schnabel: Population Size Estimates from Repeated Mark-Recapture Experiments

Description

Estimates of population abundance from Schnabel (1938) and Schumacher and Eschmeyer (1943) are calculated from repeated mark-recapture experiments following Krebs (1989).

Usage

schnabel(catch = NULL, recaps = NULL, newmarks = NULL,
 alpha = 0.05)

Value

Dataframe containing the population estimates for the Schnabel and Schumacher & Eschmeyer methods (N), the inverse standard errors (invSE), lower (LCI) and upper (UCI) confidence intervals, and the type of distribution used to set confidence intervals (CI Distribution).

Arguments

catch: A vector containing the number of animal caught in each mark-recapture experiment.
recaps: A vector containing the number of animal recaptured in each mark-recapture experiment.
newmarks: A vector containing the newly marked animals in each mark-recapture experiment.
alpha: the alpha level for confidence intervals. Default = 0.05

Author

Gary A. Nelson, Massachusetts Division of Marine Fisheries gary.nelson@mass.gov

Details

All computations follow Krebs (1989: p. 30-34). For the Schnabel method, the poisson distribution is used to set confidence intervals if the sum of all recaptures is <50,and the t distribution is used if the sum of all recaptures is >=50. For the Schumacher-Eschmeyer method, the t distribution is used to set confidence intervals.

References

Krebs, C. J. 1989. Ecological Methodologies. Harper and Row, New York, NY. 654 p.

Examples

Run this code

data(Gerking)
schnabel(catch=Gerking$C,recaps=Gerking$R, newmarks=Gerking$nM,
 alpha=0.10)

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