These cranes are used to hang the biggest catches of the day. This means the prospective buyers can examine the massive fish and various beasts of the sea that are caught by the legion of fishing vessels flowing in and out of the port. If the catch is monstrous, large but inedible, then on occasion it will be bought by a museum or one of the universities. Sometimes restaurants by the whole large catch and advertise the fact in town to attract diners to a special event where the whole creature will be cooked and served. You won't want to say that you missed out.