dietr (version 1.1.6-1)

VacuityIndex: Calculates the vacuity index, the proportion of fish which contain food in their stomach.

Description

This function calculates the vacuity index, the frequency of fish which lack food in their stomach.

Usage

VacuityIndex(StomachData)

Value

Numeric vector of length one with the calculated vacuity index.

Arguments

StomachData

Object of class data frame containing stomach data. The data frame must be set up as follows. The first column should contain the specimen identifier, the second column the stomach weight.

Author

Samuel Borstein

Details

This function calculates the vacuity index (Hureau, 1970). This is simply the percentage of empty stomachs. The function takes a data frame of stomach data, which should be formatted as follows. The first column should contain the specimen identifier and the second column should contain the weight of the stomach contents. If users also have information on fish weight, they can calculate the Gastro-somatic index, using the function GastrosomaticIndex, which has an option to calculate the vacuity index utilizing this function.

References

Hureau J-C. 1970. Biologie comparee de quelques poissons antarctiques (Nototheniidae). Bulletin de l'Institut Oceanographique de Monaco 68:1-244.

See Also

GastrosomaticIndex

Examples

data(SebastesStomachs)#load example data
My.Vacuity <- VacuityIndex(StomachData = SebastesStomachs)