Use of Epinephrine Bitartrate to Induce Settlement in Hatchery-Reared Blacklip Rock Oyster Saccostrea spathulata

The blacklip rock oyster Saccostrea spathulata has been identified as a promising candidate species for commercial aquaculture, particularly in the tropical Asia Pacific region. Currently, however, commercial production is constrained by unreliable spat production in hatcheries, with low and variable settlement rates proving a major issue. Improving larvae settlement rates during metamorphosis is a critical step toward establishing a fledgling tropical rock oyster industry. To this end, the present study examined the effects of both salinity and epinephrine bitartrate exposure on oyster settlement, survival, and spat size. It was found that salinity, epinephrine dose, epinephrine exposure and their interactions significantly impacted both oyster settlement and survival. Notably, an epinephrine dose of 1.8 × 10–4 M yielded the highest settlement rates (>30%) and was most effective at higher salinities (≥25). Survival was generally high (>75%), however, appeared to be favored by low salinities (10) and exposure to lower epinephrine dose. Finally, spat size was positively affected by increasing salinity and tended to decline with increasing epinephrine dose. Given the clear impact of the production variables reported in this study, it is envisaged that these findings can be used to enhance the production efficiency of cultured tropical rock oysters and thereby support this emerging aquaculture industry.