2.2.26 (HL)—Maximum sustainable yield

Maximum sustainable yield is the largest harvest rate that can continue without reducing the population’s long-term ability to replace itself.

Recruitment and growth vary with population size and environment. A target is sustainable only when harvest stays within replenishment and uncertainty is allowed for.

A fishery adds 800 tonnes in a year but removes 900; the 100-tonne deficit means that quota is not sustainable.

No. The safe harvest rate must fall with replenishment, or the stock declines.

MSY is not the biggest catch ever recorded; it is a continuing rate under stated conditions.

In ESS, the maximum sustainable yield of a producer or consumer system is bounded by its net primary or net secondary productivity—the biomass added after the organism's respiratory costs. Harvest above that replenishment reduces the productive store. Because productivity varies with stock size and environment, a precautionary quota should remain below an uncertain estimate rather than treating MSY as a permanent number.