Pacific Southwest Region
California, Nevada and Klamath Basin

U.S. Fish and Wildlife Service Announces Sacramento Splittail Does Not Warrant Endangered Species Act Protection

Oct 05, 2010

Oct. 5, 2010

Contact: Steve Martarano, 916-335-8841,

U.S. Fish and Wildlife Service Announces Sacramento Splittail
Does Not Warrant Endangered Species Act Protection

SACRAMENTO — The U.S. Fish and Wildlife Service announced today that the Sacramento splittail, a fish endemic to California’s Central Valley, does not warrant protection under the Endangered Species Act (ESA). The best available scientific information demonstrates no recent decline in the overall abundance of the splittail nor threats that rise to the level of being significant to the splittail at the population level.

The Service’s finding to be published in the Federal Register on Oct. 7, 2010, is based on a thorough evaluation of the current status and level of threat to the species. While habitat loss has occurred over the years, the existing data fail to show a significant long-term decline of the splittail. Available population data do not show an overall decline, but rather natural fluctuations demonstrating a pattern of successful spawning during wet years followed by reduced spawning during dry years.

The complete finding can be found at .

During flood years, Sacramento splittail can be one of the more abundant fish in the Delta,” said Dan Castleberry, Field Supervisor of the Bay-Delta Fish and Wildlife Office. “Similarly, as you would expect, during drying periods, spawning is reduced, and the abundance of splittail, especially young splittail, can be low.”

The Sacramento splittail’s range centers on the San Francisco Estuary. Spawning occurs in flooded vegetation, including in the Yolo Bypass, with older fish spawning first. Peak reproduction occurs in March and April, though splittail are fractional spawners, which release their eggs more than once through a spawning season, so the process may take months.

A number of habitat restoration actions benefitting the splittail are underway, including 29 species enhancement conservation measures being implemented through the Delta Stewardship Council (formerly known as CALFED). Restoration efforts completed at the Cosumnes River Preserve and Liberty Island in the Yolo Bypass and benefit splittail spawning efforts by creating new seasonal floodplains. Earlier this year, the California Fish and Game Commission set new state fishing regulations limiting take of splittail to two per day to help eliminate threats due to recreational fishing. Sacramento splittail is also one of the species targeted for protection under the multi-agency Bay Delta Conservation Plan.

Research has shown no evidence that south Delta water export operations have had a significant effect on splittail abundance, even though fish collection facilities can capture a large number of fish (up to 5.5 million) during wet years, when spawning on the San Joaquin River and other floodplains results in a spike in population numbers. The number of splittail captured by these facilities drops during dry years when recruitment is low (1,300 in 2007; about 5,000 in 2008) and the splittail is most vulnerable.

The Service did identify a separate Distinct Population Segment in San Pablo Bay but determined it did not warrant protection under the ESA. Recent studies have revealed that the genetic characteristics of the San Pablo population of splittail differ markedly from other populations, contributing significantly to the overall splittail population. The Service’s threats assessment for the San Pablo population did not indicate that the population is likely to become threatened or endangered now or in the foreseeable future. In addition, the Service found that the threats acted in a relatively uniform way throughout the range of the splittail, such that no significant portion of the species range warranted further consideration.

On Nov. 5, 1992, the Service received a petition seeking to add the Sacramento splittail to the federal list of threatened and endangered species, and to designate critical habitat for the species. The Service proposed to list the splittail as threatened in 1994, but the listing was delayed by three extensions of the comment period and a 1-year moratorium on all federal endangered species listings. In February 1999, the Service published a final rule listing the splittail as threatened. In 2000, a federal court ruled in support of the San Luis and Delta-Mendota Water Authority and remanded the determination to the Service for further review. On Sept. 22, 2003, the Service published a final rule in the Federal Register (68 FR 55140) removing the splittail from the endangered species list.

On Aug. 13, 2009, the Center for Biological Diversity filed a complaint in U.S. District Court for the Northern District of California, challenging the Service on the merits of the 2003 removal of the Sacramento splittail from the ESA list and alleging improper political influence by a former Department of Interior official. In a settlement dated Feb. 1, 2010, the Service agreed to submit to the Federal Register a new status review and 12-month finding as to whether listing the Sacramento splittail is warranted or not warranted, by Sept. 30, 2010.

The Service will continue to monitor splittail population range and abundance and will periodically review the status of the splittail. If future evidence suggests that these threats are contributing to significant population declines, the Service may propose the species for ESA protection. 

More information about the Sacramento splittail is available at:

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