# Calculate the number of recruits Calculates the number of recruits of each species in a year. ```r calc_recruits(SSB, stored_rec_funs, rec_args) ``` ## Arguments - `SSB`: A numeric vector of length `nfish` representing the Spawning Stock Biomass (SSB) of each species. - `stored_rec_funs`: A list object of length `nfish` that is used to store the generated stock recruitment functions. - `rec_args`: A list object of length `nfish` that is used to store the parameters of the stock recruitment functions. ## Returns A numeric vector of length `nfish` representing the number of new recruits of each species. ## Examples ```r # 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) R <- calc_recruits(SSB, stored_rec_funs, recruit_params) ``` ## References 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. Beverton, R.J.H., Holt, S.J. (1957). On the Dynamics of Exploited Fish Populations, volume 19 of Fisheries Investigations (Series 2). United Kingdom Ministry of Agriculture and Fisheries. Hall, S. J., Collie, J. S., Duplisea, D. E., Jennings, S., Bravington, M., & Link, J. (2006). A length-based multispecies model for evaluating community responses to fishing. **Canadian Journal of Fisheries and Aquatic Sciences**, 63(6):1344-1359. Ogle, D.H. (2016). Introductory Fisheries Analyses with R. CRC Press. Ricker, W.E. (1954). Stock and recruitment. **Journal of the Fisheries Research Board of Canada**, 11:559-623. 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. ## See Also `get_rec_fun`, `make_rec_fun`, `rec_BH`, `rec_Ricker`, `rec_hockey`, `rec_const`, `rec_linear` and `calc_SSB`

calc_recruits function