ORONO, Maine — Questions about rockweed harvesting in Maine vastly outnumber answers.

That was the overall problem addressed by researchers and others at a symposium Wednesday at the University of Maine in Orono.

Dozens of questions asked by scientists, harvesters, managers and landowners made it clear much more is unknown about rockweed habitat and harvesting impacts than is known. It was also clear that the majority of the people at the symposium were seeking answers.

“That is true of virtually all fisheries,” Department of Marine Resources Deputy Commissioner David Etnier said Thursday. “There is always more good research that should be done. That’s the nature of marine management.”

The symposium was sponsored by the Maine Sea Grant College Program and the Maine Department of Marine Resources. It was an opportunity to delve into issues and identify gaps in knowledge about rockweed to create areas for future scientific research.

Those attending the symposium included more than two dozen harvesters and members of the Maine Seaweed Council, a dozen scientific researchers and about four conservationists.

The research questions developed by the symposium’s participants will be used to lure graduate students into studying the issue, which is at the heart of a controversy between commercial harvesters and those who want the rockweed to remain undisturbed.

The reality, said Christopher A. Bartlett with Sea Grant Maine, is that there are neither enough research funds to conduct the studies nor enough marine researchers in the Northeast.

“A lot of this research won’t be funded,” Bartlett said. “It will be done by graduate students.”

Robert Morse of North American Kelp based in Waldoboro offered a $5,000 donation to start a research fund and encouraged others to do the same. Morse suggested specifically researching accurate assessment methods for the rockweed industry.

Rockweed is now worth about $40 a wet ton, 2 cents a pound, and a good hand harvester can cut at least a ton an hour. In 2008, there were 85 licensed seaweed harvesters, and landings totaled 12 million tons, 99 percent of which was rockweed, according to the Department of Marine Resources. The other 1 percent includes dulse, kelp and many other kinds of seaweed used for food and cosmetics, among other things.

The controversy arises from the difficulties of trying to find a balance between the value of rockweed as a commodity and the effects of the harvest on decreasing habitat.

Julie Keene of Lubec, the only commercial fisherman at the symposium, harvests periwinkles, which live in and under rockweed, in Cobscook Bay. She insisted that the harvesting must stop or be monitored more closely until its full impact is known.

Keene said the bay area fishermen need to know the relationship between the rockweed beds and the sustainability of the rest of the bay’s fishery.

“If you take 1,000 tons of seaweed out of the bay, what happens when you remove all those nutrients?” she asked. “What happens to the seals, the eagles, the clams, the lobsters, the periwinkles — the entire ecosystem that relies on the rockweed?”

Scientists at the symposium pointed out there are no long-term studies of the rockweed harvesting effects.

Dr. Jill Fegley, who studied rockweed habitat in Cobscook Bay, told those gathered that despite the lack of in-depth studies, short-term studies indicate that many species that live in rockweed are resilient and their population rebounds quickly, based on a one-time harvest.

“But there are limitations to the existing studies,” Fegley added.

She said a two-month study made in 2008 in Cobscook Bay and two older studies in Ireland showed no significant changes in plant structure or periwinkle populations, but sponges and barnacles were greatly decreased. A 1991 study found a 66 percent reduction in animal abundance in areas totally cleared of rockweed.

Some of the studies disagreed with other findings regarding impact and significance of harvesting, which caused frustration for some at the symposium.

“We’ve been at this for more than a decade,” Dr. Robin Hadlock Seeley of Cornell University said. “The last symposium like this on rockweed was held in 2000, and today we are asking the same questions we asked then. The basic questions are still unanswered, and still the harvesting goes on and escalates.”

Rockweed has long been harvested off the coast of Maine and traditionally was used as field dressing and fertilizer, harvester Robert Morse said in his presentation. It also is used as an animal feed additive and can be harvested by hand rakes or knives, or, for the past 12 years, mechanical suction pumps.

Those harvesting the sea plants maintain that it is a sustainable industry, similar to cutting hay from a field.

Opponents say vital nurseries for other sea life are being destroyed through harvesting and want independent testing and assessments.

Tom Schaeffer of the Maine Department of Inland Fisheries and Wildlife said, “As a land manager, I need to know the impacts of harvesting.”

Dr. Raul Agarte, lead scientist with Acadian Seaplants Inc., a major rockweed harvester, said he was asked by the state Department of Marine Resources to conduct an assessment of rockweed stocks in Cobscook Bay. Agarte said he had 15 years’ experience studying rockweed but was not a statistician. He could not provide the assessment, saying it was not in written form, but made a presentation Wednesday.

Using land-satellite images, aerial photos and land measurements, Agarte determined there were 1,118 rockweed beds in Cobscook Bay. He estimated the bay contained 105,000 metric tons of rockweed.

“But we need to know more about the biomass for industry purposes,” he said.

Neither his study nor his presentation mentioned conservation or environmental impacts of the harvest.

Dr. Thomas Trott of Suffolk University stressed the importance of rockweed beds as nursery areas for fish, lobster and invertebrates, feeding areas for birds and ducks, and as a refuge for sea life and a place to find food.

“Rockweed is a habitat,” Trott said, “a major year-round habitat.” He said it is a refuge for dozens of species fish and that birds, including eagles, feed in rockweed.

Some of the questions developed for future research included: Is rockweed essential for any species? How much habitat loss is too much? What role do the low-level, commercially important species that grow in rockweed play in the crop’s recovery? Are there nondestructive methods of assessing rockweed? How can long-term assessments be installed? Are there regional differences in the recovery of rockweed beds after harvesting?

Linda Mercier of the DMR said the seaweed fund that was established at $1.50 a ton based on landings by commercial harvesters would be able to fund some of the research.

“We are going to get these research priorities out on the Web and hope to interest the scientific community,” she said.

Meanwhile, Keene said, she will continue to oppose the harvesting.

“The communities being affected were not at this table,” she said of Wednesday’s symposium. “Where is the traditional knowledge? This is our home. [Cobscook Bay] is the only thing that sustains us. When the rockweed is gone and the periwinkles are gone, what do we do then? Sell the rocks?”