ExpectedCapture: Probability animals will be caught throughout the survey

In shanearichards/crrecruit: Infer recruitment from capture-recapture data

Description

A function that returns a vector containing the probabilities a randomly chosen animal will be caught during each survey event. Model parameters are provided in the input vector. Survey information must be stored in specific-named global variables (see Details).

Usage

ExpectedCapture(params)

Arguments

params

A vector containing six parameter values (see Details).

Details

The input params contains the following values:

1. [tbar] The day when recruitment peaks.

2. [sigma] The spread in recruitment (days). Approximately 95% of recruitments occur during days [tbar - 2*sigma, tbar + 2*sigma].

3. [alpha0] Baseline catch rate (per unit effort).

4. [alpha1] Age-dependence in catch rate.

5. [beta0] Base-line mortality rate (per day).

6. [beta1] Age-dependence in mortality rate.

Recruitment is described by a Guassian peak centred on day tbar with spread characterised by sigma. Per-capita catch rate is given by: alpha0*exp(alpha1*age), where age is the days since recruitment. Per-capita mortality rate is given by: beta0*exp(beta1*age).

Suppose the survey involves the capture of animals over J sampling events. The data must be stored and summarised by the following R-variables:

E

A double vector of size J quantifying the effort applied during each sampling event.

T

An integer vector of size J providing the day of each sampling event.

T.F

An integer indicating the first possible day of recruitment.

T.L

An integer (> T.F) indicating the last possible day of recruitment.

Value

A numeric vector of length J.

Author(s)

Shane A. Richards ([e-mail])

Examples

guess <- c(3.0, 3.0, 0.2, 0.0, 0.03, 0.1)
p.detect <- ExpectedCapture(guess)
plot(x = T, y = p.detect, xlab = "Day", ylab = "Probability caught")

shanearichards/crrecruit documentation built on May 29, 2019, 8:07 p.m.