‘Death spiral’: Mekong River megafish have shrunk by half, study reveals | Fish
According to a study, he found that Megafish on the Mekong River has shrunk in a worrying way in recent years due to excessive hunting. The length of the freshwater giants, the largest and most dangerous as large as grizzly bears, decreased by 40% in seven years.
Some fish, such as Mekong Giant Flue, have been examined for a longer period of time and decreased by 55% weight in the last 25 years and drops from an average of 180kg (397lb) to 80kg.
Biologist Ngor Peng Bun, one of the work team, helped to capture a gigantic catfish weighing 270kg before labeling and releasing in 2000. “Muazzam – was unforgettable,” he said, and almost alien. Types known as Trey Reach or Royal Fish in Khmer are now a shadow of their old self.
The world’s largest carp and the national fish of Cambodia, the giant barb, showed a similar orbit. Both species are under critical danger.
Scientists are a matter of survival of dimension, because large fish with higher probability of getting caught produce more eggs in folding. It can produce 10 to 20 times more offspring than a 300 kg catfish, for example a fish of 50 kg. Many of the largest species are long -lasting and mature, ie the increases in deaths can overthrow the balance of the collapse of the population.
Mekong Giants is very important for the ecosystem of the river, but it is also at the center of the livelihood of millions of people dependent on fishing. In 2022, scientists found a sign of hope when a Fisher captured and published a record -breaking 300 kg Stingray. This The biggest fresh water fish ever seen And he showed that some giants were still staying.
Fishing and Hunting usually targets the largest animals and in the Baltic Sea, the Salmon in Alaska and sharksand caused Smaller teeth in African elephants.
Nevada University, a part of the US and the work team, Professor of Research. Zeb Hogan said that it was surprising and shocking to shrink Mekong Megafish quickly.
“We saw this pattern in the Atlantic Cod fisheries, where the largest, most efficient fish of selective fisheries have removed and caused a dramatic collapse. As a decrease in body size and reproduction capacity, [the Mekong] The risk of fish, the risk of populations, but is no longer applicable to enter a ‘spiral of death’ at the risk of entering, ”he said.
Sophorn Uy, at the royal university in Phnom Penh and a part of the team, “Knowing that these giants are shrinking in both size and number is like losing a small Cambodian piece.
Study Published in Biological Corsoration magazineHe analyzed seven -year monitoring data from 23 regions in the Lower Mekong Basin and included 257 fish species. There was full data between 2007-14. Hogan said that the shrinking trend would continue.
In addition to excessive hunting, Mekong Megafish struggles with dams that prevent their migration to ovulation; Climate crisis that upset the temperature and precipitation seasonal triggers; And the destruction of seasonal flooded forests for agriculture, which is an important habitat.
Hogan said: “300KG Singray showed us that it is not too late. New records are still being established. But now they will mean very little unless these species and the river system they call home.
Stingray labeled 3 miles (5km) for two years in a protected area along the river and watched. “Connection [along rivers] And the protected habitat – this sacred bowl, Hogan said Hogan. “ If you have them, then these fish can survive. “
Scientists, capturing Megafish’i, Mekong’un flowing in some countries already illegal, but sanction is a great difficulty, he said. “Local fishermen were necessary to collect our data, Soph said Sophorn, Sophorn. “They are on the front lines and must be part of the solution.”
