a wide view of rows of red seaweed growing in shallow water, with people tending to the rows
Pemba Island, Tanzania Seaweed farmers maintaining their Spinosum farms at low tide in northern Pemba © Sébastien Jan


The Promise of Restorative Aquaculture Solutions

Where seaweed thrives, people and nature can, too.

Headshot, Lucy Magembe
Lucy Magembe Country Director, Tanzania


Seaweed farming is the third largest export industry in Tanzania—it employs over 25,000 farmers, 80 percent of whom are women. But as the planet’s ocean temperatures rise, the people who depend on coastal waters are at risk—and the very labor upon which they rely may be accelerating the decline of sensitive marine habitats. 

Seaweed aquaculture, the farming of seaweed in coastal waters, is an incredibly important industry to rural Tanzanian women, and also serves as an alternative to overfishing. But in recent years, the industry has been stagnating due to issues such as changing water quality conditions and poor seedstock—as well as the impacts of unsustainable farming practices.

However, when farmed well, seaweed aquaculture has the potential to be ecologically restorative and provide ecosystem services. In Tanzania, the marine areas in which seaweed farming are most established are actually among the highest priority regions to protect on the continent.

a graphic representation of seaweed farming in shallow water
Off-Bottom (Shallow Water) Farming Example of seaweed farming production method being used in Tanzania © Colin Hayes/TNC

Since The Nature Conservancy (TNC) first arrived in Tanzania in 2006, we have been partnering with local communities and the Tanzanian government to protect the country’s most ecologically important places. Take the co-benefits for marine habitats and water quality with its importance to thousands of livelihoods, and it becomes clear why seaweed aquaculture is a new and important focus of TNC’s work.

As such, I’m excited to announce the launch of our new community empowerment and environmental training program for seaweed farmers on Pemba Island, part of Tanzania’s Zanzibar Archipelago. This program is being conducted in collaboration with local suppliers, government partners, universities, and with Cargill through their new sustainability initiative, the Red Seaweed Promise.

Sustainable Seaweed Farming in Zanzibar Seaweed farming is a large industry in Tanzania, employing 25,000 farmers, 80% of whom are women. TNC is collaborating with Cargill, C-Weed Corporation and the government to train seaweed farmers on best management practices that would protect the environment, as well as increase productivity.

The majority of the seaweed that is farmed in Tanzania is produced, dried, and sold for use as carrageenan or agar thickening agents that are used in food products, such as ice cream and cosmetics. But there is more potential still: tropical seaweeds may prove capable of addressing other key societal needs—including sustainable animal feeds, biofuels, pharmaceuticals, and nutraceuticals.

Over the last year, TNC has been working to understand and identify the key challenges and opportunities within the seaweed aquaculture industry in Tanzania, evaluating the goals and priorities of stakeholders and farmers, and assessing where learnings from other geographies could help advance sustainable development in a way that benefits the ocean environment, coastal communities, and local economies.

Our academic, government, and industry partners have helped us identify the challenges for Tanzanian seaweed aquaculture, as well as opportunities for TNC to work with local farmers and stakeholders in addressing them. Major challenges that Tanzanian seaweed farmers and their surrounding environments are facing include the unsustainable use of mangroves as seaweed stakes, damage to seagrass, and warming water that is causing increased seaweed disease and low production. Protecting these environments while supporting seaweed aquaculture, especially through education and partnering with local women, is essential to conserving our waters and wildlife.

seaweed grows in rows in shallow water, with sea stars interspersed throughout seaweed
Pemba Island, Tanzania Spinosum farm and neighbouring sea stars exposed during low tide in Mjini Kiuyu – North Pemba © Sébastien Jan
boats of seaweed in shallow water, with people tending to them
Pemba Island, Tanzania Seaweed farmers head back to the beach unloading their boats full of freshly harvested Spinosum in Northern Pemba © Sébastien Jan

We see significant potential to improve and advance the sustainable development of seaweed farming for both the social and environmental benefit of Tanzanians. Over the next few months, we are working with local farmers in Unguia and Pemba Islands, part of the Zanzibar archipelago, to improve the efficiency of seaweed farming with a focus on trainings in better environmental management practices, smart seaweed farm siting, and improved maintenance and farm design.

I was humbled to hear from Sada Himidi Selemani, a member of the Tumbe village’s seaweed farmers group, Ipo Sababu, about the co-benefits of our conservation program for local women in Northern Pemba:

“I am happy to participate in the new training program. Local women seaweed farmers are excited to gain insight into how to improve our seaweed production, so we can earn more for our families but also look after our environment.”

The bounty off the coasts of Tanzania has empowered many women like Sada to support their families and communities over the years. As the world faces ecological challenges too big for any one nation to overcome alone, we must work together to ensure that nature and people can thrive everywhere. Seaweed is a reminder that a sustainable path is possible.

Headshot, Lucy Magembe

Lucy Magembe is the Country Director for Tanzania.

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