Proportion of fish stocks within biologically sustainable levels

The percentage of fish stocks classified as "within biologically sustainable levels" as part of the total number of stocks being reported upon. This indicator measures the sustainability of the world's marine capture fisheries by the abundance of the reported fish stocks. It constitutes SDG indicator 14.4.1, estimated by the UN Food and Agriculture Organization (FAO), and which measures progress toward reaching SDG Target 14.4 focused on ending overfishing and SDG Goal 14 to “Conserve and sustainably use the oceans, seas and marine resources for sustainable development”.

The indicator assesses whether fishing activities are conducted in a manner that does not deplete fish stocks or harm the overall health of the marine ecosystem. It measures the percentage of fish populations that are being harvested at levels allowing them to maintain their population size and reproductive capacity over the long term. Maximum Sustainable Yield (MSY) is usually used to reflect biological sustainable levels. MSY is commonly defined as the greatest average amount of catch that can be harvested in the long term from a stock under constant and current environmental conditions (e.g., habitat, water conditions, species composition and interactions, and anything that could affect birth, growth, or death rates of the stock), without affecting the long-term productivity of the stock. A fish stock for which the abundance is equal or greater than the level that can produce the MSY is classified as biologically sustainable. In contrast, when abundance falls below the MSY level, the stock is considered biologically unsustainable.