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Figure 12.3 • Sustainable harvests from wild vs. bred populations.Figure 12.3 shows two equal sustainable yields on a given populationgrowth curve, one corresponding to a wild mode of exploitation and theother a breeding mode. In the wild mode, the TC curve (not shown)would start from the right and rise to the left (increasing with capture, asin our fishery example). In the breeding mode, the TC curve would startfrom the left and rise to the right (increasing with feeding and confinementcosts of the larger population). The graph depicts a case in whichthe same SY could be had from exploiting the population in either a wildor a bred mode. Note that just as the annual-profit-maximizing owner ofa wild fishery will never push the population below MSY, the profit-maximizingowner of a bred fishery will never allow the population to grow upto the point of MSY. Can you explain why?The advantage of the wild mode is that the base population is larger,containing more biodiversity, providing more ecological fund services,and feeding is free. The advantage of the bred mode is that the smallerbase population takes up less ecological space, leaving more room forother life, wild or human. Of course the food for the captive populationrequires some ecological space as well as collection. Controlled breedingand genetic engineering would seem to require the breeding mode. Burgeoninghuman populations and the technical thrust toward genetic engineeringpush the shift toward bred genetically engineered populations(e.g., the famous 200-pound salmon). Also, the quest for higher biologicalgrowth rates to keep up with the interest rate favors the bred stock,since a smaller base population yielding the same annual increment obviouslyimplies a higher rate of growth. But smaller populations growingmore rapidly, and ever more dependent on human management for feeding,reproduction, and disease control, surely will increase the instability,brittleness, and vulnerability to uncertainty of the whole bioticsystem.