fishmethods (version 1.12-1)

alk: Create An Age-Length Key

Description

Creates an age-length key in numbers or proportions-at-age per size.

Usage

alk(age=NULL,size=NULL,binsize=NULL,type=1)

Value

A table of size, total numbers at size, and numbers (or proportions)-at-age per size class.

Arguments

age

a vector of individual age data.

size

a vector of individual size data.

binsize

size of the length class (e.g., 5-cm, 10, cm, etc.) used to group size data. The formula used to create bins is \(trunc(size/binsize)*binsize+binsize/2\). If use of the raw length classes is desired, then binsize=0.

type

If type=1, numbers-at-age per size are produced. This format is used in functions alkprop, alkss, and alkD. If type=2, proportions-at-age per size are produced.

Author

Gary A. Nelson, Massachusetts Division of Marine Fisheries

Details

Create age-length keys with either numbers-at-age per size class. Records with missing size values are deleted prior to calculation. Missing ages are allowed.

References

Quinn, T. J. and R. B. Deriso. 1999. Quantitative Fish Dynamics. Oxford University Press, New York, New York. 542 pages

See Also

alkD alkss alkprop

Examples

 if (FALSE) {
  data(pinfish) 
  with(pinfish,alk(age=round(age,0),size=sl,binsize=10))
 }