My guess is this old structure on the end of a pier was used to sort and clean fish after the day's catch. I imagine the trolly transported the catch to shore and the waiting truck which took it to local restaurants and markets. I don't know if that is even close to the real story but it's what I imagine. The pier is now in disrepair and no longer reaches the shore, but there are still trolly tracks on the shore and another old building where fish is sold. I could stop in to that store and possibly find out the real history but for now I prefer to let my imagination have a go at it. Maybe it was used by 'rum-runners' or drug smugglers...