More on the Pacific sardine: This is a continuation . In this exercise we explore further the Pacific sardine population using the model . a. If the current level of the Pacific sardine population is...

More on the Pacific sardine: This is a continuation . In this exercise we explore further the Pacific sardine population using the model .

a. If the current level of the Pacific sardine population is 50,000 tons, how long will it take for the population to recover to the optimum growth level of 1.2 million tons? [Suggestion: One way to solve this is to make a new logistic formula using K = 2.4, r = 0.338, and N (0) = 0.05.]

b. The value of r used  ignores the effects of fishing. If fishing mortality is taken into account, then r drops to 0.215 per year (with the carrying capacity still at 2.4 million tons). Answer the question in part a using this lower value of r. Note: The population estimate of 50,000 tons and the adjusted value of r are given in the paper by Murphy . Murphy points out that factoring in growth of

he competing anchovy population makes the recovery times even longer, and he adds, “It is disconcerting to realize how slowly the population will recover to its level of maximum productivity ... even if fishing stops.”