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DMR Home > Shellfish Harvest Area Data

New On-Line Data Provides Shellfish Harvest Area Management Trends for Ten Years

New searchable on-line data developed by the Maine Department of Marine Resources is now available for researchers, municipal officials and others interested in analyzing public health management efforts in shellfish harvesting areas on the Maine Coast between 2001 and 2012.

The data, available at the Maine Office of GIS (MEGIS) website, not only provides easy access to trend information, but when paired with data from agencies like the Department of Environmental Protection and the Department of Transportation, it can show correlations between land use activity and water quality changes.

“This kind of information can support more strategic decision making at the local level to protect water quality, public health and better economic opportunity, ” said Governor Paul R. LePage. “I commend the Department for taking the initiative to create this management tool.”

“This is an important step forward for the scientific and regulatory community,” said Kohl Kanwit, Director of the Department of Marine Resources Bureau of Public Health. “By making this information available online, we’re providing a powerful tool for researchers studying trends in water quality and red tide closure histories, and for municipal planners looking for links between local activity like road building or waste water discharges and changes in shellfish harvest areas.

“This data can also be useful for industry; for example someone interested in aquaculture could use it when looking for a lease site location, or a shellfish dealer could use it when determining if a site is good for storing shellfish in the water, a common practice requiring a high water-quality standard.”

Developed by Michelle Mason Webber, Shellfish Program Coordinator for the Maine Department of Marine Resources, the data is available as a downloadable file on the Maine Office of GIS (MEGIS) website and can be viewed by anyone with software that can process the data-rich files known as shapefiles.

The file displays specific outlined areas of the coast that have been classified at any point over the past ten years based on the level of bacteria or biotoxins (red tide) detected by the department’s sampling program. In many instances, some parts of the coast had numerous changes in the classification or size and shape of the affected areas, all of which can be searched and displayed as colored overlays on a map.

Each change of shellfish harvest area classification is done by the department through statutorily authorized rule changes which are posted on the DMR website and mailed or emailed to towns where shellfish harvesting takes place. Before this searchable data was available online, anyone who wanted to analyze this information in certain areas had to review the posted, mailed or emailed notices.

Viewers with software that processes GIS information can now query the data for a particular area of the coast that has been classified based on the amount of biotoxin or bacteria present. Depending on the amount of bacteria detected, shellfish harvesting, and by association the areas where it is conducted may be classified as prohibited, restricted, conditionally restricted, or conditionally approved. Locations along the coast impacted by red tide are classified as either closed or exception areas where certain shellfish species can be harvested because of an increased sampling effort that targets them.

The work of entering the data began in 2010 and involved not only creating thousands of colored outlines that display the geographic area impacted by each change of classification, but also accompanying descriptive information. The information, which is part of the searchable data, includes among other things, the date of a classification change and the exact acreage of the impacted area.

The data, identified on the MEGIS website as “Archived shellfish harvest,” can be found at and downloaded as a compressed file under the Biologic and Ecologic/Environment and Conservation heading. For more information on the data, contact Michelle Mason Webber at 624-6570.