1 / 14

Two-Stage Weighting Method for Composition Data in Fisheries Analysis

This document outlines a two-stage method for weighting composition data in fisheries studies, specifically calculating multipliers to align recommended sample sizes with assumed sample sizes for certain years. The methodology leverages residuals of mean length or age and is exemplified through a case study on Chilean hake. The approach is crucial for improving the accuracy of fisheries management models, utilizing various sample sizes from multiple commercial and artisanal fishing methods, supported by data from surveys and fishery catches. Reference to Appendix A of Francis (2011) is included for detailed methodology.

allie
Télécharger la présentation

Two-Stage Weighting Method for Composition Data in Fisheries Analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Method TA1.8* A 2-stage method of weighting composition data: Calculates multiplier, w, so that N2y = wN1y, where N1y = sample size assumed for year y in model, N2y = recommended sample size Uses residuals of mean length (or age). *See Appendix A of Francis (CJFAS 68:1124-1138, 2011)

  2. Chilean Hake example

  3. Chilean hake example Multinomial sample sizes Stage-1 Stage-2 Composition data set TA1.1+TA1.2TA1.3TA1.8 Trawl fishery 150 258 115 116 15 Commercial longline fishery 150 240 154 152 10 Artisanal longline fishery 150 557 251 248 25 Survey 150 338 232 233 69 + McAllister & Ianelli (1997)

  4. REYE Fishery Retained Catch Fleet w trawl 0.22 fix 0.24 trawl + fix 0.22 asf0.067 all 0.15

  5. REYE Fishery Discards Fleet w trawl 0.18 fix 0.18 trawl + fix 0.17

  6. REYE Surveys Survey w tri 0.41 akslope 3.2 combo 0.11 tri + akslope 0.53 tri + combo 0.17 all 0.20

  7. REYE Fishery age-at-length Fleet w trawl 0.76 asf 0.51 trawl + asf 0.61

  8. REYE Survey age-at-length Survey w combo 1.63!!

  9. AUR FisheryLengths Retained

  10. AUR Fishery Lengths Retained Fleet sex w lo hi twl sex 0.31 0.22 0.55 comb 0.75 0.45 1.72 nontr sex 0.56 0.34 1.32 comb 0.36 0.28 0.50 ALL BOTH 0.36 0.28 0.50

  11. AUR FisheryLengths Discards w = 0.97 (0.47,5.39)

  12. AUR Survey Lengths w = 0.52 (0.36,1.11)

  13. AUR TWL Age-at-length w = 0.43 (0.32, 0.74)

  14. AUR Survey Age-at-length w = 1.8 (1.4, 2.5)

More Related