Aquaculture for all

Salmon, Steelhead, and Trout in California: Status of an Emblematic Fauna

Trout Health Biosecurity +4 more

The southernmost populations of salmon, steelhead, and trout, uniquely adapted to Californias climatic regime, are in deep trouble according to a report by Peter B. Moyle, Joshua A. Israel and Sabra E. Burdy, University of California Davis.


20 of 31 living taxa (65 per cent) are in danger of extinction within the next century. Of the 22 anadromous taxa, 13 (59 per cent) are in danger of extinction, while seven (78 per cent) of the nine living inland taxa are in danger of extinction. All of these species currently support or historically supported fisheries, thus having economic as well as cultural value.

They are also strong indicators of the condition of California’s streams; large self-sustaining populations of native salmon and trout are found where streams are in reasonably good condition. The reasons for their widespread decline are complex and multiple, but basically boil down to a combination of human competition for use of the high quality water salmonids require, alteration of the landscapes through which salmonid waters flow, overfishing, and introductions of alien species as predators or competitors.

Ensuring ecologically sustainable flows, reducing migratory barriers to juveniles and adults, restoring watersheds, and minimizing competition from non-native salmonids are some of the essential steps to the recovery of California’s salmonids. Bringing these fish back from the brink of extinction will not be easy but it is possible, thanks to the inherent adaptability of California’s salmonids to changing conditions. However, the growing threats of climate change and increasing human populations, with increases in water use and in intensity of land use, will need to be addressed. In the long run, restoring fisheries for most species, however, will require reducing or at least not increasing human impacts on the California landscape.


Salmon, trout, and their relatives, which make up the fish family Salmonidae (salmonids), are the iconic fishes of the Northern Hemisphere. They are characteristic of the region’s cold productive oceans, rushing streams and rivers, and deep cold lakes. They are adapted for life in dynamic landscapes created by glaciers, volcanoes, earthquakes, and climatic extremes. Salmonids thrive through their mobility, moving freely through the ocean and large river systems, as well as their ability to adapt in isolation to extreme local conditions from deserts to rain forests. This has resulted in a handful of species producing hundreds of genetically distinct runs, races, and subspecies, many with distinctive color patterns and other attributes, all with life histories superbly tuned to local environmental conditions (e.g., Behnke 2002, Moyle 2002).

Salmonids have a long history of interactions with humans in the northern parts of the world. Salmon appear as images in Cro-Magnon cave art of 10,000 or more years ago and have been important food for indigenous peoples throughout their range. The importance of salmonids stems from their accessibility and high nutritional content; salmon bring nutrients and calories from the rich northern oceans into streams while trout and other inland forms concentrate the scarce resources present in cold water streams and lakes. In both situations they become available for human harvest and have historically been important food resources. In the 17th century, at the beginning of the Industrial Revolution, angling for trout developed in Europe as a popular source of recreation (Walton 1653).

This peculiar aesthetic led to salmonids, mainly brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss), being introduced into suitable waters all over the world, as an artifact of cultural imperialism (Crosby 1986). Their importance as food fish also led to the successful introduction of anadromous salmonids, mainly Chinook salmon (O. tshawytscha), Atlantic salmon (Salmo salar), and steelhead rainbow trout, into the southern hemisphere. Today, Atlantic salmon are cultured worldwide in cold coastal waters while rainbow trout are cultured in more inland areas; both are farmed in high-production operations to satisfy human demand for their flesh.

Despite their cultural, historic, aesthetic, and economic importance, salmonid fishes are in severe decline in many, if not most, of their native habitats and many populations have been extirpated, especially in heavily industrialized areas (Montgomery 2003). The reasons for this are complex and multiple, but basically boil down to a combination of human competition for use of the high quality water salmonids require, alteration of the landscapes through which salmonid waters flow, overfishing, and introductions of alien species as predators or competitors. Concern for the loss of salmonid fisheries led to some of the earliest fish conservation efforts in Europe but during the 20th century; the principal responses were to culture them in hatcheries while restricting fisheries.

The natural ability of salmon and trout to rapidly adapt to changing conditions has made them relatively easy to culture. Not surprisingly, their life histories and other characteristics have been modified in response to hatchery environments and to match the desires of hatchery managers. This has resulted in some varieties of trout and salmon that are true domestic animals, wonderful for meat production but poor at surviving the wild. For anadromous salmon and steelhead, hatchery operations were established to enhance wild populations, mainly for fisheries. As a result they have had to satisfy two rather contradictory goals: production of large numbers of fish, which requires producing fish adapted to an artificial environment, and production of fish that will survive and grow in the wild. Their mixed success at satisfying the second goal is best indicated by the gradual decline in most fisheries for anadromous species and rapid decline of many wild populations (Levin et al. 2000). It is also indicated by the listing of many salmonids as species threatened with extinction under the statutes of multiple countries.

Perhaps nowhere in the world is the diversity of salmonids and their problems more evident than in California. The state not only marks the southern end of the range of all anadromous species, but its dynamic geology and climate has resulted in the evolution of many distinctive inland forms, such as the three golden trout subspecies of the Sierra Nevada. The diversity of salmonids is also the result of California’s large size (411,000 km2), length (spanning 10° of latitude), and being adjacent to the California current

region of the Pacific Ocean, one of the most productive ocean regions of the world (Moyle 2002). All this has resulted in hundreds of genetically distinct populations, although there are just eight recognized native species. For the purposes of this study, we recognize 32 salmonid taxa (genetically and ecologically distinct groups) in California, 21 of them anadromous, 11, non-anadromous. These taxa are a combination of species, subspecies, and various units recognized by managers, characterized by genetics and/or life history patterns.


Our analysis of the status of California salmonids tells us that most taxa are declining rapidly and, if present trends continue, 65 per cent (20 taxa) will be gone within a 100 years, probably within 50 years. Seventy-five percent of these endangered taxa are found only in California, so fit well the definition of Waples et al. (2007) for species likely to qualify for listing as threatened or endangered, if they are not already listed. Seventy-five percent of these endangered taxa are found only in California. While each salmonid has its unique problems, they all are basically in decline because of increased competition with humans for resources, mainly water.

The cumulative impact of degraded habitats and biological threats (e.g., alien species) do not allow salmonid populations to rebound as readily in response to ‘natural’ long term physical stresses, such as extended drought. Climate change is exacerbating the problem because it ultimately will reduce the amount of cold water habitat that salmonids require. On the bright side, only one taxon, bull trout, has gone extinct so far and many have shown remarkable resilience in the face of human changes to their streams.

There are 13 different taxa of anadromous salmonids facing extinction. The two species most likely to go extinct in California are pink salmon and chum salmon, species that have never been particularly common in California although they were a recognized part of fish fauna in the 19th and 20th centuries and contributed to historic salmon harvests. However, close on the extinction heels of these two species are two ESUs of coho salmon, which numbered in the hundreds of thousands in California only 50-60 years ago and were significant players in the state’s coastal stream and ocean ecosystems (Moyle 2002). Other taxa facing extinction are the two groups of summer steelhead and the two groups of spring Chinook salmon; both types of fish are unusually vulnerable because their populations are confined to a few small headwater streams into which they migrate to spend the summer before spawning. This makes their populations exceptionally vulnerable to a wide array of factors, from poaching to climate change.

Nevertheless, some salmonids will persist in California over the next century and nine anadromous salmonids were found not to be in danger of extinction. However, even these salmonids are in decline, so fisheries for them are probably not sustainable. Remarkably, all coastal salmon and steelhead pretty much still occupy their extensive native ranges, albeit in decreased numbers. However, over the next century, most of the populations will persist only with heroic efforts to protect streams all along the California coast.

Seven of the nine remaining resident salmonids are in trouble, mostly because they are endemic to a few streams in very small areas, such as the three golden trouts of the Upper Kern River basin. In these isolated areas, they are exceptionally vulnerable to hybridization with introduced salmonids (mainly rainbow trout) and well as grazing, logging, and other factors. They could easily follow bull trout into extinction in the state due to localized effects.

Still, it is astonishing to think that most of California’s salmonids still occupy, if in a fragmented manner, most of their native ranges. This says a great deal about their resilience in the face of the ever increasing demand of humans on the resources they need to survive, especially water and diverse habitat. Saving California’s native salmonids will not be easy, but by doing so we not only protect a unique biological heritage but the ecosystem services, such as clean water, that salmonid streams provide. Saving our salmonid heritage will not be easy and will be expensive, but here are few more general actions to take:

  1. Develop and implement individualized conservation strategies for all 31 extant taxa that have as their basic goal the maintenance of self-sustaining populations through the indefinite future throughout their range. The strategies must take into account climate change as well as increasing water demand and changing land use. An initial step in the strategy would be to evaluate all species that scored 1 and 2 in this report for formal listing as threatened or endangered species.

  2. Provide immediate additional protection to ‘salmon strongholds’ where salmonid diversity is high and habitat conditions are still reasonably good, such as the Smith River and Blue Creek. This means reducing the human footprint on the watershed as much as possible by managing the streams first and foremost for fish.

  3. Develop a statewide hatchery policy that has as its first goal protection of wild populations of fish, rather than enhancing fisheries. At the very least, all hatchery fish should be marked and mark-selective fisheries instituted.

  4. Develop a salmonid awareness program for the public and public schools that strives to educate Californians about the importance, both cultural and economic that salmon, steelhead, and trout have in California, and about the unique challenges and responsibilities that come from coexisting with species at their southern-most limit.

  5. Develop a statewide research and monitoring program for salmonids and other cold-water fishes, funded by both state and federal agencies, with status reviews required at least once every 5 years.

  6. Chose a few high-profile salmonid rivers in each part of the state for focused restoration, such as the Shasta River, Lagunitas Creek, Battle Creek, and the Santa Margarita River.

  7. Continue and expand the work of citizen watershed groups to enhance and protect all California streams.

  8. Enforce and strengthen existing laws and regulations, tied to the Clean Water Act, the Endangered Species Act, State Forestry Practice Rules, the Fish and Game Code, and similar measures to increase protection for salmonids and their rivers.

  9. Fully fund ongoing efforts to restore the San Joaquin River for salmon to create a positive example of large scale recovery of a river system.

  10. Develop creative ways to fund salmonid protection, such as a surcharge on all beverages (extra for bottled water), water bills, and water transactions.

  11. Develop restoration projects for critical life stages that also benefit other conservation goals such as setback levees to open up floodplain habitat for juvenile rearing (a habitat in critically short supply) while simultaneously improving flood control and human safety.

Ultimately, as Lackey et al. (2006) bluntly point out, maintaining fisheries for each species will take a fairly radical restructuring of the way our society works and treats the resources of California and elsewhere. If present trends continue, California will have only ‘museum’ populations or runs of most salmonids, maintained with very high effort for display purposes (to remind people what has been lost).

Truly wild salmon and trout will persist in the long run only if the human population levels out or decreases, the per capita demand for water declines dramatically, and we as a species learn to live lighter on the land. Until that time, the less dramatic measures envisioned above will have to do, as the bare minimum required to keep the populations going through the hard times ahead.

December 2008