data moderate assessments for 9 groundfishes
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Data-moderate assessments for 9 groundfishes. NWFSC and SWFSC STAT teams. Context and objectives. Data-moderate = catch and index data Methods (XDB-SRA and exSSS ) already reviewed. 3 Objectives Fit index data Provide stock status (depletion) Provide OFLs for 2015, 2016.

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Presentation Transcript
slide2

Context and objectives

  • Data-moderate = catch and index data
  • Methods (XDB-SRA and exSSS) already reviewed

3 Objectives

Fit index data

Provide stock status (depletion)

Provide OFLs for 2015, 2016

slide3

Things to expect

  • First data-moderate STAR panel
    • Base cases are currently fluid
    • Terms of Reference “open”
      • How much to show
      • How to present?
      • Executive summary
  • Many topics germane to “full” assessments
  • Future research topics important
    • How can we improve future applications?
slide4

Biology and ecology

Flatfishes

Rockfishes

Nearshore-shelf (<250 m)

English sole

Shelf-slope (up to 500 m)

Rex sole

Nearshore(<120 m)

Shelf-Slope

  • Sharpchin
  • Stripetail
  • Yellowtail
    • North of 40.10
    • South of 40.10
  • Brown
  • China
  • Copper
  • Vermilion
    • North of Pt. C
    • South of Pt. C (“complex”)

Table 1: Life history parameters

slide5

Assessment scope

Yellowtail

Sharpchin

China

Vermilion

Copper

Stripetail

Rex sole

English sole

Brown

Yellowtail

slide6

Generalized Linear Mixed Models (GLMM)

  • Model set-up
  • Delta approach: models positives (binomial) and magnitude of positives (lognormal or gamma)
  • Extreme Catch Events (ECE): modeled as a mixture distribution
  • Model Interpretation
  • Convergence: Neff > 500
  • Goodness-of-fit: Q-Q plots (ECE or non-ECE?)
  • Model selection: Deviance (lognormal or gamma?)
slide7

GLMM survey stratification: Rockfishes

Sharpchin

Stripetail

Yellowtail

slide10

Interpreting trawl survey catchability

“The distance between the trawl doors is three times greater than the distance between the wings on the NWFSC trawl (Figure 2). Since abundance data was expanded to the index of biomass using net wingspread, the survey biomass estimates are three times greater than if door spread was used. The subsequent estimate of q using door spread would therefore be approximately 1, one-third of the value estimated in the assessment. Catchability in a stock assessment is solely used as a scalar and is difficult to interpret. However, the observations of herding presented here illustrate one process that contributes to a larger than expected estimate of q.”

-Bryan et al (in press)

slide14

Extended Depletion-based Stock Reduction Analysis (XDB-SRA)

Extended Simple Stock Synthesis (exSSS)

Common data (Catch, indices)

Selectivity = maturity

Age-structured

Delay-difference

Life history: Two-sex

Life history: Single-sex

VBGF parameters

No growth parameters (no SPR)

R0 prior (MLE;MCMC); depletion prior (AIS)

Depletion prior

Productivity: Steepness (h)

Productivity: FMSY/M; BMSY/B0

slide16

Depletion prior: Vulnerability analysis

The 2012 review panelrecommended that we use three bins

Unfortunately, the results were not captured in the report

This is an attempt to re-create the analysis

None of the 2013 assessment cases fall in the right-hand bin

slide17

Depletion prior: Vulnerability analysis

“Depletion”2000 = 65%: Stripetail, English and Rex sole

Beta distribution peaks at right

“Depletion”2000= 30%:Brown, China, Copper, Vermilions, Sharpchin, Yellowtails

Beta distribution peaks at left

The “uninformative” case is beta, based on all data

Has not been used in any 2013 analyses

slide19

Sharpchin rockfish: Index fits

All surveys combined

XDB-SRA

Triennial- early

Triennial- late

NWFSC

exSSS

slide31

Stripetail rockfish: Index fits

All surveys combined

XDB-SRA

exSSS

slide34

Yellowtail rockfish (N): Index fits

Triennial

NWFSC

RecFIN

CPFV

XDB-SRA

Tri early

Hake bycatch

RecFIN

NWFSC

exSSS

Tri late

Trawl CPUE

CPFV

slide36

Yellowtail (N): Index fits with combined Triennial

Triennial

RecFIN

Hake bycatch

NWFSC

CPFV

Trawl CPUE

slide40

Yellow rockfish (S): Index fits

RecFIN

cenCal/OR CPFV

XDB-SRA

exSSS

slide43

English sole: Index fits

Triennial- combined

NWFSC

XDB-SRA

Triennial- early

Triennial- late

exSSS

slide56

Rex sole: Index fits

All surveys combined

XDB-SRA

NWFSC

Triennial- early

Triennial- late

exSSS

slide69

Brown rockfish: Index fits

RecFIN

cenCal CPFV

soCal CPFV

XDB-SRA

exSSS

slide80

China rockfish (coastwide): Index fits

RecFIN

norCal/OR CPFV

cenCal CPFV

XDB-SRA

exSSS

slide103

Copper rockfish: Index fits

soCal CPFV

RecFIN

norCal/OR CPFV

cenCal CPFV

XDB-SRA

exSSS

slide114

Vermilion rockfish North: Index fits

RecFIN

cenCal CPFV

XDB-SRA

exSSS

slide124

Vermilion rockfish South: Index fits

RecFIN

soCal CPFV

Hook-and-line

XDB-SRA

exSSS

exsss adaptive importance sampling
exSSS: Adaptive Importance Sampling
  • Create initial parameter sets (N=700)
    • Sex specific M (lognormal), h (beta), and final depletion (beta)
    • Fix parameters in the assessment model and solve for R0 that meets the final depletion value under the assumed dynamics.
  • Sample from the initial parameter set based on the weights:
  • Regenerate parameter vectors (N=700) using a multivariate student’s T distribution based on the drawn parameters
  • Rerun the assessment model with each of the new parameter sets
  • Repeat steps 2-4 until the entropy criteria (e > 0.92)is met:
  • Create a large final sample (N=5000) from the parameter sets that met the entropy criterion.
  • Run the assessment model for the final time with the final parameter sets.
slide135

English sole: gamma models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide136

English sole: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide137

Rex sole: gamma models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide138

Rex sole: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide139

Sharpchin rockfish: gamma models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide140

Sharpchin rockfish: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide141

Stripetail rockfish: gamma models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide142

Stripetail rockfish: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide143

Yellowtail rockfish: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

slide144

Yellowtail rockfish: lognormal models

Triennial late

NWFSC

Triennial early

Non-ECE

ECE

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