Cailleach used to run a Fishing Co-Op but since she seems to have drifted away from the game, it's become inactive, and I've not heard of any more on Europa.
Nimuaq and I have been working on the sums in the background, and we're convinced that the Devs intended for us to trade fish, and they've programmed individual "Bad Fish" which are used above all else for each character. For me, the real problem in the Lobster set is Spiney Lobsters for instance... Nim should eventually get his vendor up and running in New Magincia (it's by the old bank, south western corner) but it has to charge a cover fee for taking and returning fish due to the costs of running a stall.