In Prob. 36 assume that you fish for 3 years, then fishing is banned for the next 3 years. Thereafter you start again. And so on. This is called intermittent harvesting. Describe qualitatively how the population will develop if intermitting is continued periodically. Find and graph the solution for the first 9 years, assuming that A = B = 1, H = 0.2, and y(0) = 2.

Data from Prob. 36

Suppose that the population y(t) of a certain kind of fish is given by the logistic equation (11), and fish are caught at a rate Hy proportional to y. Solve this so-called Schaefer model. Find the equilibrium solutions y₁ and y_2?(> 0) when H y2?is called the equilibrium harvest or sustainable yield corresponding to H. Why?

y 2 1.8 F 1.6 1.4 1.2F 1 0.8 2 4 6 8 Fig. 23. Fish population in Problem 38