A technique for finding optimal two-species harvesting policies

This paper describes a technique to find the optimal harvesting policy for a Lotka-Volterra ecosystem of two interdependent populations when harvest rate is proportional to harvesting effort and either a single stock is selectively harvested or both stocks are harvested together. A problem that yields to this technique is Chaudhuriʹs (Ecol. Model., 41: 17–25, 1986) previously unsolved problem of harvesting two competing species. The solution reveals that even if two species would coexist in the absence of harvesting, one species may be driven to extinction by the optimal policy if it is sufficiently more catchable than the other. It is suggested that the technique may be widely applicable in ecological modelling, and other recent applications are described.