Status and exploitation of the mangrove and associated fishery resources in Zanzibar

Abstract

The distribution and growth forms of the mangroves on Zanzibar island (Unguja and Pemba) were investigated. Pemba island, with approximately 12 000 ha of mangroves, had nine species; and Unguja island, with 6000 ha, had eight. Average cropping intensities in Pemba island varied between 350–1937 cut plants per ha while in Unguja these were between 777–3567 cut plants per ha. In Pemba, mangrove forests were relatively less heavily exploited compared to those in Unguja, where clear felling was common. Charcoal, lime and salt production are the major activities which involve heavy utilization of mangrove wood.

The fishery resources (shellfish and finfish) associated with the mangrove vegetation were also investigated by examining the composition of fish catches at landing stations in mangrove as well as non-mangrove zones of fishing districts. A survey on the fauna associated with mangrove forests was also conducted. A number of the local commercial fish species were found to be associated with the mangrove vegetation. The fishes of the genus Lethrinus and the rabbit fish Siganus were found to constitute the bulk of the fish caught from waters adjacent to mangroves using movable traps. The mollusc Pyrazus sp., which is commonly used by the local people for food and bait, was found only in the mangroves.