The U.S. Fish and Wildlife Service published in the Federal Register on Oct. 7, 2010 a finding that the Sacramento splittaill (Pogonichthys macrolepidotus), a fish endemic to California's Central Valley, did not warrant protection under the Endangered Species Act (ESA). The best available scientific information demonstrated 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 was 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. During flood years, Sacramento splittail can be one of the more abundant fish in the Delta.
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.
The Service continues 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.