Practical ecological knowledge for the temperate reader.

Nereocystis luetkeana - Bull-Kelp

Family: Lessoniaceae [NPS E-flora]


"Nereocystis, an annual kelp that grows primarily in deep waters and rapid tideways, can attain lengths up to 40 metres (130 feet). Internally the plant structure is similar to Macrocystis, and externally the stalk is tough and whiplike, terminating in a single large bladder containing up to 10 percent of carbon monoxide. The long leafy outgrowths from the stalk carry out photosynthesis and reproduction." [FAP Rogers]

"Since Nereocystis is an annual and the large leafy part of Alaria is similar, both these plants have to be harvested after sporing has taken place, otherwise there might be no young plants to provide an abundant supply for the following season. North of Point Sur to Vancouver Island, July is suggested as the earliest month for reaping, whilst farther north in Alaska, August would be the earliest because development is somewhat later on account of the shorter growing season." [Chapman SU]

"...the stipe of the brown alga bullwhip kelp (Nereocystis luetkeana), which can stretch by up to 30% of its length without breaking." [Mouritsen Seaweeds]

"The holdfast of the sporophyte can reach 40 cm (about 16 in) in diameter (but is usually much smaller) and is richly branched to enhance its adhesion to rocks. New holdfast haptera can grow where the stipe is joined to the holdfast. The stipe grows upwards and is usually about 10 m (33 feet) long, but there are records of specimens with stipes up to 36 m (118 feet) in length. This stipe is hollow, about 1 cm (0.5 in) in diameter basally, but wider above. Fibrils of cellulose in the walls of stipe cells are oriented mostly at a 60 degree angle to the long axis of the stipe, allowing the stipe to stretch, especially near the base, when it is stressed by water movements. Individuals with undamaged stipes can withstand impressive amounts of drag." [NPS-E-flora]

Habitat / Range: "Bathymetry: mostly subtidal to about 17 meters (56 feet); rarely extreme low intertidal World Distribution: "eastern Aleutian Islands (Umnak Island), Alaska, to San Luis Obispo County, California" [NPS E-flora]


Food Use

"During World War II, large quantities of this kelp were harvested for food as substitute for the Japanese kombu (Laminaria japonica), only the leafy parts of the fronds being utilized. ...thinner and less tasty than the Japanese kombus, ...[it]... is considered inferior in quality, and its production was terminated shortly after... ." [Tseng]

"At the top of the bladder, there is a clump of very long, broad, and thin ribbon-like blades. They benefit from the rapid growth pattern of Nereocystis and, as a result, are most delicate and eminently edible. When dried and toasted, they are crisp and delicious. The hollow stipe can also be eaten if cut up into rings and toasted or marinated." [Mouritsen Seaweeds]

"Bull Kelp (Nereocystis luetkeana and many other species) Common seaweed, known as kelp, is often seen washed up on beaches after storms. The plant is fast growing and anchors itself to the bottom of the seabed, with long, smooth blades growing from a central float. The plant can be used in many forms. The long whips can be pickled. The leaves can be used to wrap fish and vegetables for roasting. The entire plant can be dried and ground into powder. Several varieties of kelp form vast kelp forests found along the coast. These are important breeding grounds for fish as well as habitat and protection for many species of ocean life." [Jones TDFB]

Other Uses

"One of the most useful species of seaweed to the Vancouver Island Salish was Nereocystis luetkeana (Mertens) Postels and Ruprecht, (common kelp). The Comox and Pentlateh stored oulachen oil in lengths of cured kelp stipes kept coiled in chests, and the cured bulbs were used for storing oil and liquids by all Salish groups on the Island (Barnett, 1955). The broad flat kelp blades were used by the Saanich and other groups to place above and below camas bulbs, clams, deer, seal, and porpoise in steaming pits. As well as providing moisture for steam, the kelp gave flavour to the food (Harry, 1969). Some Island Salish groups placed kelp blades in shallow waters and rivermouths to catch herring spawn. Underhill (1944) described a process for making halibut hooks, in which fir knots were placed inside a hollow kelp stem and buried overnight in hot ashes to make them easy to mold. All Vancouver Island Salish used the long slender stems of kelp to make fishlines. They were gathered from the beach, or cut with a V-shaped implement across which a blade was set. This device was lowered over the stem and jerked with a string (Ravenhill, 1938). The fresh stems were then alternately soaked in fresh water and dried by stretching in the sun or smoke until they were pale coloured. Ropes made by this process were strong and flexible in water, but brittle when dry. Some of the kelp ropes made by the Salish were up to 100 fathoms long (Densmore, 1939). Kelp stems were also used to form the warp threads in baskets, mats, and even blankets (Boas, 1889). Also kelp was used by Salish children to make plugs for elderberry blowguns." [Turner&Bell1]

"Kelp was one of the most useful plants in Kwakiutl technology. The long blades were sometimes used to catch herring spawn, as were those of Macrocystis. They were eaten in the same way (Boas, 1921). The long hollow stipes were used to store oulachen grease and other kinds of oil. They were soaked in fresh water and dried, and one end tied before the grease was put in. Then the other end was tied, and the tube was coiled up and stored in a wooden box for future use. When grease was needed, one end would be untied, the required amount of grease squeezed out, and the end retied (Brown, 1969; Cranmer, 1969). The tubular stipes were also used to make ropes, fishing lines, nets, and harpoon lines, but they could only be used when wet, otherwise they were too brittle (Cranmer, 1969)." [Turner&Bell2]

Kelp tubes were sometimes put into steaming pits so that water could be poured directly on the red hot rocks at the bottom. Some Kwakiutl groups, such as the Koskimo, used to deform the heads of their infants by tying a band of kelp around their heads (Boas, 1921). As a medicine, damp kelp was heated and applied to the stomach and the small of the back of a pregnant woman, in hopes that the child would become as slippery as the kelp; and the delivery would be easy (Boas, 1930). Scabs, bums, non-pigmented spots, and swollen feet were rubbed with the long leaves of kelp. When a wound bled badly a small pebble was placed over the artery and was tied on with kelp (Boas, 1966). The powder from dried kelp leaves was rubbed into a child's head to make his hair grow long (op. cit.)." [Turner&Bell2]

"Without doubt, the most valued marine plant material in traditional Northwest Coast technology is bull kelp (Nereocystis luetkeana). This long-stiped alga was, and is used for many purposes, such as anchor lines, and especially fishing lines. To make the very best line, the stipes were cut by specially trained divers from places where they grow very long and strong. The stipes were then specially cured, by alternately soaking in fresh and salt water, drying and rubbing them along the entire length with dogfish oil until the tissue was completely saturated with oil. This process could take up to a year, according to Ditidaht cultural specialistJohn Thomas (Turner et al. 1983).Then, before it was actually used, it was soaked in water again. Sections of the line were joined together using fisherman's knots, so that lines long enough for deepsea fish like halibut could be made (Stewart 1977). Hooks of split and bent tree knot sections, or dense yew wood (Taxus brevifolia), were attached to the line. Kelp fishing line can be dried and stored for several years.... Bull kelp was also used to make fishing nets, ropes, anchor lines and harpoon lines (U'mista Cultural Centre et al. 1998)" [CPMP Turner]

"Another role for bull kelp is the use of the hollow bulbs and adjoining stalks in the process of steaming wood for bending and shaping. Kelp fronds and other seaweeds llke rockweed were used by the Kwakwaka'wakw as a source of steam in making bentwood cedar boxes (U'mista Cultural Centre et al. 1998).In the manufacture of fishhooks for halibut and other large fish, the dense knotwood of trees extracted from rotten logs in the forest was cut into lengths and shaped, then two or three inserted into a hollow kelp bulb with a little water and sealed in with a plug of wood or moss. The entire bulb was then buried in the hot sand beside a fire on the beach and left overnight. The knot lengths, heated and steamed by this treatment, became flexible. They were bent into the correct shape using a mold, then allowed to cool and dry. Fixed with a barb and bait and tied onto a leader of stinging nettle (Urtica dioica), this contrivance became a perfect blending of the forest and the sea to be used for the benefit of the saltwater people. Yewwood (Taxus brevifolia) bowstaves were treated in the same way, being placed inside a hollow length of bull kelp then steamed to make them soft and flexible so they could be formed to the right shape. Kelp bulbs and hollow stipes were also cured and used to store seal oil, oulachen grease and even molasses (Turner 1998; U'mista Cultural Centre 1998)." [CPMP Turner]

Animal Feed: "Ground seaweed is made entirely of kelps, from both macrocystis and nereocystis, hence generally called kelp meal. Its principal use is as stock feed, and analyses of it show the presence of large amounts of various minerals as well as vitamins A, B, F and G." [Tseng]

Medicinal Uses

"A somewhat peculiar remedy, if remedy indeed it is, for headaches is reported from Alaska. Here the Indians of Sitka take the stipe of the bull kelp (Nereocystis) and place the thin end in one ear and put the bulb on a hot stone so that steam is generated and passes up the hollow stipe." [Chapman SU]

"Dosages (Kelp) — 4–6 (400-mg) tablets (APA); 2–3 tsp powdered alga to 3 ×/day (APA). Contraindications, Interactions, and Side Effects (Kelp) — Class 2d. Not recommended in hyperthyroidism. Long-term use discouraged (AHP)." [HMH Duke]





"Studies done in central California have shown that removal of some blades inhibits growth of the rest of the kelp, indicating that materials used in growth are derived from the blades. A single harvest in early summer cut blade growth almost in half; workers noted that the blades would have to be harvested quite distally in order to avoid a subsequent reduction in growth." [NPS E-flora]

"Another species famous for forming large kelp forests, Bull Kelp provides important habitat for invertebrates, fish, and Sea Otters (Enhydra lutris). Urchins relish it, so where otters are abundant and their urchin prey rare, Bull Kelp flourishes. In one study, 51% of the beached Bull Kelps had telltale urchin grazing marks at the point where the stipe had broken. These sporophytes are low in caloric value, however (just 2.10 Calories per gram of dry weight). Because Bull Kelp is an opportunist, it rapidly colonizes areas stripped by urchins. In Washington State, if urchins are either naturally rare or are removed, Bull Kelp establishes extensive beds and excludes species of Agarum. Where urchins are present, however, they preferentially eat Bull Kelp, allowing Agarum to invade and become established." [NPS E-flora]

"Other work done in Washington State has shown that Bull Kelp is vulnerable to exposure to petroleum products. Weathered diesel was found to be most toxic, with unweathered intermediate fuel oil, unweathered diesel, weathered intermediate fuel oil, unweathered crude oil, and weathered crude showing decreasing amounts of toxicity." [NPS E-flora]

"Bull Kelps from southern British Columbia/northern Washington can survive water temperatures of 18°C (65°F) for at least a week, although they succumb to higher temperatures." [NPS E-flora]


"Short days (8 hours of light and 16 hours of dark), which occur in the fall, inhibit maturation. At maturity, entire spore-forming patches (called sori) are released from the blades, starting near the older, outer tips. The large holes left by these abscissions give the blades a ladderlike appearance before being sloughed. In central California, 80% of the abscission occurs from two hours before sunrise to four hours after sunrise, with an individual releasing spores for two to four days. In British Columbia, abscission occurs only at the beginning of the lowest spring tides each month. Since the sori are produced at or near the sea surface, they have the potential to be widely dispersed, but many sink to the bottom near the parent." [NPS E-flora]

"When the spore-forming organs settle, they release their spores (probably billions from each individual Bull Kelp), which can germinate and develop into microscopic filamentous gametophytes. The release of relatively heavy spore-forming organs insures that final spore release occurs near the sea floor, hence this helps maximize the reproductive potential of this species." [NPS E-flora]


Page last modified on Friday, October 14, 2022 10:08 AM