Seaweed farming: An opportunity for sustainable livelihoods

13Jul 2020
The Guardian
Seaweed farming: An opportunity for sustainable livelihoods

The economic significance of seaweed farming was recognised in Tanzania in as early as the 1950s when wild seaweed was exported from Zanzibar. Following the collapse of export trade in the late 1970s, seaweed farming started on the Zanzibar Islands in 1989.

In this regard, the development of seaweed farming as a marine resource was seen as an alternative source of income that could play an important role in improving the living standards of the people in the areas. Before the commencement of seaweed farming people relied more on subsistence farming, small scale business (petty business trading) and fishing as their major sources of income. After the commencement of seaweed farming, peoples´ economic activities were replaced by seaweed farming as the major source of income, followed by subsistence farming and small-scale business. Furthermore, studies have shown that more women abandoned subsistence farming in favour of seaweed farming as compared to men. Ownership of items such as radio cassettes, kitchenware, furniture, and clothes increased significantly after the introduction of seaweed farming. Other results include an increase in the number of bank accounts for the respective villages, improved homes for the seaweed farmers, and a reduction on the number of children suffering from malnutrition.

Seaweed farming has had widespread socio-economic impacts in Tanzania, and has become a very important source of resources for women, and is the third biggest contributor of foreign currency to the country. Ninety per cent of the farmers are women, and much of it is used by the skincare and cosmetics industry.

Seaweed farming or kelp farming is the practice of cultivating and harvesting seaweed. In its simplest form, it consists of the management of naturally found batches. In its most advanced form, it consists of fully controlling the life cycle of the algae.

Seaweed farming has frequently been developed as an alternative to improve economic conditions and to reduce fishing pressure and overexploited fisheries. Seaweeds have been harvested throughout the world as a food source as well as an export commodity for production of agar and carrageenan products.  

Several environmental problems can result from seaweed farming. Sometimes seaweed farmers cut down mangroves to use as stakes for their ropes. This, however, negatively affects farming since it reduces the water quality and mangrove biodiversity due to depletion. Farmers may also sometimes remove eelgrass from their farming areas. This, however, is also discouraged, as it adversely affects water quality.  

Seaweed farming helps to preserve coral reefs  by increasing diversity where the algae and seaweed have been introduced, and it also provides an added niche for local species of fish and invertebrates. Farming may be beneficial by increasing the production of herbivorous fishes and shellfish in the area.  

Seaweed culture can also be used to capture, absorb, and eventually incorporate excessive nutrients into living tissue.   

There has been considerable attention to how large-scale seaweed cultivation in the open ocean can act as a form of carbon sequestration to mitigate climate change. A number of academic studies have demonstrated that nearshore seaweed forests constitute a source of blue carbon, as seaweed detritus is carried by wave currents into the middle and deep ocean thereby sequestering carbon. It has therefore been suggested that growing seaweeds at scale can have a significant impact on climate change.

According to one study, covering 9 per cent of the world’s oceans with kelp forests could produce sufficient biomethane to replace all of today’s needs in fossil fuel energy, while removing 53 billion tonnes of CO2 per year from the atmosphere, restoring pre-industrial levels.