Nuremberg has a plague, the Gimeni worm that secretes a chemical that kills any plant not native to Nuremberg. It will take years of research until a possible way to fight the worm is found. Too make it worst, the planet is owned by DHC and Republican, who decided to use its vast space as military vehicle factories, polluting the planet.
As for Holstein its still undergoing terraforming, which will take years(Decades probably), until the planet can be considered suitable for any sort of "sea farming", besides, the owner, DHC, is more interested in extracting minerals from the crust and the terraforming is secondary.