rebuild_by_x: Calculate the bycatch rate needed to reach a performance goal

In ktmurray1219/mmrefpoints: Project Marine Mammal Populations and Calculate Reference Points

Description

takes a performance goal (what level you want to rebuild to) and a time window (how long you want that to take) and calculates what the bycatch rate needs to be

Usage

rebuild_by_x(
  needf.start,
  init.depl.w,
  goal.w,
  desired.prob.w,
  when.w,
  lh.params.w,
  fixed.cv.catch.w
)

Arguments

needf.start	starting guess for the bycatch mortality rate needed to recover the population
init.depl.w	initial depletion (a fraction)
goal.w	Population size goal (number of whales or pinnipeds) to rebuild to, expressed as a whole number
desired.prob.w	what probability you want (e.g., 0.75 probability that the population will rebuild to X in Y years)
when.w	the year Y when rebuilding is desired by (number of years into future; current year = 0)
lh.params.w	a list of life history parameters used by projections()
fixed.cv.catch.w	the CV of the bycatch rate - should be fixed

Value

The bycatch rate that will result in the specified rebuilding goal. If Shiny is running, it will return a list containing the bycatch rate f and a matrix of guesses that optim() has searched through to find the solution.

Examples

rebuild_by_x(
  needf.start = 0.001,
  init.depl.w = 0.5, goal.w = 4500,
  desired.prob.w = 0.8, when.w = 100,
  lh.params.w = list(
    S0 = 0.944, S1plus = 0.99,
    AgeMat = 17, nages = 19,
    z = 2.39, lambdaMax = 1.04, K1plus = 9000
  ),
  fixed.cv.catch.w = 0
)

ktmurray1219/mmrefpoints documentation built on Dec. 21, 2021, 8:40 a.m.