Science for Sustainable Sea Palm Harvesting


Karina J. Nielsen
Department of Biology
Sonoma State University
1801 E Cotati Ave
Rohnert Park, CA 94928

Tel: 707.664.2962

Carol Anne Blanchette
PISCO Research Coordinator
Marine Science Institute
UC Santa Barbara

Relevant Links:

Nielsen Homepage

Overview of use and harvest of sea palm



March 6, 2008

Sea palm at low tide

A small patch of sea palms at low tide along the edge of a surge channel at Van Damme State Park, Mendocino County. Photo credit: Karina J Nielsen

February 12, 2008

Contact: Christina S. Johnson,, 858-822-5334

Concerned by the unregulated growth of sea palm harvesting along the rocky North Coast, Sea Grant biologists have developed the rudiments of a sustainable harvesting plan for the edible brown kelp.

Solitary sea palm

A solitary sea palm growing on top of a mussel. The root-like base is the holdfast, the stalk-like stem is the stipe, and the leaf-like structures at the top are the fronds or blades. Photo credit: Sarah Ann Thompson

“Harvest once and harvest early,” said Karina Nielsen, a biology professor at Sonoma State University, summing up the crux of her Sea Grant project conducted with Carol Blanchette, a researcher with the Marine Science Institute at UC Santa Barbara, and Sea Grant Trainee Sarah Ann Thompson, a graduate student at Sonoma State.

"Our experiments show that sea palms cannot withstand multiple harvests," Nielsen said, referring to a series of field experiments in Mendocino and San Luis Obispo that looked at the effects of harvesting practices on spore production.

When a plant is harvested more than once, spore production drops to less than one percent of what it is naturally, regardless of when the plant is cut, she said. Spore production is highest when fronds are cut in late spring, a counterintuitive discovery that is welcome news for kelp harvesters who say consumers prefer early-season sea palm fronds to those collected at the end of the growing season.

"Originally scientists, including myself, were recommending that harvesting occur after the seaweeds had started producing spores, late in the summer," Nielsen said. "The harvesters probably weren't so keen on that because the product is less desirable and palatable then. Now with this experimental evidence in hand, we have a win-win outcome for the resource and the sea palm business."

Dried sea palm fronds for sale

Dried sea palm fronds for sale in the bulk foods section of Oliver’s supermarket in Sonoma County. Photo credit: Sarah Ann Thompson

Sea palms, which look a bit like rubbery wigs or miniature palm trees, compete with mussels for space along tidal rocks. The whole plant is edible, but kelp collectors usually clip only the fronds, the top of the plant, so that the rest of the plant can regenerate. The fronds are then sold dried as sea noodles or sea crunchies for $40 to $100 a pound.

To enter this niche industry, all one needs is a $100 commercial edible seaweed collection permit obtainable from the California Department of Fish and Game. The amount of sea palm harvested, when and where is not regulated. There is, however, anecdotal evidence the cottage kelp industry has grown significantly, and perhaps worrisomely, in recent years. There are now three well-established Mendocino-based companies and several individuals collecting and selling sea palms, Nielsen said. Online articles talk of "weed and wine pairings," the national chain Whole Foods sells sea palms, and "Sea Palm Strudel" is now a signature dish at Stanford Inn by the Sea in Mendocino County.

A sea palm as cut by a collector using poor technique in the field

A sea palm as cut by a collector using poor technique in the field. The uppermost blades were cut too far back to regenerate (i.e., below the base of the blade). If too many blades are removed below the base the individual will die. Photo credit: Sarah Ann Thompson

"The alarm bells go off, because this is a very vulnerable species, and there is a growing market," she said. Sea palms are annuals (they live only a year), and their spores do not disperse far. Because of their biology, a critical density of plants must be maintained to prevent local extinctions. "We are recommending that Fish and Game limit the number of people harvesting for a given site and restrict the season to protect sea palms from overharvesting."

Continuing experiments being funded by Sea Grant will allow Nielsen to say more about how different harvesting regimes affect the longer-term persistence of sea palm populations.

The views expressed here do not necessarily reflect the views of NOAA, the California Department of Fish and Game or the state of California.