FMSY

or F_MSY

the fishing mortality rate which, if applied constantly, would result in maximum sustainable yield. Can be estimated from simple biomass-aggregated production models or from age-structured models that include a stock-recruitment relationship. Reality applies, however, and as the ocean conditions change a constant fishing mortality of F_MSY would give varying catches and eventually overfishing would result. A 2/3F_MSY is used to avoid overfishing. Fishing at this level means fishermen use only two-thirds of the effort needed to achieve maximum sustainable yield but they catch 80-90% of the MSY. Their catch rate is higher