Frequently Asked Questions

Can you eat it?

Yes, Undaria is edible. It is an aquaculture species where it is native in Japan, China and Korea. The Japanese food name for Undaria and other related species is wakame. Wakame from the US West Coast is not Undaria pinnatifida, but a related native species. If you have eaten miso soup in a Japanese restaurant you have most likely eaten Undaria. However, we do not recommend eating Undaria that has been growing in polluted waterways.

Why not harvest it for food or fuel?

Currently there is not enough Undaria in the US to make commercial harvest viable. Harvesting invasive species for commercial purposes might help reduce populations, but developing a market for these species also creates an interest in making sure these populations continue.

Why is Undaria a threat on our coast?

With its rapid growth rate and high fecundity, Undaria is considered one of the world’s 100 worst invaders. In some places where it has invaded it has become a major problem for aquaculture (see Impacts page). It is a nuisance species for boaters and it has been demonstrated to outcompete native algae species on which many other marine species depend.

What will it do in the United States if we don’t get rid of it?

It is impossible to predict with certainty what Undaria will do in any new location, however, we know it has caused problems for people and natural ecosystems elsewhere (see Impacts page). Given this history, it makes sense to follow the precautionary principle and to act early to try to prevent spread rather than deal with a problem later when control becomes more difficult and costly.

Undaria has been in my marina for 10 years. It doesn’t seem to be doing anything bad.

Some non-native species do no apparent harm. Others do, sometimes years after they arrive and become established in a new location. Most non-native species are not well studied. However, one of the most reliable ways to predict whether a non-native species will become a pest is to look at its history of invasion elsewhere in the world. In the case of Undaria, negative impacts on the shellfish industry and on natural ecosystems have been documented.

To date, with one exception, all the known Undaria populations in the US are in artificial environments such as harbors and marinas, where it lives with many other native and non-native species that foul boats and marina structures. From an environmental standpoint, we are most concerned about Undaria spreading in to natural ecosystems. It has spread into a kelp forest at Catalina Island, a major recreational diving, fishing and boating location. As of yet no studies have been done there, so we do not know how it might be impacting native species and ecosystems.

Isn’t it impossible to get rid of marine invasive species?

No. There are several documented cases of eradication of invasive marine species. Eradication is easier and less costly if it is done early, before the population becomes too widespread.

How did it get here? Did it come over in ballast water?

Undaria may have originally arrived in the US via ballast water from an overseas commercial ship, but spread along the West Coast since its initial arrival apparently has been aided by small boats, to which it readily attaches. To date, Undaria has appeared mainly in small craft harbors and at a popular mooring spot on Catalina Island. It has not yet been found along the open coast in the intertidal zone or in kelp forests between infested harbors, as would be expected if it was spreading rapidly on its own.

Is it spread by other species?

There is no evidence that other species spread Undaria. The pattern of where Undaria appears implicates small boats as the main route of spread.

What should I do if I think I see it?

Remove it from the water if you can do so safely. Photograph it, save the specimen if possible (see How to Press Algae), and email the photo to us along with some basic information by clicking here (email link) or create an account with us and upload your observation information and photos directly (Sign Up Link). Do not dispose of it back in the water.