Fishing Boats loses production - why? (Not a Bug)

[HiRezAudio]

Please see the screenshot, and look where the builder is over the Crabs resource and check the yield - this is after adding fishing boats and you will notice the 2 production.
Now look just below it to an unimproved crab resource with 3 production.
Why has the fishing boat 'improvement' actually made the tile worse?
I get the production from a combination of a city state shallow water bonus & a shipyard - the fishing boat should increase production, not make it worse.
This happens on more occasions than I can deal with too - Seasteads do this, offshore wind farms do this as well - they both reduce the tile yields in some circumstances.

I have tried to file a report with 2K/Firaxis but they do not seem to care about fixing bugs at all these days.

 

[Laurana Kanan]

Looks like you have a shipyard in Cullen. Shipyards add +1 Production to unimproved tiles, so you'll lose that when you build a fishing boat there. You'll gain +1 Production, however, to the fishing boats when you research Colonialism. Is it wonky? Yes, but it is functioning correctly.

 

[PiR]

Should be moved to an improvement request here then (done).