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Tooltip Tags: Science

Yield per recruit [YPR]

Yield per recruit

The expected lifetime yield per fish recruited in the stock at a specific age. YPR depends on the exploitation pattern (fishing mortality at age, F) and natural mortality (M).

Catch in weight [C]

Catch in weight or Yield

Total weight of fish harvested from a fishery. Yield does not necessarily correspond to landed weight. The difference between the two values, yield, and landings, is mainly due to discards at sea of part of the catch which, for some reason (price, quality, storage limitations or even legal reasons), is not landed.

Stock-Recruitment relationship [SRR]

Stock‑Recruitment relationship

The relationship between the parental fish stock (spawning biomass) and the resulting recruitment (usually the number of recruits to the exploitable phase). The SRR is used to predict the average number of recruits that would be produced at different population sizes.

Spawning potential ratio [SPR]

Spawning potential ratio

The amount of eggs produced by a fish stock over its lifespan under a specific fishing regime, relative to the spawn that would have been produced over the fish stock’s lifespan if there were no fishing. It is a measure of the impact that fishing has on the ability of a fish stock to contribute to spawning.

Recruitment [R]


The amount of new fish added to the exploitable stock each year—due to population growth and/or migration into the fishing area.

Maximum sustainable yield [MSY]

Maximum sustainable yield

The largest average catches or yield that can continuously be taken from a stock over an indefinite period under existing environmental conditions.

Maximum economic yield [MEY]

Maximum economic yield

The value of the largest positive difference between total fishing revenues and total costs of fishing (including the cost of labor, capital, management, and research).

Natural mortality rate [M]

Natural mortality rate

Deaths of fish from all causes except fishing (e.g., from disease, predation, and starvation). Usually expressed as an instantaneous rate or as a percentage of fish dying in a year.

See also F.

Geographic information system [GIS]

Geographic information system

An integrated technology that enables management, analysis, and mapping of geographical information. In the fishery context, possible GIS applications are countless — as for example tracking foraging and migratory patterns of marine species, monitoring fishing vessel activities, analyzing fishing catch and effort, evaluating and planning management strategies, delimiting marine protected areas, etc.

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