Recovery timelines of vulnerable high value species under moratoria: Dealing with uncertain levels of illegal fishing

Illegal fishing (theta(j)) affects recovery time-lines and produce economic losses for having to extend moratoria, especially when targeting high value species. The lack of data concerning the level of theta(j) creates an uncertain context for decision maker to establish duration of moratorium or the need of extending it over time. With the use of a dynamic bioeconomic model on a high value species under moratorium, we calculate how a stock recovery timeline is affected by different states of the nature of possible levels of illegal fishing (theta(j)). This study also calculates the foregone net present value of resource rent when having to extend the moratoria because of existing possible levels of illegal fishing (states of nature theta(j)). Decision matrices without probabilities of occurrence of theta(j) were developed to support decision making concerning recovery timelines. Using stock biomass as the performance variable, the precautionary Minimax decision criteria was applied to select the moratoria timeline decision under possible states of nature of illegal fishing. We found that optimum moratorium duration depends on possible levels of illegal fishing taking place at the moment of deciding when could be possible to re-open a vulnerable species fishery. A Monte Carlo analysis was also undertaken to calculate the risk of falling below the stock recovery target reference point (TRP = B-MSY) with alternative moratoria timelines given a range of possible illegal fishing exploitation rates.