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The global seafood market is at a crossroads. At present, it is structurally in the Stone Age; even with all the technological advances in seacraft, nets, and sonar, it is still largely a system of capturing marine fish that resembles the pursuits of hunter gatherer societies. However, while landings by global capture fisheries have leveled off, and many fish stocks have essentially collapsed, demand for seafood has been rising steadily, leading to the fast expansion of aquaculture.1 Moreover, an even greater demand for seafood may be anticipated if the desertification of agricultural land and exhaustion of freshwater reserves continues.2 Marine aquaculture, or mariculture, does not require arable land or freshwater; it stands, therefore, as the leading contender to supply the added food demand and become the next frontier for humankind’s food.

The world seaweed industry is currently worth over US$7.4 billion, and the potential for increased seaweed use exists in many countries. The species diversity of seaweeds in Mauritius has been extremely well documented in comparison with many local islands and regions, largely due to the work of the Danish phycologist Dr F. Boergesen, published from 1940-1957. The recorded seaweed flora is currently 435 species (59 brown algae, 108 green algae and 268 red algae), which is more than have thus far been recorded in either Kenya or Tanzania, and many more than for any other similar islands in the Indian Ocean. The world seaweed industry is growing rapidly, particularly the aquaculture sector, and possibilities for sustainable seaweed utilisation in Mauritius are discussed. Most seaweed culture for human food occurs in temperate regions, and current successful industries in tropical environments, especially the culture of Eucheuma / Kappaphycus for carrageenans, are in developing countries with low average incomes, often involving the importation of non-indigenous species. Possibilities exist in the aquaculture of seaweeds including in integrated systems for bioremediation and/or as animal feed, as well as the potential for utilisation of abundant species as feed or fertiliser or in small value-added industries. As an example, the worldwide uses of Sargassum, perhaps the most abundant local genus, are discussed.

Seaweed is essentially a potassie fertilizer, being specially rich in potash, but it also contains notable amounts of nitrogen and other elements of plant food, so that it might be terined a complete manner.

Fresh seaweed in undoubtedly a watery manure, containing from 65 to 90 percent of water and it is this fact, no doubt, (the cartage being a more or less expensive feature) that limits its use to those living more or less close to the shore. A part of this useless water may be got rid of by drying the seaweed on the beach for a few days before hauling to the farm. But not withstanding its large percentage of water, seaweed compares quite favourably, weight for weight, with barnyarnd manure, and it has this advantage that it brings to the farm no weed seeds nor insects nor fungus pests. 

Analyses of many Canadian seaweeds, more especially from the Atlantic seaboard, have been made in the Experimental Farm laboratory in Ottawa, and we append in tabular form certain of the data as illustrative of their general composition. 

It’s rare to get good news from the sea. Water ­temperatures are rising, fish stocks are being depleted, and the fish we do eat are increasingly full of microplastics. But the oceans do hold one positive portent: Seaweed. It’s ­regenerative — it can grow about a foot a day — and carbon and nitrogen sequestering. Research suggests that, per acre, it can absorb more than 20 times as much carbon dioxide as a forest. In the U.S. and Canada, entrepreneurs are cultivating it and other macro algae for everything from kelp jerky to capsules containing shots of Glenlivet.

These companies have ambitious plans to grow in 2020, taking up more and more space on shelves and cleaning up more and more oceans. “We are eyes on the blue green economy,” says Chelsea Briganti, chief executive officer of utensil maker Loliware. “Seaweed represents an opportunity everywhere you look.”