It might have been a cute photograph for a coffee-table book.

A small turtle riding piggyback on a larger one.

Given that it was taken at Hanoi’s Hoan Kiem Lake, it could have also meant something to get excited about.

Were we, finally, seeing a successor to the legendary turtle in the Lake of Restored Sword?

Sadly, it was neither.

A recent photograph taken by a scientist of a red-eared slider clinging to a giant turtle’s carapace has scientists screaming blue murder.

They have long warned against pollution and illegal fishing threatening the life of the Hoan Kiem Lake turtle.

Now, they are renewing with added vigor the call for better protection of the rare giant soft-shell turtle in Hoan Kiem Lake that is being invaded by the notorious invasive species – red-eared slider turtle (Trachemys scripta elegant).

“It is difficult to assess the actual red eared slider population but their impacts on the giant turtle are obvious,” said Ha Dinh Duc, a scientist who has authored research about the lake for the past decade.

The giant soft-shell turtle (Rafetus swinhoei) has played a crucial role in Vietnamese lore for more than 2,000 years. There are only four confirmed members of the species left in the world – two living wild in Vietnamese lakes and a captive pair in China.

The Hoan Kiem Lake turtles are traditionally viewed as manifestations of the Golden Turtle God, or Kim Qui. Over the last two millennia, the deity is said to have helped design fortifications, thwart enemy armies and produce a number of enchanted weapons.

Duc said he has warned against the invasion of red eared sliders in Hoan Kiem Lake since 2004 but local authorities have taken no action against the problem.

“City leaders should discuss the issue thoroughly before launching a long-term plan to protect the giant turtle,” he said.

Dang Huy Huynh, chairman of the Vietnam Zoology Association, slammed lax surveillance in importing invasive species like the red-eared sliders.

“Vietnam has struggled several times against invasive species like the channeled apple-snail (Pomacea canaliculata) and piranha,” he said.

“The government has issued regulations to protect the Hoan Kiem Lake giant turtle. The invasion of red eared sliders in the lake is unacceptable. Related government agencies should take strict action on this issue,” he said.

Huynh advised that the population of red eared sliders in the lake is killed and strict fines imposed on those who release any more invasive animals into its waters.

Many Vietnamese people have the habit of releasing animals, including red eared sliders, into the wild to pray for good luck, an action that has been severely criticized by conservationists.