RickerHarvest: Simulated time series from a ricker model with fishing
In tanyalrogers/GPEDM: Gaussian Process regression for Empirical Dynamic Modeling

RickerHarvest

R Documentation

Simulated time series from a ricker model with fishing

Description

Contains time series simulated from a Ricker model with harvesting:

B_{t+1}=S_{t}e^{r-S_{t}/K+\epsilon_{b}}

X_{t+1}=bB_{t+1}

u_{t+1}=((1-a)u_{t}+au_{t}(B_{t+1}-B_{t})/B_{t})(1+\epsilon_{u})

C_{t+1}=B_{t+1}u_{t+1}

S_{t+1}=B_{t+1}-C_{t+1}

\epsilon_{b} \sim N(0,\sigma_{b})

\epsilon_{u} \sim Unif(-\sigma_{u},\sigma_{u})

Where B is biomass, X is a survey index of biomass with catchability b, u is the exploitation rate (which changes in response to changing biomass according to parameter a), C is catch, and S is uncaught biomass (escapement). For region "A", parameter values are r=3, K=1000, b=0.01, a=0.1, \sigma_{b}=0.1, and \sigma_{u}=0.2. The initial exploitation rate is 0.01. For region "B", parameters are indentical except b=0.005 and the initial exploitation rate is 0.8. Thus, the abundance indices for each region have different catchabilities (e.g. different survey methods are used in each region) and the regions have different catch histories.