“Reise” here is used in an ambiguous form. It generally translates as “travel" or “journey”, but it also has the archaic meaning "arise” especially when used in a nautical context. It’s sailors talk and is generally a wake up call for seamen used on boats. Here it is used with the literal interpretation in mind, but also as a metaphor for an erection, as the song talks about lonely seamen on their ships, having sex with each other or even with fishes, until they come to shore.

The song could also be seen as representing the connection between a soldier killing in the army for someone else’s gain (most likely referring to the Wehrmacht conscripts in WW2) and a fisherman killing animals for the highest bidder. They both are just doing what they have to in order to survive, being isolated, doing something they don’t really believe in.