Ta Van Son, director of the city Fisheries Department, said a group of its researchers at Dong Mo Lake spotted the turtle on October 22.

Scientists weighed, measured and took samples for genetic testing and released the animal back in the lake.

Experts from the Vietnam Academy of Science and Technology and Vietnam National University Hanoi analyzed its DNA and concluded it belongs to the species Rafetus swinhoei.

The female soft-shell turtle weighs 86 kg and measures almost 100 cm in length.

The Asian Turtle Program of Indo-Myanmar Conservation said there are at least two turtles in Dong Mo Lake after a photo taken last Friday showed another soft-shell turtle estimated to weigh 130-150 kg in the same lake.

Scientists plan to take its sample for testing in 2021. If it proves to be a male, authorities will create a sandy area around the lake so that the pair can reproduce naturally.

Another turtle was found in Xuan Khanh Lake in Hanoi, and its samples too will be tested in 2021.

Conservation units have called for expanding the search for soft-shell turtles to other large lakes such as Suoi Hai, Dong Quan and others.

A city conservation plan for the Hoan Kiem turtle in 2021-25 will identify a suitable environment for breeding the reptiles, and there will be programs for their conservation and reproduction.

Fisheries expert Bui Quang Te said it is necessary to expand the search area since he strongly believes there are more turtles living in Dong Mo.

Son Tay Town and Ba Vi District, where Dong Mo and Xuan Khanh lakes are situated, have promised to carry out propaganda and coordination activities to protect the turtles.

The Asian Turtle Program has carried out a number of conservation programs in 18 northern provinces since 2003.

The Hoan Kiem turtle, named after the Hanoi lake where the only turtle of its kind lived, is listed by the International Union for Conservation of Nature as critically endangered and is also on the list of rare and endangered animals requiring urgent conservation efforts under a 2013 government decree. The turtle in Hoan Kiem Lake died in 2016.

The creature was first described in 1873, but there has been very little research on this giant soft-shell turtle. There are thought to be four left in the world, the other two being in China.

The species used to inhabit most of the Red River Delta, but was hunted down to near extinction in the 1970s and 1980s.

The Dong Mo Lake turtle was first discovered by Asian Turtle Program conservationists in 2007. In 2008 during the historic floods in Hanoi, it got out of the lake and was caught by local residents.

Thanks to authorities and conservationists, it was returned to the lake and is monitored to this day.