View source: R/calc_recruits.R
rec_hockey | R Documentation |
Calculates the number of recruits as given by the hockey-stick stock recruitment function.
rec_hockey(SSB, rec_args)
SSB |
A numeric value representing the Spawning Stock Biomass (SSB) of a given species (g). |
rec_args |
A list object of length |
The stock recruitment function is defined as min(a*(SSB/1e9), b)
.
A numeric value representing the number of recruits of a given species.
Barrowman, N.J., Myers, R.A. (2000). Still more spawner-recruit curves: the hockey stick and its generalisations. Canadian Journal of Fisheries and Aquatic Science, 57:665–676.
Thorpe, R.B., Le Quesne, W.J.F., Luxford, F., Collie, J.S., Jennings, S. (2015). Evaluation and management implications of uncertainty in a multispecies size-structured model of population and community responses to fishing. Methods in Ecology and Evolution, 6:49-58.
calc_recruits
, make_rec_fun
, get_rec_fun
, rec_BH
, rec_Ricker
, rec_const
, rec_linear
and calc_SSB
# Set up the inputs to the function - species-independent parameters nfish <- nrow(NS_par) nsc <- 32 maxsize <- max(NS_par$Linf)*1.01 # the biggest size is 1% bigger than the largest Linf l_bound <- seq(0, maxsize, maxsize/nsc); l_bound <- l_bound[-length(l_bound)] u_bound <- seq(maxsize/nsc, maxsize, maxsize/nsc) mid <- l_bound+(u_bound-l_bound)/2 # Set up the inputs to the function - species-specific parameters Linf <- NS_par$Linf # the von-Bertalanffy asymptotic length of each species (cm). W_a <- NS_par$W_a # length-weight conversion parameter. W_b <- NS_par$W_b # length-weight conversion parameter. k <- NS_par$k # the von-Bertalnaffy growth parameter. Lmat <- NS_par$Lmat # the length at which 50\% of individuals are mature (cm). # Get phi_min tmp <- calc_phi(k, Linf, nsc, nfish, u_bound, l_bound, calc_phi_min=FALSE, phi_min=0.1) # fixed phi_min phi_min <- tmp$phi_min # Run calc_ration_growthfac() tmp <- calc_ration_growthfac(k, Linf, nsc, nfish, l_bound, u_bound, mid, W_a, W_b, phi_min) sc_Linf <- tmp$sc_Linf wgt <- tmp$wgt # Calculate maturity mature <- calc_mature(Lmat, nfish, mid, kappa=rep(10, nfish), sc_Linf) # Create recruitment functions stored_rec_funs <- get_rec_fun(rep("hockey-stick", nfish)) recruit_params <- do.call("Map", c(c, list(a=NS_par$a, b=NS_par$b))) # Get an initial population N0 <- get_N0(nsc, nfish, mid, wgt, sc_Linf, intercept=1e10, slope=-5) # Calculate the SSB SSB <- calc_SSB(mature, N0, wgt) rec_hockey(SSB[1], recruit_params[[1]])
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