Application of a threshold policy in the management of multispecies fisheries and predator culling.

Yodzis discusses how the differing biological assumptions as to predator interference on the forms of predator-prey models can influence the conclusion to be drawn from multispecies population models with respect to the way predators affect human harvesting of natural populations. To deal with these intricacies related to biological assumptions and fishery management policies, a specific management strategy called threshold policy is proposed. It is shown that its application to the same models analysed by Yodzis leaves the behaviour of the managed population less sensitive to the underlying biological features and assumptions as well as parameter uncertainties. The same management strategy is proposed for the same models in the context of the timely issue of predator culling in fisheries. Interestingly, the fishery yield for each model is exactly the same despite their different biological assumptions.