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Age (subsample) and length (all fish) of Snapper from two survey locations.

Source: R/SnapperHG1.R
SnapperHG1.Rd

A large sample (not random or proportional) of Snapper (Pagrus auratus) were aged from otoliths, with the remainder of the fish just measured for length. Note that age-20 is actually age 19+.

Format

A data frame of 18421 observations on the following 3 variables:

len

Measured lengths (cm)

age

Ages assigned from examination of otoliths

survey

Survey location (KAH8810 or KAH0012)

Source

Recreated from Tables 2, 3, and 5 in Davies, N.M. and C. Walsh. 2002. Snapper age and length samples from Kaharoa research trawl surveys KAH8810 and KAH0012 of the Hauraki Gulf. Final Research Report for Ministry of Fisheries Research Project SNA2000/01. National Institute of Water and Atmospheric Research. [Was (is?) from http://fs.fish.govt.nz/Page.aspx?pk=113&dk=22516.] CSV file

Note

The unaged fish were simulated from Table 5 assuming that the total number of fish was large enough that at least one fish was observed in each cell where a proportion was listed.

Topic(s)

  • Age-Length Key

Examples

data(SnapperHG1)
str(SnapperHG1)
#> 'data.frame':	18420 obs. of  3 variables:
#>  $ len   : int  11 11 11 11 11 11 11 11 11 11 ...
#>  $ age   : int  1 1 1 1 1 1 1 1 1 1 ...
#>  $ survey: Factor w/ 2 levels "KAH0012","KAH8810": 2 2 2 2 2 2 2 2 2 2 ...
head(SnapperHG1)
#>   len age  survey
#> 1  11   1 KAH8810
#> 2  11   1 KAH8810
#> 3  11   1 KAH8810
#> 4  11   1 KAH8810
#> 5  11   1 KAH8810
#> 6  11   1 KAH8810

## Extract one of the sample surveys
sn1 <- subset(SnapperHG1,survey=="KAH8810")

## Extract the aged sample
sn1.aged <- subset(sn1,!is.na(age))
str(sn1.aged)
#> 'data.frame':	713 obs. of  3 variables:
#>  $ len   : int  11 11 11 11 11 11 11 11 11 11 ...
#>  $ age   : int  1 1 1 1 1 1 1 1 1 1 ...
#>  $ survey: Factor w/ 2 levels "KAH0012","KAH8810": 2 2 2 2 2 2 2 2 2 2 ...

## Extract the length sample
sn1.length <- subset(sn1,is.na(age))
str(sn1.length)
#> 'data.frame':	8835 obs. of  3 variables:
#>  $ len   : int  5 5 5 6 6 6 6 6 6 6 ...
#>  $ age   : int  NA NA NA NA NA NA NA NA NA NA ...
#>  $ survey: Factor w/ 2 levels "KAH0012","KAH8810": 2 2 2 2 2 2 2 2 2 2 ...