OCEAN CITY, Maryland (Reuters) — After four decades carrying millions of New Yorkers, 44 of the city's subway cars are now home to millions of fish.

The worn-out cars were dumped on Friday into the Atlantic, 21 miles off the Maryland coast, to create an artificial reef, designed to attract fish for the state's lucrative sport-fishing industry.

"These reefs provide quality habitat for marine life off our coast which benefits not only the environment but also local businesses," said Ocean City Mayor Rick Meehan.

The 18-ton stainless steel cars — minus wheels, windows and doors — were stacked two-high on a barge where a bucket crane with a specially designed hydraulic lift picked them up one by one and dropped them into 90 feet of water.

As journalists watched from five smaller boats, the cars landed on their sides with a bang, and blew whale-like jets of spray as air escaped from their interiors. They disappeared a few seconds later beneath the gray-green waters.

The cars, dating from 1964, were among 1,662 that have been retired by New York's Metropolitan Transportation Authority and will be used by a number of states on the US East Coast to create the reefs to buoy local fishing industries.

Maryland plans four more subway-car reefs and since 2001 others have been created in Delaware and New Jersey waters from an earlier batch of about 1,200 cars released by the MTA.

Jeff Tinsman, Delaware's reef program coordinator, said a 600-car reef in that state's waters had increased the local fish population by 400 times, and boosted the number of angling trips to 13,000 a year from 300 before the reef was created.

The reefs attract fish because they provide protection from predators, and generate food like mussels, shrimp and crabs that quickly colonise the structure.

About 95 percent of the seabed off the US mid-Atlantic coast is naturally bare sand, which is much less likely to attract fish, Tinsman said.