From 12,000 years of indigenous stewardship to the collapse of native species — told two ways: by era and by species. The full story of what was lost, what persists, and why.
Incorporating data from Moyle et al. 2013 · USGS OFR 2025-1018 · USFWS Federal Register · CDFW surveysThe Clear Lake basin becomes one of the most continuously inhabited places in North America. The Pomo, Lake Miwok, and Wappo peoples develop a deep subsistence and spiritual relationship with the lake and its fisheries — particularly the spring hitch spawning runs.
Historical accounts and late-1800s observations document spawning runs of almost incomprehensible scale — tens of thousands of hitch packed into tributary streams each spring. The hitch, known as chi in the Pomo language, is a cornerstone of the annual food cycle, tied to ceremony, community gathering, and food security. The lake supports extremely abundant populations of all native species: hitch, splittail, pikeminnow, Sacramento perch, Sacramento blackfish, tule perch, prickly sculpin, Pacific lamprey, and rainbow trout.
Early settlers and observers document the extraordinary productivity of Clear Lake. The lake is described as teeming with fish, with hitch runs filling tributaries so densely they could nearly be walked across. This pre-disturbance baseline is critical context for understanding the scale of subsequent collapse.
A commercial fishery targeting hitch during spring spawning runs begins operating. Spawning fish are easily harvested in tributaries in large numbers. Despite heavy harvest, populations remain robust at this stage due to sheer abundance.
Goldfish arrive in Clear Lake, likely as escaped ornamentals. They establish and compete with native fish for food and habitat. Their sediment-disturbing behavior begins degrading submerged vegetation that native species depend on.
Common carp — one of the most destructive freshwater introductions in California history — arrives in Clear Lake alongside brown bullhead and white catfish. Carp immediately begin to expand and degrade habitat through bottom-feeding, uprooting vegetation, increasing turbidity, and consuming fish eggs. Within decades they become the dominant biomass species in the lake. By the early 1900s the carp fishery becomes commercially important, but at severe ecological cost.
Northern largemouth bass are introduced to support a recreational sport fishery. They establish rapidly and become apex predators. By 1910 they already support a strong commercial fishery. Bass are aggressive predators of juvenile native fish, fundamentally changing the food web that Clear Lake hitch and other native species depend on. By 1960 largemouth bass comprise 42% of the catch; by 1988, 67%.
Smallmouth bass (1895), golden shiner (1896), bluegill (1909–1910), and an attempted yellow perch introduction (1909, failed) follow the largemouth bass. Crappie species arrive around 1909. Black bullhead also established by this period. Each introduction further restructures the lake's ecology. Catfish species collectively become so commercially dominant that by the 1930s–1951 they represent 80% of the commercial catch.
Both species are last recorded in Clear Lake around 1894 — early casualties of habitat degradation and competition from introduced species. Pacific lamprey persists in Kelsey Creek but is extirpated from the lake itself. These are the first documented extirpations at Clear Lake, a warning sign that goes largely unheeded.
Sacramento perch — California's only native sunfish — is documented as "scarce" just 15 years after carp introduction. Carp are widely suspected as the primary driver, through habitat degradation and egg predation. The perch will fluctuate for decades but never recover to historic levels.
Despite early invasive species establishment, hitch runs in 1899 are still documented as so dense that fish crowd tributaries — the last documented period of peak abundance. Commercial harvest continues. The population is described as "extremely abundant." This is effectively the last chapter of the pre-collapse era.
The first documented instances of hitch dying en masse in drying creeks during spawning runs occur around 1910 and again in the 1930s. This foreshadows the critical role that tributary hydrology will play in the species' eventual crisis — creeks that previously flowed reliably are beginning to fail under agricultural water demand.
Dam construction on Cache Creek (Clear Lake's primary outlet) alters hydrology and blocks fish passage to upstream habitats. Rainbow trout, which historically spawned in upper Clear Lake tributaries, begin to disappear from the lake entirely — now largely restricted to tributaries above barriers. This is the first major structural change to the watershed.
The thicktail chub is documented as "declining" by 1926. Once common throughout Clear Lake and Central Valley waterways, the species is clearly in trouble. Its last confirmed observation anywhere on Earth will come just 12 years later. No formal conservation action is taken.
Redear sunfish become established in Clear Lake in the 1940s (arriving in the region earlier), and fathead minnow are introduced and establish by this period. Each new species adds competitive pressure to native fish communities. Sacramento perch, briefly abundant again in the 1930s, begins declining again.
The thicktail chub, once abundant across Central Valley waterways including Clear Lake, is last documented around 1938. It is now declared globally extinct — one of California's most significant fish extinctions. This is a direct precedent and warning for the hitch, facing many of the same stressors.
1943 is documented as the last year of large hitch spawning runs before the catastrophic mid-decade collapse. Populations are still "abundant" by the standards of the era. Three years later, spawning will nearly stop entirely. The causes — DDT/TDE contamination, habitat loss, invasive species, water diversions — are already in motion.
Between 1946 and 1948, hitch spawning nearly stops completely. A species that was "extremely abundant" in the 1890s and still running strongly in 1943 is suddenly "rare." The cause is likely a combination: DDT and DDD pesticides were applied to Clear Lake in 1949 (and earlier periods) for gnat control; agricultural water diversions were intensifying; and habitat quality in tributaries was degrading rapidly. The splittail collapses at the same time, suggesting a shared stressor.
The Clear Lake splittail begins its rapid collapse around 1940. Once "very abundant" through the 1920s–1930s, it is nearly absent by the mid-1940s. By 1973 it will be considered extirpated. This endemic species — found nowhere else on Earth — undergoes one of the fastest freshwater fish extinctions on record in California, driven by the same forces threatening hitch.
The California Department of Agriculture applies DDD (a DDT analog) to the entire surface of Clear Lake at a rate of 1:70,000,000 — intended to control the Clear Lake gnat (Chaoborus astictopus). It is one of the first large-scale pesticide applications to an entire lake ecosystem in US history. The application kills massive numbers of fish and invertebrates and bioaccumulates up the food chain, reaching lethal concentrations in western grebes. The commercial catfish fishery collapses and is closed in 1949. Further applications occur in 1954 and 1957.
Once abundant in Clear Lake through the 1930s, the Sacramento pikeminnow is documented as "nearly extinct" in the lake by 1951. The 1940s crash affected nearly all native species simultaneously — pointing to lake-wide stressors like DDD and habitat change, not species-specific factors. Pikeminnow will persist at very low numbers but never recover meaningful populations.
The early 1950s represent the nadir of hitch abundance. Some spawning is observed in the mid-to-late 1950s as populations slowly stabilize, but at a tiny fraction of historical levels. The species never returns to pre-crash abundance. Rainbow trout are now largely absent from the lake, persisting only in upper tributaries above barriers.
While most native species are in steep decline, Sacramento blackfish becomes abundant enough in the 1960s to support a commercial fishery — demonstrating that at least some native cyprinids can survive in the degraded lake environment. Tule perch and prickly sculpin also remain relatively stable, while Sacramento perch drops to extremely low numbers approaching extirpation.
Mississippi silverside is introduced to Clear Lake as a biological control for the Clear Lake gnat and as bass forage. Within one year it becomes the single most abundant fish in the entire lake — an explosive population boom. It directly competes with larval hitch for zooplankton during their most vulnerable life stage, adding a new and persistent pressure to juvenile hitch survival.
The Clear Lake splittail is last documented around 1969 and declared extirpated from the lake by 1973. An endemic species found nowhere else on Earth is gone. The entire collapse from peak abundance to extinction spans barely 30 years. The hitch is following a similar trajectory, just on a longer timeline.
By the 1980s, hitch populations have declined so severely that spawning fish are being observed attempting to spawn in storm drains and other degraded structures — wherever water flows during the spring spawning period. This is a stark indicator of how compromised the natural tributary system has become. Restoration efforts begin: a fish ladder is installed, and early habitat work commences.
Threadfin shad are illegally introduced to Clear Lake in 1985 — likely by anglers seeking to improve bass forage. They undergo an explosive population boom, then crash in the late 1980s, before being reintroduced in 1997. Their presence adds yet another forage competitor for juvenile native fish and increases the complexity of the disrupted food web.
By 2002, the native fish community has been reduced to a handful of survivors. The hitch remains one of few native species still present in notable numbers alongside Sacramento blackfish, tule perch, and prickly sculpin. Sacramento perch is now believed extirpated (confirmed 2008). The long-term trend for hitch is clearly downward — chronic low population with no sign of recovery.
Seigler Canyon Creek, historically one of the best hitch spawning sites in the watershed, records its last confirmed adult hitch observation around 2004. No adults have been documented there since — a tributary effectively lost to the species.
The Sacramento perch — California's only native sunfish, once common in Clear Lake — is believed extirpated by 2008. Its decline began with carp introduction in the 1880s and was never reversed. After more than a century of decline with brief fluctuations, the species has disappeared from the lake entirely. Another native casualty.
CDFW begins standardized visual hitch spawner surveys across Clear Lake tributaries. The first count: fewer than 500 fish — a staggering contrast to the tens of thousands documented in the 1890s. In the same year, Moyle et al. publish "The native and introduced fishes of Clear Lake: a review of the past to assist with decisions of the future" — the comprehensive species-by-species historical review that forms the scientific foundation for understanding this collapse.
CDFW formally lists the Clear Lake hitch as threatened under the California Endangered Species Act. The listing restricts take and mandates conservation efforts — but the pressures driving decline continue to mount. Water diversions, invasive species, and drought are not addressed by the listing alone.
The U.S. Geological Survey begins standardized gillnet sampling across multiple lake zones to track fish community composition and abundance. The 2017 data establishes the baseline against which the subsequent collapse will be measured. Non-native species already dominate the fish assemblage at this point.
All 1,672 hitch are observed exclusively in Kelsey Creek — the strongest year since monitoring began. But the concentration in a single tributary also highlights the species' catastrophic vulnerability: one bad year on one creek could erase the entire spawning class.
A 93% crash from the prior year. Tributaries run dry before juveniles can emigrate. The USGS gillnet survey shows hitch abundance at approximately 14% of the 2017 baseline. Three consecutive drought years have pushed the species to the brink. This is the lowest spawner count ever recorded.
Only 306 spawners counted. The USGS gillnet survey confirms hitch abundance has fallen to approximately 4% of the 2017 baseline — a 96% decline in five years. Over 20 non-native species now dominate the fish assemblage. The species is in freefall. This data triggers urgent federal-level response.
The Lake County Board of Supervisors passes an emergency resolution citing imminent risk of hitch extinction. The declaration enables expedited coordination between county, state, federal, and tribal agencies for conservation action.
An exceptionally wet winter refills tributaries and the lake. 2,548 spawners are counted — the highest number since surveys began. A fragile sign of hope that demonstrates the hitch can recover when water conditions allow. But it also underscores how entirely the species' fate depends on rainfall — there is no resilience buffer.
The California State Water Resources Control Board issues reporting orders for groundwater pumping in the Big Valley basin — the area surrounding Kelsey Creek, the hitch's most critical spawning tributary. Groundwater extraction is suspected of reducing tributary baseflows that hitch depend on for spawning and juvenile rearing.
The U.S. Fish & Wildlife Service publishes a proposed rule to list the Clear Lake hitch as threatened under the federal Endangered Species Act, with proposed critical habitat designation for Clear Lake, Thurston Lake, and 18 tributaries. The Species Status Assessment found the hitch at high risk of extinction within 50 years under most climate scenarios.
The U.S. Geological Survey publishes Open-File Report 2025-1018, documenting gillnet survey results from 2017 through 2022. The report confirms a 96% decline in hitch relative abundance and shows non-native species dominating Clear Lake's fish assemblage — over 20 introduced species established.
CDFW visual surveys count 1,567 spawners in 2025 — above the 11-year average of 1,032. Adobe and Kelsey Creeks are leading again. Collaborative monitoring between CDFW, tribal agencies, LCWPD, and community scientists continues.
Robinson Rancheria conducts carp and goldfish removal with Rojas Fisheries. Habematolel Pomo of Upper Lake runs a hitch tagging study tracking migration patterns. Big Valley Rancheria operates the Clear Lake Cyanotoxin Monitoring Program. These tribal-led efforts represent some of the most direct and consistent conservation work underway.
The Cole Creek Restoration Project aims to restore 1.55 miles of spawning habitat. The Main Street barrier on Kelsey Creek is being removed. These physical habitat improvements address one of the most direct threats to hitch spawning success.
This website — built to centralize research, data, and public awareness about the Clear Lake hitch and ecosystem in one place. A community-driven effort to ensure the story of this fish is told, its data is accessible, and its future is fought for.