WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2016 27 (CONTINUED ON PAGE 28) Shellfish In the shellfish sector, species that are more valuable than those tried in the late 1990s and early 2000s are farmed. Rather than growing Anadara, farmers are now farming shellfish mainly for production of half pearls. Shellfish farming in Zanzibar started in 2004 and in 2005 half-pearl farming was initiated (Mmochi 2015). Species farmed are Pinctada martensii, P. margaritifera, Pteria penguin, and Isognomon isognomon. From experiments and subsequent farming on Unguja Island, shellfish for pearl production has expanded to Pemba Island and mainland Tanzania, especially southern Tanzania (Mtwara) and Mafia Island off the south coast of Dar es Salaam. The bivalve Anadara is mainly used for conservation efforts in a community-based initiative known as no-take zones on the southwest coast of Zanzibar. In this initiative, juvenile bivalves are held in designated areas and grown to market size while comparing the take and no-take zones. A combination of methods in shallow and deep waters including fencing, nylon baskets, and floating rafts are used. Seed is mostly collected from the wild but sometimes it is purchased from fishermen. There are 11 farmer units engaged in shellfish farming (Fig. 2) and production was estimated at 13 kg (Fig. 3) valued at US$ 26 in 2012. Data on pearl production is not available but it is estimated that about 1,000 pearls valued at US$ 10 to 20 each were produced in 2012 (Mmochi 2015) in Tanzania. The importance of pearl production in Zanzibar is increasing as shown by a recent study on spat collection (Ishengoma et al. 2011) aimed at setting a way for sustainable pearl farming industry. The potential of pearl oyster for bioremediation has been evaluated and pearl production could be a viable economic activity for coastal communities in East Africa (Southgate et al. 2006). However, the main challenge facing pearl production in Zanzibar has been market limitation. All studies show that future pearl production can be an economically viable activity, especially if the market problem is solved. Sea Cucumber Sea cucumbers have become increasingly important as an aquaculture product in Zanzibar, especially following overexploitation and a ban on collection from the wild (Mmbaga and Mgaya 2004). Sea cucumber farming started about five years ago and takes place in Unguja and Pemba, and mainland Tanzania (southern Tanzania, Mtwara and northern Tanzania in Tanga; see Fig. 1). The main species farmed are Holothuria scabra, Actinopyga mauritiana, and A. miliaris, usually farmed in fenced enclosures and cages. Like most animal aquaculture activities in Zanzibar, sea cucumber seed is collected from the wild directly by farmers or purchased from fishermen. There are 15 sea cucumber farmer units (Fig. 2), with 13 in Pemba and 2 in Unguja. Production in 2012 was 64 kg (Fig. 3), valued at US$ 400. Stocking to harvesting requires about 12 months. Sea cucumbers are usually sold fresh but sometimes are boiled and dried. Market prices range from US$ 1-12/piece, depending on the species and size. A number of institutions and researchers are promoting sea cucumber farming A farmer holding sea cucumbers at his farm in Fukuchani village, Zanzibar, Tanzania. Women seaweed farmers working in shallow coastal waters near Paje village, Zanzibar, Tanzania. Seaweed ready for harvest. Milkfish Chanos chanos cultured in Tanzania.
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