Calculate spawners per recruit by individual stock. Appropriate for a population model with a single spatial area and an annual time steps, i.e. single season.
Usage
calc_phi_simple(Z, fec_a, mat_a, delta = 0)
calc_NPR(Z, na = length(Z), plusgroup = TRUE)Arguments
- Z
Total mortality at age
- fec_a
Fecundity at age. Vector
- mat_a
Maturity at age. Vector
- delta
Fraction of season that elapses when spawning occurs, e.g., midseason spawning when
delta = 0.5.- na
Integer, number of age classes
- plusgroup
Logical, whether the largest age class is a plusgroup accumulator age
Value
calc_phi_simple() returns the spawners per recruit.
calc_NPR() returns a vector of the numbers per recruit at age, i.e., survival.