by human activities, such as shipping traffic and commercial and recreational fishing. Ecosystem services in the sanctuary are generally improving, and in either good or fair condition.


Human Activities

A whale watching boat
Many whale watching vessels travel to SBNMS to view whales. Photo: NOAA

Stellwagen Bank National Marine Sanctuary is located 25 miles east of the port of Boston. The proximity of the sanctuary to the metropolitan region and surrounding Cape Cod communities make it highly accessible, exposing the sanctuary and its resources to a large range of human activities and pressures. Due to its offshore location, human activities in SBNMS are associated with different pressures on resources than inshore or mainland activities. Understanding the driving forces behind these pressures can aid in predicting the direction and extent of future pressures. The majority of driving forces (factors that lead to pressures) are increasing; these forces include population, per capita income, and gross domestic product (GDP) of international trading partners. Demand for seafood, demand for recreation, and import/export of goods were also identified as specific, primary drivers of pressures on SBNMS resources. Additionally, gasoline prices have been stable and relatively low, making access to the sanctuary relatively affordable. The direction of these drivers indicates that pressures will continue to increase within the sanctuary.

Water Quality

a sunset over the ocean
The sun sets over the ocean in Stellwagen Bank National Marine Sanctuary. Photo: NOAA

Despite several potential stressors, sanctuary water quality is good/fair and does not appear to be adversely impacted by human activities. The largest effluent contributor in the region and the primary potential human source of nutrients is the Massachusetts Water Resources Authority (MWRA) outfall, which is located approximately 12 nautical miles from the western boundary of SBNMS. Ongoing monitoring suggests that the MWRA outfall is currently not adversely influencing monitored water quality parameters in SBNMS, and no evidence suggests that eutrophication is occurring. The Massachusetts Bay Disposal Site (MBDS) is directly adjacent to the sanctuary’s western boundary and receives dredged material deemed suitable for open water disposal. This site incorporates the areas of two historic disposal sites containing toxic materials, though deposited toxic materials show limited mobility, and assessments have not shown any associated contamination of SBNMS. Maintenance dredging and expansion of Boston Harbor will generate 12 million cubic yards of dredged material for disposal in MBDS, but this is not expected to impact sanctuary water quality. Limited data exist to thoroughly evaluate potential impacts to water quality from vessel discharge and sediment perturbation by mobile fishing gear.

Monitoring suggests that concentrations of bacteria and toxigenic phytoplankton species rarely reach or exceed levels of concern in SBNMS and likely pose low risk to human health. However, the presence of toxigenic phytoplankton species indicates the potential for harmful algal blooms (HABs). HAB dynamics in the Gulf of Maine may be related to climate change, but current data show no explicit association between HAB occurrence and increasing temperatures in SBNMS.

Climate change impacts in SBNMS are measurable, and the threat of climate change to ecological integrity is increasing. The Gulf of Maine is warming faster than 99% of the global ocean; increases in both surface and bottom temperatures in SBNMS reflect these trends. Recent work suggests changes in seasonal temperature dynamics, longer summer seasons, and changes to primary production in and around SBNMS. Climate change is causing shifts in phenology and distributions of plankton, fish, whales, and other organisms in the Gulf of Maine. Impacts of climate change on important prey (foundation) species like sand lance and the copepod Calanus finmarchicus are particularly concerning, as these changes have the potential to drive cascading ecosystem effects and impact abundance, distribution, and health of top predators. In addition, climate change is causing impacts on commercial and recreational fisheries, local businesses, and communities. More robust monitoring of climate change effects and ocean acidification conditions in SBNMS is necessary to understand trends, seasonal fluctuations, and the possible ramifications for water quality, shell-forming invertebrates, and the larger ecosystem.


top left: boulder with attached epifauna, top right:sponge community on sand-gravel ridge, bottom right: burrowing anemones in mud-draped gravel, bottom left: sponge attached to hydroid skeletons on mud-draped gravel.
Examples of biogenic habitats in SBNMS. Clockwise from top left: boulder with attached epifauna, sponge community on sand-gravel ridge, burrowing anemones in mud-draped gravel, sponge attached to hydroid skeletons on mud-draped gravel. Photos: P. Auster/University of Connecticut and Seafloor Habitat Recovery and Monitoring Project Science Team

The sanctuary’s diverse underwater landscape is a patchwork of habitats composed of both geologic and biogenic components. Benthic substrate types are generally correlated with seafloor communities and constitute important geologic habitat components. Data suggest measurable degradation of habitat quality over the past ten years, primarily due to direct impacts of bottom-contact gear used in commercial fishing, which occurs extensively throughout SBNMS. Mobile, bottom-tending fishing gear can alter or remove important structural characteristics and/or biological components of the seabed, which is a concern for maintaining habitat integrity. Lower levels of direct impact are evident in the Western Gulf of Maine Closure Area, and the closure led to recovery in some areas. Significant increases in scallop dredging may have impacted the northwest corner of Stellwagen Bank in 2017; this effort has been reduced, but is expected to continue. Overall fishing effort has declined by around 55% since 2009; however, it is unclear whether reductions in effort have resulted in improved sanctuary benthic habitat integrity. Fixed gear has less impact on the seabed, but poses an entanglement risk for protected species. Fishing effort reductions and gear modifications have been implemented to reduce bycatch of small marine mammals and seabirds and to attempt to reduce serious injury and mortality of large whales.

Localized disturbance of benthic habitats was observed after the installation of the sanctuary’s only submerged cable, the Hibernia Atlantic cable, in the year 2000. Post-installation monitoring showed that impacts to benthic communities were not significantly different than those caused by commercial fishing. Other potential localized seabed impacts, including anchoring of recreational fishing vessels, should be evaluated.

Legacy contaminants and metals in benthic habitats have been reported; however, they do not appear to remobilize beyond sites where they have been identified, and no population effects have been documented. Limited data suggest emerging contaminants are present within Massachusetts Bay at low concentrations, with uncertain biological ramifications, and may be shifting or increasing with the continued introduction of new chemicals. No data exist regarding microplastics in SBNMS, though surface water concentrations of microplastics in the Gulf of Maine are far lower than in the North Atlantic. Abundance of marine debris in SBNMS depends on natural forces and human drivers, which may increase with increasing population growth and coastal development. Additional work to characterize and quantify emerging contaminants and microplastics in SBNMS habitats is needed.

SBNMS is an urban sanctuary, and impacts to its acoustic environment are a concern. Designated shipping lanes such as the Boston Traffic Separation Scheme (TSS) cut through the sanctuary and are used by most commercial vessels transiting to the port of Boston. Commercial fishing vessels use the sanctuary year-round. The whale watching industry has expanded, and the numbers of recreational boaters and whale watchers are rising. Human-generated underwater noise from vessels, particularly from large commercial ships, can degrade habitat quality and interrupt behavior and communication of many marine species. Increasing noise levels and impacts of noise to some marine mammal and fish species have been documented in the sanctuary and are expected to continue. SBNMS has been at the forefront of raising awareness of the potential threat of noise to organisms and has pioneered the use of several advanced passive acoustic monitoring methods and technologies to further the study of ocean noise and its impacts.

Living Resources

Whales gulp feeding while seabirds fly around
Whales and seabirds feed in the sanctuary waters. Photo: NOAA

The large-scale circulation of the Gulf of Maine and influx from the Maine Coastal Current, along with tidal fluctuations, local wind forcing, and long-term climate dynamics, drive a strong seasonal cycle of stratification, nutrient availability, and primary production that forms the foundation of the SBNMS food web and ecosystem. SBNMS supports over 575 species of invertebrates, fish, seabirds, and marine mammals. Community structure and local stability in SBNMS are maintained by several foundational species that serve as prey or biogenic habitat, including calanoid copepods, Atlantic herring, sand lance, sponges, and anemones. The status and trends of these species are variable, but generally good to fair, though data are limited in some cases, and several species may be particularly vulnerable to climate change.

Calanus finmarchicus is a crucial, lipid-rich copepod and food source for several ecologically and economically important species in SBNMS, including larval cod and haddock, herring, sand lance, and the critically endangered North Atlantic right whale. Despite a general downward trend in abundance and shifts in distribution in the larger Gulf of Maine driven by climate change, C. finmarchicus has persisted regionally.

Sand lance is a key prey species for marine mammals, seabirds, and commercially important fish in SBNMS and the larger Gulf of Maine. Data suggest that the abundance and distribution of sand lance at local and/or regional scales influence the abundance and distribution of predators including humpback whales, great shearwaters, and Atlantic cod. Sand lance are dependent on shallow, coarse grain sand habitats to escape predation and lay their eggs. Their geographic restriction to sand habitat, as well as their winter dormancy and possible water temperature-induced spawning, raises concerns about their ability to adapt to accelerated climate change. Sand lance exhibit natural, dramatic fluctuations in spatial and temporal abundance, but what drives these cycles is unknown. Atlantic herring also exhibit patchy distributions and variable abundance within SBNMS. Herring and sand lance populations in the SBNMS region typically oscillate out of phase, suggesting either bottom-up forcing of such patterns, or an effect of direct species interactions (predation, competition, or overfishing) in determining abundance. Declines in recruitment, variability in abundance and distribution, patch characteristics that increase vulnerability to overfishing, and potential climate change impacts are concerns for ecologically and commercially important forage species.

Porifera (sponges) and Cnidaria (hydroids and anemones) serve important roles as benthic, structure-forming organisms in SBNMS, as they provide shelter for associated species and contribute to habitat complexity. These species are physically fragile and sensitive to direct disturbance. Changes in the abundance and distribution of these taxa over time correspond both to larger regional and local processes as well as human-caused disturbance, but the current status of these species is uncertain.

Status of Focal Species

A lobster shelters in a rocky reef. Photo: D. Costa/NOAA
A lobster shelters in a rocky reef. Photo: D. Costa/NOAA

Stellwagen Bank National Marine Sanctuary serves as important habitat for several species whose presence and health contribute to the economic, ecological, and conservation value of the sanctuary. The status of these eight focal indicator species is mixed. Select human activities have caused severe, widespread, and/or persistent impacts to some species. Impacts from commercial fishing and commercial and recreational vessel activity are primary concerns. However, ongoing efforts to monitor and mediate threats has led to some improvement in other species, resulting in a collective rating of fair for focal species.

The sanctuary and surrounding waters are primary foraging grounds for humpback whales and critically endangered North Atlantic right whales, and poor ratings for both species drove the overall fair rating for focal species. North Atlantic right whales are at risk for extinction, as their population has been in decline since 2010, and only 12 births have been documented since 2017. Despite positive population growth of Gulf of Maine humpback whale populations, frequent fisheries interactions and serious injury and mortality in most years warrants a poor rating for this species.

SBNMS is a hot spot for reports of entangled humpback whales, though the locations of entanglement origin are often unknown. Recent SBNMS research shows that humpback whales are tightly collocated with sand lance in southern SBNMS, where trap/pot fisheries operate. In addition, recreational tuna vessels often target areas where whales are present, which can have adverse impacts for whales. In response to the critical status of right whales, NOAA’s Atlantic Large Whale Take Reduction Team, which includes SBNMS, recommended modifications to their Large Whale Take Reduction Plan to further reduce the risk of serious injury and mortality from entanglement, including reductions in the use of vertical lines and changes to closure areas.

Ship strikes to right and humpback whales in SBNMS have likely decreased following a number of actions. These include 1) working with multiple partners to shift the Boston TSS away from primary feeding areas for large whales; 2) a NOAA Fisheries regulation to limit the speed of vessels larger than 65 ft at certain times; 3) the installation of a real-time passive acoustic monitoring system along the TSS following the construction of two deepwater liquefied natural gas ports; 4) the development of an app to alert mariners to the presence of right whales; and 5) the development of a corporate responsibility report card program to evaluate mariner compliance with speed restrictions. Recreational boat strikes remain a concern for humpback whales. Recreational boating in SBNMS is mostly seasonal, but is intensive during high season and could produce concerning levels of noise.

Noise levels in the ocean and in SBNMS have increased dramatically during the last 50 years. SBNMS research has focused on characterizing the sanctuary’s low-frequency “noise budget” associated with large commercial vessels by using automatic identification system (AIS) data to document the distribution and density of vessel traffic-associated noise and its potential to “mask” biologically-important acoustic signals. Work by SBNMS and colleagues shows that baleen whale species have lost over two thirds of their communication space, primarily due to ambient noise and AIS vessel activity in SBNMS. Data also show that vessel noise can significantly impact humpback whale communication and foraging behavior. Constant high levels of low-frequency sound in SBNMS also reduced communication space for commercially important Atlantic cod and haddock during winter spawning times. Efforts to mitigate noise impacts on marine species are ongoing.

Commercial fishing occurs extensively throughout SBNMS. While large whales experience high entanglement risk from trap/pot fisheries, smaller marine mammals and seabirds are at greater risk from gillnet fisheries. Grey seals are the most commonly bycaught marine mammal, while harbor porpoise and Atlantic white-sided dolphins are also at risk of bycatch in gillnets. Great shearwaters comprise the highest bycatch of any animal in the sanctuary and are the most frequently bycaught seabird in the Gulf of Maine. Gillnets account for the vast majority of mortalities in seabirds.

Atlantic white-sided dolphins and great shearwaters are the most commonly sighted toothed whale and seabird species in SBNMS, respectively, and recent work suggests that these species may prey on sand lance. Bluefin tuna on Stellwagen Bank frequently prey on sand lance as well as herring. Abundance of bluefin tuna has increased in the Gulf of Maine and the western Atlantic, resulting in a 2017 increase in the annual bluefin tuna quota. Atlantic cod distributions are also strongly influenced by sand lance in SBNMS.

Atlantic cod is a culturally, ecologically, and economically important species in the Gulf of Maine, and SBNMS and has historically been the focus of commercial and recreational cod fishing. Research indicates that the Atlantic cod population is at a historic low and has contracted to the western Gulf of Maine, including SBNMS. This shift in distribution is primarily driven by sand lance abundance. The hyper-aggregation of cod in a small area in SBNMS makes this species vulnerable to overexploitation. SBNMS and colleagues have documented spawning aggregations of cod in SBNMS using several acoustic technologies. The western Gulf of Maine, including SBNMS, is possibly the last area with consistent aggregations of cod in the Gulf of Maine stock. A combination of fishing pressure, species interactions, and environmental change contributes to continued population decline.

Lobster are iconic in the Gulf of Maine and SBNMS. Abundance is at an all-time high following increases in growth and reproduction aided by warming water temperatures. However, consistent declines in young-of-the-year lobster since 2012 in the Gulf of Maine and the poor status and recruitment of southern New England lobster suggest that prolonged temperatures above a certain threshold negatively impact lobster, and climate change may have an adverse impact on lobsters in SBNMS in the future.

Biodiversity in SBNMS has changed since the 2007 condition report; this change was primarily driven by variability in fishing and climate at both regional and local scales. Data show that fish species richness in SBNMS and the region has increased since 2006 and fish community composition has shifted over time. Seabird community data specific to SBNMS are limited, but regional data collected along Massachusetts coastlines suggest possible changes in relative abundance over time. There are diverse communities of seafloor invertebrates within SBNMS, including three species considered rare within the Gulf of Maine region. However, it is difficult to assess the status of seafloor communities from 2007–2018 due to the disruption of a long term monitoring station, which compromised the ability to assess change over time. Additional monitoring, particularly for seabirds and invertebrates, and at regional and local scales, is needed.

The number of non-indigenous species in SBNMS is likely low, though limited information on these species is available. High levels of vessel traffic in and around the sanctuary have the potential to introduce non-indigenous species through ballast water or fouling on hulls or other equipment (fishing nets, etc.). In addition, climate change may result in increased introductions of non-indigenous species due to altered species ranges influenced by warming waters and changes in ocean circulation. Didemnum vexillum, an invasive tunicate, was documented in the sanctuary in small, isolated areas dominated by hard bottom habitats, but this species is unlikely to be an issue in SBNMS because its preferred habitat (hard bottom) is not abundant.

Maritime Heritage Resources

A painting of Steamship Portland
The steamship Portland is one shipwreck found in the sanctuary. Image: Antonio Jacobsen courtesy of Maine Historical Society

Forty-seven historic shipwreck sites have been inventoried in the sanctuary, representing a long, rich maritime history. The condition of the sanctuary’s heritage resources varies due to natural deterioration and human impacts, and as non-renewable resources, their decline is irreversible. Commercial fishing activity continues to be the greatest source of disturbance to maritime heritage resource integrity. Incidental contact from fishing gear has impacted nearly every maritime heritage resource in SBNMS. The diminished condition of some heritage resources has reduced their historical, archaeological, scientific, or educational value.

Recreational diving in SBNMS has increased since 2007, and some evidence suggests that divers occasionally disturb wrecks through movement of artifacts or by anchoring on wrecks; degradation from recreational diving, however, does not appear to be widespread. More frequent monitoring and documentation of shipwreck sites is required to track site degradation over time and to broaden our knowledge of and connection to New England maritime history and our sense of place.

Ecosystem Services

A bottom trawler fishes on Stellwagen Bank
A bottom trawler fishes on Stellwagen Bank. Photo: NOAA

Seven ecosystem services were evaluated for this condition report: heritage, food supply, consumptive recreation, non-consumptive recreation, sense of place, science, and education.

Maritime heritage is the recognition of historical or heritage legacy. There are significant products telling the stories of historic shipwrecks in the sanctuary, all of which indicate there is significant economic value associated with maritime heritage in SBNMS. At the same time, resource indicators show some decline in integrity due to natural degradation and commercial fishing gear damage, but overall, damage is not severe.

The food supply ecosystem service is defined as the capacity to support market demands for nutrition-related commodities, namely fish, through various fisheries. Economic indicators have mixed results. From 2007 to 2016, the total value of landings (cumulative revenue across all years, in 2017$) from species caught in the sanctuary was in excess of $194 million. Trends in both landings values and pounds from 2007 to 2016 for sea scallops, lobster, and Atlantic mackerel were generally increasing. Additionally, some resource indicators suggest a decline in the natural stock, but it is important to note that this trend is not widespread or across all stocks (e.g., there may be emerging stocks as a result of changing species distributions within the region). More information is needed for both economic and non-economic indicators on costs-and-earnings to assess whether there are above normal returns on investments that result in more fishing effort, and non-economic indicators are needed that gauge the socio-demographic profiles of fishers.

Consumptive recreation includes recreational activities that result in the removal of or damage to natural and cultural resources. For SBNMS, this activity is primarily recreational fishing. While the number of charter boat and party boat anglers has declined over most of the time period of interest, private boat registrations have generally remained stable but increased recently. Local communities are also highly engaged in recreational fishing. Yet, the resource (recreational fishing stocks) condition is mixed. These factors suggest that there is significant and augmented economic value associated with consumptive recreational resources in SBNMS, but there are mixed results among the indicators, as well as information gaps. In addition, very little information is available for fishing on private household boats, and there is a lack of other ancillary socioeconomic data for recreational fishing.

Sanctuary visitors also participate in non-consumptive recreational activities that do not result in the removal of or damage to natural and heritage resources. The primary non-consumptive recreational activities conducted in SBNMS include whale watching and other wildlife observation, scuba diving, sailing, and motor boating. Economic indicators suggest there are significant economic contributions associated with non-consumptive recreation in SBNMS that are either stable or increasing. As of 2008, the majority of whale watching in the New England region occurred within SBNMS, amounting to spending of approximately $100 million (2017$). Resource indicators suggest that, with the exception of an increase in bird sightings, there has been a decline in the natural resources that support non-consumptive recreation in the sanctuary, however, the decline is not widespread across affected resources.

Sense of place is the aesthetic and spiritual attraction of a particular location, as well as the level of recognition and appreciation given to efforts to protect a place’s iconic elements. Several studies show that people put positive economic value on natural resources and are willing to pay to protect them. These valuation corollaries, trends in environmental attitudes, and growth in real per capita incomes suggest that economic indicators are positive and increasing. Though there has been a decline in some natural resources, like whales, it has not been widespread across all relevant resources, and other indicators, like water quality, have not been affected.

The ecosystem service of science is defined as the capacity to acquire and contribute information and knowledge. Research occuring in SBNMS, led by sanctuary staff and partners, is expanding and has gained international recognition. There is, however, a noteworthy information gap of indicators to estimate the economic value and contributions of science in SBNMS. Non-economic indicators, on the other hand (the number of research hours and days on the R/V Auk, citizen science hours, and the number of volunteers) have been increasing or stable through time. Further, SBNMS is at the forefront of anthropogenic noise and humpback and fin whale research. As a result of the research being conducted in SBNMS by site staff and partners, the body of scientific work in SBNMS has contributed significantly to the state of knowledge of resource conditions.

Many people of all ages study ecosystems and their importance through both formal and informal education. When people derive benefits from educational experiences or products resulting from the sanctuary, this is considered an ecosystem service. Although there have been no economic valuation studies done for education programs in SBNMS, studies of other environmental education programs indicate a positive value for hands-on education experiences. Further, several non-economic indicators have been increasing. Specifically, the number of volunteers and volunteer hours has increased since 2011, and related social media presence, as measured by the number of SBNMS followers on Facebook and Twitter, has increased since 2015, indicating that education work in SBNMS has contributed to public knowledge about SBNMS resources.