remove unneeded natatage()=0

[Rick-Methot-NOAA]

Concisely describe what has been changed/addressed in the pull request.

• Resolves issue [Bug]: 3.30.24 prerelease difference in seasonal model forecasts #700 to correct a problem introduced with
  to correct a problem introduced with [Bug]: error in time delay between spawning and settlement when settlement age is not equal to 0 #691
  @CaitlinAkselrud-NOAA

What tests have been done?

detailed examination of natage tables using the two season sardine example that has spawning at beginning of season 2 and recruitment at age 0 at the beginning of the following year.

Where are the relevant files?

<-- - [x] No test files are required for this pull request. -->

What tests/review still need to be done?

Is there an input change for users to Stock Synthesis?

<-- - [x] No, there was no input change. -->

Additional information (optional).

[Rick-Methot-NOAA]

Caitlin - I vaguely recall that sardine uses a six-month shifted calendar, i.e. Jan is really July. Is that true? Also review the logic behind saying that they are ae 0 , not age 1, on their first January. Then they are age 18 months when they first spawn still at age 0.

[CaitlinAkselrud-NOAA]

Hi Rick, Yes, the sardine spawning calendar-year is late spring, so recruits would be calendar-year early summer. Our seasons are as follows: Sardine Model Year July-June Model year s1 Jul-Dec Model year s2 Jan-Jun Why are they still age-0 when they first spawn at 18 months? I think some are supposed to be able to spawn at the end of spring of their first year (age-0, S2 or the Jan-June time period).

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On Mon, Aug 11, 2025 at 9:47 AM Richard Methot ***@***.***> wrote: *Rick-Methot-NOAA* left a comment (nmfs-ost/ss3-source-code#701) <#701 (comment)> Caitlin - I vaguely recall that sardine uses a six-month shifted calendar, i.e. Jan is really July. Is that true? Also review the logic behind saying that they are ae 0 , not age 1, on their first January. Then they are age 18 months when they first spawn still at age 0. — Reply to this email directly, view it on GitHub <#701 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/APUHJYOTLI2PZKJFDIAUZ5T3NDCI7AVCNFSM6AAAAACDPLEDQ2VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTCNZVHA3DGMJVHA> . You are receiving this because you were mentioned.Message ID: ***@***.***>

-- *Caitlin Allen Akselrud, M.S.* Research Fish Biologist Fisheries Resources Division NOAA National Marine Fisheries Service Southwest Fisheries Science Center 8901 La Jolla Shores Drive, La Jolla, CA 92037 ‬ email: ***@***.*** phone: 858-546-5613 fax: 858-202-5302