In the fate of the Delta smelt, warnings of conservation gone wrong

Sharon Levy writes:

Peter Moyle, an eminent authority on the ecology and conservation of California’s fishes, stands on the narrow deck of a survey boat and gazes out over the sloughs of Suisun Marsh. The tall, tubular stems of tule reeds bend in the wind as a flock of pelicans soars past, their white wings edged in black. It’s an idyllic scene that hints at an earlier time, back before the Gold Rush, when undisturbed creeks and tidal marsh covered the Sacramento-San Joaquin Delta.

The Delta smelt has high odds of becoming the first fish to go extinct in the wild while under the protection of the federal Endangered Species Act.

In the delta, two of California’s greatest rivers meet and mingle with the ebb and flow of tides from San Francisco Bay, forming the largest estuary on the Pacific coast of the Americas. Moyle knows well how this place has changed. The delta’s once wild labyrinth of meandering rivulets and floating tule islands have been replaced by a network of levees that wall off agricultural fields, towns, and remnants of wildlife habitat from the tides. A legion of invasive species now course through the reshaped channels. The many tributaries that run down from the Sierras to feed the delta have been dammed and diverted to provide water for cities and farms — a maze of infrastructure and engineering that has pushed several species of native fish into steep decline.

The creature Moyle has studied the longest and knows most intimately is the Delta smelt, now on the brink of extinction.

Moyle was a young fishery ecologist, newly hired at the University of California, Davis, when he first encountered the finger-length, translucent fish in 1972. He chose to study the Delta smelt because it was abundant but little understood. During the 1980s, he documented a crash in the smelt population, and by 1993, the fish was listed as “threatened” under both the federal and California endangered species acts. As head of a team responsible for charting a course toward the smelt’s recovery, Moyle suggested a radical solution: Conservation in the delta, he said, should focus not just on the smelt, but on an array of native fish with different life histories and habitat needs, including steelhead and sturgeon. All of their populations were dwindling as humans reshaped the ecosystem, but only the smelt and winter-run Chinook salmon were officially listed as threatened.

Moyle’s idea didn’t take hold and government efforts instead followed the letter of the federal Endangered Species Act, focusing only on the smelt. Years of intense study and controversy followed, including a series of court cases over allocating water for smelt habitat. The species continued to dwindle. In 2009, California officials changed the smelt’s status in their listing from threatened to endangered, and by then, another run of Chinook salmon, a run of steelhead, and the region’s population of green sturgeon had all joined the smelt on the federal endangered species list.

In the spring of 2015, a survey of wild spawning smelt found only six fish. Today, an estimated 48,000 survive in the wild — a small remnant of pre-crash populations. About the same number live in culture facilities created to prevent the smelt’s extinction. To some Californians, that’s of little consequence, and they regard efforts to protect remaining smelt as an exemplar of absurd environmental overreach. Why should an obscure fish, rarely seen by anyone but researchers, impair the flow of precious delta water to the thirsty farms and cities of Southern California?

But many ecologists, Moyle among them, consider the smelt’s rapid disappearance the signature of both an ecosystem, and a conservation strategy, in crisis. [Continue reading…]

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