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George Bank Cod Base –Similar to GARM2005 assessment Fleet_dome Survey_dome Survey_and_Fleet_dome Purpose: test models ability to estimate correctly when.

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Presentation on theme: "George Bank Cod Base –Similar to GARM2005 assessment Fleet_dome Survey_dome Survey_and_Fleet_dome Purpose: test models ability to estimate correctly when."— Presentation transcript:

1 George Bank Cod Base –Similar to GARM2005 assessment Fleet_dome Survey_dome Survey_and_Fleet_dome Purpose: test models ability to estimate correctly when doming occurs

2 GB cod basic setup Years (27 years) Ages 1-25, 10+ Lengths cm 3 market categories 3 surveys (CVs 20%, 30%, 25%) CV on landings 5% Growth stdevs 5.0 initial, 2.0 projection Von B params 148.2, , % Mature ~42 cm Selectivity flat-topped, 50% selected 64 cm M = 0.2 F high ( ) then reduced in final years (0.48, 0.35)

3 GB cod test cases Fleet_dome –Moved ascending limb of selectivity curve left to allow for nearly full selectivity at peak of dome

4 GB cod test cases Survey_dome –Each survey mirrored for descending limb of selectivity curve at age 7

5 Georges Bank Cod BASEFleet Dome Survey Dome Fleet&Surv. Dome AIM SSB: strong bias F: -40% to+20% ASPICOne way trip problem SCALE SSB: 5-30% + F: ~30% - VPA SSB: slightly + F: slightly - ASAP SSB: slightly + F: slightly -

6 AIM Issues with low (or no) sampling in some years

7 Georges Bank Cod BASEFleet Dome Survey Dome Fleet&Surv. Dome AIM SSB: strong bias F: -40% to+20% Division by zero problem ASPICOne way trip problem SCALE SSB: 5-30% + F: ~30% - VPA SSB: slightly + F: slightly - ASAP SSB: slightly + F: slightly -

8 Georges Bank Cod BASEFleet Dome Survey Dome Fleet&Surv. Dome AIM SSB: strong bias F: -40% to+20% Division by zero problem ASPICOne way trip problem SCALE SSB: 5-30% + F: ~30% - Low simulated length sampling obscured the effect we were testing for VPA SSB: slightly + F: slightly - ASAP SSB: slightly + F: slightly -

9 SCALE Issues with very low sampling in some years

10 Georges Bank Cod BASEFleet Dome Survey Dome Fleet&Surv. Dome AIM SSB: strong bias F: -40% to+20% Division by zero problem ASPICOne way trip problem SCALE SSB: 5-30% + F: ~30% - Low simulated length sampling obscured the effect we were testing for VPA SSB: slightly + F: slightly - slightly - slightly + Same as base (‘E.coast way’) Same as “Fleet Dome” ASAP SSB: slightly + F: slightly -

11 VPA (SSB) Poor performance for ages>6

12 VPA (FAA) Poor performance for ages>6

13 Georges Bank Cod BASEFleet Dome Survey Dome Fleet&Surv. Dome AIM SSB: strong bias F: -40% to+20% Division by zero problem ASPICOne way trip problem SCALE SSB: 5-30% + F: ~30% - Low simulated length sampling obscured the effect we were testing for VPA SSB: slightly + F: slightly - slightly - slightly + Same as base (‘E.coast way’) Same as “Fleet Dome” ASAP SSB: slightly + F: slightly - slightly - Same as base (‘E.coast way’) Same as “Fleet Dome”

14 ASAP

15 VPA vs ASAP (NAA)

16

17 Precision (SSB and F) AIM: ~ 0.1, did not vary by case SCALE: (increased with retros) VPA*: (poor ages>6), did not vary ASAP: <0.05, did not vary *VPA CVs are for age-specific SSB, F

18 GB Cod Conclusions Simulation set-up precluded model comparisons for AIM, ASPIC, and SCALE Between VPA and ASAP, bias was similar, but VPA estimates at age degraded faster than ASAP; ASAP more precise Dome not an issue for survey because of age- specific indices (rather than age comp. for total N index) Dome effect in fleet probably minimized because of large simulated F (fewer older fish, so misspecifying those selectivities added little bias)

19 VPA PR BaseFleet Dome

20 VPA Fleet Dome Retro

21 VPA q “East Coast Style” Survey DomeBase


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