Calculating matrix of discards-at-age - Public Forums - Stock Synthesis

This would be a good output to add to SS.  What you can use now is in the Age_selex section of report.sso.   Look for the sel_num vector and the sel*ret_num vector and calculate difference between them.  Also, the catch_at_age table is essentially the result from numbers at age times Sel_num.

Rick 

You would need to multiply by the apical F in order to get discards in absolute numbers.

Note that if selectivity is length selectivity, then the resultant age selectivity probably will not have a max of 1.0.  All that matters to the internal calculations is the product of the F multiplier and the  selectivity-at-age.  So be cautious in interpreting the absolute values of the F multiplier independently of the selectivity to which they are applied.

On the airplane ride home yesterday I augmented the Catch_at_Age output in report.sso to also include information on discards at age.  In doing so, the current Catch_at_age is more precisely labelled as dead catch at age because it contains the retained catch and the mortal fraction of the discarded catch.  Then, only for fleets that have discarding, SS reports:  selected numbers at age, retained numbers at age, and discarded numbers at age.  This will be in SS3.30.12 when we finally get around to releasing it.  I will get it uploaded to the beta version of 3.30.12 soon.

Rick

Many thanks, having that output returned will be useful at least for those of us moving SS3 fits into FLR.

I will let you know how the reconstruction of discards, even if based on a single year of selectivity, goes. The intent is to partition future catches into discards and landings, so using the last year of selectivity for this is not such a bad assumption.And there is always a way in FLR to set different future discard patterns.

The latest beta version of SS3.30.12 has discard-at-age output in report.sso immediately after the catch_at-age.  There is an extra column in catch_at_age to more clearly label it as the "dead" catch_at_age, and there are corresponding labels in the discard_at_age.  It is possible that this extra column will foil r4ss, so a new version of r4ss will get released soon.

Rick