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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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)


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

MSY


What is the status of jm population1

Whatisthe status of JM population?

(Cooper, 2006)


Estimating the msy in jm

Estimatingthe MSY in JM


Recruitments

Recruitments


What is the status of jm population2

Whatisthe status of JM population?


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


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

The target isreachedafter 8 years

It is necessary more than 10 yrs to reach the target


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

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


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

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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