Description Usage Arguments Value Examples
This function calculates the ratio change in a fished population after a marine protected area is implemented assuming closed population. It also calculates metrics of the transient response of an MPA using the methods described in White et al. 2013 'Transient responses of fished populations to marine reserve establishment' published in conservation letters. It uses a Leslies matrix and the output is metrics that evaluate the transient dynamic for a closed population
1 | closedpop_metrics(tf, maxage, Lmat, Lfish, M, Fi, Linf, k, a0, pW, qW, lambda)
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tf: |
the time step to run the population |
maxage: |
max age of the species ie. number of age classes |
Lmat: |
length at maturity |
M: |
the natural mortality rate, if unknown generally use 0.2 |
Fi: |
the fishing mortality rate, F, find in stock assessment if don't have more localized estimate |
Linf: |
asymptotic growth rate used in von-Bertallanfy growth equation, can find on fishbase |
k: |
von-bertallanfy growth parameter estimate |
a0:the |
age at length 0 used in the von-Bertallanfy growth equation |
pW: |
weight length relationship estimate, same as a on fishbase.org but need to divide by 1000 to get in kg not grams |
qW: |
weight length relationship estmate, same as b on fishbase.org |
lambda: |
the population growth rate in the MPA |
P1: the period of oscillations
rho: the rate of return to the stable age distribution in the MPA
theta: the angle between the initial conditions of the fished state and the stable age distribution in the MPA
Nratio: the abundance changes over time
Bratio: the biomass changes over time
fm_ratio: the fishing mortality rate to natural mortality rate ratio
transient_length: the approximate length of the transient duration
1 2 | closedpop_metrics(tf=50, maxage=25,Lmat=18,Lfish=25,M=0.2,Fi=0.17, Linf=37.8,k=0.23,a0=-0.7,pW=6.29e-06,qW=3.172,lambda=1)
closedpop_metrics()
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