Example of continuous data from fish prey lengths of brown trout

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Description

The example reproduces data published in Kahilainen & Lehtonen (2001) on prey lengths from a sample of 59 individuals of stocked (S) and native (N) brown trout (Salmo trutta) in the subarctic Lake Muddusjarvi in northern Finland.

Column names refer to:

- FishID: a unique identifier for each individual fish within the geographic area;

- Type: stocked (S) and native (N) brown trout.

All other columns are lengths (in mm) of fish prey found in stomachs.

Usage

1

References

Kahilainen, K. and Lehtonen, H. 2001. Resource use of native and stocked brown trout Salmo trutta L., in a subarctic lake. Fisheries Management and Ecology 8: 83-94.

Examples

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# Summary of total length of preys in stomach content
# by geographic region
data(Trout)
# Mean prey length by individual
# First change zeros to NA
troutTMP = Trout
troutTMP[ troutTMP == 0] = NA
individuals = by(troutTMP[, 3:7], troutTMP[, 2], rowMeans, na.rm=TRUE)
TroutN = subset(Trout, Type == "N", PL1:PL5)
TroutN = TroutN[TroutN > 0]
TroutS = subset(Trout, Type == "S", PL1:PL5)
TroutS = TroutN[TroutS > 0]
boxplot(c(TroutS, TroutN) ~ c(rep("N", length(TroutN)), rep("S", length(TroutS))))
rm(list=ls(all=TRUE))