Zanzibar Seaweed: Sourcing Guide

Overview

Zanzibar is the centre of Tanzania’s commercial seaweed industry — almost entirely Eucheuma denticulatum (“spinosum”), farmed mainly by women’s groups using off-bottom/peg-and-line methods on the intertidal flats of Unguja and Pemba (Paje, Jambiani, Bwejuu, Fumba, and sites across Pemba). A smaller, separately-measured mainland Tanzania sector (Tanga region) also exists and is reported in wet weight rather than the dry weight used for the Zanzibar figures below — the two are not directly comparable, and widely-circulated “100,000+ ton” Tanzania figures are wet-weight, roughly 10x the dry-weight export-relevant volume.

Production

Zanzibar’s dry-weight production (Zanzibar Statistical Abstract, as compiled by Good Neighbors Tanzania’s 2023 value-chain survey): 16,724t (2015), 11,114t (2016), 10,981t (2017), 10,425t (2018), 9,908t (2019), 8,785t (2020), 10,531t (2021). An earlier UNIDO estimate put 2012 spinosum output above 15,000 tonnes, roughly a third of the world’s spinosum trade at the time, up from under 1,000 tonnes in 1990.

Kappaphycus alvarezii (“cottonii”) has effectively collapsed as a Zanzibar crop — from being recorded jointly with spinosum (no price difference) before 2001, to just 1-130 tonnes/year since 2015 against spinosum’s 8,700-16,700 tonnes/year in the same years. Every source reviewed for this guide (UNIDO, REPOA, Good Neighbors, The Nature Conservancy) attributes this to repeated “ice-ice disease” outbreaks and rising seawater temperature, not to farmers abandoning the species by choice.

The number of registered seaweed farmers has fallen by roughly a third over the past decade — from 23,654 in 2011 to 15,859 in 2020 — attributed to low farm-gate returns in what multiple sources describe as an oligopolistic buying market, compounded by the climate-driven cottonii losses above.

Export & Trade

Roughly 98-99% of Zanzibar’s seaweed leaves the islands raw and dried, sold to carrageenan processors in Denmark, China, South Korea, the USA, Spain and France. Export value: $7.2M (2013), $1.6M (2016), $4.0M (2019), $5.4M (2020, +35% year-on-year). Export volume peaked at 11,961 tonnes in 2021 in the series reviewed here.

Zanzibar’s own realized FOB export price has consistently trailed every major comparator producer by a wide margin — $386-471/tonne (2015-2017) versus $700-7,600/tonne for Indonesia, the Philippines, Malaysia, Japan, Chile and Taiwan in the same years. REPOA’s 2021 policy brief attributes this directly to Zanzibar exporting almost exclusively raw, unprocessed seaweed rather than carrageenan or other value-added product — the same raw-vs-processed price gap shows up locally too: one 2011 survey found seaweed powder selling for roughly 20x the price of raw dried seaweed by weight.

Thirteen licensed companies currently export Zanzibar seaweed, led by the government-owned Zanzibar Seaweed Company (ZASCO, formerly the Zanzibar Seaweed Trade Cooperation) alongside private exporters including C-Weed Corporation, ZANEA Seaweed Co. Ltd, Zanque Aqua Farm and S.M Rashid Investment Limited. A 2% government export tax applies on sales value.

Quality Standards

The Zanzibar Bureau of Standards’ draft national standard PCD 435:2022 (WTO-notified 2023) sets the export specification for dried raw seaweed: a minimum 45-day culture period, single-species lots free of visible ice-ice disease or epiphytism, and three grades by Clean Anhydrous Seaweed content (Grade A ≥90%, Grade B ≥80%, Grade C ≥70%). Maximum moisture content is set separately by species — 35% for cottonii, 30% for spinosum — with maximum 1% sand and 3% other impurities/debris, plus heavy-metal limits (arsenic, lead, mercury, cadmium). A companion standard, PCD 436:2022, covers processed seaweed powder (maximum 13.5% moisture) made only from PCD 435-compliant raw material. Both standards were still formally “draft” as of their 2023 WTO notification.

Local Value Addition

Local processing remains small (under 2% of output) but real: the Zanzibar Seaweed Cluster Initiative, founded by marine scientist Dr. Flower E. Msuya, trains women’s groups to turn seaweed into soap, body creams, massage oil, powder, and food products (cakes, cookies, jam). Named farmer groups and cooperatives include JUWAMWAZA (Zanzibar Seaweed Farmers Association), JUWAMPE (its Pemba counterpart), and the Paje-based Seaweed Centre Company Ltd and Mwani Zanzibar Co. Ltd. On the institutional side, a 2020 “Red Seaweed Promise” partnership between The Nature Conservancy, Cargill and C-Weed Corporation has trained farmers in three northern villages on improved, lower-impact farming methods; separately, a World Bank-funded $117 million fisheries/aquaculture project (TASFAM) is funding a seaweed processing factory at Muungoni village, alongside an earlier-announced North Pemba processing plant (TZS 7.4-8 billion, reported variously as a 30,000 t/yr facility) built with UK partner Nutri-San Limited.

A Note on Conflicting Figures

Two credible sources disagree on Zanzibar’s global ranking among red-seaweed producers: REPOA (2021) places it 3rd in the world after Indonesia and the Philippines; Good Neighbors Tanzania (2023) places it 4th, after Indonesia, the Philippines and Malaysia. Neither claim is preferred over the other here.