Maximum sustainable yield (MSY) is the greatest quantity of biomass that can theoretically be harvested from a system repeatedly without reducing its capacity to replace that biomass. In IB ESS subtopic 2.2, MSY is equivalent to the system's net primary productivity or net secondary productivity and is HL-only content.
How MSY Works
A system gains biomass through productivity but loses biomass through cellular respiration. Net productivity (NP) is the biomass remaining after respiratory losses:
For example, if a population has gross productivity of and respiratory losses of , its net productivity is:
