Gadget3 projected quotas

Add projected fishing quotas / MSE

g3_quota_hockeyfleet(
        predstocks,
        preystocks,
        preyprop_fs = 1,
        btrigger = g3_parameterized("hf.btrigger", by_stock = predstocks),
        harvest_rate = g3_parameterized("hf.harvest_rate", by_stock = predstocks),
        stddev = g3_parameterized("hf.stddev", by_stock = predstocks, value = 0) )

g3_quota_assess(
        predstocks,
        preystocks,
        assess_f,
        unit = c("biomass-year", "biomass", "harvest-rate", "harvest-rate-year",
                 "individuals", "individuals-year") )

g3_quota(
        function_f,
        quota_name = attr(function_f, 'quota_name'),
        year_length = 1L,
        start_step = 1L,
        interim_value = NULL,
        run_revstep = -1,
        run_f = TRUE,
        run_at = g3_action_order$quota )

Arguments

predstocks, preystocks

Lists of g3_stock objects to represent the predators/fleets and prey when forming the quota.

preyprop_fs

A formula or list of formulas representing the proportion of that prey that makes up the Spawning Stock Biomass (SSB). The proportions do not need to sum to 1, for example you may use preyprop_fs = 0.4 to assume that 40

Using a suitability function is also supported, e.g. g3_suitability_exponentiall50.

btrigger

Trigger biomass, see formula

harvest_rate

Harvest rate, see formula

stddev

If > 0, then apply log-normal noise to the output quota.

assess_f

A formula that runs an assessment model & returns a quota. See vignette TODO:

unit

A single string representing the unit of the value that assess_f returns.

function_f

Output of one of the g3_quota_* functions, responsible for choosing the next quota

quota_name

A name used to refer to the quota internally, by default a combination of the quota function and the stocks used.

year_length

The length of the fishing year, in years, see details.

start_step

The initial step of the fishing year, in model steps, see details. This can be used to offset the fishing year from the calendar year for, if your fishing year should run autumn–autum. It can also offset from the start of the model, if your model starts at 1998 and your fishing year should run 2000–2005.

run_revstep

A negative integer, defining which step in the fishing year an assessment for next year is performed. If NULL, run every step.

run_f

When the quota should be recalculated, in addition to any condition defined by run_revstep.

interim_value

A formula that provides the interim value to bridge the gap between historical landings & projected quota values, see examples.

run_at

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

Details

Variables defined in your model

Once added the following variables can be reported:

quota_quota_name__var: A vector of quota values, one per fishing year in your model, see quota_hockeyfleet_fl__var in example below

Fishing year

Instead of generating a quota per calendar year or step, as we do with other projections, quotas are per fishing year.

The schedule of the fishing calendar is defined with:

year_length: The length of the fishing year, in years. If > 1, the same yearly quota will be used for all years
start_step: Offset of the initial fishing year, in model steps. So you can both start your fishing year in autumn, and have a fishing year that is offset against the model start year
run_revstep: The step in the fishing year that the quota for the next year should be calculated

In addition, g3a_predate_catchability_project will allow you to assign proportions of a quota to model steps.

Examples:

year_length = 2, start_step = 3, run_revstep = -2: A 2 year fishing calendar, i.e. a quota will be calculated every other year and the same value used for the next 2 years. Assuming 4 model steps, the quota will be calculated in winter for the next fishing year in summer.
year_length = 5, start_step = 4 * 2: A 5 year fishing calendar, the quota will be recalulated every 5 years in the autumn (the final step before the next fishing year starts). If our model starts at 1998 and have 4 steps, 4 * 2 means our first full fishing year is 2000–2005.

Value

g3_quota_hockeyfleet

A formula for use in g3_quota

$$ H (\sum_{predators}{\sum_{preys}{S_{p,p} P_p}}) {minmax}(\sum_{preys}\frac{B_p}{T}, 0, 1) $$

$H$: Harvest rate, provided by harvest_rate argument, by default the hf.harvest_rate parameter
$T$: Trigger biomass, provided by btrigger argument, by default the hf.btrigger parameter
$P_p$: Prey proportion, provided by preyprop_fs (i.e. the proportion of the prey stock that can be considered part of the spawning stock)
$S_{p, p}$: Total suitable biomass for predator/prey combination
$B_p$: Total abundance of prey in biomass

g3_quota_assess