The concept of a safe biological limit has been developed and is being used increasingly in stock assessments to indicate the status of stocks. Stocks are considered to be within safe biological limits if the spawning stock biomass is above a precautionary value which is higher than the level at which recruitment is impaired and fishing mortality is below a precautionary value which is lower than that which would give rise to a high probability of recruitment failure. Poor recruitment or a high level of fishing mortality do not in themselves, therefore, give an indication of the real status of a stock.; Stock is considered to be outside safe biological limits (SBL) when the spawning stock biomass (SSB) (the mature part of a stock) is below a biomass precautionary approach reference point (Bpa), or when the fishing mortality (F) (an expression of the proportion of a stock that is removed by fishing activities in a year) exceeds a fishing mortality precautionary approach reference point (Fpa). However, a stock can be considered within safe biological limits even when the spawning stock biomass is lower than the biomass precautionary approach reference point (Bpa) but the Fishing mortality is lower than the fishing mortality precautionary approach reference point (Fpa) (SSB<Bpa but Fpa<F).; 3. A Limit reference point, usually the stock biomassbelow which recruitment will decline substantially.