WR79: Ages and lengths for a hypothetical sample from Westerheim...
In droglenc/FSA: Simple Fisheries Stock Assessment Methods

WR79	R Documentation

Ages and lengths for a hypothetical sample from Westerheim and Ricker (1979).

Description

Ages and lengths for a hypothetical sample in Westerheim and Ricker (1979).

Format

A data frame of 2369 observations on the following 3 variables:

ID: Unique fish identifiers
len: Length of an individual fish
age: Age of an individual fish

Details

Age-length data in 5-cm increments taken exactly from Table 2A of the source which was a sample from a hypothetical population in which year-class strength varied in the ratio 2:1 and the rate of increase in length decreased with age. Actual lengths in each 5-cm interval were simulated with a uniform distribution. The aged fish in this file were randomly selected and an assessed age was assigned according to the information in Table 2A.

Topic(s)

Age-Length Key

Source

Simulated from Table 2A in Westerheim, S.J. and W.E. Ricker. 1979. Bias in using age-length key to estimate age-frequency distributions. Journal of the Fisheries Research Board of Canada. 35:184-189. CSV file

Examples

str(WR79)
head(WR79)

## Extract the aged sample
WR79.aged <- subset(WR79,!is.na(age))
str(WR79.aged)

## Extract the length sample
WR79.length <- subset(WR79,is.na(age))
str(WR79.length)

droglenc/FSA documentation built on Aug. 30, 2023, 12:51 a.m.