Figure 3

The optimal harvesting effort and the maximum of ESY. Some paraments are taken: \(r_{1}=0.5\), \(r_{2}=0.05\), \(b_{1}=0.5\), \(b_{2}=0.6\), \(D_{1}=0.2\), \(D_{2}=0.3\), \(d_{1}=0.2\), \(d_{2}=0.5\), \(\alpha_{1}=0.4\), \(\alpha_{2}=0.3\), \(\sigma_{11}=0\), \(\sigma_{12}=0\), \(\sigma_{21}=0\), \(\sigma_{22}=0\), \(\xi_{1}(\theta)=0.3+0.03\sin\theta\), \(\xi_{2}(\theta)=0.1+0.05\cos\theta\), \(\theta\in [-2,0]\). Red line is with \(E_{1}=E_{1}^{*}=0.2451\), \(E_{2}=E_{2}^{*}=0.0369\), blue line is with \(E_{1}=0.35\), \(E_{2}=0.02\), and green line is with \(E_{1}=0.1\), \(E_{2}=0.2\).