Recently, as shoreline landowners in Lubec, my wife and I received a letter from Acadian Seaplants, providing their answers to persistent questions about the harvest of rockweed in Cobscook Bay and hoping for our support of their efforts when they resume cutting in 2010. Because I am a long-time environmental scientist, I did what comes naturally: I looked for scientific information about rockweed and its role in coastal ecosystems.
Rockweed is one of many “seaweeds” that sustain coastal marine ecosystems throughout the world. The growth of rockweed provides the food and shelter for invertebrates, which are the basis of the food web that sustains higher-level fisheries of coastal Maine. Rockweed also provides critical nursery habitat for young fish that are attractive to predators. Seaweeds are threatened in many areas, disappearing at a rate of 7 percent per year worldwide, according to a recent study published in the Proceedings of the National Academy of Sciences.
One need not look far to see the abandoned sardine factories and codfish fisheries of New England, signs of overexploitation of the marine environment. Good management of marine resources should balance catch against annual production, so that the economic livelihood of the sea is sustained for generations.
Unfortunately, cod and sardines were overharvested in many areas, and those fisheries are now gone.
Now that we have removed these higher-level fish and some invertebrates, such as sea urchins, the rockweed cutters are focused on the base of the food chain itself. Will we allow rockweed to be overharvested as well, so that it declines and disappears from Cobscook Bay and the surrounding waters? Protecting rockweed is important if we are to sustain periwinkle and mussel fisheries, which provide local jobs.
So, as an aid to the local economy, we registered our shoreline with Downeast Coastal Conservancy as a “no-harvest” area.
Acadian Seaplants vows that it will not remove more than 17 percent of the annual growth of rockweed — a level deemed sustainable in studies by R.L. Vadas of the biology department at the University of Maine. To ensure recovery, Dr. Vadas also advises not to harvest any area in consecutive years. The other major player, North American Kelp of Waldoboro, also plans to adhere to a maximum 17 percent harvest, after subtracting biomass that cannot be harvested from protected lands.
We can only hope that all those who harvest rockweed will comply with the new state regulations passed in June 2009, codifying a maximum 17 percent harvest, because no amount of tax will bring back the rockweed if it disappears from the coast of Maine.
The best policy would probably be to prohibit the harvest of rockweed, since it sustains the basis of the fish and shellfish industries in this region. Even so, it is unclear who has monitored and enforced the past levels of harvest and how accurately any of these parameters can be measured.
The Marine Resources Committee will soon hold a workshop to evaluate the success of the regulation of rockweed cutting during the 2009 season. Currently, a surcharge on rockweed harvest is earmarked to help pay for monitoring by the commissioner of marine resources. Indeed, the current legislation requires that the proper harvest of rockweed must be verified by a third party starting with the 2010 harvest season. Done well, these provisions would provide welcome oversight of the rockweed resource and protect its critical role in the coastal marine ecosystem.
Alternatively, the passing of rockweed would mark the end of the marine fisheries ecosystem — top to bottom — within the span of a couple of decades in eastern, coastal Maine.
William H. Schlesinger is president of the Cary Institute of Ecosystem Studies in Millbrook, N.Y. and a shoreline property owner in Lubec.