Stock assessment
The application of statistical and mathematical tools to relevant data in order to obtain a quantitative understanding of the status of the stock relative to management benchmarks (e.g. SSBMSY). A stock assessment is needed to make quantitative predictions of the stock’s reactions to alternative management measures.
Stock
Biological unit of one species forming a group of similar ecological characteristics which is the subject of assessment and management in fisheries management studies. T‑RFMOs recognize 23 stocks of major commercial tunas.
Status of the stocks report
An annual ISSF Report formally called “Status of the World Fisheries for Tuna.” It provides information on the status of tuna stocks as well as on bycatch and mitigation issues and reviews programs undertaken by RFMOs to manage tunas and related species.
Spawning (stock) biomass
An indicator of the status of the stock and its reproductive capacity. It can be defined as the combined weight of all individuals in a fish stock (usually females only) that have reached sexual maturity and are capable of reproducing.
Rebuilding
Rebuilding is an action that forms part of a management strategy, implemented to recover the status of fish stocks that are found to be overfished or at risk of being overfished. A rebuilding plan usually has three elements: a target, the desired time to reach a target, and a probability level with which to achieve it. A rebuilding plan generally implies a reduction in fishing pressure.
Overfished
The state of a stock that has been exploited beyond an ecologically sustainable limit and whose population size has become too low to ensure safe reproduction. Overfished stocks can be managed under a rebuilding plan that, over time, returns the population to optimal ecological levels. The stock may remain overfished for some time even though fishing pressure might be reduced or suppressed.
Overfishing
A form of over‑exploitation of fishery resources where the fishing intensity exceeds the capacity of a stock to maintain a sustainable ecological level. In overfishing, the fish stock is diminished to such an extent that the remaining adult fish are not able to replenish their population through natural reproduction. Prolonged overfishing rates lead to depletion of fish populations and the collapse of fisheries.
Limit reference point
A type of biological reference point that defines the beginning of the “danger zone” for a stock. A Limit Reference Point indicates the limit beyond which the state of a fishery and/or a resource is undesirable and should be avoided with high probability.
