Every few minutes, she would tease out a tiny river shrimp that had become stranded in the mud, and then dropping it into a bucket of water. Beside her, dozens of other Tibetans toiled in the noonday sun, among them small children and old people who, from afar, appeared to be panning for gold.

Buddhists are encouraged to demonstrate a reverence for all sentient beings; some believers spurn meat while others buy animals destined for slaughter and then set them free. Here in Yushu, a largely Tibetan city where more than 3,000 people died in an earthquake four years ago, the faithful have been flocking to the Batang River to rescue a minuscule aquatic crustacean that would hardly seem deserving of such attention.

Buddhist monks say the growing interest in “life liberation” or “mercy release,” as it is sometimes called, is part of a surge in religious devotion that followed the quake, which flattened much of Yushu. Donations to local monasteries have soared, they said, as have ordinary acts of kindness among strangers in this city of 120,000 roughly 1,300 miles northwest of Hong Kong.

“To save these lives is not only for me and my family but for all the people who died in the earthquake,” said Gelazomo, who like many Tibetans goes by a single name.

Working with her infant son strapped to her back, she said the loss and trauma experienced by so many people in Yushu had fortified their commitment to Buddhist teachings that emphasize respect for all living creatures.

Several others said these specks of life could very well be the reincarnated souls of relatives or friends who perished in the earthquake.

Chenrup, 67, a nomad, said the prospect of being reborn as a fly or a dog could not be dismissed. “We have the same feelings as the fish,” said Chenrup, a vegetarian who spends eight hours a day digging in the mud. “It is our duty to liberate them from pain and suffering.”

From early morning until dusk, the soul-savers work to extract creatures that have become stranded as the river, which is fed by snow-draped mountains, recedes in summer. The shrimp, about the size of a fingernail clipping, are almost impossible to see in the sunbaked muck and only make themselves known by writhing faintly. After collecting them in buckets or paper cups, the diggers set them free into the river.

From the thousands of multicolor prayer flags that flutter across barren mountainsides to the monasteries that fleck even the most remote valleys, religious devotion suffuses every aspect of life on the Tibetan Plateau. Although many people here consume meat — and tending livestock sustains most rural families — it is not uncommon to see yaks or goats adorned with colorful strands of yarn, an indication that their lives have been spared.

Across the plateau, the practice of life liberation supports a growing mini-industry. Since 2008, the Kilung Monastery in Sichuan Province has saved hundreds of yaks, sheep and goats through a program financed largely by believers overseas. For $1,000 a yak and $100 a goat, participants can buy an animal headed to the slaughterhouse. A nomadic family will also set aside an animal in their herd and dedicate it to providing wool ($165) or milk ($35). The monastery accepts online payments, including Visa and MasterCard.

Local monks acknowledge that the practice has a negligible impact on the number of animals destined for slaughter, but they say it serves to remind people about the sanctity of life and can also produce concrete benefits for adherents.

In an essay to his followers, Chatral Rinpoche, a 101-year-old Tibetan religious figure who is said to have saved more than a million animals in his lifetime, said mercy release could lead to better harvests and healthier, longer lives for practitioners. “No greater crime is there than taking life away, and no conditioned virtue brings greater merit than the act of saving beings and ransoming their lives,” he wrote in a widely circulated essay. “Therefore, should you wish for happiness and good, exert yourself in this, the most supreme of paths.”

As increasing numbers of Chinese rediscover Buddhism after decades of state-enforced atheism, animal release has become a popular way to express religious devotion, especially among the ranks of middle-class urbanites who buy turtles or fish from produce markets and set them free in parks or temple ponds.

The practice, though, has its detractors, who say releasing tropical creatures in northern climes begets a different kind of cruel death — by winter’s freezing temperatures. Across Asia, especially in cities with large Chinese communities, caged birds are sold outside temples; once released, the birds are sometimes trapped again and resold, but more often they are unable to fend for themselves and die.

The practice, environmentalists say, also leads to the introduction of invasive species, with potentially ruinous results. In the United States, the northern snakehead fish, a voracious Chinese predator thought to have been freed during mercy release ceremonies, has been found in waters from the Potomac River to Lake Michigan, alarming bass fishermen and aquatic biologists who worry about the northern snakehead’s potential to consume and crowd out native species.

In Yushu, which is also known by its Tibetan name Jiegu, mountains and rivers are embraced as holy places and ordinary Tibetans display a sophisticated appreciation of the ecologically fragile landscape that sustains them.

In recent years, protesters have tried to block illegal mining operations, leading to violent clashes inside the Three-River Source Nature Reserve, a protected area outside Yushu that contains the headwaters of the Yangtze, Yellow and Mekong rivers.

Last August, dozens of people were reportedly injured after the police used batons, tear gas and electric prods to break up a large, three-day demonstration outside an open-pit diamond mine, according to Tibetan exile groups.

Chuyan Dorjee, 26, a monk who joined the throngs digging alongside the Batang River one recent morning, explained why many Tibetans felt so strongly about safeguarding the environment. “If human beings are to live in this world, we have to protect the animals and the grass,” he said. “We are all connected to one another. If they have no place to live, we will have no place to live.”

The sight of so many people toiling in the sun, many of them well into their 70s and 80s, was contagious. Among the diggers was Ha Kaimu, 20, a sock and underwear salesman who took the day off from his stall at the local market.

Mr. Kaimu, an ethnic Hui Muslim who recently moved to Yushu from neighboring Gansu Province, said he was deeply moved by the collective act of benevolence.

“In my hometown, if there was a much larger animal facing such a predicament, no one would lift a finger, but look at all these people working to save a tiny creature,” he said as several women offered him a hearty thumbs-up. “How could anyone not be moved?”