Delta smelt remain on the brink of extinction – We can change that

Recent fish surveys confirm what many biologists, ecologists, and water experts have known for some time – Delta smelt remain on the brink of extinction. Zero Delta smelt were found in the California Department of Fish and Wildlife’s recent Fall Midwater Trawl Survey. Even the Enhanced Delta Smelt Monitoring Program, which is specifically designed to capture the tiny fish, only successfully caught two Delta smelt from September 8 to December 11, 2020.

Improving the health of native species like Delta smelt is an imperative, as it is critical to the health of our environment and the reliability of our water supplies. As an indicator species, the Delta smelt’s absence tells a grim story about the health of the Delta ecosystem, making these recent findings all the more concerning.

These results are not surprising, when California has made slow progress on actions like habitat restoration that are essential to restoring native fish populations.

Photo: US Fish and Wildlife Service

For many years flows, meaning pumping from the Delta, have been blamed as the primary cause for the decline in Delta smelt. As a result, restrictions on pumping from the Delta have been the default approach to protecting these fish.

The fact that Delta smelt populations are still desperately low – despite years of restricted pumping – confirms that a flows-only approach isn’t effectively protecting Delta smelt populations.

Equally concerning is the fact that a flows only approach has at the same time had a detrimental impact on the agriculture industry and the communities that rely on surface water, not only in the Central Valley but for anyone who buys and eats food grown there.

In fact, there are a multitude of stressors on native fish populations – including invasive and predatory non-native species, loss of habitat, contaminants, and changes in food availability and quality – and restoring the health of Delta smelt requires a broad-based approach that includes targeted actions to effectively address all these factors.

Let’s use another analogy: Responding to the near-extinction of Delta smelt by relying on pumping restrictions alone is as effective in restoring their overall health as responding to the COVID-19 pandemic by relying on bar and restaurant restrictions alone. Can some data-based restrictions be a lever for change? Absolutely. But aggressive, austere restrictions that are not supported by the science cannot be relied upon to solve the entirety of the crisis – particularly when there are severe economic consequences associated with the restrictions, too.

Ultimately, we must pursue a combination of functional flow and non-flow measures, including habitat restoration and adaptive management, to meet the needs of native fish and wildlife species. Without a more holistic approach, the Delta smelt will go from endangered to extinct.

Invasive Species in the Delta: +1?

Invasive Species in California’s Delta: Nutria

Another invasive species is threatening to invade California’s Delta. Joining a long list of non-native & invasive species damaging ecosystems, degrading infrastructure, and hurting wildlife, Nutria have been found near the ailing Delta.

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LEARN MORE ABOUT NUTRIA

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Past invasive non-native species that have found their way into the Delta, like water hyacinth, Chinese mitten crabs, and American Bullfrogs remain persistent challenges, bringing a host of problems for native species, particularly those already threatened or endangered.

Not content to just compete for food and habitat, many invasive species also introduce parasites and disease, or actively prey on native species like Chinook salmon and the Delta Smelt.

Nutria, are a non-native species once intentionally brought into California (for fur) like large-mouth bass (recreational fishing), and American Bullfrogs (as food) for the purposes of economic development. Today, they are widely known to threaten native species by damaging habitat, degrading infrastructure, and introducing disease.

California’s Delta faces numerous invasive challenges that alter habitats, deplete the food web, and impair water quality, including emerging algal blooms, as well as long term issues from numerous non-native plants.

HOW CAN CALIFORNIA HELP THE DELTA?

There is hope for the Delta, bolstered by emerging science and an understanding that more than just increased water flows are needed for healthy ecosystems. Identifying the problems that plague California’s native landscapes is the first step in determining a sensible course of action to correct them.