bheq2: Length-based Beverton-Holt Equilibrium Total Instantaneous Mortality Estimator with Bias-Correction
Description
The equilibrium Beverton-Holt estimator of instantaneous total mortality (Z) from length data using Ehrhardt and Ault (1992) bias-correction
Usage
bheq2(len = NULL, Linf = NULL, K = NULL, Lc = NULL, La = NULL, nboot = 100)
Arguments
len
the vector of length data. Each row represents one record per individual fish.
K
the growth coefficient from a von Bertalanffy growth model.
Linf
the L-infinity coefficient from a von Bertalanffy growth model.
Lc
the length at first capture.
La
the largest length of the largest size class.
nboot
the number of bootstrap runs. Default=100.
Value
Details
The Beverton-Holt equilibrium estimator of instantaneous total mortality (Z)
from length data (page 365 in Quinn and Deriso (1999)) using Ehrhardt and Ault (1992) bias-correction is calculated. The mean length
for lengths >=Lc is calculated automatically. Missing data are removed prior to calculation.
Estimates of standard error are made by bootstrapping length data >=Lc using package boot.
References
Quinn, T. J. and R. B. Deriso. 1999. Quantitative Fish Dynamics. Oxford University Press, New York, New York. 542 pages
Ehrhardt, N. M. and J. S. Ault. 1992. Analysis of two length-based mortality models applied to bounded
catch length frequencies. Trans. Am. Fish. Soc. 121:115-122.