Zanzibar sea farmers grow sponges to survive increasing ocean temperature

By Nneka Nwogwugwu

Research by the State University of Zanzibar shows that more than 90% of seaweed farmers on the island are women, and that they have seen changing water temperatures, rainfall patterns and ocean salinity hit production in recent years.

Thomson Reuters Foundation news posted the research on its site last week Wednesday.

Using data that shows Zanzibar warming over the past 40 years, a 2012 study from the Global Climate Adaptation Partnership and Britain’s former Department for International Development, projected the island’s average maximum monthly temperature would rise by 1.5 to 2 degrees Celsius by the 2050s.

Nasir Hassan Haji never thought of herself as a farmer or a swimmer, but as she waded into Zanzibar’s blue waters with goggles pulled over her headscarf to examine her floating sponge farm, she realised she had surprised herself by becoming both.

Alongside 12 other women in Jambiani village on the Indian Ocean coast, Haji has come to rely on the climate-resilient, natural sponges bobbing on thick ropes where they grow for months before the women harvest, clean and sell them to shops and tourists.

“I learned to swim and to farm sponges so I could be free and not depend on any man,” Haji said later, sitting on the floor in her home on the Tanzanian island.

Before farming sponges – which resemble a white, textured rock but are actually simple, multicellular animals – Haji cultivated seaweed, until increasing ocean temperatures fuelled by global warming made it difficult to grow her cash crop.

Haji and other women dependent on the ocean for their livelihoods – from seaweed farming to fishing and tourism – have seen warmer, rising seas threaten their work, but they are adapting by finding ways to diversify what they do to get by.

Local conservationists say this has become even more urgent as COVID-19 travel restrictions around the world have stalled the flow of tourists to the tropical holiday destination, forcing islanders to look to nature to eke out a living.

“We are seeing people who relied on tourism now turning to fishing or cutting wood from the forests… It is a tug of war between economics and the environment,” said Mohamed Okala, a conservationist and tour guide from Jambiani.

Locals say they have already seen fish stocks depleting over the past year. But for women like Haji, sponge farming has acted as a buffer against both the climate and economic shocks the island has endured.

The sponges are only sold locally for now to minimise costs and push a larger share of the revenue to the women farmers, said Vaterlaus.