Extinction scenarios in exploited system: Combined and selective harvesting approaches

This paper illustrates the effects of exploitation for yield maximization in prey–predator system where two predators are competing over same resource. Harvesting the prey (bottom trophic level) for yield maximization causes the extinction of the predators, but exploitation of either predator at MSY level becomes biologically sustainable policy. We show that harvesting multiple trophic levels including the prey species for total yield maximization may be sustainable under equal harvesting effort, but predator species goes to extinction under independent harvesting efforts. We also establish that neither predator goes to extinction if both predator trophic levels (i.e., excluding the prey species) are exploited under independent effort at maximum level; though either predator may be driven to extinction under combined harvesting effort.