Hitch Archive

Second year of the District's annual CLH visual spawner program, covering 14 sites on 10 tributaries (Feb 20 to May 30, 2025). Documented 266 adult hitch at Forbes and Copsey creeks, a large increase over the 23 observed in 2024, and thousands of larval fish across most monitored tributaries.

First year of the District's community science CLH spawner program, deploying 33 trained volunteers across 36 fixed sites on 26 tributaries from March 9 through May 17, 2025. Community scientists collectively observed 3,347 adult hitch, the most geographically comprehensive single-season spawner survey in the program's history.

First year of the District's annual CLH visual spawner survey program, monitoring 14 sites on 10 tributaries from March 20 through July 18, 2024. Confirmed adult hitch at three tributaries and documented large juvenile cohorts in Burns Valley Creek.

CDFW's 2025 annual visual spawner survey covering primary spawning tributaries including Adobe, Kelsey, and Manning creeks. Combined with District and Community Science data, the 2025 total reached 1,567 spawners, a solid year above recent low points, though well below the 2023 record.

CDFW's 2024 spawner survey documenting 1,042 adult hitch across Clear Lake tributaries. Despite adequate rainfall and a high in-lake CDFW capture rate, spawner counts were lower than expected, a finding that informed the hypothesis that hitch may not rely on tributaries for spawning every year.

Documents the record 2023 spawning season in which 2,548 adult hitch were observed, the highest count in the history of the monitoring program. The surge followed three consecutive drought years (2020 to 2022) that severely depressed spawning activity.

Documents the second consecutive crisis-level spawning season with only 306 adult hitch observed, a small recovery from 2021's catastrophic 120-fish low but still over 88% below the 2020 count.

Documents the lowest single-year spawner count in CDFW survey history: only 120 adult hitch observed. A catastrophic drought-induced crash following the strong 2020 season of 1,672 spawners, a 93% year-over-year decline.

Documents the strongest spawning season since surveys began, with 1,672 adult hitch observed, all concentrated in Kelsey Creek. A notable single-tributary dominance event suggesting Kelsey was the only tributary with adequate flow that year.

Below-average year with 612 adult hitch observed. USGS gillnet data from the same year showed catches already ~55% below the 2017 baseline, suggesting the in-lake population decline was already underway.

Strong year with 1,153 adult hitch observed. Adobe Creek was the most frequented tributary. USGS gillnet surveys had just launched the prior year, providing the first systematic in-lake abundance baseline.

Baseline year for modern monitoring with 517 adult hitch observed. The concurrent launch of USGS gillnet surveys established the quantitative in-lake abundance benchmark against which the subsequent 96% decline was measured.

693 adult hitch observed. Adobe Creek was again the most frequently used spawning tributary. PIT tagging program active at Kelsey and Adobe.

1,119 adult hitch observed in the same year the hitch was formally listed as threatened under the California ESA. Active PIT tagging program at Kelsey and Adobe creeks.

Annual mark-recapture based estimate of the Clear Lake hitch population within Clear Lake itself, using standardized gillnet surveys. Provides the in-lake abundance index to complement the tributary-based spawner counts.

In-lake mark-recapture population estimate for 2024. High capture rates relative to low tributary spawner counts that year raised the hypothesis that the hitch population does not uniformly rely on annual tributary spawning.

In-lake population estimate conducted during the second consecutive drought-crisis year. Cross-referenced with USGS gillnet data showing ~4% of 2017 baseline, confirming a catastrophic population collapse in-lake as well as in tributaries.

In-lake mark-recapture survey during the 2021 catastrophic drought year. Combined with only 120 tributary spawners, this dataset represented the lowest point in the documented history of the hitch population.

In-lake population estimate from the strong 2020 spawning season. All 1,672 tributary spawners were observed in Kelsey Creek, and this estimate captures the in-lake cohort that season produced.

In-lake mark-recapture estimate from 2019, a below-average year with 612 tributary spawners. USGS gillnet data simultaneously showed catches ~55% below the 2017 baseline.

Population survey of the Clear Lake hitch subpopulation in Thurston Lake, a hydrologically isolated waterbody that supports a genetically distinct, conservation-critical refuge population. Thurston Lake is treated as a separate demographic unit by USFWS.

Early mark-recapture survey focused specifically on Cole and Kelsey Creek populations, prior to the establishment of the full lake-wide monitoring program. Provides the earliest standardized baseline for these two critical southern tributaries.

Final year of the four-year PIT tagging study at Kelsey and Adobe creeks. Tracked individual hitch movement, migration timing, and tributary fidelity using passive integrated transponder tags, the most direct method for monitoring individual spawning behavior.

Third year of PIT tagging program tracking individual hitch movement between Clear Lake and spawning tributaries at Kelsey and Adobe creeks.

Second year of PIT tagging at Kelsey and Adobe creeks. Recapture data beginning to reveal multi-year migration patterns and individual site fidelity.

First year of the PIT tagging program at Kelsey and Adobe creeks, launched in the same year the hitch received state threatened status. Established baseline migration timing and detection protocols.

Emergency fish rescue operation at Adobe Creek during the 2022 drought-crisis spawning season. Hitch stranded in isolated pools were relocated to safe water.

Fish rescue operation at Thompson Creek during the 2019 spawning season. Thompson Creek joins Manning Creek upstream and has been confirmed for adult hitch in CDFW 2024 to 2025 surveys.

Fish rescue at Cole Creek during the 2018 season. Cole Creek flows into Clear Lake adjacent to Kelsey Creek and is the focus of an active 1.55-mile habitat restoration project.

Fish rescue at Cole Creek during the 2016 spawning season, two years prior to the 2018 rescue at the same location, suggesting recurring stranding risk on this tributary.

Fish rescue at both Adobe Creek and Cooper Creek during the first year of the CESA-listed period (2014). Simultaneous rescues at two tributaries in the same season.

Broad-based fish assemblage survey of Clear Lake covering native and introduced species. Provides current-year context for the hitch's competitive and predation environment.

Fish assemblage survey of Clear Lake conducted in the same year as the record 2,548 spawner count. Documents species composition during a recovery year after drought.

Historical fish assemblage survey providing a pre-modern-monitoring-program baseline for species composition in Clear Lake. Useful for long-term comparisons with current assemblage data.

Fish survey of Highland Springs Reservoir, which is hydraulically connected to Adobe Creek, one of the most important Clear Lake hitch spawning tributaries.

Fish survey of Highland Springs Reservoir in 2024, providing species composition data for the Adobe Creek tributary system.

Baseline fish survey of Highland Springs Reservoir from 2015, part of the broader first wave of tributary and reservoir assessments following the 2014 CESA listing.

Fish survey of Tule Lake, located northwest of Clear Lake in the Cold Creek drainage. Tule Lake is historically connected to Clear Lake through the Cold Creek to Scotts Creek corridor, which was rerouted by geological activity. Relevant for understanding potential CLH refugia.

Fish survey of Lower Blue Lake conducted alongside the 2024 USGS gillnet study. No CLH were detected in either survey, consistent with 2015 results and the lack of known translocation events into Lower Blue Lake.

Historical baseline survey of Lower Blue Lake from 2015. No CLH were detected, establishing the long-term absence of hitch in this waterbody prior to any translocation events.

Fish survey of Upper Blue Lake, conducted the same year Robinson Rancheria rescued and translocated 295 CLH from Cooper Creek into Upper Blue Lake. Upper Blue Lake is connected to Lower Blue Lake by a seasonally inundated creek.

Age-structure analysis of the Clear Lake hitch population using otolith and scale aging methods. Provides foundational life history data (age distribution, growth rates, and cohort composition) for the population at the start of the modern monitoring era.

Systematic fish observations at Adobe Creek and adjacent Adobe Reservoir from the first year after CESA listing. Provides baseline species composition, hitch presence and abundance, and documents the relationship between reservoir conditions and downstream spawning habitat.

Gillnet survey of Adobe Reservoir documenting species present and relative abundance. Relevant for assessing non-native species that could potentially move downstream into Adobe Creek spawning habitat.

Broad evaluation of Clear Lake's fishery and physical habitat conditions spanning 2014 to 2015. Assesses shoreline conditions, aquatic vegetation, dissolved oxygen, temperature stratification, and fish community structure across the lake.

Dedicated spawning survey from the year of CESA listing, providing the formal observational baseline for the modern conservation era. Documents 1,119 adult spawners.

Peer-reviewed study using standardized gillnet methodology to determine whether CLH are present in Lower Blue Lake, a historically connected but geologically isolated waterbody northwest of Clear Lake. No hitch were detected in 49 gillnet deployments in October 2024.

The most comprehensive recent assessment of Clear Lake fish populations. Documents a 96% decline in hitch relative abundance between 2017 and 2022 based on six years of standardized gillnet surveys. Captures 986 individual hitch across 1,529 gillnet deployments.

Peer-reviewed study using otolith strontium isotope ratios (⁸⁷Sr/⁸⁶Sr) to trace which tributaries adult hitch recruit from, and how long juveniles spend in natal streams before emigrating to Clear Lake. The isoscape differentiated Clear Lake from 8 of 10 key tributaries.

The first in-lake habitat use study for CLH using systematic gillnet sampling. Found dissolved oxygen was the dominant driver of hitch spatial distribution, fish strongly avoided hypoxic water below 2 mg/L, which excluded them from large portions of the lake.

Comprehensive synthesis of Clear Lake's fish community history from the 1870s to present. Correlates native species declines with the timing of human impacts including 25 non-native fish introductions, habitat alteration, mercury mining, and water diversions over 150 years.

Fish passage reconnaissance conducted April 25, 2006 on Middle Creek, Clover Creek bypass, and Kelsey Creek near Main Street. Identified significant passage barriers blocking hitch migration and assessed restoration potential using CDFG protocols.

The federal proposal to list the Clear Lake hitch as threatened under the Endangered Species Act with a Section 4(d) rule. The proposal deferred designation of critical habitat to a later date. Based on a comprehensive Species Status Assessment evaluating population viability under multiple climate scenarios.

Lake County officially declared a local state of emergency due to the imminent risk of hitch extinction. The resolution followed multiple consecutive drought years that caused near-total spawning failure and was triggered by 2021 and 2022 spawner counts of 120 and 306 fish respectively.

The formal status review that resulted in the Clear Lake hitch being listed as threatened under CESA in August 2014. Comprehensively assessed population trends, habitat conditions, and threats including drought, tributary dewatering, invasive species, and agricultural diversions.