spr.hpp File Reference

Spawning biomass per recruit, for the Amendment-56 SPR proxies. More...

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Functions
template<class Type>
vector< Type >	per_recruit_survivors (const vector< Type > &Z)
	Survivors at age from one recruit under a fixed mortality schedule.
template<class Type>
Type	spawning_biomass_per_recruit (const vector< Type > &n, const vector< Type > &Z, const vector< Type > &weight, const vector< Type > &mature_female, Type spawn_month)
	Female spawning biomass per recruit, given a survivor schedule.

Detailed Description

Spawning biomass per recruit, for the Amendment-56 SPR proxies.

F40% and F35% are the F that leave a target fraction of unfished spawning output per recruit; the template finds them by penalising SPR(F)/SPR(0) against that fraction (section 13, JNLL_REFPT_PENALTY). Under Beverton-Holt or Ricker, SPR0 also sets steepness and R0 and SPRFinit sets R_init (section 6.3), which scales the initial age structure (section 6.4) – so these values reach the hindcast and the objective under any harvest control rule, not just the reference points.

Both functions work on the female schedule (sex index 0) and report spawning output per TOTAL recruit: the caller supplies spawning output per fish with maturity already folded in, and the female fraction separately.

Not defined under predation, where total mortality carries M2 and so tracks predator abundance rather than the prey stock alone: data_check() refuses the switch combinations that would read it.

Definition in file spr.hpp.

Function Documentation

per_recruit_survivors()

template<class Type>

vector< Type > per_recruit_survivors

(

const vector< Type > &

Z

)

Survivors at age from one recruit under a fixed mortality schedule.

The oldest bin is a plus group, so it also accumulates the tail of survivors that stay in it: / (1 - exp(-Z_plus)). Two unchecked preconditions, kept off the AD path and unreachable for any age-structured species: Z.size() >= 2, since the plus group reads the age below it, and a plus-group Z above zero, or that tail divides by zero.

Parameters

Z	Total instantaneous mortality at age (yr^-1), length nages >= 2.

Returns

Numbers at age per recruit.

Definition at line 38 of file spr.hpp.

spawning_biomass_per_recruit()

template<class Type>

Type spawning_biomass_per_recruit	(	const vector< Type > &	n,
		const vector< Type > &	Z,
		const vector< Type > &	weight,
		const vector< Type > &	mature_female,
		Type	spawn_month )

Female spawning biomass per recruit, given a survivor schedule.

Parameters

n	Numbers at age per recruit, from per_recruit_survivors().
Z	The schedule that produced n, reused for the mortality served before spawning within the year.
weight	Spawning output per fish at age (kg): spawn_output (section 5.7), with maturity and, for a one-sex species, the female fraction already in it.
mature_female	Female fraction of a recruit's cohort: the recruitment split for a two-sex species, 1 otherwise.
spawn_month	Month of spawning, 0-12; 0 spawns at the start of the year.

Returns

Spawning biomass per recruit (kg per recruit).

Definition at line 69 of file spr.hpp.