Fish stocks outside safe biological limits

Generic metadata

Classification

Fisheries

Coasts and seas

Water

Identification

Geographical coverage:

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The ratio of the number of overfished stocks (used here to denote stocks ouside safe biological limits) to the number of commercial stocks (for which assessment of their status has been carried out) per fishing area is presented in Figures 1 and 2. As commercial stocks have been defined as the stocks of economic importance, on which the fishing effort is focused upon in each area aiming at a profit. It is a broader term encompassing target species, bycatches and industrial species that are of economic importance to the market. Since stock assessment is based on fishing areas for the majority of the stocks the indicator depicts areas with heavy fishing pressure.

In general terms stocks are characterised as being outside safe biological limits (or overfished stocks) when the fishing pressure (mortality) exerted on them, exceeds sustainability i.e. when mortality exceeds recruitment and growth. By comparing trends over time in recruitment (R) (the number of new fish produced each year by the mature part of the stock), spawning stock biomass (SSB), landings (estimate of the most likely removal from the stock, sometimes including discards) and fishing mortality (F), a fairly reliable picture of stock development can be derived.

More precise, with the introduction of the precautionary approach, a 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).