VPA Fisheries

[Mark Maunder]

The seminar today on F in SS was very informative. Thanks Rick. 

The new flexible F method 4 (I think) will be very useful. One thing I have been wanting for a while is a related approach where some fisheries can be treated like a VPA. Would it be possible to have a hybrid approach to solve the catch equation by age. It could be implemented by creating a fishery for each age, but having it automated for a single fishery would be more convenient. 

This would avoid having to implement time varying selectivity to fisheries with good catch at age data. 

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[Richard Methot - NOAA Federal]

Hi Mark,

I'm glad to hear that this webinar approach was helpful.

I do not see a way to implement your request without internall creating a separate fleet for each age, which would be a major coding project.  I think it best to leave this to a user configuration.  You would create a separate fleet for each age, give it catch (in numbers or biomass) in the catch data, then in F_Method 4 allow it to stay in hybrid for all iterations, or if there is some uncertainty in the catch then allow some ages to transition to parameters.  Separate fleets for separate ages will be messy in the benchmark and forecasts because the relative catch among fleets will now depend on the scaling of F across the fleets.

Rick