KEY LARGO, Fla. (AP) _ Seven rehabilitated rough-toothed dolphins were released Tuesday off the Florida Keys, two months after stranding on a mud flat near Marathon in the middle Keys.

Marine Mammal Conservancy volunteers took the dolphins to a point in the Atlantic Ocean about 14 nautical miles off Key Largo in two catamaran dive boats. They were released almost simultaneously and stayed together, and were seen foraging for food.

The day was a triumph for the MMC volunteers, who invested thousands of hours in the rehabilitation effort, working round-the-clock.

``This is the day we live for,'' said Robert Lingenfelser, MMC president. ``This is all the payoff for all the hard work, the dedication of our volunteers and the Florida Keys community.''

The mammals were among 68 that grounded March 2. Thirty-six of the dolphins died on the beach or in the water, but 32 were treated at three South Florida marine mammal centers. Five are still being treated. It is not known when they will be released.

Before their release, each animal was fitted with a VHF radio transmitter and two had satellite transponders. The tracking gear should automatically fall off in about six weeks, Gomez said.

Marine mammal experts still do not know why the animals stranded. Some conjecture that sonar, from a Navy submarine operating off the Keys around the time of the stranding, may be to blame.

``We don't have a smoking gun,'' said Sarah Gomez, a biologist with the National Oceanic and Atmospheric Administration's Fisheries service. She said it could take up to a year before a final report is issued.

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On the Net:

Marine Mammal Conservancy: http://www.marinemammalconservancy.org

NOAA Marine Fisheries: http://www.nmfs.noaa.gov/