Error: Fmsy/mey is <1/3 of Fspr are you sure? check for convergence

[Laura Lee]

Hi all!

I'm running into this error:

Fmsy/mey is <1/3 of Fspr are you sure?  check for convergence

I would appreciate any assistance in diagnosing this.

Thanks for your time and attention.

Best,

Laura

[Richard Methot - NOAA Federal]

Hi Laura,

Fmsy is legitimately much less than Fspr40% if steepness is low.  If steepness is > ~0.7, then they should be comparable.

With regard to convergence in the search, that information is in forecast-report.sso, although rather cryptically labelled there.

Search for:  find_Fmsy_to_maximize_dead_catch

and examine the table below.  There is a row for each iteration of the search.  You should see the gradient get very small, although usually does not get to 0.0.

The first row of the search uses an F that is the same as the ending F for the preceding search for F_Btarget.  So also check to see if that search seems to make sense and possibly change the value being searched for:

0.3 # Biomass target (e.g. 0.40) as fraction of SSB_virgin if depletion basis = 1 or time_vary compatibility = 0, else as fraction of SSB_unfished in benchmark

Another check is to examine the table in report.sso labelled:  SPR/YPR_Profile report:54.  This is graphed by r4ss or can be easily examined to find the F_std that produces the maximum catch.

Rick

Richard  D. Methot Jr.

Stock Assessment Research Scientist (ST)

Northwest Fisheries Science Center

NOAA Fisheries | U.S. Department of Commerce

Office: (425) 666-9893

Mobile: (301) 830-2454

www.fisheries.noaa.gov 

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