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Seeking assistance with projections

Laura Lee, modified 3 Years ago.

Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Hi all,

I am working in SS version V3.30.14.01-safe. I am interested in doing projections to determine the appropriate quota based on different scenarios in which we assume different values for fishing mortality and different assumptions about recruitment. I need help in better understanding the options in the forecast file so I can amend to meet my needs. I would appreciate if someone wouldn't mind working with me to guide me in this process.

Thanks in advance for your assistance.

Cheers,

Laura

Richard Methot, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts
Laura,
We'll be glad to help. Go ahead and post your initial questions here so that all can benefit from the response.  Then if needed we can take followup into a one:one conversation.
You are using a fix version of SS 3.30.14.01.  3.30.15.00 was released in the spring and we should be getting 3.30.16.00 out very soon.  Any version that does not end with .00 is still in testing.

Let me start by posting, from forecast.ss_new, the main set of options that are available.
For forecast F, the main option is:
4 # Forecast: -1=none; 0=simple_1yr; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar
Also, there is a rather new option to allow for time-varying selectivity in the forecast:
0 # Forecast selectivity (0=fcast selex is mean from year range; 1=fcast selectivity from annual time-vary parms)

and recruitment in the forecast period also has recently been expanded with the basic options being:
0 #_Forecast recruitment:  0= spawn_recr; 1=value*spawn_recr_fxn; 2=value*VirginRecr; 3=recent mean from yr range above (need to set phase to -1 in control to get constant recruitment in MCMC)

Rick
Richard D. Methot Jr. Ph.D.
NOAA Fisheries Senior Scientist for Stock Assessments
Mobile: 301-787-0241


On Wed, Aug 5, 2020 at 9:53 AM Laura Lee <VLab.Notifications@noaa.gov> wrote:

Hi all,

I am working in SS version V3.30.14.01-safe. I am interested in doing projections to determine the appropriate quota based on different scenarios in which we assume different values for fishing mortality and different assumptions about recruitment. I need help in better understanding the options in the forecast file so I can amend to meet my needs. I would appreciate if someone wouldn't mind working with me to guide me in this process.

Thanks in advance for your assistance.

Cheers,

Laura


--
Laura Lee Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11035915 VLab.Notifications@noaa.gov
Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Rick,

 

Thanks so much. So, as I said, I’m trying to find the appropriate quota for nine different scenarios. There are three values of F to explore: F2017 (terminal year) = 0.27; Fthreshold (F35%) = 0.13, estimated by SS; and Ftarget (F45%) = 0.18, estimated by SS. Then there are three sets of years from which we want to pull recruitment from: 1991-2017 (whole time series); 2004-2017 (recent years); and 1993-2001. None of the selectivity curves varied over time so the mean from the whole time series can be used. I would like to use the SS version that I built the original model on, that is why I have not yet moved to the upgraded version.

 

My questions are: exactly what options do I need to modify? After the model is run, where in the results do I find the information to lead me to the best new quota? Does the quota include dead discards?

 

Thank you so much for your time and all your help.

 

Cheers,

 

Laura

 

 

From: Richard Methot [mailto:VLab.Notifications@noaa.gov]
Sent: Wednesday, August 5, 2020 1:21 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Laura,

We'll be glad to help. Go ahead and post your initial questions here so that all can benefit from the response.  Then if needed we can take followup into a one:one conversation.

You are using a fix version of SS 3.30.14.01.  3.30.15.00 was released in the spring and we should be getting 3.30.16.00 out very soon.  Any version that does not end with .00 is still in testing.

 

Let me start by posting, from forecast.ss_new, the main set of options that are available.

For forecast F, the main option is:

4 # Forecast: -1=none; 0=simple_1yr; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar

Also, there is a rather new option to allow for time-varying selectivity in the forecast:

0 # Forecast selectivity (0=fcast selex is mean from year range; 1=fcast selectivity from annual time-vary parms)

 

and recruitment in the forecast period also has recently been expanded with the basic options being:

0 #_Forecast recruitment:  0= spawn_recr; 1=value*spawn_recr_fxn; 2=value*VirginRecr; 3=recent mean from yr range above (need to set phase to -1 in control to get constant recruitment in MCMC)

 

Rick

Richard D. Methot Jr. Ph.D.
NOAA Fisheries Senior Scientist for Stock Assessments

Mobile: 301-787-0241

 

 

On Wed, Aug 5, 2020 at 9:53 AM Laura Lee <VLab.Notifications@noaa.gov> wrote:

Hi all,

I am working in SS version V3.30.14.01-safe. I am interested in doing projections to determine the appropriate quota based on different scenarios in which we assume different values for fishing mortality and different assumptions about recruitment. I need help in better understanding the options in the forecast file so I can amend to meet my needs. I would appreciate if someone wouldn't mind working with me to guide me in this process.

Thanks in advance for your assistance.

Cheers,

Laura


--
Laura Lee Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11035915 VLab.Notifications@noaa.gov


--
Richard Methot Stock Synthesis Virtual Lab Forum http://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11036667 VLab.Notifications@noaa.gov

IT
Ian Taylor, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 117 Join Date: 12/8/14 Recent Posts

Hi Laura,

Here are some answers for you. Rick can correct me if I get any of this wrong.

 
Specifying forecast F
You can specify a specific F value for use in the forecast via this option:
5 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar
where you would then enter two lines later something like
0.13 # F scalar (only used for Do_Forecast==5)
 
However, the better way to do that for FXX% rates would be to use a combination of the benchmark reference points at the top of the forecast file and the other forecast options. For F_SPR=35% you would use 
0.35 # SPR target (e.g. 0.40)
...
1 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar
while for an F associated with a biomass target, you would set the biomass target and use forecast option 3 instead.
 
To forecast with F2017, you could again input a fixed F value, but the best way is to use the "Ave F" forecast option:
4 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar
 
where you would then set the 3rd and 4th entry of this vector to 0 (or equivalently to 2017):
#_Fcast_years:  beg_selex, end_selex, beg_relF, end_relF, beg_recruits, end_recruits  (enter actual year, or values of 0 or -integer to be rel. endyr)
 0 0 0 0 0 0
 
Specifying forecast recruitment:
To set a range of reference years on which to base forecast recruitment, use the 5th and 6th entries of the vector noted above:
#_Fcast_years:  beg_selex, end_selex, beg_relF, end_relF, beg_mean recruits, end_recruits  (enter actual year, or values of 0 or -integer to be rel. endyr)
 0 0 0 0 1993 2001
and then a few lines later set
3 #_Forecast recruitment:  0= spawn_recr; 1=value*spawn_recr_fxn; 2=value*VirginRecr; 3=recent mean from yr range above (need to set phase to -1 in control to get constant recruitment in MCMC)
 
Also in the control file, you will want to check the "last year of main recr_devs" input to make sure that it reflects what you want (because whatever forecast.  For instance, if you have zero information in the data about 2017 recruitment, then it might be better to set that value to 2016 and use average recruitment over a period ending in 2016 for forecast recruitment which would then cause 2017 recruitment to equal that average. Note that if you want your model to reflect the uncertainty around the average forecast recruitment, you should have a non-negative value for "forecast_recruitment phase (incl. late recr) (0 value resets to maxphase+1)" in the control file. Otherwise the uncertainty in things like spawning biomass will shrink over time in the forecast as a function of fixed recruitments.
 
If the last year of your model is 2017, you may also want to specify fixed catches at the bottom of the forecast file for the years 2018-2020 or whatever period can no longer be influenced by the harvest advice the model is being used to explore.
 
You should be able to confirm that your settings are working looking at the values in the TIME_SERIES output ($timeseries in r4ss). Note that there could be an interaction with the F_report_units specified in the starter file, so check that value as well.
 
Lastly, the "OFLCatch_YYYY" values under DERIVED_QUANTITIES ($derived_quants in r4ss) should be the forecast OFL values including dead discards, while the ForeCatch_YYYY would be the ABC values that include any buffer specified in the forecast file (next to "Buffer"), and if you used a control rule to get the forecast F (as opposed to inputting a fixed F), those ForeCatch_YYYY values should match the total dead catch in the time series output.
 
Let us know if any of this doesn't make sense or you have further questions.
-Ian
Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

These instructions were fantastic and we were able to run the projections without any difficulties. Thanks so much.

 

I do have a question about the results I’m hoping someone can help with. The stock was found to be overfished and overfishing in the terminal year. The projected quota starts out relatively small in the first projection year and then gradually increases to a point at which it levels out within a few years. In practice/reality, should we follow this same trajectory when implementing the quota; that is, start out at the relatively small value and build up over a few years or can we go right to the value at which the projected quota levels out?

 

Thanks again for all your help and time!

 

From: Ian Taylor [mailto:VLab.Notifications@noaa.gov]
Sent: Friday, August 7, 2020 6:43 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Hi Laura,

Here are some answers for you. Rick can correct me if I get any of this wrong.

 

Specifying forecast F

You can specify a specific F value for use in the forecast via this option:

5 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar

where you would then enter two lines later something like

0.13 # F scalar (only used for Do_Forecast==5)

 

However, the better way to do that for FXX% rates would be to use a combination of the benchmark reference points at the top of the forecast file and the other forecast options. For F_SPR=35% you would use 

0.35 # SPR target (e.g. 0.40)

...

1 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar

while for an F associated with a biomass target, you would set the biomass target and use forecast option 3 instead.

 

To forecast with F2017, you could again input a fixed F value, but the best way is to use the "Ave F" forecast option:

4 # Forecast: 0=none; 1=F(SPR); 2=F(MSY) 3=F(Btgt) or F0.1; 4=Ave F (uses first-last relF yrs); 5=input annual F scalar

 

where you would then set the 3rd and 4th entry of this vector to 0 (or equivalently to 2017):

#_Fcast_years:  beg_selex, end_selex, beg_relF, end_relF, beg_recruits, end_recruits  (enter actual year, or values of 0 or -integer to be rel. endyr)
 0 0 0 0 0 0

 

Specifying forecast recruitment:

To set a range of reference years on which to base forecast recruitment, use the 5th and 6th entries of the vector noted above:

#_Fcast_years:  beg_selex, end_selex, beg_relF, end_relF, beg_mean recruits, end_recruits  (enter actual year, or values of 0 or -integer to be rel. endyr)
 0 0 0 0 1993 2001

and then a few lines later set

3 #_Forecast recruitment:  0= spawn_recr; 1=value*spawn_recr_fxn; 2=value*VirginRecr; 3=recent mean from yr range above (need to set phase to -1 in control to get constant recruitment in MCMC)

 

Also in the control file, you will want to check the "last year of main recr_devs" input to make sure that it reflects what you want (because whatever forecast.  For instance, if you have zero information in the data about 2017 recruitment, then it might be better to set that value to 2016 and use average recruitment over a period ending in 2016 for forecast recruitment which would then cause 2017 recruitment to equal that average. Note that if you want your model to reflect the uncertainty around the average forecast recruitment, you should have a non-negative value for "forecast_recruitment phase (incl. late recr) (0 value resets to maxphase+1)" in the control file. Otherwise the uncertainty in things like spawning biomass will shrink over time in the forecast as a function of fixed recruitments.

 

If the last year of your model is 2017, you may also want to specify fixed catches at the bottom of the forecast file for the years 2018-2020 or whatever period can no longer be influenced by the harvest advice the model is being used to explore.

 

You should be able to confirm that your settings are working looking at the values in the TIME_SERIES output ($timeseries in r4ss). Note that there could be an interaction with the F_report_units specified in the starter file, so check that value as well.

 

Lastly, the "OFLCatch_YYYY" values under DERIVED_QUANTITIES ($derived_quants in r4ss) should be the forecast OFL values including dead discards, while the ForeCatch_YYYY would be the ABC values that include any buffer specified in the forecast file (next to "Buffer"), and if you used a control rule to get the forecast F (as opposed to inputting a fixed F), those ForeCatch_YYYY values should match the total dead catch in the time series output.

 

Let us know if any of this doesn't make sense or you have further questions.

-Ian


--
Ian Taylor Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11063864 VLab.Notifications@noaa.gov

Richard Methot, modified 3 Years ago.

Thanks RE: Seeking assistance with projections

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts

Thanks Ian. All that I would add is for everyone to be mindful about the units of F.  F is a simple concept only in a biomass dynamics model for which F really is just a single number. With multiple fleets and dome-shaped selectivity and seasons and perhaps areas - F as a single number is quite complex. I attach some information in this regard.

Rick

Laura Lee, modified 3 Years ago.

RE: Thanks RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Thanks Ian and Rick! This is all very helpful. Will let you know if I run into any issues.

 

From: Richard Methot [mailto:VLab.Notifications@noaa.gov]
Sent: Monday, August 10, 2020 4:14 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Thanks RE: Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Thanks Ian. All that I would add is for everyone to be mindful about the units of F.  F is a simple concept only in a biomass dynamics model for which F really is just a single number. With multiple fleets and dome-shaped selectivity and seasons and perhaps areas - F as a single number is quite complex. I attach some information in this regard.

Rick


--
Richard Methot Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11091426 VLab.Notifications@noaa.gov

Richard Methot, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts

Hi Laura,

Your new question goes beyond "How do I use SS well?" to "How should we manage our fishery?", so I'll avoid getting into the latter here is this forum.

The catch trajectory you see in the forecast is created by the control rule specified in forecast.ss. There are some aspects of the control rule that you need to tailor to the way in which your fishery management plan is designed.

In the forecast module of SS, the first pass through the forecast produces the catch and the resultant population trajectory if the catch was according to the F limit (e.g. Fmsy, F35%, or whatever you selected). In the parlance of U.S. federal fishery management plans, this is designed to show what would happen if catch was right at the overfishing limit each year. 

The second pass through the forecast now applies the control rule which can have a buffer between the Flimit and the now F target, and this Ftarget can have an increasingly large buffer as biomass drops below some specified level. The controls for this look like:

1 # Control rule method (1: ramp does catch=f(SSB), buffer on F; 2: ramp does F=f(SSB), buffer on F; 3: ramp does catch=f(SSB), buffer on catch; 4: ramp does F=f(SSB), buffer on catch) 
0.4 # Control rule Biomass level for constant F (as frac of Bzero, e.g. 0.40); (Must be > the no F level below) 
0.1 # Control rule Biomass level for no F (as frac of Bzero, e.g. 0.10) 
0.75 # Buffer:  enter Control rule target as fraction of Flimit (e.g. 0.75), negative value invokes list of [year, scalar] with filling from year to YrMax 
In U.S. FMPs, the catch level coming from this second loop is often considered as the ABC (e.g. Acceptable Biological Catch).

The third loop through the forecast then is for getting better variance estimates. It starts by freezing the ABC values from loop 2 and now allows for random recruitment variability and/or implementation error in the catch.  The intention is to show quantities like the probability of F/Fmsy and B/Bmsy if future catches attempted to follow the specified ABC while population was also being affected by recruitment variability.

So, I suggest that you review the control rule settings in your forecast file before deciding what recommendations to deliver to the fishery managers.

Rick

 

Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

I did not modify those options when I ran my projections mostly due to lack of understanding. So, we define our overfished based on SSB35%. If the spawning stock biomass is below this level, then we have 10 years to rebuild. We ran projection three projection scenarios with varying assumptions about F: (1) assume F level is the same as in the terminal year of the assessment, (2) assume F is F45%--our target level, and (3) assume F is 35%--our threshold level. I would appreciate any additional advice you could provide in setting these particular values.

 

From: Richard Methot [mailto:VLab.Notifications@noaa.gov]
Sent: Wednesday, September 2, 2020 1:20 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Hi Laura,

Your new question goes beyond "How do I use SS well?" to "How should we manage our fishery?", so I'll avoid getting into the latter here is this forum.

The catch trajectory you see in the forecast is created by the control rule specified in forecast.ss. There are some aspects of the control rule that you need to tailor to the way in which your fishery management plan is designed.

In the forecast module of SS, the first pass through the forecast produces the catch and the resultant population trajectory if the catch was according to the F limit (e.g. Fmsy, F35%, or whatever you selected). In the parlance of U.S. federal fishery management plans, this is designed to show what would happen if catch was right at the overfishing limit each year. 

The second pass through the forecast now applies the control rule which can have a buffer between the Flimit and the now F target, and this Ftarget can have an increasingly large buffer as biomass drops below some specified level. The controls for this look like:

1 # Control rule method (1: ramp does catch=f(SSB), buffer on F; 2: ramp does F=f(SSB), buffer on F; 3: ramp does catch=f(SSB), buffer on catch; 4: ramp does F=f(SSB), buffer on catch) 
0.4 # Control rule Biomass level for constant F (as frac of Bzero, e.g. 0.40); (Must be > the no F level below) 
0.1 # Control rule Biomass level for no F (as frac of Bzero, e.g. 0.10) 
0.75 # Buffer:  enter Control rule target as fraction of Flimit (e.g. 0.75), negative value invokes list of [year, scalar] with filling from year to YrMax 
In U.S. FMPs, the catch level coming from this second loop is often considered as the ABC (e.g. Acceptable Biological Catch).

The third loop through the forecast then is for getting better variance estimates. It starts by freezing the ABC values from loop 2 and now allows for random recruitment variability and/or implementation error in the catch.  The intention is to show quantities like the probability of F/Fmsy and B/Bmsy if future catches attempted to follow the specified ABC while population was also being affected by recruitment variability.

So, I suggest that you review the control rule settings in your forecast file before deciding what recommendations to deliver to the fishery managers.

Rick

 


--
Richard Methot Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11682818 VLab.Notifications@noaa.gov

Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Rick,

 

After I presented the projections, there were some questions I couldn’t quite answer. I think the answer is here, but I don’t think it’s clear to me. I projected the population at our Ftarget in one scenario and our Fthreshold in another; however, in the first couple years of the projections (years after which catch was fixed), the Report file shows F is actually below the F set in the forecast file. Is this due to recruitment variability and the assumed catches for those initial projection years?

 

Thanks as always for your time and insights,

 

Laura

 

From: Richard Methot [mailto:VLab.Notifications@noaa.gov]
Sent: Wednesday, September 2, 2020 1:20 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Hi Laura,

Your new question goes beyond "How do I use SS well?" to "How should we manage our fishery?", so I'll avoid getting into the latter here is this forum.

The catch trajectory you see in the forecast is created by the control rule specified in forecast.ss. There are some aspects of the control rule that you need to tailor to the way in which your fishery management plan is designed.

In the forecast module of SS, the first pass through the forecast produces the catch and the resultant population trajectory if the catch was according to the F limit (e.g. Fmsy, F35%, or whatever you selected). In the parlance of U.S. federal fishery management plans, this is designed to show what would happen if catch was right at the overfishing limit each year. 

The second pass through the forecast now applies the control rule which can have a buffer between the Flimit and the now F target, and this Ftarget can have an increasingly large buffer as biomass drops below some specified level. The controls for this look like:

1 # Control rule method (1: ramp does catch=f(SSB), buffer on F; 2: ramp does F=f(SSB), buffer on F; 3: ramp does catch=f(SSB), buffer on catch; 4: ramp does F=f(SSB), buffer on catch) 
0.4 # Control rule Biomass level for constant F (as frac of Bzero, e.g. 0.40); (Must be > the no F level below) 
0.1 # Control rule Biomass level for no F (as frac of Bzero, e.g. 0.10) 
0.75 # Buffer:  enter Control rule target as fraction of Flimit (e.g. 0.75), negative value invokes list of [year, scalar] with filling from year to YrMax 
In U.S. FMPs, the catch level coming from this second loop is often considered as the ABC (e.g. Acceptable Biological Catch).

The third loop through the forecast then is for getting better variance estimates. It starts by freezing the ABC values from loop 2 and now allows for random recruitment variability and/or implementation error in the catch.  The intention is to show quantities like the probability of F/Fmsy and B/Bmsy if future catches attempted to follow the specified ABC while population was also being affected by recruitment variability.

So, I suggest that you review the control rule settings in your forecast file before deciding what recommendations to deliver to the fishery managers.

Rick

 


--
Richard Methot Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11682818 VLab.Notifications@noaa.gov

Richard Methot, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts

Laura,

Your approach seems reasonable.

However, your forecast file does contain a specific control rule setup that may give you unintended consequences. If you want to get forecasts with a constant F at the specified SPR_target level (e.g. F35%), then the control rule should be set to these settings:

1 # Control rule method (1: ramp does catch=f(SSB), buffer on F; 2: ramp does F=f(SSB), buffer on F; 3: ramp does catch=f(SSB), buffer on catch; 4: ramp does F=f(SSB), buffer on catch) 
0.002 # Control rule Biomass level for constant F (as frac of Bzero, e.g. 0.40); (Must be > the no F level below) 
0.001 # Control rule Biomass level for no F (as frac of Bzero, e.g. 0.10) 
1.0 # Control rule target as fraction of Flimit (e.g. 0.75) 

This conversation indicates to me that SS needs to include a simpler control rule option. I will create a new method, 0, that ignores all the input regarding ramps and buffers and simply sets Ftarget to be the same as Flimit.

 

Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Rick,

 

Thanks so much for the clarification. This is a big help!

 

Cheers,

 

Laura

 

From: Richard Methot [mailto:VLab.Notifications@noaa.gov]
Sent: Friday, September 4, 2020 3:59 PM
To: VLab.Notifications@noaa.gov
Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

CAUTION: External email. Do not click links or open attachments unless you verify. Send all suspicious email as an attachment to report.spam@nc.gov

 

Laura,

Your approach seems reasonable.

However, your forecast file does contain a specific control rule setup that may give you unintended consequences. If you want to get forecasts with a constant F at the specified SPR_target level (e.g. F35%), then the control rule should be set to these settings:

1 # Control rule method (1: ramp does catch=f(SSB), buffer on F; 2: ramp does F=f(SSB), buffer on F; 3: ramp does catch=f(SSB), buffer on catch; 4: ramp does F=f(SSB), buffer on catch) 
0.002 # Control rule Biomass level for constant F (as frac of Bzero, e.g. 0.40); (Must be > the no F level below) 
0.001 # Control rule Biomass level for no F (as frac of Bzero, e.g. 0.10) 
1.0 # Control rule target as fraction of Flimit (e.g. 0.75) 

This conversation indicates to me that SS needs to include a simpler control rule option. I will create a new method, 0, that ignores all the input regarding ramps and buffers and simply sets Ftarget to be the same as Flimit.

 


--
Richard Methot Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/11708297 VLab.Notifications@noaa.gov

Richard Methot, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts

Hi Laura,

I think your explanation is correct.  You can verify by removing the fixed input catches, then compare those catch levels to the levels that will now be calculated from the Flimit and Ftarget.

Rick

Laura Lee, modified 3 Years ago.

RE: Seeking assistance with projections

Youngling Posts: 95 Join Date: 3/31/16 Recent Posts

Thanks so much!

 

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Subject: [External] [Stock Synthesis - SS usage questions] Seeking assistance with projections

 

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Hi Laura,

I think your explanation is correct.  You can verify by removing the fixed input catches, then compare those catch levels to the levels that will now be calculated from the Flimit and Ftarget.

Rick


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