Weird. I guess I missed that part. Still weird. If you look at the first image above it has improved one of the tiles but I don't there there was a cabin in any of those cities, since they lack the connection to the capital. The second image, Les Opels, is right next to them and doesn't have one either and that is just turns apart or something.
(edit2) I didn't read this properly. It also improved lake shrimp. I guess I just didn't notice that part since all my cities are lake adjacent or coast adjacent so I could just send out a workboat and/or had already done so, I think one city had even had a fortress canal to the lake so I could send a workboat before I built the cabin there.
Also I have had cities that didn't spawn any shrimp, I guess it was not coastal marshes but river marshes and they don't count apparently. Or it was just random between 0-3 shrimps. Don't think I have seen more then 3 shrimps spawn on foundation.
(edit) I found and went back to a save close to when I took the images and it seems that the cabin built in Les Opels did improve the first of the marsh shrimp tiles in the image the following turn. So it improved a tile that didn't belong to it, that shrimp was worked by La Chapelle. I guess it's just range then and not who actually owns the tile. Don't think it was the original owner or spawn city either but I can't recall for sure. Cause Nouvelle was built first of the three, then Les Opels and last La Chapelle. So I could have moved the tile to another city.
(edit3) That said if you pack your cities somewhat close you can have mega-shrimp cities where you transfer the shrimp tiles to one city. I managed to create a couple of cities like that that are working five shrimp each.
The city pop movement from cities that are angryredfist works quite well with various events and such that triggers unhappiness or resistance to (such as the ever present hurricanes etc that strikes cities close to you but in rival lands). That said the free pops are not really always a positive aspect, good mechanic but annoying to play versus since it becomes somewhat of a happiness issues. It's hard to plan for or against as you can just all of a sudden get some extra pops from a rival city which tanks your happiness to. Even if you had locked your pop growth it adds extra pops just like some buildings and policies do which is fine. But perhaps that ability should have some kind of a cooldown, it's not cool so to the speak when you grow a new pop every other turn sometimes in some close border cities. Or I need an event with options that I can push all these refugees or whatever they should be referred to as away.With ominous consequences or something.
(edit4) Also the range seems a bit extreme, of there even is a range. So far I gotten people from cities in distress 29 tiles away from the city they went to.
I have some cities that are just on the border with the Iroqs, or well there is their island and our island and a one tile water between our islands, and as soon as they get unhappy that city just get flooded with people that makes keeping that city by itself happy a problem. So I have to resort to some happiness shenanigans in other cities to create an empire happiness buffer.
Perhaps a most unfortunate random world as the Iroqs got their own island, with just a couple of city states. So they sort of exploded out. When the world power poll was shown their power was more then the following 4 civs combined. I guess it's a good thing they are still crap at amphibious warfare and landings as you just have to sort of sit back and gun them down at range.Still it is/was impossible to have a small navy or something as the Iroq deathfleet is always just outside of visual range ready to move in at a moments notice.
In that regard defensive wise it kinda blows until you get the Mikmaqs, certainly so if you are squeezed in between Darius and the Iroqs. But once you get them it's spike time and good bye Darius!
Also taking and keeping cities is bad since it won't spawn shrimps. As they can only spawn on foundation so it's usually better in that regard to burn and resettle so you get your shrimps. It's not the shrimps as a luxury that matters, it's that the shrimp tiles just become extremely good workable tiles. Perhaps the cabin should/could spawn a shrimp if there is a valid location to? Otherwise as noted conquered cities are usually quite bad, so far I have burned down three or four of Darius cities and two-three cities from Byzan. Only to resettle near or close to their locations. Simply to spawn more shrimp as the tile becomes better then more or less any other tiles.
I like the icon for the great musician (krewe), that said it looks more like some evil Cthulhu cultist icon even tho I get it is supposed to be a mardi gras mask of some kind.
Shrimp resources on coasts, lakes and bayou (coastal marshes) when founded. While a rival city is in 
Resistance, 
citizens from it may migrate to your cities. Migrations brings +50 
Faith and 
Culture, scaling with Era.
, -10% 
Movement and Sight, Ignores Zone of Control, While at full health, causes blockaded enemy cities to enter 
Great Musician Point by Sea Resources and Atolls worked by the City.
Food and 
Gold.
Tourism.
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, the shrimp effect.
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