March 1, 2013

Undaria pinnatifida
Native range: Japan Sea
Invasive range: Southern California, San Francisco Bay, New Zealand, Australia, Europe, Argentina
Habitat: Opportunistic seaweed, can be found on hard substrates including rocky reefs, pylons, buoys, boat hulls, and abalone and bivalve shells.
Description: Golden brown seaweed, growing up to nine feet. Forms thick canopy. Reproductive sporophyll in mature plants is fluted and ruffled, forming around the main stem or stipe near holdfast of kelp. (Not found in native kelps.) Also known as Asian kelp.


Well, I asked for something to eat
I’m hungry as a hog
So I get brown rice, seaweed
And a dirty hot dog
I’ve got a hole
Where my stomach disappeared
Then you ask why I don’t live here
Honey, I gotta think you’re really weird.

“Brown rice, seaweed, and a dirty hot dog”: back in 1965 Bob Dylan, with just 10 words, sent the macrobiotic diet limping off the field in “On the Road Again.”

The “seaweed” in question was Asian kelp or wakame. It wasn’t an invasive species then but it is now, on the coast of California, having stowed away on cargo ships from Japan and China, where it’s native.

Since the 1960s, the word wakame has largely replaced the term “sea mustard” in the US. Originally the popularity of the macrobiotic diet created enough demand for the product to be imported dried from Japan and sold at natural-food stores and Asian-American grocery stores. Demand for wakame, if not for the macrobiotic diet, increased in the 1970s, thanks to the growing number of Japanese restaurants and sushi bars.

Wakame, or Asian kelp, Undaria pinnatifida, is an annual brown algae native to the northwestern coast of the Japan Sea: Japan, Korea, southeastern Russia, and eastern China. It has been recorded in Australia, New Zealand, Italy, Mexico, and Argentina. The likely means of these accidental introductions are farmed shellfish imported from Asia, or ballast-water or fouling organisms discharged by international cargo-ships coming from the Far East. It was deliberately introduced in Brittany as a crop in 1983, and then spread to Spain, the UK, Belgium, and the Netherlands. Wakame has been nominated one of the 100 worst invasive species on the Global Invasive Species Database.

Wakame invaded the east coast of Tasmania in the 1980s, probably introduced from the ballast of Japanese ships. License has been granted to divers for its harvest and its sale, fresh and dried, to restaurants and to home cooks in Australia.

Although it has been a very serious invader in New Zealand––so serious that all harvest of it has been banned––it does not appear, so far, to have serious impacts in California, where it was first recorded in 2000 in several estuaries from San Francisco Bay south to San Diego. It usually can’t compete with the native perennial brown algae, but if native algae aren’t present, it can colonize rapidly and form dense kelp forests. Wakame, like invaders on land, occurs in high densities in recently disturbed areas. The familiar “disturbed areas” that invaders love.

Mature Asian kelp with diagnostic sporophyll on bottom.

Once wakame has established in an estuary, it spreads in two ways: millions of microscopic spores are released by each fruiting body, and the weeds attach to ship hulls and to aquaculture equipment. Like all good invaders, it’s tolerant and opportunistic, growing on stones, rocks and reefs, shells, ropes, pontoons, buoys, and ships’ hulls. In the early stages of its life cycle, it can grow on other algae and sea-grasses. As an adult, it grows into kelp “forests.” The large canopy it forms modifies the habitats of the species that end up below, reducing light levels and water movement. The fronds may attach their holdfasts to shellfish on the seabed, whether the shellfish or their prey like it or not.

* * *

On the West Coast, scientists and managers have been removing the invasive kelp from infested marinas. This summer, workers in Oregon have been removing wakame and other marine organisms from docks and debris moved by in the Japanese tsunami. Controlling spread is critical to halting its impact.


Boat owners: The most important thing you can do is inspect and clean your boat of kelp before you move it.

Read more from the California Invasive Plant Council here.


Wakame has been farmed in Japan and Korea for centuries, since the 1940s in China, and since the ’80s in France (where it is now invasive). It’s consumed for its taste and as a nutritional supplement. Most often served in soups–but also roasted, sprinkled on rice, and pickled–wakame fronds have a subtly sweet flavour and slippery texture. The leaves should be cut into small pieces since they will expand during cooking.

Use kitchen shears rather than a knife to cut fresh wakame. Remove the thick stems, which are not edible.

Cucumber and Wakame Salad
Adapted from About.com

Make 4 small servings.

1 small cucumber, sliced into thin rounds
2 oz wakame seaweed, cut into about 2-inch lengths
4 tbsp rice vinegar
2 tbsp sugar
1/2 tsp salt

Put cucumber in a bowl and sprinkle with salt. Set aside for about 5 minutes, then squeeze cucumber slices to remove the liquid.

Mix vinegar and sugar in a bowl. Add cucumber and wakame and mix well.

Australian recipes, using invasive wild Tasmanian wakame

    { 1 comment… read it below or add one }

    Asian Carp April 17, 2015 at 6:05 pm

    This is funny because I buy wakame at my local ethnic grocer every weekend. To think that the stuff I purchase is imported from Asia and we have some right here in the Bay Area?!!! We need to go back to basics, eat local.


    Cancel reply

    Leave a Comment



    Blue Plate Special Garden Snail

    Summer is coming to a close. It’s time to start harvesting in the garden–and gathering the garden snails.

      EAT ME!
      nopales con huevo

      Prickly Pear

      Fall is here, and the “cactus fig” is in season. Time to plate-up another widespread invader.

        EAT ME!
        Screen Shot 2012-11-18 at 8.02.21 AM

        Sow Thistle

        It’s spring and time to weed. Sow thistle is a delicious invader found throughout the continent.

          EAT ME!

          Lamb’s Quarters

          Lamb’s quarters was a popular spring tonic in the South—an early season edible green—but its leaves are good throughout the summer.       Chenopodium album Native range: Described by Linnaeus in 1753, this European native has been transferred throughout much of the world. Because its spread was rarely recorded, C. album‘s native and invasive [...]

            EAT ME!

            Garlic Mustard

              Alliaria petiolata Native range: Europe, Asia, Northwest Africa Invasive range: Much of the Lower 48, Alaska, and Canada. (See map.) Habitat: Moist, shaded soil of floodplains, forests, roadsides, edges of woods, and forest openings. Often dominant in disturbed areas. Description: Biennial herb. First-year plant has a rosette of green leaves close to the ground. [...]

              EAT ME!




              The common periwinkle, which first appeared in New England in the 1860s, is now found along the coast wherever there’s hard substrate–rocks, riprap, broken concrete, or docks–from Labrador to . . .

                EAT ME!
                Pterois volitans


                Some say it started in 1992 in Miami when Hurricane Andrew smashed an aquarium tank. Don’t blame the weather, others say; in the mid-nineties, disappointed yet softhearted hobbyists…

                  EAT ME!
                  chuka wakame


                    Undaria pinnatifida Native range: Japan Sea Invasive range: Southern California, San Francisco Bay, New Zealand, Australia, Europe, Argentina Habitat: Opportunistic seaweed, can be found on hard substrates including rocky reefs, pylons, buoys, boat hulls, and abalone and bivalve shells. Description: Golden brown seaweed, growing up to nine feet. Forms thick canopy. Reproductive sporophyll in [...]

                    EAT ME!

                    Asian Shore Crab

                    The first sighting of the Asian shore crab in the United States was at Townsend Inlet, Cape May County, New Jersey, in 1988. Though the source is unknown . . .

                      EAT ME!

                      Green Crab

                      Since the green crab was first recorded off southern Massachusetts in 1817, it has been hard to ignore. A few minutes of rock-flipping in Maine can turn up dozens of them, brandishing their claws as they retreat…

                        EAT ME!




                          Nasturtium officianale Native Range: Northern Africa, Europe, temperate Asia, and India Invasive Range: In USA: all lower 48 states, except North Dakota. Found in Alaska, Puerto Rico, and the Virgin Islands. Also southern Canada, Sub-Saharan Africa, South America, Australasia, and parts of tropical Asia. Habitat: Common along stream margins, ditches, and other areas with [...]

                          EAT ME!


                            There are numerous invasive crayfish. We include details for the red swamp crayfish (Procambarus clarkii) and the rusty crayfish (Orenectes rusticus). The same recipes can be used for both species–and many other invasive crayfish. Red Swamp Crayfish Native range: Known as Louisiana crayfish, crawdad, and mudbug, Procambarus clarkii is native to the south central [...]

                            EAT ME!
                            Distinguishing _ Channa argus

                            Northern Snakehead

                            His sister was ailing, and the man in Maryland remembered that, back home in Hong Kong, there was a fish that was considered a delicacy and a restorative. He would make a fish soup…

                              EAT ME!


                              “They live in a wide variety of habitats, colonize new ones readily, and eat everything that fits into their mouths,” says Dr. Peter Moyle of the Center for Watershed Sciences at UC-Davis…

                                EAT ME!
                                Picture 1

                                Common Carp

                                For a bottom-feeder, what is the good life? The common carp isn’t very demanding: any body of water that’s sluggish and murky will do. One catching sewage or…

                                  EAT ME!

                                  Field Notes


                                  Defeating Invaders by Eating Invaders

                                  In some biology classes, students read about invasive species. Last week, in professor Joe Roman’s course, Marine Ecology and Conservation, his students were eating them. Read more here.

                                    EAT ME!

                                    Invaders on the Rise

                                    During the last 200 years, the number of new invasive species has increased worldwide, with more than a third of all first introductions recorded between 1970 and 2014. More new invasions are expected among all groups of species in the near future, with the exception of mammals and fishes. Read the study here.

                                      EAT ME!

                                      Burn the Invaders

                                      Marabu is an invasive plant that has taken over much of Cuba’s abandoned farm lands. Artisinal charcoal from the tree is now the first legal export from Cuba to the United States in more than 50 years. Read more about the plan here.

                                        EAT ME!

                                        Pests for Dinner

                                        New Scientist reports on the annual dinner at the Explorers Club in New York. Gene Rurka, the club’s resident chef, served grilled lionfish, Asian carp sushi, and iguana meatballs with a plum dipping sauce. An actual iguana splayed out on a bed of greens made a feral centerpiece. “I see this as a way of [...]

                                          EAT ME!

                                          Bun Lai, Champion of Change

                                          ETI’s colleague and friend, Bun Lai, is named a White House Champion of Change. His restaurant, Miya’s Sushi, in New Haven, offers the world’s only invasive species menu, featuring dishes made of foraged ingredients that are threatening to the region’s indigenous species. Read more about Bun and the rest of the sustainable seafood champions here.

                                            EAT ME!

                                            “There’s a world of food growing volunteer, if you just know where to look for it.”

                                            Charles Frazier, Cold Mountain

                                              Previous post:

                                              Next post: