fishmethods (version 1.3-0)

agesurv: Age-based Survival Estimators

Description

Calculates annual survival (S) and instantaneous total mortality rates (Z) from age frequency by using catch curve (ln(numbers) versus age in linear regression), Heincke, and Chapman-Robson methods.

Usage

agesurv(age = NULL, full = NULL, last = NULL, 
estimate = c("s", "z"), method = c("cc", "he", "cr"))

Arguments

age

the vector of ages. Each row represents the age of an individual.

full

the fully-recruited age

last

the maximum age to include in the calculation. If not specified, the oldest age is used.

estimate

argument to select estimate type: "s" for annual survival, "z" for instantaneous total mortality. Default is both.

method

argument to select the estimation method: "cc" for catch curve, "he" for Heincke, and "cr" for Chapman-Robson. Default is all.

Value

• results
  list element containing table of parameters and standard errors.
• data
  list element containing the age frequency data used in the analysis.

Details

The individual age data are tabulated and subsetted based on the full and last arguments. Most calculations follow descriptions in Seber(1982), pages 414-418. If only two ages are present, a warning message is generated and the catch curve method is not calculated. Plus groups are not allowed.

References

Seber, G. A. F. 1982. The Estimation of Animal Abundance and Related Parameters, Second Edition. The Blackburn Press, Caldwell, New Jersey. 654 pages. Quinn, T. J. and R. B. Deriso. 1999. Quantitative Fish Dynamics. Oxford University Press, New York, New York. 542 pages.

Examples

data(rockbass)
agesurv(age=rockbass$age,full=6)