gnomonic {gnomonicM}

Gnomonic deterministic

Description

Estimate natural mortality based on gnomonic interval approach.

Usage

gnomonic(
  nInterval,
  eggDuration,
  addInfo = NULL,
  longevity,
  fecundity,
  a_init = 2
)

Arguments

nInterval

a numeric value that represents the number of gnomonic intervals.

eggDuration

a numeric value with the egg stage (first gnomonic interval) duration in days.

addInfo

a numeric vector with additional information related to the observed duration of the other gnomonic intervals different than the first interval (egg stage duration). Write addInfo = NULL if you do not provide additional information.

longevity

a numeric value indicating the lifespan of the species in days.

fecundity

a numeric value indicating the mean lifetime fecundity (MLF) as the number of eggs produced for a female.

a_init

a numeric value indicating the initial parameter related to the proportionality optimized by iterative solution via univariate (1-dim.) minimization. a_init = 2 as default value.

Details

Estimate natural mortality (M) based on gnomonic interval approach.

The argument nInterval is NULL by default. If you have -at least- one observed value for the duration of the other gnomonic intervals you should provide this as a vector which length must be nInterval - 1, for example addInfo = c(3, NA, NA, NA, NA, NA)) for a nInterval = 7.

Value

A list of class 'gnomos'.

a the proportionality constant.

G the constant proportion of the overall natural death rate.

results a dataframe with the duration ("interval_duration_day") and natural mortality ("M_day" and "M_year") for each gnomonic interval.

References

Caddy JF (1996). Modelling natural mortality with age in short-lived invertebrate populations: definition of a strategy of gnomonic time division. Aquat Living Resour 9:197–207. doi: 10.1051/alr:1996023.

Examples

#The values are based on Caddy (1996).
model <- gnomonic(nInterval = 7, eggDuration = 2, addInfo = NULL,
longevity = 365, fecundity = 200000, a_init = 2)

model
model$a
model$G
model$results

#Additional information for the duration of the second gnomonic intervals.
model <- gnomonic(nInterval = 7, eggDuration = 2, addInfo = c(3, NA, NA, NA, NA, NA),
longevity = 365, fecundity = 200000, a_init = 2)

model
model$a
model$G
model$results