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

Anexample of harvest rule control forrecoverythejackmackerelpopulation

Cristian Canales- IFOP- Chile

main questions
Mainquestions
  • Whatwewantto do withjackmackerel (JM) population?
  • Whatisthe status of JM population?
  • Why and howrebuildthe JM population?
what we want to do with jm population
Whatwewantto do with JM population?
  • Wesupposethere’sanimplicitdesire, thatistheconservation. Whatdoesconservation mean?
  • Thesustainableexploitation: allcountrieswantto be at thebussinessforlong time.
  • Ideally, wewanttogetthemaximumyield and maintainitover time (MSY). Howthereachit?
believe or not believe in msy
“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.
what is the status of jm population
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)
two ways to recovery the population
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

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The target isreachedafter 8 years

It is necessary more than 10 yrs to reach the target

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

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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

remarks
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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