[Pharo-users] implementing #release in a domain object

Lets say I'm modeling a navy that is comprised of many ships each with their own soldiers and jobs. If I want one of the ships to be GC'd do I need to implement #release in the soldier and job objects and send it to each of those soldiers and jobs that live and work on the ship I want GC'd or is removing the references between the ship and the navy enough to have the whole ship (including its soldiers and jobs) GC'd?