Consequently, the MSY occurs when net recruitment and fishing mortality are in equilibrium at 50% of the population's carrying capacity (Fig. 10.9).
Moreover, to sustain the population, a fishery would remove only large adults that already have contributed their reproductive output to the next generation. The size of the individuals is critical because only sexually mature adults can reproduce and support the recruitment of the population. Removing the smaller individuals, especially the immature juveniles, will both decrease the overall biomass and diminish the recruitment capacity.
This concept of sustainability is forward-looking, with a view toward balancing the utilization and perpetuation of natural resources. When living resources are harvested, there is an economic incentive to maximize the yield with the minimal amount of effort. Such commercial interests underlie short-term perspectives that generally lead to depletion of the populations at the heart of the enterprise. Maximizing the yield while maintaining the vitality of the harvested populations requires innovative solutions that bridge economics, science, and policy.
How can living resources sustainably be harvested without diminishing the renewal capacity of their populations?
Despite the scientific underpinnings, resource management policies largely have been structured for economic and political purposes. For example, comments about the scandalous waste of raw whale materials (Morch, 1908)—''. . . About 1,600 carcasses were let adrift in one season! Mankind of to-day does not take kindly to wholesale waste of such proportions. . . .''—revealed strategies for increasing profits from whaling. Consequently, within a couple of years the United Kingdom began issuing licenses for utilizing entire whale carcasses rather than
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