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RE: linear growth period

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MC
Marta Cousido, modified 2 Months ago.

linear growth period

Youngling Posts: 5 Join Date: 3/4/24 Recent Posts

Dear SS experts,

 

I am working with a sex-specific length-based model for hake and have a question about growth.

 

More specifically, the question is about the parameters that control the linear growth period.

In the control file, I set "_Age(post-settlement)_for_L1 (Amin)" to 0.5 and then let L1 be estimated. The model estimates L1 to be 20.21. However, when we look at the plot (attached), the growth is linear up to an age beyond 0.5, and the associated length is not the value of 20.21 that was estimated for L1.

 

I've read that Amin should be based on real age and not calendar age, but I believe it should be correct as it is, since in our case the spawning month is 1, and we have two settlements in months 1 and 7. I understand that Amin should be set relative to the first, right? Then I understand that Amin at 0.5 means that the fish will have length L1 in July and the growth will be linear until then.

 

Many thanks in advance,

 

Marta Cousido Rocha

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IT
Ian Taylor, modified 2 Months ago.

RE: linear growth period

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

Hi Marta Cousido Rocha,

This is the fault of the r4ss plot created by the SSplotBiology() filtering to only show values associated with season 1, even in models with multiple seasons. I'm not sure why I chose to set it up that way long ago instead of showing the growth across seasons. The code is here: https://github.com/r4ss/r4ss/blob/main/R/SSplotBiology.R#L183. 

If you look at the table in Report.sso with header "Biology_at_age_in_endyr" (returned by r4ss::SS_output() as $endgrowth) and sort by season within each year, you should be able to see the seasonal growth patterns.

I will add refinement of the plot to show seasons to the r4ss wishlist.

-Ian

Richard Methot, modified 2 Months ago.

RE: linear growth period

Youngling Posts: 219 Join Date: 11/24/14 Recent Posts
Hi Marta.  For Amin, it is applied to each settlement separately, so for the month 7 settlement, they will be age 0.5 the following Jan 1.  

Richard D. Methot Jr. Ph.D.
NOAA Fisheries Senior Scientist for Stock Assessments
Mobile: 301-787-0241 (primary)
G. Voice: 425-666-9893‬


On Tue, Mar 5, 2024 at 9:23 AM Ian Taylor <VLab.Notifications@noaa.gov> wrote:

Hi Marta Cousido Rocha,

This is the fault of the r4ss plot created by the SSplotBiology() filtering to only show values associated with season 1, even in models with multiple seasons. I'm not sure why I chose to set it up that way long ago instead of showing the growth across seasons. The code is here: https://github.com/r4ss/r4ss/blob/main/R/SSplotBiology.R#L183. 

If you look at the table in Report.sso with header "Biology_at_age_in_endyr" (returned by r4ss::SS_output() as $endgrowth) and sort by season within each year, you should be able to see the seasonal growth patterns.

I will add refinement of the plot to show seasons to the r4ss wishlist.

-Ian


--
Ian Taylor Stock Synthesis Virtual Lab Forum https://vlab.noaa.gov/web/stock-synthesis/public-forums/-/message_boards/view_message/35690554VLab.Notifications@noaa.gov
MC
Marta Cousido, modified 2 Months ago.

RE: linear growth period

Youngling Posts: 5 Join Date: 3/4/24 Recent Posts

Thank you both for your answers, we now understand growth more clearly.