By Peter Moyle
Three-fourths of California’s native fishes are now officially designated as being in trouble, or potentially so.
Years ago, state wildlife managers created a “species of special concern” designation for California fauna that are not legally classified as “threatened” or “endangered” but nonetheless appear bound for extinction without some intervention. Though the label carries no legal clout, it has brought research and management attention to these animals at risk.
To be considered a species of special concern, a fish species must be (1) declining in both geographic distribution and abundance, (2) relatively small in population and/or (3) have an extremely limited distribution.
A team of fish biologists at UC Davis and the California Department of Fish and Wildlife made these evaluations and, following peer review, reported the results in the department’s recently released “Fish Species of Special Concern in California, Third Edition.”
This is the first update on the status of these fishes in 20 years, and it shows an overall continued dramatic decline in population levels. The downward trend is fundamentally tied to an increasing human demand for natural resources, especially water. Natural factors such as the current drought exacerbate the situation.
The fishes in the report are found in all regions of the state and encompass a wide range of taxonomic groups. They include obscure species with small ranges, such as Red Hills roach and Saratoga Springs pupfish, as well as the commercially valuable Central Valley fall-run and late fall-run Chinook salmon.
The previous report, published in 1995, identified 57 species of special concern. Here is what has happened to the status of those fishes:
- 42 continue to warrant the designation
- 11 (19 percent) were undesignated because they had been legally declared threatened or endangered
- 3 were undesignated because their previous assessment was found to be flawed
- 1 species went extinct – the High Rock Springs tui chub of Lassen County, Calif.
The bottom line: Since 1995, 22 percent of the special concern species either became extinct or listed as threatened or endangered, and 21 newly evaluated fishes became species of special concern, for a total of 63.
The team of biologists based the assignment of special concern status on a systematic evaluation and subsequent peer review by experts on each species.
The scientists used information from published and unpublished sources to score each species on seven metrics: (1) area occupied (current range), (2) adult abundance, (3) intervention dependence, (4) tolerance to adverse conditions, (5) genetic risk, (6) vulnerability to climate change and (6) anthropogenic threats.
A 2013 study supported the climate change determinations. On human-caused threats, the scientists analyzed the importance of 15 factors that could limit a fish species’ viability, ranging from effects of major dams to fishing.
Finally, for each species, the team rated how certain they were of their evaluations. They assigned the highest rating to those that were viewed by peers and backed by extensive surveys. The lowest rating went to those based mostly on professional judgment. Each account in the report makes recommendations for conservation actions.
The biologists made their approach scientific and easy to duplicate so others could independently assess the status of fishes using the same process. This approach also makes it easier to change status as new information becomes available. Using the same methods for future status reports will make it easier to determine the overall success or failure of conservation efforts.
Many fishes currently listed as threatened or endangered started out as species of special concern. The species evaluations in the report indicate that is not an inevitable pathway, provided protective action is taken soon.
Given that 64 percent of California native fishes are found only in California, their continued decline is a truly California problem, needing solutions by Californians.
Peter Moyle, a UC Davis professor emeritus of fish biology, led the Fish Species of Special Concern in California study with the help of his former graduate students, Rebecca Quiñones and Jacob Katz, and Jeff Weaver, a fisheries biologist with the California Department of Fish and Wildlife.
Moyle P.B., J. D. Kiernan, P. K. Crain, and R. M. Quiñones. 2013. Climate change vulnerability of native and alien freshwater fishes of California: a systematic assessment approach. PLoS One
Moyle, P. B., R. M. Yoshiyama, J. E. Williams, and E. D. Wikramanayake. 1995. Fish species of special concern of California. California Department of Fish and Game, Sacramento, California. 2nd ed. 272 pp