The Crescent Duck Farm in Aquebogue, which lost its entire flock of 99,000 to an outbreak of bird flu, has begun the long, methodical process of sanitizing its facilities.

The highly infectious H5N1 strain has caused outbreaks across the country. Now, Long Island’s last duck farm must kill its entire flock and may go out of business, its owner said.

The owner of the Crescent Duck Farm in Aquebogue, N.Y., has been forced to euthanize its flock of more than 100,000 ducks due to positive bird flu tests.