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pacific-hake / pacifichakemse

A Management Strategy Evaluation for Pacific Hake
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AAV Management procedures #7

Open cgrandin opened 3 years ago

cgrandin commented 3 years ago

Coming soon is the request for AAV-based MPs. These are going to be requested by the Canadian JMC. Here is a brain dump of my thinking on the matter so far which came from an email sent to the Canadian JMC lead on Dec 15, 2020. They asked for advice on how to frame the request.

We may have to set the AAV to some exact values and implement this in multiple MPs, for example 30%, 20%, 15%, and 10%. It may be possible to manipulate the HCR catch (capping at +/-15% from previous year) to allow values between 0% and 15% AAV in a single MP so we don't have to force static values. That would mean we have only one MP for this instead of say 4 or 5. That said, and the more I think about it, it may actually be easier for us all to interpret multiple MPs at different exact AAV values.

I am also thinking that we should define the first simulation year catch to be some value, for example the mean catch of the last ten years, because AAV is going to start from there and be relative to it through the time series.

For performance metrics, in the case of multiple MPs, all of the current ones would be available (ST catch, LT catch, and biomass relative to the reference points), but when looking at the violin plots the AAV would be a single horizontal line at the value for that MP. If there were a single MP the AAV violin plot would show a (hopefully) equal distribution between 0-15% which would be essentially useless for management but would give us assurance of equal representation of the various values possible between 0 and 15%.

Using the multiple MP approach we could find out at what level the performance metrics fail. Goal (F) in the table would likely have to be changed from "Maintain low catch variability" to something like "Maintain catch variability at a level that ensures acceptance of biomass-based and catch-based performance metrics."

iantaylor-NOAA commented 3 years ago

Thanks for getting this conversation started @cgrandin. I understand that the IPHC uses some form of this approach. Before putting in all the work to explore different approaches, I think it would be useful to get in touch with those involved in their MSE to understand more detail on how the HCR is configured and how they were tested via MSE.