Download FAR 2025/17 Annual survey of the Foveaux Strait oyster (Ostrea chilensis) fishery (OYU 5) and Bonamia exitiosa prevalence, intensity, and disease mortality in February 2024

• The Foveaux Strait oyster fishery (OYU 5) is a high value, nationally important fishery.
• A defining feature of the OYU 5 fishery is the recurrent infection by the parasite Bonamia exitiosa (Bonamia)
• Annual research surveys monitor both oyster abundance within the fishery and the prevalence of Bonamia infection annually.
• A dredge survey was undertaken in February 2024, in collaboration with the Bluff Oyster Management Company Ltd on FV Golden Harvest.
• Oyster densities have declined since 2021.
• In 2024, 1755 oysters were tested from 71 stations, with 18.1% testing positive for Bonamia.
• The prevalence of infection is higher than in 2023 (8.7%) and the highest it has been since at least 2015.
• The increased prevalence of infection is expected to affect the number of recruit-sized oysters in the population.