The 'dinosaur' fish in America is gradually reviving

The number of sturgeon, living animals and the dinosaurs that once dominated the river system in the United States, has risen again after a long period of over-hunting and extinction.

A scientist holds a short-nosed sturgeon, an animal that is threatened with extinction, after the individual loses its net on the Saco River in Biddeford, Maine.Animals once dominated the river system in the United States have fallen rapidly in the 20th century, due to fever for sturgeon eggs.(Photo: AP).

The fish will be sampled and chip attached.Due to being threatened with extinction, many sturgeon research and protection projects have been implemented, helping the population of this species gradually recover in nature.(Photo: AP).

Sturgeon are often referred to as "prehistoric fish" because their evolutionary characteristics have not changed since hundreds of millions of years ago.This species can grow to a gigantic size, with a record of 1,571 kg and 7.2 meters in length recorded in 1827. (Photo: AP).

Besides the demand for salted sturgeon (caviar), the pollution of the river environment, dam construction is also the cause of a sharp decline in sturgeon in the US in the 20th century. (Photo: AP) .

By the 1990s, sturgeon is said to be extinct in the Chesapeake Bay area.However, with the government's strong conservation measures, the number of animals that once lived at the same time as the dinosaurs is gradually recovering.(Photo: AP).

A Atlantic sturgeon was released back to the James River in Charles City, Virginia state, after being fitted with a tracking device.With strict fishing bans and improved water environment, the biggest obstacle to the revival of current sturgeon is dams.(Photo: AP).

In Maine, the number of short-nosed sturgeon has doubled since the 1970s until the 2000s. While the living environment has improved, the sturgeon's resurgence will continue to be hampered by the climate change and water temperature increase.(Photo: AP).