Mangroves in Zanzibar have a high value for biodiversity and scenic beauty. However, mangroves are susceptible to anthropogenic and natural environmental disturbances. Although global mangrove monitoring systems exist, it is the practitioners focused on small mangrove areas who are knowledgeable about the area in which they work. This study examined the change in mangrove cover in Chwaka Bay and Menai Bay, between 1973 and 2020, using Landsat satellite data. The transformed divergence (TD) index and Jeffries–Matusita (J-M) distance were used to calculate separability of land cover classes before classification. The overall accuracies ranged between 82.5 and 92.7% for Chwaka Bay and 85.5 and 94.5% for Menai Bay. The kappa coefficients (ĸ) were in the range of 0.72–0.90, while the producer’s and user’s accuracies were between 72 and 100%. Chwaka Bay’s annual decrease in mangrove cover between 1973 and 2020 was 48.5 ha, compared to Menai’s 6.8 ha. The loss of mangroves in Zanzibar is linked to illegal timber/pole cutting, firewood collection, charcoal burning, unsustainable aquaculture, and agricultural and urban development. Others are changes in environmental conditions that are suitable for mangroves and climate change. This study is crucial in providing a basis for the ecological restoration and management of Zanzibar’s mangrove ecosystem.

The aim of this study was to examine the challenges of the policies and regulatory framework and strategies for the sustainable mangrove management in Zanzibar, from 1890 to present. The study collected both primary and secondary data. The secondary data were collected through the a review of previous policies, legal documents, by laws, ministry/department reports, research reports, newspapers and articles. The primary data were mainly collected through focus group discussions (FGDs) and semi-structured interviews. The study found that, before Zanzibar became a British protectorate in 1890, the forests were communally managed with the guidance of forest guardians, chiefs and elders. The colonial government enacted a number of land administration laws, policies, and arrangements aimed at conserving the natural resources, including the mangrove forests. From 1930 to the end of the Second World War (WWII), mangrove forests were severely degraded because the colonial government paid little attention to their conservation and management. The policy arrangements put in place after independence, such as the National Forest Conservation and Management Act of 1996, laid the legal groundwork for the introduction of the participation of the local communities in the conservation of mangroves. However, they were not sufficient enough to promote the sustainable use of mangrove forests. This study proposes that there is a need for more inclusive and diverse regulations. Furthermore, for the effective conservation and management of mangroves, conflicting laws and responsibilities between government departments should be harmonized.