By Peter B. Moyle

There are about 130 fish species (as defined by the federal Endangered Species Act) native to the fresh waters of California. Most (80%) are arguably on trajectories to extinction. Seven species are already extirpated from the state (Thicktail Chub, Clear Lake Splittail, High Rock Springs Tui Chub, Bull Trout, Tecopa Pupfish, Humpback Chub, Colorado Pikeminnow). Two other endemic fishes, Delta Smelt and Winter Run Chinook Salmon, have not yet been extirpated because efforts by multiple agencies and NGOs (e.g., CalTrout, The Nature Conservancy) have allowed them to be reared in hatcheries along with other actions focused on improving habitat. In short, from my perspective, extinction is not an abstract possibility for many of California’s native fishes but a high likelihood.

In this essay, I look at the extirpation history of Bull Trout in California. Its decline is well documented from the 19^thCentury on because it was sought, along with endemic rainbow trout, by wealthy anglers fishing the McCloud River, the only river where it occurred in California. The species still lives in a wide range in cold water streams across the western USA and Canada (Moyle 2002, Behnke 2002). They are listed as threatened under the federal ESA in their remaining home streams in the USA.

The Bull Trout is also of interest because it became extirpated in California only recently (1970s) and I was involved in documenting its disappearance.  My involvement started when The Nature Conservancy (TNC) was given six miles of the McCloud River to establish a preserve that featured endemic trout. It also was a test of the concept that angling could be compatible with the recent (1972) passage of the federal Endangered Species Act. The final years of California Bull Trout on the headed-for-extinction list were documented by a crew of UC Davis students working with TNC (Sturgess and Moyle 1978) 

The McCloud River was on my mind when I came to UC Davis as an Assistant Professor in 1972. I knew the river only from reading documents, which gave the impression of a poorly under understood river that was incredibly cold for a California River. It also was known to be extraordinarily productive of Chinook salmon and Steelhead. It was most famous, however, for its fishery and for bright-colored Rainbow (and Redband) Trout as well as for being the only river in California that supported the highly prized Bull Trout. The river also supported four runs of Chinook salmon (fall, late-fall, winter, and spring). The year-around abundance of salmon and Steelhead made the banks of the river a home for many indigenous people, mainly the McCloud Winnemem Wintu. Bull Trout were known to the Winnemem as “wye-dar-deekit” which means “the fish from the North”. Bull Trout were noted by Baird hatchery founder, Livingston Stone (1874), as “being caught only in the head or northern waters of the McCloud.” Stone further remarked:

“ … [It is] very rare in the Lower McCloud, but abundant in the head-waters, and being a very handsome and delicious fish, is the favorite fish for fifty miles around. They are considered very fine eating at Soda Springs [Upper/Little Sacramento River]. The salted one which I ate was certainly very fine.”

This abundance of fish also attracted the early attention of proponents of fish culture who established the McCloud as the site for the first major salmon and trout hatchery (Baird Hatchery) on the West Coast, in 1872. The hatchery was constructed with the help of the local Winnemem people, then still living along the McCloud. The basic assumption of the hatchery builders was that hatcheries could keep salmon abundant in California rivers, as required even then by protective laws. The Baird Hatchery was regarded as a success because not only did it produce large numbers of Chinook Salmon and Steelhead fry that were released into the river, but it produced thousands of fertilized eggs that were shipped worldwide to create new salmon and steelhead populations, most notably in New Zealand and Australia.

As salmon and steelhead declined in McCloud River, the sport fishery focused on resident Rainbow Trout, non-native Brown Trout, and Bull Trout. The fishery was possible because the Southern Pacific Railroad could take anglers to Dunsmuir. From there, the anglers rode 15 miles by horseback to fishing camps on the McCloud River where anglers could fish for trout, including Bull Trout (then known as Dolly Varden). Chinook Salmon populations had already declined, presumably due to unregulated commercial fishing in the Sacramento River and Estuary. The focus of the fishery in the McCloud River then became resident Rainbow Trout. By 1900 or so, much of the river below the impassible lower falls had been acquired by private interests and access to the river for public fishing became very limited. Records from the McCloud River Club indicated that Bull Trout were present but were rarely caught by anglers. This was still the situation when CDFG biologist J. H. Wales evaluated the river and its fishery in 1938.  There may also have been a small population of Bull Trout in the spring-fed reaches of the Sacramento River,  but it was poorly documented.

Then, in 1945, Shasta Dam was completed, blocking access of migratory salmon and steelhead to the river. The resident trout population was further challenged by the construction of McCloud Dam in 1965, which captured 80% of the river’s flow for hydropower. The diverted water wound up in the Pit River, also tributary to Shasta Reservoir. The remaining flows below the dam allowed the fishery for resident Rainbow Trout to continue. Bull Trout were occasionally caught but became increasingly rare, and they were regarded as extirpated by the California Department of Fish and Game (CDFG; now CDFW/Wildlife ) (Rode 1990; Moyle 2002). 

In 1973, six miles of the lower river and a large tract of old growth forest, mostly Douglas fir were donated to The Nature Conservancy by the McCloud River Club to create a preserve to protect the river and its fish.  I became more formally acquainted with the river after I was asked by TNC in 1973 to evaluate the fish populations in the lower river to provide a basis for management, including determining if Bull Trout were still present. Two graduate students (Bill Tippets and Jamie Sturgess) were hired to conduct a survey of the fish and fisheries over the summers. Intensive sampling showed a healthy, if slow-growing, population of Rainbow Trout as well as a population of non-native Brown Trout that lived in Shasta Reservoir and has spawning runs up the lower river. Juvenile Brown Trout remain in in the river for 1-2 years. 

So, why did the Bull Trout become extirpated from the lower McCloud River? The river would seem to still be suitable for them, as a cold, spring-fed river with trout fry, sculpins, and diverse invertebrates as prey. But in fact today’s McCloud River has only a superficial resemblance to the historic river and its ecosystem:

• It is a much smaller river, with 80% of its flow diverted. This results in a river below McCloud Dam that is several degrees warmer in summer than the original McCloud. The lowermost reaches of the river are now underwater much of the time, thanks to Shasta Dam and Reservoir. 
• Salmon are absent from the river, which were presumably a major source of food for Bull Trout, known to be voracious predators on juvenile salmon and other fish. The unrestricted fishery for Chinook Salmon in the 19^thCentury in the Sacramento River and Delta would have greatly reduced numbers of adults returning to the McCloud in most years.
• Dams blocked access of spawners to likely spawning and rearing areas upstream, as well stopping recruitment of gravel and wood from upstream sources.
• Brown Trout, a predatory non-native species, were present as a likely competitor for instream resources. The Brown Trout had a distinct advantage over Bull Trout because their juveniles could move down to Shasta Reservoir, enabling them to grow to large sizes more quickly, before returning to the river for spawning. Bull Trout in the McCloud River were apparently not migratory.
• The watershed has been logged on both private and public lands, resulting in some debris and mud flows into the river (e.g. by Claiborne Creek).

The diversity and incremental nature of threats indicates that causes of extinction were likely multiple and interacting, reflecting major changes to the river and its watershed over many years. It remains a lovely cold river with glacial ‘flour’ in the water giving it distinct blue color. Efforts are now underway to see if a run of Winter-run Chinook Salmon can be returned  to the McCloud River, provided their migration is assisted over or around the two major dams. There is also renewed discussion of raising Shasta Dam to enlarge Shasta Reservoir which ostensively would provide more cold water for Chinook Salmon and Steelhead. But dam raising would inundate more of the little remaining habitat for native salmonids in the lower river. The river also flows through several culturally significant sites of the Winnemem people. 

In short, the McCloud River, with its legendary salmon and trout populations, continues to remind us of the special nature of the river, even in its diminished state. It also reminds us that extirpation of native fishes is real, caused by a long list of factors. The continued existence of the remaining native fishes depends on  our willingness to find ways to manage California’s streams and rivers to favor California’s unique fish fauna.

Acknowledgements

Thanks to Ron Yoshiyama and Bill Tippets for much needed reviews of drafts of this blog.

About the Author

Peter B. Moyle is a Distinguished Professor Emeritus at the University of California, Davis and is Associate Director of the Center for Watershed Sciences. 

Further Reading

Baumsteiger, J. and P.B. Moyle 2017. Assessing extinction. Bioscience 67: 357-366.

Behnke, R.J. 2002. Trout and Salmon of North America. Free Press, Simon and Shuster, Inc. New York, New York. 359 pp.

Campbell M.A . et al. 2023 Systematics of Redband Trout from genome-wide DNA sequencing substantiates the description of a new taxon (Salmonidae: Oncorhynchus mykiss calisulat) from the McCloud River. Zootaxa. 2023 0Mar 9;5254(1):1-29.

 Moyle, P.B. 2002 . Inland Fishes of California, Revised and Expanded. Berkeley: University of California Press.

Moyle, P.B., R. A. Lusardi, and P. Samuels. 2017. Salmon, Steelhead, and Trout in California: Status of an Emblematic Fauna. California Trout and UC Davis Center for Watershed Sciences.

Stone, L. 1874. Report of Operations During 1872 at the United States Salmon-Hatching Establishment on the M’Cloud River, and on the California Salmonidae Generally; With a List of Specimens Collected. United States Commission of Fish and Fisheries, Report of the Commissioner for 1872 and 1873. Appendix B-VI, pp. 168-215,

Sturgess, J. A., and P. B. Moyle. 1978. Biology of rainbow trout (Salmo gairdneri), brown trout (S. trutta), and interior Dolly Varden (Salvelinus confluentus) in the McCloud River, California, in relation to management. Cal-Neva Wildlife 1978:239-250.

Tippets, W. E., and P. B. Moyle. 1978. Epibenthic feeding by rainbow trout (Salmo gairdneri) in the McCloud River, California. Journal of Animal Ecology 47:549-559.

Wales, J.H. 1939. General report of investigations on the McCloud River drainage in 1938. California Fish and Game 25(4): 272-309. 

Yoshiyama, R. M. 2002. The Salmon. Pages 85-100 in A.R. Hoveman, Journey to Justice: the Wintu People and the Salmon. Redding: Turtle Bay Exploration Park.

Yoshiyama R.M. and F. W. Fisher 2001. Long Time Past: Baird Station and the McCloud Wintu. Fisheries 26 (3): 6-22. DOI: 10.1577/1548-8446(2001)026<0006:LTPBSA>2.0.CO;2

Yoshiyama, R. M., E. R. Gerstung, F. W. Fisher, and P. B. Moyle. 2001. Historical and present distribution of Chinook salmon in the Central Valley. Pages 71-176 in R. Brown, ed. Contributions to the Biology of Central Valley Salmonids. CDFG Fish Bulletin 179. https://escholarship.org/uc/item/6sd4z5b2

Yoshiyama, R. M., F. W. Fisher, and P. B. Moyle. 1998. Historical abundance and decline of Chinook salmon in the Central Valley region of California. North American Journal of Fisheries Management 18: 487-521.