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Approaches to estimate proxy BRP values

Approaches to estimate proxy BRP values. Estimate equilibrium yield by a deterministic method, identify F x% and related BRPs, perform sensitivity analysis of various input parameter values

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Approaches to estimate proxy BRP values

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  1. Approaches to estimate proxy BRP values • Estimate equilibrium yield by a deterministic method, identify Fx% and related BRPs, perform sensitivity analysis of various input parameter values • Estimate average yields from 100-year fishery by projection modeling with stochastic S-R, identify Fx% and related BRPs • Perform various diagnostic tests on selected Fx% by projection modeling with stochastic S-R: (a) rebuilding possibility of a severely depleted stock under the chosen Fx% with a less productive S-R curve (B-H with Tau=0.3), (b) distribution of relative mean ESB for a range of Fx% values, ( c) CV of yield for a range of Fx% values, and (d) extinction probability of the stock for a range of Fx% values

  2. Equilibrium Approach – Deterministic Simulation

  3. Stochastic Approach – Projection Modeling

  4. What is F%? e.g. F20% is an F which produces a SSB/RF equivalent to 20% SSB/R0 SSB/R0 SSB/RF

  5. Identification of FX% • Red king crab example - EXCEL

  6. Year class development for stochastic simulation – stock projection modeling

  7. Testing the Stochastic Program • Stochastic program produced results coinciding with the deterministic estimates. e.g., R and Y predictions

  8. Rebuilding red king crab stock from a 20%ESBMSY to MSY level under proposed harvest control rule with F50. The data points correspond to 100-year fishery simulation under stochastic Beverton-Holt S-R model with female ESB, overall recruitment variability,  =0.7, serial correlation, = .5, M = 0.18, h = 0.2, mating ratio=1:3, and =0.3

  9. Proportion of years ESB has depleted to < 25%ESBMSYvs. relative ESB/R from 100-year fishery for the red king crab stock. The estimates are made under stochastic Beverton and Holt and Ricker stock-recruitment models with female ESB, M = 0.18, h = 0.2, mating ratio = 1:3, overall recruitment variability,  = 0.7, serial correlation,  = 0.5, and τ = 0.1-0.3. The proportion of years ESB has depleted below 25%ESBMSY is < 0.02 at F50for all τ values up to 0.3.

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