The winged pearl oyster, Pteria penguin (Röding, 1798), is widely cultured for the production of high-quality mabé pearls (half-pearls) in the Kingdom of Tonga and the Pacific. Mabé pearl culture provides a sustainable, culturally appropriate income source to many remote coastal communities and supports a diverse range of pearl-based livelihoods. Mabé pearls are cultured by attaching hemispherical nuclei to the inner nacreous (mother-of-pearl) surfaces of pearl oyster shells. Successive layers of nacre are then deposited over the nuclei to produce mabé pearls of commercial nacre thickness within 9-12 months. The Kingdom of Tonga is the leading producer of mabé pearls in the south Pacific and has considerable potential for sector development and livelihood support. Despite this, optimal environmental and culture conditions for growth and mabé pearl production by P. penguin in Tonga are unknown. This paucity of information limits the production potential of the mabé pearl sector and its’ associated livelihood benefits to communities in Tonga and the Pacific.