BULL KELP
Bull kelp (Nereocystis luetkeana) is a giant brown seaweed of the Pacific coast of North America, from Alaska down to California. It's not found in British waters — but it's one of the more remarkable seaweeds in the world, and worth knowing about.
What It Looks Like
Bull kelp has an unmistakable shape: a long hollow stipe, sometimes 30 metres, rising from the seabed to a single gas-filled bulb at the surface, from which a crown of long blades trails out like hair.
The bulb is a float that holds the blades up in the light. Curiously, the gas inside it contains a proportion of carbon monoxide alongside the oxygen and nitrogen — one of the odder pieces of seaweed biology, and still not fully explained.
It Grows in a Single Season
Unlike most large kelps, bull kelp is an annual. Everything — 30 metres of stipe, the float, the full crown of blades — grows from a spore in one season, then dies back over winter.
At peak it can add tens of centimetres a day, which puts it among the fastest-growing organisms of any kind. The forests it forms shelter otters, seals, fish and invertebrates, and they rebuild themselves from scratch every year.
What It Tastes Like
Mild, clean and salty, without the strong iodine note of the larger perennial kelps. The stipe is crisp and firm — genuinely crunchy — while the blades are softer and more delicate.
The texture is the main appeal, and it's the reason bull kelp is pickled more often than it's cooked.
How It's Used
- Pickled — the classic preparation. The hollow stipe is sliced into rings and pickled with vinegar, sugar and spices, producing something between a pickled onion and a cucumber. Widely made along the Pacific Northwest coast.
- As a wrapper — the broad blades hold fish or vegetables for cooking over coals, adding flavour and preventing scorching.
- Dried and ground — as a savoury seasoning for grains, soups and dressings.
- In relish and salsa — the firm stipe chopped fine and used for texture.
Traditional Use
Coastal First Nations of the Pacific Northwest have long used bull kelp for more than food. The hollow stipe was cured and used as storage vessels for oil and fish, as fishing line, and as tubing. The bulbs were used as containers, and the whole plant as a food and a preserving medium.
It's one of the clearest examples of a seaweed used as material as much as as a crop.
Nutrition
Bull kelp contains calcium, magnesium, phosphorus, iron and iodine, along with vitamin A, B vitamins and dietary fibre. Like all kelps it can be high in iodine, and regular consumption of dried kelp or kelp supplements affects thyroid function — anyone pregnant, breastfeeding or with a thyroid condition should take medical advice before using it regularly.
Related
Bull kelp is one of the brown seaweeds. For the species you'll actually find around Britain, see sugar kelp, oar weed and alaria, or our guide to edible seaweed in the UK. The full guide to edible seaweed covers the wider picture.
Seaweed has been a source of savoury flavour for centuries. Sozyë's sauces are brewed from a blend of wild Scottish seaweeds, harvested off the north coast of Scotland.