Growth is computed on start-of-year biomass and a year of fishing removes
B (1 - exp(-F)), so equilibrium is B/K = 1 - h/r with harvest rate
h = 1 - exp(-F), hmsy = r/2 and B/Bmsy = 2 - h/hmsy exactly. ffmsy()
returns h/hmsy. (Using r/2 for instantaneous F overstates F/Fmsy for fast
stocks: for r = 1.4, Fmsy = -log(1 - r/2) = 1.2, not 0.7.)
Arguments
- F
instantaneous annual F (vector, or matrix with stocks in columns).
- r
intrinsic growth rate(s), one per stock.
- h
if
TRUE,Fis already a harvest rate.
Examples
ffmsy(-log(1 - 0.7), r = 1.4) # 1: fished at MSY
#> [1] 1