stable_AD: Stable Age Distribution

In vquennessen/densityratio: Using Density Ratios to Help Manage Fisheries In And Around Marine Reserves

Stable Age Distribution

Description

stableAD produces the stable age distribution, or the proportional numbers at age from recruitment age to maximum age at equilibrium, after enough years of no fishing for proportional numbers at age to stabilize

Usage

stable_AD(
  Rec_age,
  Max_age,
  W,
  R0,
  Mat,
  H,
  B0,
  Sigma_R,
  Fb,
  S,
  M,
  eq_time = 150,
  A50_mat,
  Recruitment_Var = FALSE,
  Rho_R,
  Recruitment_mode = "pool",
  A = 5
)

Arguments

Rec_age	numeric value, the age at recruitment, in years.
Max_age	numeric value, the maximum age of fish or total lifespan, in years.
W	numeric vector, the estimated weight at age from age at recruitment to maximum age, in kg.
R0	numeric value, set arbitrarily, the unfished recruitment.
Mat	numeric vector, the estimated fraction of individuals mature at each age, from age at recruitment to maximum age, on the interval (0, 1).
H	numeric value, the steepness of the stock-recruitment curve.
B0	numeric value, the unfished biomass, in kg.
Sigma_R	numeric value, the recruitment standard deviation.
Fb	numeric value, the historical fishing effort for the fished species.
S	numeric vector, the selectivities at age from age at recruitment to maximum age, on the interval (0, 1).
M	numeric value, the natural mortality on the interval (0, 1).
eq_time	numeric value, the number of years to run the function to determine the stable age distribution. Default value is 150.
A50_mat	numeric value, the first age at which 50% or more individuals are estimated to be mature, on the interval (Rec_age, Max_age).
Recruitment_Var	logical vector, does recruitment contain a stochastic component? Default value is FALSE.
Rho_R	numeric value, the recruitment autocorrelation on the interval (-1, 1). Default value is 0.
Recruitment_mode	character value, values can be: 'closed' - the recruits in each area originate from adults in that area. 'pool' - the recruits in each area come from a pool of larvae produced by adults in all areas. 'regional_DD' - larvae experience regional density dependence before settling evenly across all areas 'local_DD' - larvae experience local density dependence before settling evely across all areas Default value is 'pool'.
A	numeric value, the number of areas. Default value is 5.

Value

a numeric vector of numbers at age after enough years with no fishing that proportions remain stable over time.

Examples

L <- length_age(Rec_age = 2, Max_age = 35, A1 = 5, L1 = 32.21, A2 = 15,
   L2 = 47.95, K = 0.2022, All_ages = FALSE)
W <- weight(L, WA = 1.68e-5, WB = 3)
Mat <- maturity(Rec_age = 2, Max_age = 35, K_mat = -0.4103, L, L50 = 39.53)
S <- selectivity(Rec_age = 2, Max_age = 35, A1 = 5, L1 = 32.21, A2 = 15,
   L2 = 47.95, K = 0.2022, Fleets = c('sport', 'hook', 'trawl'),
   A50_up = c(2, 5, 10), A50_down = c(6, 16, 35), Alpha = c(0.33, 0.6, 0.64),
   F_fin = c(0.25, 0.06, 1), Beta = c(1.2, 0.6, 0), Cf = c(0.71, 0.28, 0.01))
stable_AD(Rec_age = 2, Max_age = 35, W, R0 = 1e+5, Mat, H = 0.65,
   B0 = 1e+5/1.1, Sigma_R = 0.5, Fb = 0.2, S, M = 0.14, eq_time = 150,
   A50_mat = 8, Recruitment_Var = FALSE, Rho_R = 0, Recruitment_mode = 'pool',
   A = 5)

vquennessen/densityratio documentation built on Aug. 28, 2022, 5:36 p.m.