1. An overfished stock or stock complex "whose size is sufficiently small that a change in management practises is required to achieve an appropriate level and rate of rebuilding". A stock or stock complex is considered overfished when its population size falls below the minimum stock size threshold (MSST). A rebuilding plan is required for stocks that are deemed overfished; 2. A stock is considered "overfished" when exploited beyond an explicit limit beyond which its abundance is considered 'too low' to ensure safe reproduction. In many fisheries the term is used when biomass has been estimated to be below a limit biological reference point that is used as the signpost defining an "overfished condition". This signpost is often taken as being FMSY, but the usage of the term may not always be consistent.