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Black Seaweed - Nori
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Black seaweed (nori)

nori on rocks
Photo © 2004 Madelon Mottet
Porphyra abbottae attached to rocks high in the intertidal.

There are a number of species of black seaweed in this area. One of the most popular is Porphyra abbottae which grows into frilly, long slender fronds. It prefers fairly exposed habitats and grows high in the intertidal. It is typically collected in May. In June the cells in the fronds begin to turn into reproductive spores and the plant shrinks and completely disappears from the intertidal over the summer. It cannot tolerate warm temperatures. The spores that are shed by these fronds will probably attach and grow on shells in perhaps 30 feet of water. In this stage of the life history, the plant looks like small colored spots on shells (called the conchocelis stage). The following spring, these "spots" will release the spores that grow into the plants that grow on the shore.
Black seaweed (nori) is among the most valuable of all cultured marine species, and supports an industry worth two billion dollars. There is very little commercial harvest from the wild. Almost all commercial nori is grown on nets, mostly in Japan, Korea, and China. About 20 million dollars worth is imported into North America.
Growing nori is a lot like growing wine. If you can get the right mix of species, habitat, and culture practices, it is possible to produce a product that is worth far more than average. The abundance of natural species and lush spring growth suggests that this area may be capable of producing superior products. Though this area has the right climate for culturing nori, but there will have to be a series grow out trials to determine which species and processes have the best potential in the marketplace.
Locally, nori fronds are hand collected from rocks during low tides and is sun dried and ground into small nibble-sized pieces. This product is produced at Metlakatla for personal consumption as a snack food or as flavoring sprinkles. It is possible that this product could be marketed commercially as sprinkles combined with sesame seeds and flavoring agents.

nori being sun dried
©Madelon Mottet 2004
Local nori being sun dried.

In Asian markets, it is generally ground up and formed into sheets in a sophisticated paper-making process. Most North Americans are most familiar with it as the black, paper like wrapping used to wrap rice in certain forms of sushi. To produce high quality sheets requires that the product be harvested and dried within a few hours, and there are many other issues. (I have translated a Japanese manual on the details of producing quality nori sheets.)

Picture from Wikipedia
Nori that has been made into sheets. The sheets are black when they are made, but turn green if they are heated.

In the best quality species of nori, the fronds are only a single cell thick, and the fronds turn black when they are dried. Porphyra abbottae has both of these characteristics. (However, it may be less tender than the most desirable cultured species.) The single layer of cells can be seen in the picture below.

single layer of nori cells
Photo 2004 ©Madelon Mottet
Single layer of cells in a frond of Porphyra abbottae.

© 2008 Madelon Mottet

Contact information:
RAM Marine Station
333 9th Ave. W, Prince Rupert, British Columbia V8J 2S6, Canada
Telephone/Fax 1-250-624-2097
email: madelon.mottet@gmail.com or Allen Johnson at abalone55@hotmail.com