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Assessment of Icelandic Cod Stock

This study analyzes data on the Icelandic cod stock to assess its development, predict catch numbers, and provide short-term advice. It includes components such as landings, catch per unit effort, stock assessments, otoliths, logbooks, surveys, and indices.

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Assessment of Icelandic Cod Stock

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  1. . Assessment of the Icelandic cod stock Björn Ævarr Steinarsson Marine Research Institute

  2. Data Data analysis Assess. Prediction Components of advice(short-term) Landings Catch in numbers Length meas. Predicted developm. of stock and catch Otoliths CPUE Stock assessment Logbooks Surveys Indices Otoliths Length m.

  3. Input data • Catch in numbers by age groups • Survey indices • Catch per unit effort (CPUE) from the fleet

  4. Icelandic cod. Landings1906-1996

  5. CodLandings by gear

  6. Distribution of cod catches

  7. Distribution of cod catches

  8. Sampling from landings • Allocation • Samples alloced proportional to landings in each fleet category - Real time. • Implementation • MRI staff • Inspectors from the Fisheries Directorate • The Coast Guard • Magnitude • Annually about 150.000 length measurements and 15000 otoliths for ageing.

  9. CodCatch in number by age groups CV  20

  10. Icelandic Groundfish SurveyIGFS • Annually about 600 fixed trawl stations taken in March all around Iceland since 1985. • Performed by 4-5 identical trawlers • Standarized trawl, trawling distance, trawling speed etc. • About 50 000 length measured and 5 000 otoliths taken for ageing • Gutted and ungutted weight, liver weight, gonad weight, stomach content anlysis, maturity etc.

  11. IGFSTowing station in spring survey

  12. IGFS- Primary objectives - • Independent estimate of relative abundance. • Annual indices of recruitment. • Various biological parameters.

  13. IGFSTotal biomass index CV  10-16

  14. IGFSRelative abundance index by age groups in 2002

  15. Survey abundance vs number alive in the sea Number of fish of age a in the sea Number of fish of age a in survey

  16. IGFS - CODIndex of 3 years old vs. 4 years old a year later

  17. LogbooksExample

  18. Distribution of Logbooks records herring Capelin Herring Shrimp trawl Bottom trawl Pelagic trawl Dragnót Longline

  19. LogbooksObjectives • Collecting data to estimate CPUE/Effort • Behavior of the fishing fleet • Relationship with fishermen

  20. CPUE vs Biomass Biomass (tonnes) CPUE (tonn/hour)

  21. CODCPUE 1991-2001 by gears

  22. Distribution of cod catches

  23. Greenland HalibutMain fishing areas

  24. CODCatch in numbers 1991-2000 (Millions) Yearclass 1988

  25. CODIGFS index vs. VPA estimate of age group 6 120 2 R = 0.8513 90 100 80 89 86 60 VPA 85 95 91 40 88 96 87 93 97 20 94 92 0 0 20 40 60 80 100 120 IGFS-Index

  26. COD Estimated 4+ biomass by different assessment models.

  27. COD Probability plots of estimated fishable biomass in 2002-2005

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