Qinghai Lake, China's largest inland saltwater lake, is witnessing its annual summer spectacle as the Qinghai naked carp's upstream spawning migration entered peak season.
From May to August each year, the carp leave the lake and swim against the current into freshwater rivers to spawn, a journey that spans over 100 kilometers and faces deadly challenges at every turn.
The first obstacle is a deadly ambush: thousands of brown-headed gulls and gull-billed terns converge at the river mouths, where the fish must slow down to adjust their body osmotic pressure in the brackish water, making them easy prey.
In the middle reaches of Qinghai Province's Quanji River, the carp will meet their second hurdle. They must leap over a 20-meter stretch of rocks with a cumulative height difference nearly equal to an adult human.
The third challenge is a four-kilometer maze of shallow shoals, where average depths drop to just 20 centimeters and fish frequently become stranded in drying pools after storms or droughts.
"They prefer to spawn in calm, shallow water, but these spawning grounds carry risks. After upstream rainstorms, fish can be washed onto previously dry shallows, and when water levels drop after the rain, they become stranded. Sudden high temperatures and drought can also lower water levels in these already shallow spawning grounds and strand them," explained Luo Ying, senior engineer at the Qinghai Lake Naked Carp Rescue Center.
Local fish conservation workers work daily to save the stranded carp, clearing blocked channels and relocating over 10 tons - nearly 80,000 fish, each season.
The arduous journey makes sure that those naked carp that reach the upstream spawning grounds carry the highest quality eggs and strongest genes. The migration itself also serves as a vital energy link between the lake and river ecosystems.
Qinghai's naked carp migration enters peak season
