SULLIVAN — One thing was made clear at a recent conference on rockweed harvesting organized by Frenchman Bay Partners — there are no simple answers.
Rockweed landings comprise about 90 percent of seaweed landings in Maine, representing a $20-million industry in the state.
The harvesting practices have come under scrutiny because rockweed landings in Maine have increased from more than 3 million pounds in 2003 to more than 14 million pounds in 2012.
Speakers at the meeting April 2 addressed both sides of the issue of whether current harvesting practices are eroding the plant’s sustainability and provided details on a pending and related court case.
Rockweed, or Ascophyllum nodosum, is a nutrient-packed algae that is harvested for use in food, fertilizer, soil conditioners, animal feed and other products.
The algae provides food, shelter and spawning habitat for a variety of animals and attracts feeding seabirds and shorebirds.
Frenchman Bay Partners — comprised of fishermen, the aquaculture industry, scientists and community members — organized the meeting to gather information to help the group decide in May whether to add rockweed to its list of conservation “targets.”
The group’s current targets include eelgrass, benthic habitat, mudflats and diadromous fish.
Anna Farrell, program coordinator for the Community Environmental Health Laboratory at MDI Biological Laboratory, which helps coordinate Frenchman Bay Partners, said the more than 70 people in attendance “seemed to come away feeling they were more educated about it, which was the whole purpose of the meeting.”
The first speaker, Robin Hadlock Seeley of the Shoals Marine Lab at Cornell University, said rockweed beds provide ecological havens for more than 100 marine mammals.
The rate of rockweed regrowth, she said, can vary from 1½ inches per year in some areas to 10 inches per year in parts of Nova Scotia.
Seeley said the issue is not whether rockweed harvesting is sustainable for the harvesters, but whether the ecology and biomass can withstand the current level of harvesting.
Jeff Romano, an attorney speaking for the Maine Coast Heritage Trust, spoke about the lawsuit pending in Washington County Superior Court.
The suit was filed in December 2015 by three landowners against Acadia Seaplants Ltd. of Nova Scotia.
At issue, Romano said, is who owns the rockweed growing in the intertidal zone — the property owner on land or the harvesters.
Another question is whether harvesting rockweed is considered “fishing” under laws dating back to colonial times that preserve the intertidal zone for public fishing, fowling and navigation.
Romano said the Maine Supreme Court has been inconsistent on the issue.
The Maine Coast Heritage Trust’s position on the matter, he said, is that rockweed growing in the intertidal zone is considered alluvial —land-based — and therefore owned by the landowner.
Raul Ugarte of Acadian Seaplants, said rockweed harvesting is a $50-million business in Canada.
He said harvest areas are subdivided and monitored with set limits on the quantity that can be cut and harvesters are continually monitoring the rockweed stock via aerial and satellite imagery.
Ugarte added that rockweed is the hardiest of seaweeds.
“It’s not a delicate flower,” Ugarte said.
Jessica Muhlin, associate professor of marine biology at Maine Maritime Academy, said rockweed regenerates at widely varying rates depending on its geographic location and reproduces along the full length of the plant’s sheath.
Another factor that could affect rockweed, she said, are the temperature anomalies — specifically the warming trend observed in the Gulf of Maine dating back to 2005.
“This may shift the reproductive timing and output,” Muhlin said.
She compared rockweed harvesting to the annual “tipping” of evergreen trees to make Christmas wreaths.
Currently, the Department of Marine Resources requires rockweed harvesters to report their landings and restricts the cuttings to 16 inches above the “holdfast,” which anchors the plant to the rocks below.
The Cobscook Bay Rockweed Management Area statute is more restrictive.
The law, among other things, requires pre-harvest plans from harvesters and divides the bay into 36 assigned harvest sectors, capping the harvest in each sector to 17 percent of the biomass.