Are droughts here to stay? No one knows for sure, but just in case, the California Department of Fish and Wildlife (CDFW) has ramped up efforts over the past four years to deal with future droughts, including the creation of a variety of “Drought Response Projects” to protect fish from the effects of drought that have occurred in the past and that may recur in the future.
According to information the CDFW has posted online at https://www.wildlife. ca.gov/Drought/Projects, the department has “conducted stream and wildlife population monitoring, fish rescues, restoration projects, and many other actions to protect native fish and wildlife threatened or impacted by the statewide drought.” The Website includes links to detailed drought-related fishery monitoring reports for 53 locations, including waters that are prized by fly fishers. These reports focus on drought stressors, which are stream characteristics that vary as the result of droughts, such as water temperature, dissolved oxygen, acidity, alkalinity, and changes in streamside habitat. The reports “reflect efforts at various locations along the coast, the Central Valley, mountains, and deserts of California.” Each report focuses on species, location, need for stressor monitoring, current efforts, and conclusions about the impact. Here are some of the CDFW’s findings from the drought-stressor reports that are available online.
The Upper Sacramento River: Winter-Run Chinook Salmon Redd Dewatering Prevention
Location — The Sacramento River is home to four distinct runs of Chinook salmon: fall, late fall, spring, and winter. Winter-run Chinook salmon are unlike other salmon species found on the West Coast in that they spawn during the warm summer months. While this may not seem like an advantageous strategy, historically, winter-run salmon have spawned in upstream tributaries fed by cold-water springs that would stay cool all summer long. Construction of the Shasta and Keswick Dams blocked winter-run salmon from these spawning grounds. This left the uppermost reaches of the Sacramento River in Redding as the only location with suitable spawning habitat and the cold water temperatures needed for successful incubation of the winter-run salmon eggs.
Findings — From April 4 through November 5, 2016, a total of 28 redds were identified as being at risk of being left without water and were closely monitored following every reduction in releases from Keswick Dam. Each flow reduction was done in increments of 250 cubic feet per second to prevent any unexpected dewatering. If any redds became too close to being dewatered, future flow reductions would be postponed until the eggs had hatched from that redd. Due to close monitoring of these redds by the CDFW and the Pacific State Marine Fisheries Commission and excellent communication with the Bureau of Reclamation to ensure that flows were high enough, no winter-run redds became dewatered. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Upper-Sacramento/2016-Update.
Russian River Tributaries Coho Salmon Rescue and Relocation 2015
Location — Many streams in the Russian River basin where natural-origin or hatchery-origin coho salmon occur are monitored for their coho population status and habitat conditions.
Findings — The Russian River Coho Salmon Captive Broodstock Program is an essential component of the species’ recovery. Persistent drought conditions were placing juvenile salmonids in imminent danger of perishing due to rapidly drying habitat and associated deteriorating water quality and increased predation. In many instances, small pools where juvenile coho salmon are known to reside can dry up completely within a matter of a few days or even overnight. Since May 2015, CDFW regional staff captured and relocated juvenile coho salmon and other juvenile salmonids rearing
in seven different streams in the Russian River basin. The primary motivation for these efforts was to facilitate outmigration of smolts that were trapped in disconnected and drying pools by capturing and relocating them to nearby Dry Creek or the main stem Russian River. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Russian-River-Coho-Rescue.
The Lower American River: Abundance, Growth, Condition, Health, and Survival of Juvenile Steelhead during the 2014 Drought
Location — The American River is the second-largest tributary to the Sacramento River in the Central Valley. Nimbus Dam, which regulates flows on the lower American River, marks the upstream limit to the migration of anadromous fish at river mile 23. Nimbus Fish Hatchery is located just downstream of the dam and produces Chinook salmon and steelhead trout. With 2014 being the third consecutive drought year for California, there was concern for the fate of juvenile steelhead on the lower American River, where late summer conditions are typically a survival bottleneck because high water temperatures promote the growth of bacteria, fungi, and parasites, which are common in such environments and infect coldwater fishes such as steelhead at disease levels.
Findings — Between May and October 2014, 453 juvenile steelhead were caught with a seine on the lower American River. Of those, 83 (18 percent) were of natural origin, while the remaining 370 (82 percent) were of hatchery origin. A subsample of the daily catch was tagged and released, and the catch on each subsequent sampling occasion was examined for recaptured fish. Fourteen juvenile steelhead of natural origin were tagged, and one was recaptured 26 days after it had been first captured. The growth rate for this particular fish was .05 inches per day, which is very high for the species. Fifty-nine hatchery-origin steelhead were tagged, and three were recaptured. These three fish had an average growth rate of .04 inches per day. Water temperatures on the lower American River were relatively high compared with previous years. The average monthly water temperature was 68 degrees Fahrenheit during July through September, with the highest water temperature observed (73 degrees) at lower Sunrise Bar in mid-August. Despite the higher than average water temperatures, there were no visible signs of stress in the captured fish. See the full report at https://www.wildlife.ca.gov/Drought/Projects/American-River.
Butte Creek Central Valley Spring-Run Chinook Salmon
Location — Butte Creek is one of only three Central Valley streams that continue to harbor a self-sustaining population of spring-run Chinook salmon, which have been listed as threatened under both the California and federal Endangered Species Acts since 1999. In 2016, California experienced its fifth consecutive extremely dry year, constituting one of the worst droughts in the state’s recorded history. Elevated creek temperatures during the hot summer holding period can result in an increase of spring-run Chinook salmon mortalities. However, mortalities can be reduced when water-releases from the creek’s dams help mitigate “heat storms,” thereby reducing water temperatures in the creek.
Findings –CDFW personnel conducted weekly snorkel surveys of the entire holding habitat, a 17.7 kilometer reach of the stream. Among other things, survey crews documented the number of spring-run Chinook salmon that died off prior to spawning. Monitoring was done from Quartz Bowl down to the Honey Run Covered Bridge. Carcass surveys begin at the initiation of spawning in mid-September to estimate the number of spring-run that survived over the summer to spawn. The 2016 carcass survey indicated that 4,450 spring-run Chinook salmon successfully spawned in Butte Creek, a marked increase from 2015, when surveys indicated that only 413 spring-run Chinooks had spawned successfully. Collaboration coupled with real-time adaptive management strategies of water releases contributed to the annual success of spring-run Chinook salmon surviving the long, hot summer drought conditions and into the spawning season. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Butte-Creek-Spring/2017-Update.
The San Joaquin and Stanislaus Rivers: Dissolved Oxygen Monitoring
Location — The CDFW is investigating drought effects on dissolved oxygen in the Stanislaus and San Joaquin Rivers, which can impact fall-run Chinook salmon, a federally listed species of concern, and steelhead, a federally listed threatened species.
Findings — Lower dissolved oxygen levels in the fall of 2015 caused concern for the fall-run Chinook salmon population, which migrates from the ocean into the Stanislaus River during October and November to return to spawning grounds. Very low dissolved oxygen levels (less than 4.2 milligrams per liter) can block adult salmon migration. Fortunately, dissolved oxygen readings at Vernalis and Ripon were consistently higher than such levels. However, the CDFW is not currently able to determine the effects of drought on dissolved oxygen concentrations in the Tuolumne and Merced Rivers, the other tributaries of the lower San Joaquin River, due to a lack of additional monitoring locations. See the full report at https://www.wildlife.ca.gov/Drought/Projects/San-Joaquin.
Stanislaus River Salmonid Stranding Survey and Rescue
Location — The Stanislaus Operations Group (SOG) is tasked with managing flows on the Stanislaus River below Goodwin Dam to protect native fish stocks, including endangered Chinook salmon and steelhead. In March 2016, SOG agreed on a pulse flow schedule that included several high-flow peaks to encourage juvenile salmon out-migration before river water temperatures increase during the summer months. The abrupt flow declines after these peaks caused concern, because the peak flows would activate some otherwise dry side channels, causing juvenile salmonids to become trapped when flows abruptly receded. Fish trapped in diminishing pools would be subject to low dissolved oxygen, high temperatures, and predation. The CDFW chose to monitor known sites with stranding potential after flow drops. Two of the five sites were inundated during the peak flow, and 48 salmonids were identified from both sites during the April 6, 2016 surveys.
Findings — Fish observed in the pools were very small. The average fork length for steelhead trout and Chinook salmon was 1.2 inches and 1.7 inches, respectively. All rescued salmonids were released back to the Stanislaus River. There were three Chinook salmon mortalities in a pool, likely due to low dissolved oxygen. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Stanislaus-River.
By-Day Creek Lahontan Cutthroat Trout Rescue and Relocation 2015
Location — The By-Day Creek Ecological Reserve in Mono County is a 460-acre, CDFW-owned property that contains a portion of By-Day Creek, a small tributary stream in the headwaters of the Walker River basin, home to a remnant population of Walker Basin Lahontan cutthroat trout. The property was acquired for the preservation of critical aquatic and riparian habitat for this species. The reserve is entirely surrounded by public lands of the Humboldt-Toiyabe National Forest.
Lahontan cutthroat trout are listed as threatened under the Federal Endangered Species Act and were one of the original fishes listed under the act. Lahontan cutthroat trout management and recovery efforts have resulted in the completion of stream-restoration projects such as channel stabilization and enhancement of fish cover. But nearly all of California’s wild Lahontan cutthroat trout populations are found in small-stream habitats such as By-Day Creek and are particularly vulnerable to climate change, so despite these efforts, the Walker Basin Lahontan cutthroat trout population has continued to decline.
Findings —Electrofishing gear was used along with dip nets to remove trout from the designated reaches of By-Day creek. The rescued Lahontans were placed into two established refuge populations at Slinkard Creek and Wolf Creek. By-Day Creek habitat, stream flows, and temperature were monitored during the summer of 2015. If habitat conditions deteriorate further, to the point that additional Lahontan cutthroat trout may need to be rescued, options being considered have included further translocations and possibly rescue to captivity at a hatchery isolation facility if the population declines to critically low numbers. See the full report at https://www.wildlife.ca.gov/Drought/Projects/By-Day-Creek-Lahontan-Cutthroat-Trout.
Volcanic Creek: California Golden Trout Population Structure and Stream Habitat Monitoring
Location — California golden trout, a subspecies of rainbow trout, are native to the South Fork of the Kern River and Golden Trout Creek watersheds in Tulare County on the western slope of the Sierra. Most populations of golden trout have interbred with other rainbow trout, diluting their genetic integrity. Volcanic Creek supports one of the few remaining genetically pure populations of golden trout because it is remote and only intermittently connected to Golden Trout Creek. Volcanic Creek’s dependence on spring water and lack of connectivity to Golden Trout Creek pose risks to the sustainability of the creek’s small Golden Trout population. Extended drought conditions make these challenges even greater by further reducing water supply and available habitat.
Findings — Habitat conditions in 2016 were either similar to or improved over those in 2015, but were generally worse than those observed in 2013 and 2014. For example, in June 2016, a survey of Volcanic Creek (the Meadow reach) found that stream habitat was wetted 34 percent longer than observed in June 2015 but 10 percent shorter than observed in June 2014 and 38 percent shorter than in September 2013. From July 2014 to June 2016, the number of golden trout documented declined by 81 percent in Volcanic Creek and 71 percent in lower Left Stringer Volcanic Creek. Both sites saw declines in counts over the winters of 2014–2015 and 2015–2016. This is especially true of lower Left Stringer and is likely due to the formation of anchor ice, which forms in stream bottom habitat and prevents fish from escaping freezing conditions. Due to low fish population counts, the threat of winter kill from anchor ice and unknown impacts to wetted reaches, the CDFW rescued 52 golden trout from the three reaches and transported them to the American River Hatchery. They will be kept at the hatchery until conditions improve and they can be safely returned back to Volcanic Creek and Left Stringer Volcanic Creek. The need for this rescue would not have been understood without drought stressor monitoring. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Volcanic-Creek/2017-Update.
Drought Effects Present in Anadromous Reaches of Four Southern California Steelhead Streams
Location —In four creeks in Santa Barbara and Ventura Counties (Rattlesnake, Arroyo Hondo, Santa Paula, and North Fork Matilja Creeks) that are known to provide spawning and rearing habitat for steelhead, CDFW staff assessed drought and habitat conditions and mapped habitat reductions. During the surveys, CDFW biologists collected GPS location points of wet and dry reaches of the streams and assessed the extent that streams were drying.
Findings — Rattlesnake Creek lost the most wetted habitat (an almost 90 percent loss from spring to fall 2014), but all four creeks experienced significant drying. The CDFW began assessing whether to conduct fish rescues from the drying reaches based on these results. Unfortunately, because of the limited amount of stream habitat available, it can be difficult to find release locations for rescued steelhead, and available habitat often cannot support any more fish. Thus, the benefits of rescue to the population can be unclear. See the full report at https://www.wildlife.ca.gov/Drought/Projects/Santa-Barbara-Ventura. See the reports on all 53 of the drought-monitoring areas at http://www.wildlife.ca.gov/Drought/Projects.
