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

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Anexample of harvest rule control forrecoverythejackmackerelpopulation

Cristian Canales- IFOP- Chile


Mainquestions

  • Whatwewantto do withjackmackerel (JM) population?

  • Whatisthe status of JM population?

  • Why and howrebuildthe 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?


“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.


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)


MSY


Whatisthe status of JM population?

(Cooper, 2006)


Estimatingthe MSY in JM


Recruitments


Whatisthe status of JM 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


The target isreachedafter 8 years

It is necessary more than 10 yrs to reach the target


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


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

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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