Effective co-management and long-term reef fish recovery from severe coral bleaching: Insights from Misali Island, PECCA, Tanzania

Misali, an uninhabited islet along the east coast of Pemba Island off the mainland Tanzanian coast, is a biodiversity hotspot and Marine Protected Area (MPA), consisting of a core non-extraction zone (NEZ) surrounded by a larger area where some artisanal fishing is allowed. Within a year of receiving official protection under a co-management agreement, the island underwent a catastrophic bleaching event in 1998, and funding and enforcement in the protected area have been inconsistent since a restructuring of management in 2006. In this study, we investigate current health of the island's fish community, and report 186 observed fish species. We estimate that, including unseen species and those outside the study area, the total species richness may be comparable to the historical baseline of 244 species; however, this represents a decline from the 270 species estimated in 2001 and the 350 species observed in 2004, after several years of successful protections. Patterns of species richness over time likely reflect changes in management effectiveness and engagement of Misali's fishing communities. Diversity of indicator (Chaetodontidae) and keystone (Scarinae) taxa were comparable to historical levels and greatest inside the NEZ, suggesting continued reef health and resilience. However, we found no other significant differences between fish communities inside and outside the NEZ, which observations indicate is poorly enforced, and the disproportionate loss of large predatory fish species may indicate overfishing. The case study of Misali suggests that a temporary reduction in fishing pressure while the island was recovering from a severe bleaching event may have had long-lasting benefits for reef health and resilience. For future management, we recommend consideration of species-specific protections, a possible re-designation of NEZ boundaries to include more unique habitat types, and reintegration of local fishing communities into MPA co-management.