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 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…

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…

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 stock biomass capable of producing maximum sustainable yield This is the stock size (biomass) of spawners that would result on average if FMSY was applied constantly year after year. SSBMSY is often measured by the biomass of female spawners. See also SB.

Recruitment 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 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 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 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.

Global Environmental Facility A global foundation that represents an alternative asset manager dedicated to the energy, environmental, and natural resources sectors.