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Beginning in November 2026, a rockweed harvester educational course (12 M.R.S. §6803 (Subsection 6)), will be required by the Maine Department of Marine Resources (DMR) for rockweed (Ascophyllum nodosum) harvesters to obtain their seaweed licenses for the 2027 harvest season and subsequent harvest seasons. The course is a multiple choice, open-book, exam provided to harvesters through the LEEDS licensing system. It can be taken multiple times and requires an 80% or higher score to pass. Answers to the exam are in the information below. The exam can be taken online in the LEEDS licensing system, or in person at the DMR licensing office in Augusta. If you would like a copy of the exam emailed or mailed to you to obtain your seaweed license, please contact DMR licensing at licensing.dmr@maine.gov (207-624-6550). Once a rockweed harvester has successfully passed this exam, they will not be required to take it again to obtain their seaweed license for subsequent harvest seasons. Please note, if this exam is updated in the future the DMR will notify harvesters if they need to take the exam again to obtain their seaweed licenses.
Introduction
Ascophyllum nodosum (also known as knotted wrack) is a commercially harvested species of rockweed found along Maine's rocky coastline. It will be referred to as rockweed below. Maine seaweed harvesters gather rockweed to sell for use as packaging, bio stimulant, soil conditioner, animal feed additives, human hygiene and food products, and other commodities.
Biology
Rockweed is a brown marine algae in the Phylum Ochrophyta. While it may look like a plant, it is a species of macroalgae. Rockweed does not have roots, stems, leaves, or a vascular system like terrestrial plants. Instead, rockweed has a holdfast (that helps connect it to hard substrates), branches, and air bladders (which lift the algae to the surface of the water column). The thallus is the entire algal body. The thallus can also be referred to as the stalk or the stem.
Rockweed reproduces in the spring. Rockweed has structures called receptacles which contain gametes (eggs and sperm). Receptacles form in the fall and winter, release gametes in the spring for reproduction, and then fall off the thallus in the summer.
Rockweed grows an average of 3-4 inches annually from the tips. The algae's minimum age can be determined by counting the number of air bladders on the primary thallus. Every air bladder represents another year of growth. Air bladders provide buoyancy for rockweed so they can rise in the water column for better access to sunlight to photosynthesize.
Ecology
Rockweed is primarily found in the marine rocky intertidal zone, between the mean high water and the mean low water mark. In North America, it is distributed along the north Atlantic coast extending from Canada south to New Jersey (See reference pictures to the left).
Rockweed beds are a major component of the intertidal habitat in Maine. Not only does rockweed provide habitat for numerous species including birds, fish and crustaceans, it is a great food source for grazers and feeders on decomposed material. It also functions like a marine canopy (see reference pictures to the left). Because rockweed can photosynthesize, it is also a primary producer, providing energy for the entire food web. Rockweed absorbs carbon dioxide (CO2), helps to maintain water quality and is involved in nutrient cycling.
Rockweed Harvesting
On March 28, 2019, the Maine Supreme Judicial Court issued a decision in Ross v. Acadian Seaplants, LTD (2019 ME 45) stating… “that rockweed in the intertidal zone belongs to the upland property owner and therefore is not public property, is not held in trust by the State for public use and cannot be harvested by members of the public as a matter of right.” Based on this decision, rockweed located in the intertidal zone is the property of the intertidal landowner, which may be the adjacent upland landowner. Harvesters may be in violation of the law and subject to possible criminal or civil legal action if they do not have intertidal landowner permission to remove intertidal rockweed. If a dispute occurs over the harvest of intertidal rockweed, harvesters should stay calm, record details and contact DMR Marine Patrol for guidance before continuing to harvest at that location.
Rockweed harvesting can occur year-round but typically takes place between May through September. Harvesters may prefer to wait for the spring to begin harvesting after seaweed reproduction has finished. There are two harvesting methods. Hand harvesting is usually performed from a boat with a specially designed hand rake, or on foot with a knife. Mechanical harvesting is also done by boat, using machinery that incorporates a catch net, a 16” recessed, suction cutter with water jet propulsion (pictures to the left). Both methods require proper care of equipment and attention to cutting requirements and height restrictions. Knives, rakes and cutters must be kept sharp enough to cut through rockweed no less than 16 inches above the holdfast, and so that the holdfast is not removed from substrate. Removal of the holdfast eliminates the possibility for future growth of the algae thallus. Efforts to minimize holdfast removal and bycatch (such as marine snails and green crabs) should be made in both harvesting practices. Bycatch minimization ensures sustainability of the marine ecosystem. Slight under water vibrations produced by mechanical harvesting help this method to reduce bycatch. Harvesters can review boating safety guidelines at Maine DMR website outlining boating safety.DMR Regulations
The DMR manages rockweed harvesting through relevant statutes and regulation. Certain activities require harvesters and seaweed buyers to obtain DMR seaweed permits, supplemental permits and buyers permits annually. Details of these permits outlining exceptions and fees can be found in the following statutes and regulations: Title 12, §6803: Seaweed permit; Title 12, §6803-A: Seaweed buyer's license; Title 12, §6803-B: Seaweed buyer's surcharge. An individual who harvests, possesses, ships or transports no more than 50 pounds of seaweed a day for non-commercial purposes is not required to have a seaweed permit. DMR Chapter 29 has definitions for rockweed holdfasts and lateral branching, and includes the following rockweed harvesting requirements:
- the lowest lateral branches shall remain undisturbed and attached to the main *stalk of the rockweed that is attached to the substrate
- a minimum of 16 inches of the rockweed shall remain above the holdfast.
*The term "stalk" is referred to as thallus elsewhere on this page.
DMR Landings Program Reporting Requirements
Reporting for seaweed harvesting and seaweed buyer’s surcharge rules can be found in DMR Chapter 8. Section 8.10 and Section 8.20 include primary buyer permit reporting and surcharge requirements and include that each seaweed harvester must report harvesting activity for all seaweed species on forms supplied by the DMR. Records must be kept on a daily basis, and trip level reports must be mailed to the DMR monthly. Reports for each month’s activity shall be mailed to the DMR within 10 days of the end of the month.
DMR License Consent to Inspection; violation
In the field, Marine Patrol Officers are responsible for the enforcement of all marine resource related laws and rules. License holders have the duty to submit to inspection and the search for violations related to licensed activities. Refusal to permit inspection or seizure shall be basis for suspension of any or all licenses. In addition, a license may be suspended for a finding of violation or a conviction of marine resources law under M.R.S.A. Title 12, Section 6351 or 6371.
Cobscook Bay
The coast of Maine is divided into harvesting sectors (top left figure). Intertidal areas in state parks, and federally owned lands are closed to commercial harvesting. In Cobscook Bay, intertidal areas of public and private conservation areas are also closed to commercial harvesting (Harvest Sectors with Areas Closed to Harvest Adjacent to Conserved Lands — Map Viewer). Cobscook Bay is divided into 36 management sectors (see bottom left figure). Individuals wishing to harvest rockweed from Cobscook Bay must submit their intent to harvest in writing to DMR prior to January 1 of the year in which they intend to harvest. They must also submit a harvest plan by March 1. The total biomass removed in a management sector may not exceed 17% of the harvestable biomass that is eligible to be harvested annually.
DMR Rockweed Fishery Management Plan (FMP)
The DMR Rockweed FMP can be found on the DMR website. It was created in January 2014, by the DMR and the Rockweed Plan Development Team. Although it has not been adopted as a management plan by the DMR, it contains valuable rockweed information including rockweed morphology and rockweed harvest methods.
Seaweed Fisheries Advisory Council
The Seaweed Fisheries Advisory Council (SFAC) established by Title 5, section 12004-I,subsection 57-H consists of 7 members appointed by the DMR Commissioner who make recommendations to the commissioner on all matters concerning the health of the seaweed resource, its ecosystem and the industry it supports. The SFAC also makes recommendations to the commissioner regarding expenditures from the Seaweed Management Fund as in section 6806. Meetings are held annually. Dates and meeting times are announced in DMR Gov Deliveries, as well as on the DMR homepage.
CONTACT INFORMATION
- For seaweed management and policy inquiries, please reach out to Jen Harris, DMR Resource Management Coordinator at jennifer.harris@maine.gov or 207-458-9234.
- For seaweed biology and ecology inquiries, please reach out to Katie Tilton, DMR Marine Resource Scientist I at katie.tilton@maine.gov or 207-350-6453.
- If you do not currently receive emails from DMR Gov Deliveries and would like to do so, please go to the bottom of the DMR homepage at www.maine.gov/dmr/home, click on the “Subscribe to Email Notifications” link and follow the subscription prompts.