St. Lawrence species

Laver seaweed

Porphyra sp. There are several genera of porphyria. Genetic analysis is often the only way to identify the species with certainty.

Type of resource

  • Algae
  • Red algae

Status of the resource

  • Not a cause for concern

In season

Processed all year round. Generally as a dried product.

SIZE : Up to 50 cm.

LIFE EXPECTANCY : Less than a year.

LIFE CYCLE : Nori can reproduce in two ways:

  • A neutral cell dissociates from the algae, germinates and forms a new algae.
  • A complex sexual reproduction in which female cells are fertilized by male cells. Spores, called carpospores, are released after fertilization of the egg. As they germinate, the spores become conchocelis, a microscopic filamentous form. The conchocelis in turn release spores, which disperse, attach to the substrate, and develop into a new male or female nori.

Growth starts at the tips, mainly in summer. When young, nori has a greenish color, later turning red to brown. This algae is most visible in spring and summer.

Mother of the sea

Given its complex reproductive cycle, the Japanese could not figure out how to make their traditional nori cultivations more productive. In 1949, British botanist Kathleen Drew-Baker discovered the reproduction process of this algae, paving the way for artificial algaculture of this species. In 1963, a statue was erected in southern Japan and an annual festival is held in honor of the scientist, now known as the “Mother of the Sea”, for having saved the nori industry.

The fronds of this algae are smooth, very fine and translucent, a little like sea lettuce. They vary in shape and are as wide as they are long. Their color ranges from red to dark brown. At low tide, the porphyra loses water and turns green or black, but regains its color when the tide comes in.

Porphyra has no visible stipe. It attaches to the substrate with a holdfast, which can be navel-shaped in the case of Porphyra umbilicalis.

Coastal zone.

Nori does well in the open air. However, it favors shady, rocky environments exposed to waves and currents.

It clings to rocks or other algae in a scattered manner.


Credit : Éric Tamigneaux


Solar energy


Herbivorous molluscs
Grazing fish

MACHINES : Hand harvesting.

Permit required. Cut every other frond at the top of its holdfast with a sharp object. Best harvested between August and October.

Nori is one of the most widely cultivated edible algae in Asia, with crops covering several hundred hectares.

In Quebec, teachers and students at ÉPAQ have succeeded in completing, in a laboratory, the life cycle of a nori, Wildemania amplissima, found in the waters of the St. Lawrence. This paves the way for future cultivation activities.

 Frozen and alive

Nori is one of the few algae that can be frozen without dying after being partially dehydrated. This characteristic is very useful for sea farms, which grow nori on nets that can be dried and then stored in freezers. This allows them to be used later if necessary. For example, in the event of bad weather or disease affecting the sea farm, these nori nets can be thawed, re-hydrated and then implanted in the farming facilities.

Nori is the richest algae in terms of protein, not to mention the minerals, vitamins, and Omega-3 fatty acids it also contains. Some of its compounds are used in cosmetics for their ability to protect against ultraviolet (UV) rays.

Delicate, woodsy flavor similar to that of tea and dried mushrooms, with a seafood aroma. Its popularity in Japanese cuisine is well established: sushi, ramen, onigiri, omelettes, rice, sauces…

In traditional Welsh cuisine, Porphyra umbilicalis is used to make a puree, which is then fried in bacon fat and served with eggs for breakfast. The dish is called laverbread. An original idea for your next brunch?


  • Raw nori is difficult to chew, so it is not much recommended. It is best to toast it before eating, or to use its dried form.

The waters of the St. Lawrence are known for their good quality. However, as algae absorb the elements present in the water in order to grow, it is preferable to make sure that the harvesting site is clean before eating them fresh.

A long wait

In 8th century Japan, eating nori was a privilege reserved for nobles, due to its limited harvest. Initially consumed as a paste, dried nori leaf was finally produced in the Edo period, around 1750, making it accessible to the general public.