Gadget3 weightloss action

Add weight loss events to a g3 model

g3a_weightloss(
        stock,
        rel_loss = NULL,
        abs_loss = NULL,
        min_weight = 1e-7,
        apply_to_pop = quote( stock__num ),
        run_f = TRUE,
        run_step = NULL,
        run_at = g3_action_order$naturalmortality )

Arguments

stock

The g3_stock that will lose weight in this action.

rel_loss

Fractional weight loss, 0.1 will result in the stock having 90 NULL means no fractional weight loss will be applied.

abs_loss

Absolute weight loss, applied after rel_loss. NULL means no absolute weight loss will be applied.

min_weight

Minimum weight below which weight cannot fall further. Should be more than zero to avoid models returning NaN.

apply_to_pop

Stock instance weightloss applies to, by default applies to whole stock. Used by g3a_spawn to apply to subset that spawned.

run_step

Which step to perform renewal in, or NULL for continuous spawning. Adds cur_step == (run_step) into default run_f.

run_f

formula specifying a condition for running this action, default always runs.

run_at

Integer order that spawning actions will be run within model, see g3_action_order.

Value

g3a_weightloss

An action (i.e. list of formula objects) that will, for the given stock...

1. Apply rel_loss and abs_loss to the parent stock

See also

g3a_naturalmortality, g3a_spawn, g3_stock

Examples

  st <- g3_stock('st', 10:20) |> g3s_age(3, 5)

  actions <- list(
    g3a_time(2000, 2005, step_lengths = c(3, 3, 3, 3)),
    g3a_initialconditions(st,
        # Set initial abundance & weight based on age
        ~1e5 + 0 * st__midlen,
        ~1000 * age + 0 * st__midlen ),
    g3a_age(st),

    g3a_weightloss(st,
        # 20% of body weight should be shed in autumn
        rel_loss = g3_parameterized("rel_loss_autumn", by_stock = TRUE, value = 0.2),
        run_step = 4 ),

    g3a_weightloss(st,
        # Remove "10" from body weight, with a minimum based on length
        abs_loss = g3_parameterized("absloss_length_mw", by_stock = TRUE, value = 10),
        min_weight = g3_formula(
            wmin.a * st__midlen^wmin.b,
            wmin.a = g3_parameterized("wmin.a", by_stock = TRUE, value = 10),
            wmin.b = g3_parameterized("wmin.a", by_stock = TRUE, value = 2) )),
    NULL)

  model_fn <- g3_to_r(c(actions, g3a_report_detail(actions)))
  r <- model_fn(attr(model_fn, 'parameter_template'))
  g3_array_agg(attr(r, "dstart_st__wgt"), c("age", "time"))
#>       time
#> age    2000-01 2000-02 2000-03 2000-04 2001-01 2001-02 2001-03 2001-04  2002-01
#>   age3   33000   32890   32780   32670 27149.1 27039.1 26929.1 26819.1 22468.38
#>   age4   44000   43890   43780   43670 27149.1 27039.1 26929.1 26819.1 22468.38
#>   age5   55000   54890   54780   54670 40349.1 40239.1 40129.1 40019.1 29508.38
#>       time
#> age     2002-02  2002-03  2002-04 2003-01 2003-02 2003-03 2003-04  2004-01
#>   age3 22358.38 22248.38 22138.38 18723.8 18613.8 18503.8 18393.8 15728.14
#>   age4 22358.38 22248.38 22138.38 18723.8 18613.8 18503.8 18393.8 15728.14
#>   age5 29398.38 29288.38 29178.38 24355.8 24245.8 24135.8 24025.8 20233.74
#>       time
#> age     2004-02  2004-03  2004-04  2005-01  2005-02  2005-03  2005-04
#>   age3 15618.14 15508.14 15398.14 13331.61 13221.61 13111.61 13001.61
#>   age4 15618.14 15508.14 15398.14 13331.61 13221.61 13111.61 13001.61
#>   age5 20123.74 20013.74 19903.74 16936.09 16826.09 16716.09 16606.09

  ## See g3a_spawn for an example of weightloss in spawning