Photographer: Ton Koene/VWPics/Redux

Mystery Disease in Warming Ocean Halts Zanzibar Seaweed Plan

Zanzibar, one of the world’s largest producers of seaweed, is unable to increase production of the sushi covering because of a mystery disease thought to be caused by warming oceans.

The island nation, off the coast of Tanzania, expects to produce 16,000 metric tons of dry seaweed this year, unchanged from last year, Juma Ali Juma, a permanent secretary in Zanzibar’s fisheries ministry, said in a phone interview Aug. 26. The government is targeting output of 20,000 tons by 2020, the Dar es Salaam-based Daily News newspaper reported Aug. 24, citing Zanzibar Agriculture Minister Hamad Rashid Mohammed. Output in 2014 was 13,000 tons, according to the newspaper.

“Because of climate change, the water temperature is heating yet the seaweed needs cool water,” Juma said. “So it has developed a sort of disease for which we are now undertaking research. We have asked the Food and Agriculture Organization to give us some assistance because they are well versed in this kind of research.”

Zanzibar ranks as Africa’s largest and the world’s seventh-biggest producer of seaweed. The global market for the aquatic plant is about $5.6 billion, according to the FAO. The world’s oceans are warmer than at any point in the past 50 years, with the top layer heating up at a rate of 0.2 degrees Fahrenheit per decade, according to the U.S. Environmental Protection Agency.

Prices for Zanzibari seaweed have fallen about 38 percent this year to about 370 Tanzanian shillings ($0.17) per kilogram (2.2 pounds) because of increasing production in competing nations like China, Indonesia and the Philippines, according to Juma. That’s also hampering growers’ plans to boost production, he said.

Seaweed earned Zanzibar 9 billion shillings in 2015, the third-largest foreign-currency earner after tourism and cloves. About 24,000 households, 80 percent of them headed by women, grow seaweed on the semi-autonomous island.

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