Since the late 1940's, Zanzibar has exported Eucheuma which has been harvested from wild stocks washed ashore. The main areas where collection took place were the islands of Pemba, Zanzibar and Mafia. From the beginning of this trade, the Government of Zanzibar passed legislation to avoid over-harvesting and introduced a licensing system to prevent over-exploitation. By 1951, Zanzibar was exporting 387 tonnes of dried seaweed.
During the late 1960's, annual export tonnage amounted to 500 – 800 tonnes dry weight, mainly destined for European markets. The exporters were private businessmen, who obtained the seaweed through a system of middlemen. These middlemen purchased dried and wet seaweeds from individual collectors in coastal communities. Harvesting was undertaken by fisherfolk who hand-picked the wild seaweeds during the spring low tides. The most important species exported were E. spinosum and E. striatum (sold under the trade name E. cotonii). Some E. okamurai and E. platycladum was also exported.
At the start of the 1970's, the export trade was taken over by the Zanzibar State Trading Corporation whose lack of experience led to a poor quality mixed product and the consequent decline of the sector. Those private businessmen who had been involved in the trade moved to mainland Tanzania but were unable to re-establish their trade.
The export trade began to recover slightly with the re-entry of the private sector at the beginning of the 1980's.
Apart from the use of seaweed (Ulva and Enteromorpha species) as fish bait by trap fishermen and a green algae used for medicinal purposes in one village (Kipumbwi, near Tanga), no seaweed has been harvested for local use.
In the early 1980's, the University of Dar-es-Salaam recognised the potential for Eucheuma farming in Tanzania and initiated pilot farming activities, funded by USAID. Three coastal villages were selected: Kigombe in Tanga region, Fumba Bay in Zanzibar and Fundo Island in Pemba. The areas were selected because wide reefs on the shores of these localities supported dense populations of seaweeds as the reef flats were protected from violent ocean waves by coral reefs and offshore islands. Pilot farming activities focused on E. spinosum and E.striatum using the off bottom (fixed bottom) cultivation method. The pilot farms were also intended to act as farming demonstration centres for local communities in the area and provide extension services improving the quality of dried seaweed. Three fisheries officers went to the Philippines for practical training on Eucheuma, farming technology and were incorporated into the project on their return.
At all three sites the pilot farms were unsuccessful, attributed to two reasons. Firstly, it is claimed that there was a change in ocean currents and secondly, funds were insufficient to cover the running costs of the farms. In retrospect, these pilot farms should be regarded simply as test sites for seaweed farming as they were never operational as pilot farms or demonstration centres.
