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Mysterious fish return: How did the Elwha River's fish population return to 400,000?
On the Olympic Peninsula in Washington state, the restoration of the Elwha River marks the rebirth of an ecological miracle. The 45-mile-long river flows from the Elwha Finger in the Olympic Mountains to the Strait of Juan de Fuca. After more than a century of obstruction, fish in the Elwha River, especially Pacific salmon, are making a stunning comeback thanks to nature's gift.
The Elwha River was once home to 400,000 adult salmon that returned each year, and now, with the removal of the dams, this spectacular sight is expected to return.
Historically, the flow of the Elwha River was blocked by two dams, which prevented salmon from returning to their traditional spawning grounds. From 1911 to 2014, the presence of these dams suppressed salmon populations to fewer than 4,000 per year. The $325 million Elwha National Park Restoration Project began in 2011 and was completed in 2014 through the National Park Service. This is the largest dam removal program in history, which not only opened up a channel for salmon to return, but also brought changes to the entire ecosystem of the Elwha River.
Completion of the restoration project means salmon will be able to freely return to their familiar 70-mile spawning grounds.
The Elwha River's watershed is primarily located within Olympic National Park, which is rich in natural resources and biodiversity. The river is one of the few areas in the Pacific Northwest that has five native salmon and four migratory trout species. When the dams are removed, rivers will carry sediment to the estuary, creating new ecosystems that support a variety of shellfish and other aquatic species and encourage the natural reproduction of salmon and other fish.
The National Park Service's model predicts that up to 392,000 fish will repopulate the 70-mile river, theoretically reaching a "pre-dam peak."
With the dams removed, the Elwha River is flowing more freely, which not only changes the structure of the riverbed, but also promotes the movement of sediments and accelerates the recovery of the ecosystem. It also brings a new sense of hope to local communities, enabling them to bear witness to the power of nature’s recovery. By November 2014, 30 percent of the sediment had been pushed to the estuary, creating 70 acres of intertidal habitat that supports valuable marine life and wetland ecology.
For this land that once faced ecological challenges, this is not only a rebirth, but also an opportunity to regain harmonious coexistence with nature. The return of salmon helps improve the health of the entire ecosystem, brings richer biodiversity, and promotes the sustainable management of biological resources.
Finally, this exciting scene has attracted the attention of many environmentalists and scientists, and it makes us think together: In the face of climate change and ecological challenges, how can we better protect and restore our natural resources? What about the ecosystem?
