Is the drought hastening the decline of California’s native fish? Will they be able to recolonize once normal conditions return?
To help find out, a team of researchers with the UC Davis Center for Watershed Sciences took the pulse of about 70 streams and rivers across northern and central California this summer, examining habitat conditions and recording the composition and density of fish communities. The selected streams all have data from earlier fish surveys for comparison. Here, the scientists leading the effort report on some of the more obscure streams fed mainly by springs rather than snowmelt and rain runoff.
Peter Moyle and Rebecca M. Quiñones
In a severe drought, a cold, free-flowing stream is a marvel. This past summer, we traveled around Northern California looking for such streams. Our guide was field notes from UC Davis fish-sampling trips 10 to 30 years ago, which tell us where the best places should be.
We were often discouraged, finding dry stream beds or just a few stagnant pools. But we also found a few streams that persisted no matter the drought. These are spring-fed streams, and it was stunning to see them in the dry landscapes we visited. Many clearly are refuges for native fishes.
We are not referring to the large and famous spring streams, such as Hat Creek and the Fall and McCloud rivers, but much smaller streams that are often neglected. We visited six such streams in recent weeks. Here are some observations:
Parson Springs and Mill creeks, Modoc County. These two cold headwater streams did not appear to have changed much since the 1980s. Protected by the U.S. Forest Service, Parson Springs Creek is a small, classic meadow stream abundant with small trout. Mill Creek is similar except heavily grazed, with little riparian vegetation. Both streams ultimately irrigate farms in Jess Valley, leaving little water to support the South Fork Pit River, which is now dry.
Sagehen Creek, Placer and Nevada counties. Sagehen is one of the most studied streams in California, with fish surveys dating to the 1950s. Although there have been shifts in the creek’s trout species, summer flows have been remarkably constant over the years. Fish, especially sculpins, have remained abundant in the upper watershed. Flows were not exceptionally low in this drought year. However, recent studies indicate that the flows are from snowfall two years earlier. Thus, the drought may not strongly affect the creek until next year.
Willow Creek, Lassen County. This tributary of the lower Susan River starts as a series of cold springs in a chain of meadows. The meadows and streamside are heavily grazed. Riparian vegetation is sparse. The creek nevertheless seems to maintain much of its integrity and flows. We found that it continues to support large populations of native fishes such as speckled dace, Lahontan redside and Tahoe sucker. Trout, however, were rare.
Pine Creek, Lassen County. This is the only major tributary to Eagle Lake, which is perhaps the only natural lake in California free of non-native fishes. Drought has reduced Eagle to remarkably low levels. We found most of Pine Creek to be dry, eliminating stream populations of two native fishes (both found in the lake, fortunately). There is a concentrated effort to restore Pine Creek as the spawning stream for endemic Eagle Lake rainbow trout. The biggest obstacle are the abundant brook trout in the headwater springs (Carmona-Catot et al. 2012). In the 2 to 3 miles of creek still flowing with spring water, we found mainly brook trout and a few speckled dace. In years past, the two species had been equally abundant.
Martis Creek, Placer County. We visited the lower 3 miles of Martis, near Truckee, where fish ecology studies have been conducted for the past 30 years (Kiernan et al. 2012). The fish populations have a complex relationship with high-flow events. The reach below Martis Creek Dam (a flood control structure that maintains flows in the lower creek, like a spring) has been dominated most years by four to five native fishes that can tolerate fairly warm water. In contrast, the lowermost reach has consistently been dominated by non-native rainbow and brown trout, in part because springs enhance flows and decrease temperatures. The same pattern was found this summer, with native species being exceptionally abundant just below the dam.
Our studies show that small spring streams can be important refuges for native and other desirable fishes during drought.
It is increasingly evident that all spring streams in California need to be identified and need additional protections, such as fencing off cattle to preserve streamside vegetation. We need to understand what governs flows from springs and how much each stream is isolated from others as the result of human changes to the landscape.
In long droughts, even spring streams may dry up, especially in poorly managed watersheds with limited infiltration of rain and snowmelt. Managing small spring streams should be an important part of a statewide strategy for protecting our native aquatic biota.
The need for a statewide conservation strategy for our streams and their biota is even more apparent in the new book by Lynn Ingram and Frances Malamud-Roam, “The West without Water: What Past Floods, Droughts and other Climatic Clues Tell Us about Tomorrow.” The book makes the case for regarding present conditions as being rather benign. Much worse droughts, followed by massive floods, have occurred regularly in the past 1,000 or more years.
This reality is hard to grasp as we splash around in cold streams. But do the fish in even these seemingly permanent streams have a future under our present management? Read the book and think about it.
Peter Moyle is a distinguished professor of fish biology and Rebecca M. Quiñones is a post-doctoral researcher with the UC Davis Center for Watershed Sciences.
Carmona-Catot, G., P. B. Moyle, and R. E. Simmons. 2012. Long-term captive breeding does not necessarily prevent reestablishment: lessons learned from Eagle Lake Rainbow Trout. Reviews in Fish Biology and Fisheries 22:325-342
Ingram, L.B., and F. Malamud-Roam. 2014. “The West without Water: What Past Floods, Droughts and other Climatic Clues Tell Us about Tomorrow.” University of California Press.
Kiernan, J. D., and P. B. Moyle. 2012. Flows, droughts, and aliens: factors affecting the fish assemblage in a Sierra Nevada, California, stream. Ecological Applications 22:1146-1161
Manfree, Amber. Drought Journal: Search for Sierra fish goes from bad to worse. California WaterBlog, Aug. 18, 2014