I found a pair of skins in a pile of leaves at my bus stop in Queen Anne (southbound stop on Aurora Ave / Galer St stairs). They are in reasonably good shape, so I don't think they were thrown away.
Perhaps they were lost. They might also have been stolen and discarded. They were found near a greenbelt where people have been camping.
PM me if they might be yours. I'm not sure on length, but can measure if needed.