age_slicing: Age slicing

In ALKr: Generate Age-Length Keys for fish populations

Description

Estimation of a population's age distribution from its length distribution based on von Bertalanffy's growth curve, as described by Kell and Kell (2011)

Usage

age_slicing(fi, li = as.numeric(names(fi)), vb_params, age_limits,
  timing = 0.5)

Arguments

fi	A vector with the number of individuals per length class.
li	A vector containing the length value for each length class. If blank, will use as.numeric(names(fi)).
vb_params	A named vector with the parameters of the von Bertalanffy growth equation, Linf, K and t0.
age_limits	A vector with two elements, containing the lowest and highest age classes.
timing	Correction for the offset between the data collection and recruitment. Defaults to 0.5, i.e. half a year

Details

Age distribution is calculated by using the inverse of the von Bertalanffy growth curve, whose parameters must be known. Limits for the minimum and maximum ages must also be given.

Value

A vector containing the number of individuals in each age class.

References

Kell, L., Kell, A. (2011). A comparison of age slicing and statistical age estimation for mediterranean swordfish (Xiphias gladius). Collect. Vol. Sci. Pap. ICCAT. 66/4, 1522-1534

Examples

data(hom)
age_slicing(fi = hom$F1992,
  vb_params = c(Linf = 54.98, K = 0.064, t0 = -4.68),
  age_limits = c(0,5))

Example output

    0     1     2     3     4     5 
48627 43724 34162  8216  4962 10246 

ALKr documentation built on May 30, 2017, 7:42 a.m.