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

Description

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)

Topic(s)

• Age-Length Key

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.

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.]

Examples

data(SnapperHG1)
str(SnapperHG1)
head(SnapperHG1)

## 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)

## Extract the length sample
sn1.length <- subset(sn1,is.na(age))
str(sn1.length)