Harvesting of mangrove products, especially for commercial use, is a major direct cause of biodiversity loss in Rufiji, Wami, and Ruvu Deltas. Mangrove products are important to the people of Rufiji Delta because, as they said, “about 75 percent of our life depends on mangrove. The remaining 25 percent is divided between fishing and farming.”7 Data on the extent of harvesting of mangrove forest products in the deltas is scanty and inconsistent, but project officials believe legal harvesting is high, and illegal harvesting is even higher. There is a management plan, but it is not followed effectively.
Harvesting of mangrove products for subsistence use is small scale (Semesi, 1991). Mangroves are harvested and used locally in construction as poles, for boat-making, including for dhow ribs and rails, and to a lesser extent keels, as firewood and charcoal, and for preparing fish traps. Most of the houses in Rufiji and Bagamoyo are constructed with mangrove poles. In some fish landing areas and rice farms, people live in huts built on platforms supported by mangrove poles (Semesi, 1994; field observation).
Income generation is the driving force behind commercial harvesting of mangrove poles. People sell them to traders for eventual use in construction. Mangrove cutting is an economic activity that supports other sources of revenue and provides employment for many in Rufiji Delta and Bagamoyo. For example, in Rufiji Delta, about 60-100 dhows in the Delta employ up to ten youths each as seamen. Boat construction is a thriving business, which engages about six people per dhow.
Harvesting of mangrove products for firewood or charcoal is another important direct cause of the loss of biodiversity in the deltas. While firewood collection is permitted only from dead trees, commercial charcoal production involves felling trees. In Bagamoyo, charcoal-makers stay in the mangrove forests temporarily to harvest these resources. Charcoal-making is more widely practiced in the Ruvu and Wami Deltas than in Rufiji. Charcoal and firewood are sold in Zanzibar, Bagamoyo, and Dar es Salaam. Charcoal-making and firewood-selling are also important sources of revenue and employment for most of the people in Bagamoyo District.