Fishermen in the central province of Binh Dinh on Thursday found a 3-meter, 1.5-ton whale shark washed up on the beach.
The fish, nearly 5.5 meters long and having no teeth, was trapped among rocks off the coast of Quy Nhon Town, witnesses said.
Some said the fish must have been weak and swum to the coast when the tide was high, but unable to swim back as the waters receded.
Nguyen Huu Hao, vice director of Binh Dinh department for marine resources exploitation and prevention, said while local agencies were yet to send specific equipment to move the fish given its giant size and rocky location, fishermen had already cut parts of the fish to eat and sell in the local market.
Hao said the whale shark, the largest living fish species, was named in Vietnam's red list and categorized as "vulnerable" by the International Union for Conservation of Nature.
Binh Dinh fishermen have caught three sharks weighing between 60 kilograms and one ton each since last July when attacks by unidentified fish on humans were reported and the local government began handing out money for their capture.
Overfishing has pushed sharks to the brink of extinction in many parts of the world. Scientists have pointed out that sharks are an essential element of oceanic ecosystems and governments should strive to preserve them.
The use of scarce financial resources by the Binh Dinh People's Committee to reward the killing of sharks has been strongly criticized by some experts.
At least ten people have been bitten by fish in Binh Dinh recently. The latest victim was a 17-year-old boy who suffered a foot injury last month.