Attributions of cause of oyster mortality on the British Columbia coast: oyster growers’ and scientists’ perspectives

Highlights

• Unexplained oyster mass mortalities threaten Canadian west coast shellfish industry.
• Expert elicitation yielded calibrated judgement of causes of oyster mass mortalities.
• Scientists and oyster growers have low agreement about causative factor groups.
• Risk communication can highlight differing opinions and clarify misconceptions.

Abstract

Unexplained oyster mass mortalities threaten to destabilize the oyster industry on Canada’s west coast if left unexplored. A range of potentially causative factors have been identified by the industry and the scientific community but the effects and magnitudes of these factors on oyster mortality risks remain unknown. Through a structured expert elicitation questionnaire, this study presents industry and scientific experts’ calibrated judgements of cause of this multifactorial problem. We document low agreement among scientists and oyster growers with regards to important causative groups of factors. There is some agreement that factors like water temperature, seasonality, bacterial pathogens, affect oysters suspended in water and reared in trays, particularly if they are large oysters. However, both scientists and growers harbored differing views about the age and size of oysters susceptible to mass mortalities and the role of food availability and gametogenesis in contributing to mass mortalities. We discuss potential sources of these differing opinions and misconceptions. Our findings also highlight the need for additional research to resolve some of the uncertainty in experts’ perceptions of cause. Risk communication efforts in the future should focus on these differing perspectives to work toward mutually viable decisions and solutions.

Advani S. & Satterfield T., 2024. Attributions of cause of oyster mortality on the British Columbia coast: oyster growers’ and scientists’ perspectives. Ocean & Coastal Management 251: 107066. doi: 10.1016/j.ocecoaman.2024.107066. Article.

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