We study the economic impact of the viral disease AVG, its stochastic transmission across abalone reefs in southern Australia, and the optimal management response as AVG approaches an uninfected reef. Using conservative estimates of the virulence and mortality rates associated with the disease, we find it optimal to maintain the pre-AVG steady-state biomass on reef j until AVG has reached reef j - 1. The size of the optimal harvest when AVG has reached reef j - 1 is significant, ranging from 85% of the pre-AVG steady-state stock plus its annual growth, to 100% when the mortality rate associated with the virus reaches 80%. Increases in the probability of transmission, P, also increase the size of the drawdown but to a lesser extent than the mortality rate. A regime shift in the intrinsic growth rate following infection also plays a central role in determining the level of pre-emptive harvesting.


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