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'))
  attr(r, "detail_st__wgt")[1,,]
#>       time
#> age    2000-01 2000-02 2000-03 2000-04 2001-01 2001-02 2001-03 2001-04 2002-01
#>   age3    3000    2990    2980    2970  2412.1  2402.1  2392.1  2382.1 1941.78
#>   age4    4000    3990    3980    3970  2412.1  2402.1  2392.1  2382.1 1941.78
#>   age5    5000    4990    4980    4970  3612.1  3602.1  3592.1  3582.1 2581.78
#>       time
#> age    2002-02 2002-03 2002-04  2003-01  2003-02  2003-03  2003-04  2004-01
#>   age3 1931.78 1921.78 1911.78 1565.524 1555.524 1545.524 1535.524 1264.519
#>   age4 1931.78 1921.78 1911.78 1565.524 1555.524 1545.524 1535.524 1264.519
#>   age5 2571.78 2561.78 2551.78 2077.524 2067.524 2057.524 2047.524 1674.119
#>       time
#> age     2004-02  2004-03  2004-04  2005-01  2005-02  2005-03   2005-04
#>   age3 1254.519 1244.519 1234.519 1023.715 1013.715 1003.715  993.7154
#>   age4 1254.519 1244.519 1234.519 1023.715 1013.715 1003.715  993.7154
#>   age5 1664.119 1654.119 1644.119 1351.395 1341.395 1331.395 1321.3954

  ## See g3a_spawn for an example of weightloss in spawning