Embracing Uncertainty in Fisheries Reference Points

Fishery reference points are typically derived using point estimates for uncertain quantities such as natural mortality and stock-recruit relationships.  These uncertainties are only taken into account in a post-hoc manner, by setting fishing mortality targets below the estimated F_MSY as part of a precautionary approach to management.  I discuss a method to integrate parameter uncertainty directly into the reference point calculations. Estimates of F_MSY that incorporate uncertainty are often lower than traditional estimates, especially for less resilient “low steepness” stocks. The method also allows for evaluation of the tradeoff between the loss of expected yield from fishing below F_MSY, and the risk of overfishing or stock collapse.   As an example, I show that at the same yield level, an overall reduction in fishing mortality is more effective in reducing the risk of overfishing or stock collapse than implementing a marine reserve.