Gulfwatch Contaminants Monitoring Program

2024 UPDATE: Gulfwatch Sample Archive Available for Research

Thanks to funding from Fisheries and Oceans Canada’s (DFO) Marine Environmental Quality Program, the Huntsman Marine Science Centre is providing archival support for the Gulf of Maine Council’s collected Gulfwatch mussel samples.

Gulfwatch’s transboundary chemical contaminants monitoring program involved the collection of blue mussels (Mytilus edulis) at rotating sites in all jurisdictions around the Gulf of Maine (i.e., Nova Scotia, New Brunswick, Maine, New Hampshire and Massachusetts). Samples were collected between 1993 through 2012. The existence and preservation of these samples presents an invaluable opportunity to:

  • gain a regional perspective on the distribution and concentrations of toxic contaminants,

  • establish a baseline reference for future monitoring efforts, and

  • improve our understanding of issues that threaten the overall environmental quality of coastal waters within the Gulf of Maine and Bay of Fundy region.

Researchers interested in accessing archived samples must submit a research proposal to the Gulfwatch Archive Steering Committee. Proposal submission guidelines must be followed as outlined within the Gulfwatch Management Plan.


  • Publication: Swam, Lauren M., Apeti, Dennis A., Rider, Mary M., Jones, Stephen; Reed, Lou Ann. (2023). An Assessment of Legacy Organic Contaminants and Trace Metals in the Gulf of Maine. National Centers for Coastal Ocean Science (U.S.), Consolidated Safety Services, Inc., and University of New Hampshire. NOAA technical memorandum NOS NCCOS: 319. DOI:
    • Description: The National Oceanic and Atmospheric Administration (NOAA) Mussel Watch Program (MWP) conducted an assessment of the presence, distribution, and concentrations of legacy organic contaminants and trace metals in blue mussels from the Gulf of Maine’s coastal waters, in collaboration with the Gulf of Maine Council on the Marine Environment (GOMC) Gulfwatch Program. Like the national MWP, the Gulfwatch monitoring program utilizes a sentinel-based monitoring approach by collecting and analyzing bivalves as surrogates for coastal water pollution.


Gulfwatch is a chemical-contaminants monitoring program organized and administered by the Gulf of Maine Council on the Marine Environment. Between 1993 through 2012, Gulfwatch measured contaminants in blue mussels (Mytilus edulis) to assess the types and concentration of contaminants in coastal waters of the Gulf of Maine. It was one of the few monitoring programs and the only one in the Gulf of Maine to be coordinated across international borders.

Gulfwatch was coordinated and conducted by scientists and managers from agencies and universities around the Gulf. The program operated under the guidance of the Gulf of Maine Council’s Gulfwatch Contaminants Monitoring Committee and was supported with funding from the Gulf of Maine Council on the Marine Environment and the U.S. Environmental Protection Agency.

Each fall, scientists collected blue mussels, rotating among 38 sites around the Gulf of Maine, and analyzed their whole tissues for a variety of contaminants. Additional sites were sampled in a particular year as part of other projects associated with Gulfwatch. Data indicated where contaminant concentrations may be high and enabled researchers to compare concentrations at different locations. Data also showed changes in concentrations over time.

Dozens of chemicals and metals were monitored

Polycyclic aromatic hydrocarbons (PAHs) come from municipal and industrial effluents, fossil fuel combustion, wastewater from refineries and offshore oil rigs, and petroleum spills. Gulfwatch measured 12 low-molecular-weight PAHs and 12 high-molecular-weight PAHs.

Polychlorinated biphenyls (PCBs) are synthetic chemicals comprised of chlorine atoms arranged on a biphenyl molecule. They are highly persistent in the environment and may be highly toxic. Gulfwatch measured 22 PCBs.

Chlorinated pesticides are synthetic chemicals that have been used as pesticides, such as DDT and dieldrin. Most are highly persistent in the environment. Gulfwatch measured 16 chlorinated pesticides.

Metals occur naturally but human activities may increase their concentration and availability from fertilizers, fossil fuel combustion, metal smelting, industries, and domestic waste. Gulfwatch measured 9 metals.

Sites ranged from Massachusetts to Nova Scotia

Since 1993, Gulfwatch has sampled more than three dozen sites along the coast of Massachusetts, New Hampshire, Maine, New Brunswick, and Nova Scotia. List of sampling sites, including site names, latitude/longitude, years sampled, and substrate:

View online (HTML) | Text file (5 KB) | Excel file (28 KB)

The Council established Gulfwatch in 1991

In December 1989, the premiers of Nova Scotia and New Brunswick and the governors of Maine, New Hampshire, and Massachusetts signed the Agreement on the Conservation of the Marine Environment of the Gulf of Maine. This agreement established the Gulf of Maine Council on the Marine Environment, whose mission is to maintain and enhance environmental quality in the Gulf of Maine. In 1989, the Gulf of Maine Council formed the Contaminants Monitoring to provide resource managers with information to support sustainable use of the Gulf and allow assessment and management of risks to public and environmental health. The EQMC established three monitoring goals, which include providing information on:

  • The status, trends, and risks of contaminants to the Gulf of Maine ecosystem.
  • The human health risks from contaminants in the Gulf of Maine ecosystem.
  • Monitoring information to resource managers that will allow both efficient and effective management action and evaluation of such action.

As a step toward meeting these goals, the EQMC established Gulfwatch. At the outset of the Gulfwatch program, an important objective was to test the feasibility and cooperation required for Gulf-wide monitoring. After a two-year pilot project that showed Gulfwatch could succeed, a study design was developed to:

  • Conduct regional contaminant monitoring using the blue mussel as an indicator of habitat exposure to organic and inorganic contaminants.
  • Assess the status and trends of chemical contaminants in coastal waters of the Gulf of Maine and Bay of Fundy.
  • Establish a baseline reference for future monitoring efforts on trace chemicals.

Monitoring the entire Gulf is an important challenge

The Gulf of Maine is a semi-enclosed sea that is bound on three sides by Massachusetts, Maine, New Hampshire, New Brunswick, and Nova Scotia and flanked on the east by Browns Bank and Georges Bank, and includes the Bay of Fundy. Many environmental, social, and political challenges make it difficult to monitor the health of this ecosystem. Some of these are:

The Gulf of Maine watershed is large

The Gulf of Maine watershed spans 69,115 square miles (165,185 square kilometer) and the Gulf of Maine spans 36,000 square miles (90,700 square kilometer). One challenge is deciding what, where, and how often environmental variables should be monitored.

Pollution comes from near and far

More than 60 rivers pour 250 billion gallons (950 million cubic meters) of water—and contaminants—into the Gulf each year. Chemicals may also enter the Gulf from the atmosphere, overland runoff, or other human sources. Effectively identifying, quantifying, or remediating many pollution problems is challenging.

Our population is growing

Nearly six million people live in the watershed, and the population is growing rapidly. Land and water resources in the region face enormous pressure. Monitoring programs must continuously respond to new scientific concerns.

Managing a shared resource is difficult

U.S. and Canadian government agencies face the challenge of having to collaborate and communicate with each other to manage a shared resource. Cooperation is generally high, but sometimes there is disagreement over management priorities.

The Gulfwatch program is growing

In the coming years, Gulfwatch will continue its assessment of trends in chemical contaminants throughout the Gulf of Maine, while adapting to meet the evolving needs of resource managers and surrounding communities, and also being responsive to changes in technology and assessments of the environmental integrity of the Gulf of Maine. Gulfwatch is networked to similar programs such as the NOAA National Status and Trends Program Mussel Watch Project. Gulfwatch is adding bioeffects measures to its regular sampling, and it is encouraging research and monitoring partnerships to strengthen mussel monitoring and to utilize other indicators of ecosystem health in the Gulf of Maine and Bay of Fundy.

Contact us

For information about Gulfwatch, please contact Peter Wells, Canadian Co-chair of the Gulfwatch Contaminants Monitoring Committee,