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An example of harvest rule control for recovery the jack mackerel population

An example of harvest rule control for recovery the jack mackerel population. Cristian Canales- IFOP- Chile. Main questions. What we want to do with jack mackerel (JM) population ? What is the status of JM population ? Why and how rebuild the JM population ?.

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An example of harvest rule control for recovery the jack mackerel population

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  1. Anexample of harvest rule control forrecoverythejackmackerelpopulation Cristian Canales- IFOP- Chile

  2. Mainquestions • Whatwewantto do withjackmackerel (JM) population? • Whatisthe status of JM population? • Why and howrebuildthe JM population?

  3. Whatwewantto do with JM population? • Wesupposethere’sanimplicitdesire, thatistheconservation. Whatdoesconservation mean? • Thesustainableexploitation: allcountrieswantto be at thebussinessforlong time. • Ideally, wewanttogetthemaximumyield and maintainitover time (MSY). Howthereachit?

  4. “Believeornotbelieve in MSY” • Why in fishery management is considered a biomass escapement level?. • When we accept the existence of S-R relationship (no parents -> no recruits), we are accepting the existence of MSY implicitly.

  5. Whatisthe status of JM population? • A general target of many fishery resources is to maintain the population and its fishery around MSY (Bmsy and Fmsy). • In this sense, the pair (Bmsy; Fmsy) defines the Biological Reference Points - BRP (or any quantity close to these). When we cannot estimate the MSY variables properly, we can adopt a proxy (~40%Bo) • We have talked about about this. See Canales C.(SWG-11-JM-01, 2012), Canales & Hintzen (SWG-11-JM-09, 2012)

  6. MSY

  7. Whatisthe status of JM population? (Cooper, 2006)

  8. Estimatingthe MSY in JM

  9. Recruitments

  10. Whatisthe status of JM population?

  11. Twowaystorecoverythepopulation Constantfishingmortality(F=Fmsy), HereFmsyisappliedindependently of population status 2) Rampstrategy(F = Fmsy * SSB/SSBo), Here the Fmsy is reduced as a proportion of population depletion when the overfished have been declared

  12. The target isreachedafter 8 years It is necessary more than 10 yrs to reach the target

  13. Ramp strategy: The cost are lower catches at the beginning , but in the future, landings will be larger.

  14. If the recruitment doesn’t back to historical level, the MSY won’t be reached never. If a regime shift is going on, the BRP should be re-evaluated

  15. Remarks 1. To recovery the population, it is necessary to declare the condition as overfished 2. To declare the overfished condition, it is necessary define BRP (target and/or limit) 3. The population recovery may be reached, considering the variables related to MSY (or proxy) as biological reference points (BRP) 4. Considering the uncertainty of the future recruitments, a harvest rule control should be defined in order to sure the population’s rebuild.

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