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Convert target catches to fishing mortality rates for multiple fleets

catch_to_F_multifleet.Rd

Solves for the vector of fleet-specific fishing mortality rates \(\mathbf{F} = (F_1, \ldots, F_k)\) that simultaneously satisfy the Baranov catch equations for all fleets, given a vector of target catches. Total mortality at age accounts for retained and discard mortality contributions from all fleets: \(Z_a = M_a + \sum_f (F_f \, s_{a,f} \, r_{a,f} + F_f \, s_{a,f} \, (1 - r_{a,f}) \, d_f)\), where \(r_{a,f}\) is retention selectivity and \(d_f\) is fleet-specific discard mortality. The system of equations is solved via nleqslv. Intended for closed-loop MSE harvest control rules with multiple interacting fishery fleets.

Usage

catch_to_F_multifleet(
  target_catch,
  NAA,
  WAA,
  natmort,
  fish_sel,
  ret_sel = array(1, dim = dim(fish_sel)),
  dmr = rep(0, length(target_catch)),
  f_init = 0.05,
  control = list(btol = 1e-06)
)

Arguments

target_catch

Numeric vector [n_fleets]. Target catch in biomass units for each fleet.

NAA

Numeric matrix [n_ages x n_sexes]. Numbers-at-age.

WAA

Numeric matrix [n_ages x n_sexes]. Weight-at-age.

natmort

Numeric matrix [n_ages x n_sexes]. Instantaneous natural mortality rate.

fish_sel

Numeric array [n_ages x n_sexes x n_fleets]. Fishery selectivity for each fleet.

ret_sel

Numeric array [n_ages x n_sexes x n_fleets]. Retention selectivity for each fleet, i.e. the proportion of selected catch that is retained. Default is an array of 1s matching dim(fish_sel) (full retention for all fleets).

dmr

Numeric vector [n_fleets]. Fleet-specific discard mortality rates, i.e. the fraction of discarded fish that die. Default rep(0, length(target_catch)) (all discards survive).

f_init

Numeric scalar or vector [n_fleets]. Starting values for the \(F\) solver. If a scalar is supplied it is recycled across all fleets. Default 0.05.

control

Named list of control parameters passed to nleqslv. Default list(btol = 1e-6).

Value

Numeric vector [n_fleets] of solved fishing mortality rates, one per fleet.

See also

Other Closed Loop Simulations: catch_to_F_singlefleet(), condition_closed_loop_simulations(), get_closed_loop_reference_points()