dynamics: Generate one marine mammal population trajectory

In mcsiple/mmrefpoints: Project Marine Mammal Populations and Calculate Reference Points

Generate one marine mammal population trajectory

Description

This function generates one trajectory for a marine mammal population, starting at a user-specified depletion level InitDepl.

Usage

dynamics(lh.params, InitDepl, ConstantCatch = NA, ConstantF = NA, nyears)

Arguments

lh.params	A list containing life history parameters: S0 Calf/pup survival, a numeric value between 0 and 1 S1plus Survival for animals age 1 year and older, a numeric value between 0 and 1 K1plus The pre-exploitation population size of individuals aged 1 and older. If this value is unavailable, it can be approximated by using the initial depletion and the estimate of current abundance AgeMat Age at maturity in years (assumed to be age at first parturition - 1) nages "Maximum" age, treated as the plus group age. The plus group age can be set equal to the age at maturity +2 years without losing accuracy. Must be greater than AgeMat. z The degree of compensation. The default value is z = 2.39. lambdaMax Maximum steady rate of increase (population growth rate)
InitDepl	Starting depletion level
ConstantCatch	Total bycatch each year, expressed as a vector of length nyears
ConstantF	vector (length = nyears) rate of bycatch each year
nyears	Number of years to project

Details

The population model is a single-sex age-structured model in which the number of calves or pups born each year is density dependent, with the extent of density dependence a function of the number of mature adults \tildeN, the fecundity (pregnancy rate) at pre-exploitation equilibrium f_0, the maximum theoretical fecundity rate fmax, the degree of compensation z, and the abundance of individuals aged 1+ N_{y+1}^{1+} relative to carrying capacity K^{1+}. This function can be used alone but is intended to be used with Projections() to generate multiple simulations. NOTE: Either ConstantCatch or ConstantF can be specified, but not both.

Value

A list containing a matrix N of numbers at age (dimensions nyears (rows) x nages (columns)) and one vector TotalPop (a vector of length nyears), containing the number of age 1+ individuals in the population.

Examples

# Generate a time series of abundance for a bowhead whale
dynamics(lh.params = list(S0 = 0.944, S1plus = 0.99, 
K1plus = 9000, AgeMat = 17,nages = 25,
z = 2.39, lambdaMax = 1.04),
 InitDepl = 0.6, ConstantCatch = NA, ConstantF = rep(0.01, times = 100), 
 nyears = 100)

mcsiple/mmrefpoints documentation built on June 17, 2022, 8:41 p.m.