National Marine Sanctuary of American Samoa (NMSAS) is a place of extraordinary beauty and is the most remote of the United States’ national marine sanctuaries. It is located off the shores of American Samoa, the southernmost territory in the U.S. and one of only two U.S. territories that are south of the equator. NMSAS is composed of six separate protected areas that cover 13,581 square miles of ocean waters, making it the largest national marine sanctuary in the U.S. It is home to a great diversity of marine life, including corals and other invertebrates, fish, turtles, marine plants, and marine mammals. It is the only true tropical reef within the National Marine Sanctuary System and is home to some of the oldest and largest Porites coral colonies in the world. Its vast open ocean areas encompass two atolls, deep-water corals, seamounts, hydrothermal vents, and an undersea volcano.
The small islands that compose American Samoa are not just unique because of their stunning natural environment, but also because cultural traditions and values thrive in these islands where one people, one language, and one common set of cultural practices, commonly referred to as Fa’a Samoa, or traditional Samoan way of life, continue to be perpetuated. NMSAS is located in the cradle of Polynesia’s oldest culture, Samoa, which dates back 3,000 years. Despite Western influences, Samoan heritage is perpetuated in all facets of life, through family, village, activity, and place, by Samoan people with a strong hold to ongoing cultural traditions. In addition to other practices, use of Samoan as the primary language spoken in American Samoa is an important attribute that makes NMSAS strikingly unique in comparison to other sites across the National Marine Sanctuary System.
The purpose of this condition report is to use the best available information to assess the status and trends of various components of NMSAS, including its natural and maritime heritage resources. The report is structured around a management-logic model called the Drivers-Pressure-State-Ecosystem Services-Response, or DPSER, model. This model enables NMSAS to comprehensively document the many factors that affect management responses, including the influence of societal drivers on pressures, the effects of those pressures on the condition of resources, and the effects of changing conditions on the services they provide to society.
The first condition report, which assessed resources in Fagatele Bay National Marine Sanctuary, was published in 2007. This condition report marks an updated and comprehensive description of the expanded sanctuary—National Marine Sanctuary of American Samoa. It includes status and trends of resources, covering the broad categories of water quality, habitat, living resources, and maritime heritage resources. This report also includes the status and trends of ecosystem services—the ways humans derive benefits from different ecosystem attributes that they care about for their lives and livelihoods. Ecosystem services evaluated in this report include non-consumptive recreation, consumptive recreation, science, education, heritage, sense of place, commercial harvest, subsistence harvest, and coastal protection. The report documents the condition of sanctuary resources and ecosystem services from 2008–2020, unless otherwise noted. Throughout the report’s development, sanctuary staff worked with numerous partners to identify and compile information and make assessments on resource and ecosystem service status and trends.
The report also identifies gaps in current monitoring efforts, as well as factors that may require monitoring and potential remediation through management actions in the coming years. The ratings and conclusions in this report generally represent the shared perspective of sanctuary managers and subject matter experts on prior changes in resource status, and will inform future management, primarily through the management plan review process, to address significant challenges stemming from pressures on resources.
Drivers and Pressures
The pressures on NMSAS resources associated with human activities are diverse, operate at varying scales, and differ significantly in their impact. Changes in ocean conditions resulting from accelerated climate change, pollution, marine debris, vessel groundings, visitor use, scientific and management activities, and nuisance species outbreaks operate throughout the sanctuary and likely cause the greatest impacts. Fishing also occurs in the sanctuary, and while it may be viewed as a pressure, it is also an ecosystem service, contributing to the wellbeing, livelihoods, and food security of many of the communities in American Samoa.
The societal drivers behind these pressures are not something NMSAS can manage, as they are primarily influenced by global, regional, and local demand for goods and services. Still, it is helpful to understand the connections between drivers and pressures in order to prioritize management actions. Drivers include economic factors, such as income and spending; demographics, like population levels and development; and societal values, such as levels of conservation awareness, political leanings, or changing opinions about the acceptability of specific behaviors (e.g., littering). All drivers influence pressures on resources by changing human preferences and, consequently, the levels of activities needed to meet the demand for resources and services.
State of the Resources
The Samoan archipelago lies along the northern edge of the South Pacific Gyre, a series of connected ocean currents with a counterclockwise flow that spans the Pacific Basin. Surface waters in the region are low in nutrients and high in oxygen (oligotrophic) except for nearshore areas around populated islands affected by terrestrial runoff. Deep waters are nutrient rich, as American Samoa lies along the Circumpolar Deep Water flow, part of the global ocean conveyor belt that circulates oxygen- and nutrient-rich water in deep-sea areas.
In general, water quality in the sanctuary is good. The limited data available indicate that nutrient and contaminant levels are below recommended thresholds. However, the close proximity of the Futiga landfill to Fagatele Bay and Fagalua/Fogama’a, continued development, and the presence of a shallow sewage outfall in Aunu’u may require further monitoring.
Of significant concern, however, are the changing conditions associated with climate change. Pacific Islands are among the most vulnerable areas in the world to the predicted effects of climate change. Changes in ocean conditions resulting from accelerated climate change, like increased ocean temperatures and rising sea levels, are already affecting marine ecosystems across NMSAS. Rising temperatures have led to significant coral bleaching events in 2015, 2017, and 2020, and a smaller event at Swains Island in 2016. During periods of high temperatures, corals eject their algal symbionts and appear white, or bleached. These events may result in widespread coral mortality. In addition, the prevalence of many coral diseases increases with rising ocean temperatures and thermal stress events. Even on a small scale, bleaching and disease can alter community structure, reduce reproductive output, and decrease coral cover. Global sea level rise has been locally exacerbated by rapid subsidence, leading to increased coastal erosion and shifts in intertidal ecosystems.
Many marine organisms are also threatened by ocean acidification, which results in a reduction of the pH of ocean water due to uptake of increased atmospheric carbon dioxide. Acidified waters compromise carbonate accretion and therefore directly affect the ability of calcifying organisms, such as corals, to secrete their calcareous skeletal structures. Lowered pH may also alter the behavior of larval fish and invertebrates, influence settlement success due to changes in suitable settlement substrate, and alter larval development or energy budgets. Fortunately, despite decreasing regional pH levels, aragonite saturation and calcification remain high in American Samoa; however, regional carbonate dynamics and acidification effects are not well understood. Climate change and ocean acidification are likely to have a significant influence on the status and trends of sanctuary resources in the future, and it is important that NMSAS work with partners to improve climate monitoring and research moving forward.
Due to its vast geographic extent, NMSAS includes a diverse array of habitats. Shallow-water habitats (e.g., rocky shore, reef flat, coral reef) and mesophotic coral ecosystems generally only occur 0.5 to 2 miles from shore along the small insular shelf and atoll slopes. Pelagic (open-ocean) waters constitute the primary habitat within the archipelago. The sanctuary also includes banks, deep ocean floor habitats, an undersea volcano, hydrothermal vents, and seamounts.
Despite some fluctuations over the reporting period, habitats in the sanctuary are in good/fair condition. Shallow nearshore habitats were exposed to disturbances such as cyclones, coral bleaching events, and crown-of-thorns starfish invasions. Fortunately, these habitats, particularly coral reefs, have demonstrated resilience to these events. Shallow nearshore habitats are also exposed to anthropogenic impacts. For example, a vessel grounding in Aunu’u had a severe impact on coral reef habitat, but effects were constrained to a small area. Iron enrichment from a 1993 vessel grounding at Rose Atoll persists, but continues to improve. Marine debris continues to be a chronic but minor problem across all habitats. Data for habitats in the mesophotic and pelagic zones are limited, but there are no indications of any substantial impacts. Recent deep-sea expeditions have not identified any recent impacts or immediate threats to these habitats, but data are extremely limited and no previous data are available for comparison.
Living resources within the sanctuary have not been fully documented, but are best characterized in shallow coral reef ecosystems. Coral reefs are diverse, complex systems, and many species are highly specialized, making it difficult to identify keystone species. In the sanctuary’s mesophotic and deep-sea ecosystems, too little is known about ecological interactions and individual species’ roles in the ecosystem. Therefore, groups of ecologically important species were evaluated for their combined contributions to the ecological integrity of their respective ecosystems. Keystone and foundation species groupings include zooxanthellate scleractinian corals, crustose coralline algae, reef sharks, large parrotfish, surgeonfish and unicornfish, mesophotic corals, and deep-sea corals and sponges.
Stony (scleractinian) corals are important foundation species for shallow coral reef ecosystems, providing structure and food for many other reef organisms. Over 150 species of coral have been documented in the sanctuary, but species-specific data are limited. Scleractinian corals in the sanctuary are robust and include healthy populations of both large, old corals and recruits. Although repeated bleaching has affected these communities, particularly at Swains Island, they remain resilient. Crustose coralline algae are an important component of the reef in American Samoa, cementing the reef substrate together, stabilizing rubble after disturbances, building algal ridges along high-energy reef margins, creating habitat for fish and invertebrates, and attracting coral larvae to settle on reefs. Crustose coralline algae cover in the sanctuary remains high and has even increased at many sites.
Sharks, parrotfish, surgeonfish, and unicornfish are all important components of coral reef ecosystems. Whitetip, gray reef, blacktip, and nurse sharks are the most common reef sharks encountered in American Samoa; however, surveys have recorded very low shark densities in American Samoa compared to some other islands in the South Pacific. Large parrotfish, through their diverse feeding strategies, play an important role in coral reef ecosystem dynamics by removing algae, opening up substrate for coral settlement, and keeping fast-growing coral species in check. Surgeonfish and unicornfish are also important, filling a number of functional roles as grazers, browsers, detritivores, and planktivores. Low abundances of large fish, particularly sharks, large parrotfish, and surgeonfish, in the sanctuary are of great concern. Sharks are at 4–8% of their potential biomass, bumphead parrotfish are now functionally extinct, abundances of other large parrotfish species remain low, and low biomass estimates may indicate unsustainable fishing pressure. The continued lack of large predators and large herbivores in shallow coral reef habitats is a major concern, as this may compromise ecosystem resilience. Approximately 110 species of scleractinian corals are found at mesophotic depths in American Samoa, and corals and sponges provide important habitat for echinoderms and other organisms in the deep-sea habitats. Although there are limited monitoring data for mesophotic coral ecosystems and deep-sea corals and sponges, available information suggests that these species are in good condition. However, limited data in these areas do suggest that recruitment is low for deep-sea coral species.
Other focal species in NMSAS include giant Porites corals, giant clams, humphead wrasse, sea turtles, and humpback whales. The abundance of harvested species, including giant clams, targeted food fish species, and humphead wrasse, is low and recovery is uncertain due to continued harvesting and life cycle characteristics. The decline in giant clams from 1996 to 2006 is particularly worrisome to resource managers, and there is some concern that ocean acidification and elevated seawater temperatures may be affecting these species. Data on sea turtles suggest that resident populations may be slowly recovering, but nesting activity is still limited. Humpback whale populations may also be increasing, but data are limited, and increasing ocean temperatures may shift the preferred habitat for this species away from American Samoa. More specific survey efforts for giant clams, humphead wrasse, and rare food fish species, as well as expanded survey efforts for sea turtles and humpback whales, are recommended.
Non-indigenous species have been observed in American Samoa, but have not exhibited invasive characteristics within sanctuary units. A tunicate and a green alga have recently exhibited invasive behavior, but are believed to be native species. No recent surveys have been conducted specifically to look for invasive species, and this is an important biosecurity gap that needs to be addressed.
Overall, biological diversity is high in NMSAS, but needs to be further explored, as additional species continue to be documented and new species have been recently discovered. Recent mesophotic and deep-sea expeditions have expanded the list of known species within the sanctuary, and further study is likely to expand this list further. The effect of disturbance events on species diversity has not been well documented in shallow coral reef habitats, and mesophotic, deep-sea, seabird, and marine mammal surveys have been limited.
Maritime Heritage Resources
Maritime heritage resources are those tangible and intangible properties (archaeological, cultural, historical resources) that capture our human connections to ocean areas. Current knowledge of the nature, location, and significance of maritime heritage resources within NMSAS is limited. The most relevant information for addressing the condition of maritime heritage resources in the sanctuary comes from an existing desk-based assessment of heritage resources for the entirety of American Samoa, which includes the sanctuary. Therefore, resources outside the immediate boundaries of NMSAS were considered in order to estimate possible conditions of resources within the sanctuary itself. In general, maritime heritage resources have not been subject to human impacts that might otherwise diminish their aesthetic, cultural, historical, archaeological, scientific, or educational value. However, they have been subject to natural deterioration, erosion, and high-energy shoreline events. Resources like submerged shipwrecks and aircraft, which likely exist within the sanctuary, are presumed to be slowly degrading, primarily due to these natural processes.
State of Ecosystem Services
Ecosystem services are the tangible and intangible benefits that humans receive from natural and cultural resources. Nine types are considered in this report: non-consumptive and consumptive recreation, science, education, heritage, sense of place, commercial and subsistence harvest, and coastal protection.
Non-consumptive recreation services within the sanctuary are those that do not result in the intentional removal of or damage to natural and heritage resources, like swimming, snorkeling, scuba diving, boating, beach recreation, and beach camping. There have been no studies specific to these non-consumptive recreational activities in NMSAS, therefore, territory-wide studies were assessed as a proxy. These proxy data show that swimming and beach recreation are relatively common activities in American Samoa. Although the number of cruise ship arrivals has increased, the number of overall tourist arrivals to American Samoa decreased from 2007–2015. Visitation to the nearby National Park of American Samoa has increased since 2008, with peak visitation occurring in 2017. Yet, despite increasing awareness of the sanctuary and recreational opportunities available, a lack of infrastructure to promote access continues to be a limiting factor for non-consumptive recreation.
Consumptive recreation is a term used to describe recreational activities that may result in the death of or disturbance to wildlife, or the destruction of natural habitats. This typically includes recreational fishing, sport fishing, and beachcombing. Within the National Marine Sanctuary System, sites try to balance access to these activities with resource protection to maintain this ecosystem service. Evaluating this service in the Pacific Islands is difficult, as island communities rely on fishing for subsistence and do not view it as a recreational activity. The majority of those who benefit from consumptive recreation in American Samoa are local residents, but they generally do not conduct the activity solely for recreational purposes, but rather, do so in conjunction with other responsibilities, such as food provision. The expansion of NMSAS restricted fishing access in two sites, but likely had a minimal impact on recreational fishing activities.
Science is an important ecosystem service for NMSAS, and activities such as in situ research, publications, science capacity, and partnerships have been increasing. Sanctuary staff have successfully worked with partners to support research cruises for shallow coral reef ecosystem and deep-sea exploration, exploration of mesophotic systems, investigation of contaminants in Fagatele Bay, and installation of a buoy to monitor ocean acidification in Fagatele Bay. In addition, college interns and fellows have supported science efforts, and outreach staff have incorporated science into ocean literacy efforts. However, there are limitations on this service due to lack of vessel access and limited science staff capacity.
Education and outreach is another important ecosystem service that has benefitted a wide range of audiences, participants, partners, communities, and networks locally, regionally, nationally, and internationally. Education and outreach efforts at NMSAS have consistently grown. A significant success has been harnessing support and building capacity for local residents, including students, teachers, village communities, and partners. Ensuring residents were the first to benefit from training, programs, activities, or other opportunities aimed at building pride in protecting sanctuary resources and enhancing skills has been essential. Additionally, the sanctuary has collaborated with local, regional, national, and international partners in order to gain a wider reach, projecting the place, people, special resources, and ecosystems of NMSAS via films, publications, and expeditions.
Heritage and Sense of Place
NMSAS is tasked with interpreting, protecting, and preserving historic and cultural resources and incorporating traditional knowledge and stewardship into management. Fa’a Samoa, the traditional Samoan way of life, provides the cultural context for all sanctuary activities and functions. The chiefs who were engaged in the condition report process stated that culture is too important and complex to capture in a rating. Therefore, there are no formal graded assessments for heritage and sense of place, as to do so would be considered inappropriate. Instead, the value of cultural heritage is presented in a narrative form, which includes the historical and cultural background of American Samoa and a summary of related resources and activities, such as community engagement and education and outreach events. These events highlight the cultural traditions and values of family, village, ecosystem, and Fa’a Samoa. Heritage and sense of place should be understood as shared and strongly supported by NMSAS and by the community of American Samoa.
Worldwide, there is heavy pressure on fish assemblages from fishery activities, and assessments have demonstrated declines in reef fish abundance across the Pacific Islands. Except at Swains Island, reef fish populations across the territory are well below the biological potential for these systems. Fishing may quickly reduce the population of commercial reef fish species in constrained bays like Fagatele Bay and remote sites like Rose Atoll with limited fish recruitment. Fishing is now prohibited in Fagatele Bay and limited in other units like Aunu’u and Muliāva. Commercial fisheries data specific to sanctuary areas were not available, therefore aggregate data for the territory were evaluated for this service. These data indicate that the number of fishing vessels and fishers in the territory have declined over time. In 2019, pelagic catches were the lowest in the past decade, and NOAA Fisheries determined that the bottomfish fishery was overfished and experiencing overfishing. Social surveys suggest that reef shark populations have improved, but octopus, giant clams, akule, and palolo have declined or remained the same. Fishery independent data suggest that shallow reef fish biomass and giant clam abundance have declined. Due to the change in fishing regulations and lack of sanctuary-specific data, the status of this service was undetermined.
Subsistence harvest is important to the American Samoan community to ensure that families have food on the table, have a healthy diet, and maintain a connection to the past through traditional fishing methods. Data indicate that most households have at least one member who fishes. The most common reasons for fishing are to feed family members and give to pastors and village leaders. But while most continue to participate in subsistence harvesting, many residents believe reef fishing is worse now than when they were young, including for the traditional harvest of species such as palolo, giant clams (faisua), and bigeye scad (akule). Also, although people may still be engaged in subsistence harvest, the frequency of harvest has decreased.
Coral reefs protect infrastructure and support economic activity. Coral reefs and mangroves help to reduce flooding and wave energy at the shoreline. Rising sea level is of great concern, as it affects a large number of sites currently protected by these habitats. In addition to global sea level rise, American Samoa has experienced rapid subsidence since a powerful 2009 earthquake doublet in the Tonga Trench. The rate of subsidence in American Samoa is about 8–16 millimeters per year, making the island’s relative sea level rise rate about 5 times the global average. This may make it difficult for coral reefs to maintain their capacity for coastal protection, as many species grow more slowly than this. Coral bleaching events, storms, and vessel groundings have impaired this function in some sanctuary areas, particularly Aunu’u. Although coastal protection is rated as fair in most sanctuary units, Muliāva is considered to be good/fair and Aunu’u is fair/poor.
Response to Pressures
NMSAS is co-managed by the National Oceanic and Atmospheric Administration (NOAA) and the government of American Samoa. Partnerships with sanctuary-adjacent communities and Fa’a Samoa are highly valued as part of this management structure. In American Samoa, the relationship between the sanctuary and the village council is critical to the success of this partnership. Since the designation of Fagatele Bay National Marine Sanctuary in 1986, local administration of the sanctuary has been conducted through a cooperative agreement with the government of American Samoa. In 2002, a memorandum of agreement established a co-management relationship between the NOAA Office of National Marine Sanctuaries and the American Samoa Department of Commerce. The co-development of a world class visitor and learning facility known as the Tauese P.F. Sunia Ocean Center and further collaboration on several efforts with the American Samoa Department of Commerce increased the reach and presence of the newly expanded NMSAS. In 2013, the government of American Samoa shifted co-management from the American Samoa Department of Commerce to the American Samoa Department of Marine and Wildlife Resources. With this change, NMSAS continued to engage the Department of Marine and Wildlife Resources on a regular basis and collaborated on opportunities that benefitted the territory, such as crown-of-thorns starfish removal and the Fagota mo Taeao Fishing Tournament.
The most significant management action since 2008 was the expansion of the sanctuary, which took place in 2012. During this process, the Office of National Marine Sanctuaries worked with stakeholders to evaluate issues affecting the sanctuary. This process led to regulatory changes, including the establishment of a no-take area in Fagatele Bay and prohibitions on damaging activities like anchoring throughout the sanctuary. Any exceptions to these regulations must be reviewed and permitted by the Office of National Marine Sanctuaries. Action plans were also developed through this process to guide sanctuary management on topics including resource protection and enforcement, climate change, cultural heritage and community engagement, and ocean literacy. NMSAS has implemented many of the strategies listed in the action plans to improve sanctuary management and respond to pressures. This includes expanded educational programs, improved science capacity, and implementation of resource protection activities such as crown-of-thorns starfish removal. In 2016, the sanctuary expansion allowed the Office of National Marine Sanctuaries to remove the fishing vessel No. 1 Ji Hyun from important fishing grounds in Aunu’u under the authority of the National Marine Sanctuaries Act.
Recommended actions are not presented in this report; however, in 2022, the Office of National Marine Sanctuaries will begin updating the NMSAS management plan, and the findings of this condition report will serve as an important foundation for recommendations of new action plans designed to address priority needs.