In Northern BC, where the Pacific waters flow around the deep-water harbour of Prince Rupert, Ecotrust Canada is working with Metlakatla First Nation on a regenerative ocean farming project. For locals who take a boat out on the water, it’s hard to miss the bobbing network of buoys on the four sites in and around the harbour.
In this remote region, 50km from the Alaskan border and with approximately 14,000 residents, there has been a growing curiosity about this work. What is a regenerative ocean farm, and what grows there?
There’s a lot to learn about this emerging industry. This guide breaks down key terms and jargon to help you understand the fundamentals of growing seaweed and scallops — and the potential they hold for our food systems, communities, and ecosystems.
Mariculture
Mariculture is the technical term for farming in seawater. It is a combination of the words “marine,” meaning of the sea, and “aquaculture,” meaning agriculture of aquatic animals and plants.
Integrated Multi-Trophic Aquaculture
Metlakatla First Nation is experimenting with a mariculture method called Integrated Multi-Trophic Aquaculture. In this method, multiple species are grown together in the same area, with the aim of achieving mutually beneficial outcomes. For example, when kelp and shellfish are grown together, the kelp could benefit the shellfish by making the water less acidic, and the shellfish could benefit the kelp by making the water clearer. Less acidic water makes it easier for shellfish to produce their shells. Clearer water allows more sunlight to reach the blades of the kelp. Other benefits include extending the harvest season and creating diverse revenue streams for the farmer.
Common to All Three Seaweeds Grown on the Farm
Kelp Anatomy
- While kelp species differ in appearance, they share some common components. Wild kelps anchor themselves to the seafloor using a claw-like organ called a holdfast. On the farm, the holdfast grips a rope strung between two buoys. A tough, flexible stalk called a stipe extends from the holdfast to the gas-filled floats and the blades. The blades absorb energy from the sun, like the leaves on a tree.
Environmental Impact of Kelp Farming
- Locally farmed kelp has a relatively low impact on the environment compared to most foods produced on land and can have site-specific effects on water quality and habitat. Farming kelp requires no fertilizer, pesticides, or irrigation and does not compete for valuable land. Kelp farms are made with ropes, buoys, and anchors and are tended by small boats.
- During the growing season, kelp absorbs carbon and other nutrients from the water, which can be beneficial in acidic water or water with excess nutrients due to sewage or agricultural runoff. The time it takes for these nutrients to be stored depends on how quickly the kelp breaks down, which varies depending on the conditions at each site. Wild species can also use the kelp farm as a habitat. Depending on which species choose to inhabit the farm, this can be beneficial or detrimental.
What does Metlakatla’s Ocean Farm Grow?
Sugar kelp (saccharina latissima)
| Description | Named for the sweet-tasting powder that forms on the blades when dried, sugar kelp is currently the most farmed kelp species in Europe and North America. Sugar kelp is prized for its fast growth rate and wide variety of uses. | |
| Nutrition | Relative to other seaweed species, sugar kelp is high in iodine. It is also rich in both carbohydrates and protein and contains all essential amino acids. Eating a small amount of seaweed each day is the best way to enjoy its nutritional benefits. | |
| Culinary Uses | Sugar kelp is already being used in plant-based burgers, pasta, and seasonings and its culinary applications continue to grow. For preservation, freshly harvested sugar kelp is typically blanched and frozen, or dried. | |
Winged kelp (alaria marginata)
| Description | Winged kelp features a long wavy-edged blade with a raised mid-rib. Near the bottom of the stipe, there are several short blades used for reproduction. | |
| Nutrition | Winged kelp is an excellent source of calcium as well as many other vitamins and minerals including B-12, potassium, and iron. It also contains a high amount of fucoidan, a chemical currently being researched for a variety of potential medicinal purposes including treating cancer, arthritis, and high blood pressure. | |
| Culinary Uses | Winged kelp is a relative of wakame, a key ingredient of Japanese miso soup. Its noodle-like texture and savoury flavour make it a delicious addition to chili. It also excels as a wrap for cooking fish. | |
Giant kelp (macrocystis pyrifera)
| Description | Giant kelp, as its name suggests, is the largest seaweed on earth, growing to as long as 45 metres over its life span in the wild. Its ruffled blades float on the surface, each supported by a float. |
| Nutrition | Giant kelp contains a wide variety of vitamins and minerals. It is particularly high in fibre, protein, and essential fatty acids. |
| Culinary Uses | The mild briny taste of giant kelp makes it a versatile culinary ingredient. It is a great addition to dishes containing whitefish, such as halibut and lingcod. It has even been dipped in chocolate and eaten as a dessert! |
Yesso scallops (mizuhopecten yessoensis)
| Description | Scallops have eyes and can swim! Like oysters, clams, and mussels, scallops eat by filtering small particles from the seawater. Metlakatla’s ocean farm currently grows Yesso scallops, a species native to Northern Japan. |
| Nutrition | For the same number of calories, scallops have a protein content near that of chicken breast, with less fat and cholesterol. |
| Culinary Uses | The most common part of the scallop that is eaten is the large white adductor muscle. The mantle and the gonad are also edible. Searing scallops on both sides in a hot frying pan is a simple and delicious way to enjoy them at home. |
That’s all the mariculture lingo to share with you for now. We’ll update this page with more information as needed. Learn more about our Food Systems program here.
Sources
- Amanda Swinimer, The Science and Spirit of Seaweed: Discovering Food, Medicine and Purpose in the Kelp Forests of the Pacific Northwest, Harbour Publishing, 2021
- Sæther, M., Diehl, N., Monteiro, C. et al. The sugar kelp Saccharina latissima II: Recent advances in farming and applications. J Appl Phycol 36, 1953–1985 (2024).
- My Food Data – Nutrition Comparison Tool, accessed January 15/2025, https://tools.myfooddata.com/nutrition-comparison/171140-167742/200cals-200cals/1-1/1
- Memorial Sloan Kettering Cancer Center – Fucoidan, accessed January 15, 2025, https://www.mskcc.org/cancer-care/integrative-medicine/herbs/fucoidan
[Published January 29, 2025]