San Diego - Some dolphins used by the Navy to track down mines will soon lose their jobs to robots - but they'll be reassigned, not retired.Starting in 2017, 24 of the Navy's 80 military-trained dolphins will be replaced by a 3.6m unmanned torpedo-shaped vehicle, according to the newspaper UT San Diego.The military said the machines can do some of the same mine-hunting duties as the sea creatures. And they can be manufactured quickly, unlike the seven years it takes to train a dolphin.The dolphins won't be relieved of duty. They'll be used along with sea lions for port security and retrieving objects from the sea floor, the newspaper reported.The Navy's $28m marine-mammal programme dates back to the late 1950s and once included killer whales and sharks. Based in San Diego, it currently uses 80 bottle-nosed dolphins and 40 California sea lions.In recent years, dolphins have been deployed to Iraq and Bahrain to patrol for enemy divers and mark the locations of mines.Using their innate sonar, the mammals find and mark mines in shallow water, in deep water when tethers are used, and on the bottom where sediment cover and plant growth can hide the devices.Dolphins are carried aboard Navy ships in large movable pools, about 6m in diameter. Dolphins traveled on the amphibious ship Gunston Hall in 2003 for the Iraq war.Most of the Navy's dolphins and sea lions are housed at Point Loma Naval Base, in pools sectioned off from the bay. Others guard Navy submarine bases in Georgia and Washington state, according to UT San Diego.The military is responsible for the mammals' care throughout their lives, even after they're retired from active duty. Sometimes Navy dolphins are loaned to animal parks, such as Sea World, later in life.