Depensation - Wikipedia

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Inpopulation dynamics,depensationis the effect on apopulation(such as afish stock^[1]) whereby, due to certain causes, a decrease in the breeding population (mature individuals) leads to reduced production and survival of eggs or offspring.^[2]The causes may include predation levels rising per offspring (given the same level of overall predator pressure) and theAllee effect,particularly the reduced likelihood of finding a mate.

Critical depensation

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When the level of depensation is high enough that the population is no longer able to sustain itself, it is said to be acritical depensation.This occurs when the population size has a tendency to decline when the population drops below a certain level (known as the "Critical depensation level" ).^[2]Ultimately this may lead to the population or fishery's collapse (resource depletion), or evenlocal extinction.^[3]

The phenomenon of critical depensation may be modelled or defined by a negative second orderderivativeof population growth rate with respect of populationbiomass,which describes a situation where a decline in population biomass is not compensated by a corresponding increase in marginal growth per unit of biomass.

References

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^Maroto, Jose M.; Moran, Manuel. "Detecting the presence of depensation in collapsed fisheries: The case of the Northern cod stock".Ecological Economics.97.
^^a ^bQuinn, Terrance (25 March 1999).Quantitative Fish Dynamics.Oxford University Press. p. 99.ISBN 9780195360400.
^Kar, Tapan Kumar; Misra, Swarnakamal. "Optimal Control of a Fishery under Critical Depensation".Journal of Fisheries and Aquatic Science.1.

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Critical depensation

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