A Tiny California Fish Is On Brink Of Extinction And The Ramifications Are Huge

Delta smelt, Hypomesus transpacificus. CREDIT: WIKIMEDIA COMMONS
Delta smelt, Hypomesus transpacificus. CREDIT: WIKIMEDIA COMMONS

Life for the Delta smelt has gone from bad to worse.

This three-inch fish, which has played a central role in California’s efforts to manage its precious water resources, is on the verge of extinction according to the latest trawl survey in areas of the Sacramento-San Joaquin Delta where the fish normally congregate.

University of California-Davis fish biologist Peter Moyle recently told a group of scientists with the Delta Stewardship Council to “prepare for the extinction of the Delta Smelt in the wild.”

“That trawl survey came up with just six smelt, four females and two males,” he said. “Normally because they can target smelt, they would have gotten several hundred. It tells you that the smelt populations are very close to extinction. These six smelt were caught in an area where they should have been catching them in large numbers. It’s the spawning time.”


According to Moyle, the Delta smelt is functionally extinct, but the U.S. Fish and Wildlife Service (FWS) says it’s too soon to make that call just yet.

Steve Martarano, public affairs specialist with the FWS’s Bay-Delta Office, told ThinkProgress that while Delta smelt numbers have been declining for decades, “there are still Delta smelt out there.”

“It’s not a very good situation though,” he said. “These are the lowest numbers they have even been surveyed at.” The Delta smelt represents much more to the San Francisco Bay-Delta than its small size would imply. Martarano said it has always been considered an indicator species and that “in the time when it was in abundance and very healthy, so was the rest of the Delta.”

Jeff Miller, a California-based conservationist with the Center for Biological Diversity, agrees. He said the record-low numbers of Delta smelt in recent years indicate the Delta ecosystem is unraveling.

“Delta smelt, longfin smelt, several populations of salmon, steelhead trout, green sturgeon, and Sacramento splittail are facing extinction in the Delta,” he told ThinkProgress. “If state and federal regulators carry on with business as usual, allowing wealthy agribusiness interests to dictate water policy, we will lose all of these fish.”

Delta smelt annual abundances as determined by fall mid-water trawl surveys.

CREDIT: Source: California Department of Fish and Wildlife

The smelt has been listed as threatened since 1993 under the federal Endangered Species Act. A 2008 decision by the FWS to safeguard the fish restricted the amount of water that can be pumped from the Sacramento-San Joaquin Delta and sent south to agricultural interests and water districts. With water in increasingly high demand as California enters a fourth year of devastating drought, the fish’s role in this allocation is more controversial then ever.


This tension culminated in January when the U.S. Supreme Court refused to consider appeals by the Central Valley Farmers and water districts that want to pump for water from the Delta. Farmers argue that the smelt regulations cause valuable water to flow out to the ocean through the Delta, rather than helping relieve them of the hardships of the drought.

“You frequently hear the criticism that Delta outflow is just being wasted in the ocean,” said Martarano. “But it provides many other ecosystem functions: it dilutes pollutants, provides habitat for waterfowl, and provides water-freshening benefits to the Delta.”

Martarano also said that even if the Delta smelt was to be declared extinct in a few years, the presence of another endangered species — the Chinook salmon — would still limit the amount of water that can be pumped from the Delta and transported south. The water pumps themselves are a big part of the problem, as studies have shown that they kill large numbers of these species, jeopardizing their well-being.

Agricultural use has dominated what used to be a major wetland area , as detailed in the San Francisco Estuary Institute report “A Delta Transformed.”

CREDIT: Courtesy: San Francisco Estuary Institute

Miller said while the drought is having a huge impact, the biggest problem is excessive water pumping.

Last year, in an effort to confront the drought, the the California State Water Resources Control Board waived some of the environmental requirements for fresh water flows through the Delta. Twenty-five million Californians depend at least in part on freshwater from the Delta, which is a 1,150-square-mile floodplain fed by the Sacramento and San Joaquin rivers. About 750,000 acres of farmland also gets some amount of water from the Delta.


With the first 80 days of 2015 offering little respite from the drought, on Thursday California Gov. Jerry Brown and state lawmakers are proposing a $1 billion emergency drought relief plan, the second such effort in as many years. Winter is normally California’s rainy season, but the state has been parched since several big storms swept through late last year. Large reservoirs are doing slightly better than a year ago — Shasta Lake, California’s largest reservoir, is 58 percent full, compared with 45 percent a year ago, and Lake Oroville is half full, compared with 45 percent a year ago — but further rationing is still in order: the Sierra Nevada snowpack, source of about 60 percent of the state’s fresh water, was 12 percent of average as of earlier this week.

This week, the the water board approved new statewide restrictions on water use. The new rules prohibit residents from watering lawns within 48 hours after a rain storm and limit watering to just two days a week, among other efforts to curtail demand. According to water board officials, this is the first time any state in the country has imposed an emergency water conservation measurements on every local water agency under its jurisdiction.

For the time being, these emergency measures will do little to lessen the ongoing struggle of the Delta smelt as it comes precariously close to extinction in the wild.