The Demise of Sacramento River Spring-Run, Fall-Run, and Late-Fall-Run Chinook Salmon

We all know the story of the demise of Sacramento River winter-run Chinook salmon below Shasta Dam over the past several decades (Figure 1).1 But what has happened to the other three Chinook runs: the spring, fall, and late-fall runs? They too have declined (Figure 2-4). Just 50 years ago, 300-500 thousand Chinook salmon ascended the Sacramento River to spawn. This was decades after most of the big Central Valley dams were built. Today, less than 10,000 Chinook salmon return to spawn near Redding. Most of these are Battle Creek and Livingston Stone hatchery fish, plus strays from Feather, American, Mokelumne, and Merced hatcheries. Wild, native Chinook are becoming increasingly rare with each decade.

There are many factors that have led to the demise of Sacramento River Chinook salmon. No doubt, the two major droughts (76-77 and 87-92) had major roles. There was bad management and lack of regulatory protection on many levels. Today, the details of a post mortem are of less value than recognizing the problem and doing something about it.

Much has been tried and accomplished (three of the four runs substantially improved around the turn of the century). A decade of effort and wet years achieved much. However, the three major droughts since (07-09, 13-15, and 20-22) have undone much of those gains and more.

What needs to be done now to bring the salmon back from the brink of extinction is the following:

  1. Recognize and acknowledge the problem (we haven’t)
  2. Develop a single integrated, comprehensive plan to solve it (there isn’t one)
  3. Overhaul the massive salmon hatchery program (we spend huge sums raising and releasing over 30 million salmon smolts each year – the price per pound is astounding – most never reach the ocean)
  4. Overhaul our salmon fisheries program managed by the Pacific Fisheries Management Council (it’s not working – the stocks are in a constant state of over-fishing – and the fishery is not the most important problem – shutting fishery gates after fish have escaped the corral doesn’t solve the problem)
  5. Overhaul the Central Valley water supply management system (it’s taking all the water for humans and leaving none for the salmon – don’t let folks blind you, it’s true)
  6. Overhaul the Central Valley water quality management system (drought “emergencies” routinely bring weakening of standards, wiping out annual salmon runs)
  7. Rebuild salmon habitat from the ground up (much is gone and what is left is degrading fast, as past and present efforts at watershed restoration literally burn away each year).
  8. Implement the comprehensive plan with prioritized short- and long-term goals, objectives, and actions.

The sooner we implement these actions the better – Sacramento River salmon are facing a “Passenger Pigeon” moment. The longer we wait, the tougher it is going to be and the less chance there is we will succeed.

Graph of Adult Escapement (fish/year) Mainstem, Upstream of RBDD, Sacramento River, spawn years 1970-2021 In-River Winter Chinook

Figure 1. Sacramento River Winter-Run Chinook

Graph of Adult Escapement (fish/year) Mainstem, Upstream of RBDD, Sacramento River, spawn years 1969-2021, In-River Spring Chinook

Figure 2. Sacramento River Spring-Run Chinook

Graph of Adult Escapement (fish/year) Mainstem, Keswick Dam to Red Bluff Diversion Dam spawn years 1952-2021, In-Rier Fall Chinook

Figure 3. Sacramento River FallRun Chinook

Graph of Adult Escapement (fish/year) Mainstem, Upstream of RBDD, Sacramento River, spawn years 1971-2021, In-River Late-Fall Chinook

Figure 4. Sacramento River Late-Fall-Run Chinook


How did Winter-Run Salmon do in Summer 2022? Not Good.

First the bad news. The production in 2022 of winter-run salmon fry in the upper Sacramento River near Redding was at record low levels, similar to the disaster years 2014 and 2015, maybe worse (Figure 1).

Next, more bad news (there is no good news). Most of the fry are now in the 100-mile reach below Red Bluff, with only a small proportion to date (November 7) reaching Knights Landing below Chico (Figure 2). Flows (Figure 3) remain too low for good fry survival, with little flow increase following late October and early November rains. Clear water conditions make it easy for the tens of thousands of striped bass and smallmouth bass residing in the 100-mile reach to pick off migrating juvenile salmon. Up till late October, water temperatures above 60ºF kept bass active (also Figure 3). With conditions expected to be similar to last year, one can only expect this year’s production to be similar to last year’s poor production (Figure 4).

Some might say increased hatchery winter run production in 2022 is good news. Higher than normal numbers of hatchery fry are being raised in the Livingston-Stone Fish Hatchery for release next winter. But last winter’s hatchery releases during critical drought conditions did not fare well, as shown by the very small numbers that reached the Delta (Figure 5). To compensate, Interior began increasing egg-taking1 for the hatchery and transporting adults and hatchery smolts to upper reaches of Battle Creek. While these actions are worthwhile, the problem remains that drought year release returns (harvest plus escapement) average about 0.2%, compared to 2% returns in wet years.2

The prognosis for the winter-run salmon from all these sources of recruitment during the 2020-2022 drought to return as adults into fishery catches and the spawning runs is grim.3 The population does recover after wetter year periods (2016-2019, Figure 6), but not without the support of the hatchery. More needs to be done to improve wild and hatchery fry survival and smolt production to safely recover the winter-run salmon population. Flow pulses and enforcement of the state water temperature standards are needed. Vitamin injections, more hatchery egg-taking, and taxi rides alone will not do the job.

Graph showing Run Size from 2007 through 2022

Figure 1. Annual catch of unmarked juvenile winter run salmon in screw traps near Red Bluff as of November 13, 2022. (Source)

Graphs showing Water Temperature and Daily Estimated Passage

Figure 2. Juvenile winter-run salmon catch in Red Bluff and Colusa screw traps in 2022. (Source)

Graph showing flow CFS and Temp

Figure 3. Water temperature and flow rate below Keswick Dam (KWK, RM 300), at Bend near Red Bluff (BND, RM 250), and below Wilkins Slough (WLK, RM 120) in 2022. (Source)

Graph of Cumulative Catch per Brood Year

Figure 4. Annual catch of unmarked juvenile winter run salmon in screw Chipps Island trawls near Pittsburg, CA. Red arrow shows 2021 catch. (Source)

Graph of Observed Chinook Salvage at SWP and CVP Delta Fish Facilities

Figure 5. Salmon salvage at south Delta export facilities in 2021. Salvage of hatchery release groups is color coded. Red arrow shows winter-run hatchery smolt release group and the subsequent capture/salvage of two smolts from the group in late March. (Source)

Graph California Central Valley Population Database Report CDFW GrandTab Adult Escapement

Figure 6. Winter run salmon escapement 1970-2021. (Source)

Wild Salmon Sanctuaries

In a 2014 blog post, Peter Moyle wrote about the Blue Creek Salmon Sanctuary on a large tributary of the lower Klamath River.  The Blue Creek effort is one of the most important initiatives toward saving salmon in California, and also serves as a demonstration and an inspiration.  California needs more salmon sanctuaries to preserve the state’s wild salmon heritage.

There are many potential salmon sanctuaries throughout California.  In this post, I list highly recommended rivers plus and few new ones.  I include only those I personally know well, but there are likely more that fit the paradigm.

My suggestions come from two major watersheds that deserve special mention and attention.

Klamath River Watershed:

 The Salmon River is a wild, natural tributary of the lower Klamath River that retains the last wild population of endangered spring-run Chinook salmon. Its watershed now suffers from the ravages of recent forest fires.  The river is a special place to the Karuk Tribe.

  • The Scott River, the eastern neighbor to the Salmon River, features the last significant wild population of Coho salmon in California. While nearly ruined by logging, fires, and ranch development, the Coho hang on almost belligerently with the help of the Trinity and Marble Mountains and from some of the ranching community.  The river begs for the return of its beaver, so it can again be called “Beaver Valley.”  Some of the ranchers deserve credit for keeping the river and its fish on life-support.
  • The Shasta River is the next neighbor to the east of the Scott River. The river sustains the Klamath’s largest population of wild fall-run Chinook salmon, thanks in large part to the efforts of the Nature Conservancy.  The river has hope for the return of the Coho salmon with the help of ranchers, Sierra Pacific Industries, the tribes, and Crystal Geyser.  Ranchers, please no more revolts.
  • Deming Creek, among the headwaters of the Sprague River, a major Klamath River tributary in Oregon that drains into California, is a historical remnant of a creek that once supported wild spawning Klamath spring-run salmon and steelhead (really). It still has the southernmost extant population of endangered bull trout, which once occurred in California but are now extirpated in this state.  If the Klamath dams are removed, will the salmon return to Deming Creek?  I suspect the salmon will need some help getting to this beautiful place.

Sacramento River Watershed:

  •  The upper McCloud River above and below McCloud Falls is one of the most beautiful places in California. The McCloud once sustained winter-run and spring-run salmon below the falls.  Above the falls on the south flank of Mt. Shasta is the McCloud Redband Trout Refuge.  If part of the strategy is for trap-and-haul sanctuaries, this is a great place to put winter-run or spring-run salmon.
  • Upper Mill Creek and Deer Creek on the south flank of Mt. Lassen are two gems that retain small populations of spring-run Chinook salmon at the highest elevations known for the species.  Ravaged by fires in recent years, they too need help.  At least salmon in theses streams do not need a taxi service.
  • To the south of Deer and Mill creeks, Butte Meadows on upper Butte Creek upstream of falls and water diversions has much potential as a sanctuary. This location needs a taxi service only for adult spawners, but not their offspring should be able to migrate downstream volitionally.
  • Upstream of Lake Almanor, the upper North Fork Feather River drains the southern flank of Mt. Lassen, eventually finding its way past a series of dams into the Central Valley and the Sacramento River. This is another trap-and-haul sanctuary with strong potential, though it was severely affected by the recent Dixie Fire.
  • The upper North Yuba River above Bullards Bar Reservoir is a gem of a stream that once supported spring-run Chinook salmon. Again, this would be a trap-and-haul option.
  • The Middle Fork American River well upstream of Folsom Reservoir, another historical spring-run salmon stronghold, is also a good candidate. Badly damaged in the 2022 Mosquito Fire, the Middle Fork American is in need both of help with the forest and of a two-way taxi service for reintroduced salmon.

One thing common to many of these potential sanctuary locations is a legacy of massive fires in recent years.  A substantial effort is needed to restore these Klamath-Trinity and Sierra ecosystems to make them sustainable once again for California salmon and steelhead.

I also advocate for Chinook salmon sanctuaries below all our major Central Valley rim dams.  The dams were built with the promise of mitigation for the salmon runs.  It is time these many-decades-old promises were kept.   Though most of the lower rivers have escaped the direct ravages of fire, the consequences to their upper watersheds still affect the Valley reaches.  Without the remnant Valley salmon, there would be few salmon left in California.

Time has taken a toll on the Valley salmon below the rim dams.  To weather the effects of droughts, fires, and climate change, and to restore viable populations in the major salmon-bearing rivers, sanctuaries in both the upper watersheds above the dams and downstream of the dams are necessary.

For more information on California’s Chinook salmon see:

San Joaquin Salmon Population Status – End of 2021

Following some improvement in the numbers of adult fall-run Chinook salmon returning to spawn in the Stanislaus River and the Merced River from 2012-2017, overall escapement in 2020 and 2021 to San Joaquin River tributaries was severely depressed.  Better flows and water temperatures could help reverse this decline.

In February 2017, I wrote about the fall Chinook salmon runs on the San Joaquin River’s three major tributaries over the previous six years.  Salmon counts in San Joaquin tributaries showed an increase in returning adults in the 2012-2015 drought compared to the poor returns in 2007-2009 drought (see Figures 1 and 2).   The numbers of spawners in 2012-2015 were still well below the returns in the eighties and nineties that corresponded to wet water year sequences, but the increase seemed to suggest progress.

In a December 2019 update, I  updated the earlier post with numbers from the 2016-2018 runs. The 2016 and 2017 runs were the product of poor rearing conditions in 2014 and 2015, both critical drought years, but with good fall adult migration conditions.  The 2018 run was a product of normal-water-year rearing (2016), but poor adult migrating conditions.  The 2016 and 2017 runs were strong in the Stanislaus and Merced rivers (see Figure 3), with both rivers benefitting from hatchery production and strays.  The markedly smaller runs in the Tuolumne (typical throughout the last decade) also benefitted from hatchery strays (Figure 4).  One strong component of the strays was the unusually high proportion of strays from the upper Sacramento River’s Battle Creek hatchery, whose managers’ strategy during the 2014-2015 drought was to truck their fall-run salmon smolts to the Bay, a practice that causes high straying rates, including to the San Joaquin tributary runs.

The 2018 San Joaquin run was lower, but still an improvement over the drought-influenced runs in 2007-2011 (Figure 2).  Spring rearing conditions in 2016 and fall adult migration conditions in 2018 were generally better than they were during the critical drought years, although still stressful.  Also, most of the Mokelumne and Merced hatchery smolts were released to the Bay and west Delta, respectively, in 2016, a likely positive factor in contributing strays to overall escapement.  A further explanation for this improvement was better hydrology-related habitat and migration conditions prescribed in the 2008-09 federal biological opinions that generally led to improved habitat conditions.

In the three years (2019-2021) since 2018, runs generally declined (Figure 3) despite being the product of two wet (2017 and 2019) and one normal (2018) year.  One reason for the reductions was that there were fewer strays from hatcheries. For example, the Merced hatchery smolt releases in 2017 were at the hatchery instead of in the Bay, and thus had poor returns.  Battle Creek hatchery returns were also lower, with less straying by smolts released near the hatchery.

The poor returns in 2020 in all three rivers are especially troubling, given they are the product of a good wet year run (2017) and reasonable rearing conditions in winter and spring of normal year 2018.  One factor in the San Joaquin watershed in late summer and early fall 2020 was unusually low flows and high water temperatures for a normal water year (Figures 5 and 6).  Based on the high number of returns of 2018 Merced hatchery smolt releases straying to other rivers (Figure 7), it appears that a compounding factor to these low flows and high water temperatures was high rates of straying by salmon sourced in San Joaquin watershed to the Mokelumne, American, and Feather Rivers.

The relatively high proportion of the Stanislaus River escapement in the 2021 San Joaquin run appears to be a result of attraction to the Stanislaus from a very warm lower San Joaquin River (Figure 8).  The Stanislaus is the first cool tributary encountered by salmon on their journey up the warm San Joaquin in late summer and early fall.

In summary, there is much straying to and from the San Joaquin salmon spawning tributaries.  Adult run size (escapement) is a function of straying, winter-spring flows and water temperature in the San Joaquin and its tributaries during the winter-spring rearing season, and streamflows and water temperatures during the annual late summer and fall spawning run.  The release locations of smolts from the Merced River hatchery and other hatcheries also plays a role.

Salmon runs to the San Joaquin and its tributaries could be improved with better streamflow and water temperature management.

Grandtab Table

Figure 1. Fall run salmon escapement to San Joaquin River and tributaries 1989-2021. Source: Grandtab.

Bar chart from Grandtab data

Figure 2. Plot of 1975-2021 fall run salmon escapement to San Joaquin River tributaries. Data source: GrandTab.

Stacked Barchart Grandab Data

Figure 3. Plot of 2015-2021 fall run salmon escapement to the San Joaquin River tributaries. Data source: GrandTab.

Pie chart rmpc.prg data

Figure 4. Returns of code-wire-tagged (cwt) salmon to Tuolumne River in 2016-2017 from five Central Valley hatcheries. Source: cwt return data in

Line graph USGS data

Figure 5. July-December water temperature in San Joaquin River at Vernalis in 2020, and historical average.

Line chart USGS data

Figure 6. July-December streamflow in San Joaquin River at Vernalis in 2020, and historical average.

Pie chart data

Figure 7. Adult spawner returns to four hatcheries and spawning grounds in 2020 of 2018 Merced Hatchery tagged smolts released in Bay. (Note there were no records for Battle Creek returns.)
Source: cwt return data in

Line graph and map

Figure 8. Water temperatures in the lower San Joaquin River at Vernalis (VNS), Brant Bridge (BDT), and Mud Slough (MSG), and Ripon (RIP) on the lower Stanislaus River in September 2020. Note adult salmon generally avoid 72°F water.


Review of Decade-Old Misdirection on Delta Smelt

For several decades, scientific literature and state and federal permits have documented the decline in Delta smelt and promoted actions designed to slow the Delta smelt’s demise or even reverse it. However, that soundly based and widely promoted recovery strategy has often been undermined by some scientists and engineers funded by water-related industries and users intent on minimizing constraints on their water operations. The undermining of traditional science and regulatory institutions has been insidious and aggressive, to the point of nearly destroying the Central Valley and Bay-Delta ecosystem and many of its public trust resources. I know this from working nearly 50 years on these conflicts.

A recent interest takes me back to some of these undermining efforts from a decade ago. In this post, I evaluate past theories from such efforts and further characterize the “science” used to support them. I believe such hindsight reviews of these historical efforts helps to daylight and counteract similar present and future attempts to undermine institutional protections. I focus on unsubstantiated conclusions, on misuse of data or analytical tools, and on the authors’ general strategy of promoting misinformation to argue their points.

The “scientific paper” I review in this post on Delta smelt is William J. Miller, Bryan F. J. Manly, Dennis D. Murphy, David Fullerton & Rob Roy Ramey (Miller et al.) (2012): An Investigation of Factors Affecting the Decline of Delta Smelt (Hypomesus transpacificus) in the Sacramento-San Joaquin Estuary, Reviews in Fisheries Science, 20:1, 1-19, DOI: 10.1080/10641262.2011.634930.1

In commenting below, I show quotations from the paper in quotes and italics.

Comments on the Authors’ Major Conclusion in the Abstract

  • “Strong evidence was found of density-dependent population regulation.” The authors made no attempt to describe such “regulation” of the Delta smelt population. First, the meaning of “strong” is unclear. I assume the authors mean that two variables appear closely related. I found a “density-dependent” relationship (see my Figure 1, below), wherein summer abundance is positively related to previous fall abundance. Second, the meaning of “regulation” is unclear. I assume by “regulation” they mean that at very high numbers of adults, recruitment tails off, as implied in the blue curve in Figure 1. But as shown in the figure, the inference is far from a “strong evidence” of “population regulation” due to density.

  • “The density of prey was the most important environmental factor explaining variations in delta smelt abundance from 1972 to 2006 and over the recent period of decline in the abundance of the fish.” Association does not necessarily mean cause and effect. In Figure 1, I show that wet years have, on average, ten times more recruitment than dry years. That could be why prey appears important, because smelt prey densities (and feeding habitat conditions) tend to be better in wet years. However, water temperatures are also higher in dry years, as is entrainment of smelt in the south Delta. Just because prey has the highest correlation does not mean it is the cause or has any direct effect. These variables are not independent from one another.

  • “Predation and water temperature showed possible effects.” The authors also noted other positive relationships. The problem with such statistical analyses is that the “independent variables” being tested against smelt abundance are not independent from each other. Therefore, no judgement can be made as to cause and relationship, only inferences.

  • “Entrainment of delta smelt at south Delta pumping plants showed statistically significant effects on adult-to-juvenile survival but not over the fish’s life cycle.” Here again, cause and effect are inferred. The authors state the fact that recruitment is related to the number of adult spawners, yet they immediately state otherwise. Entrainment of adult smelt is something that has been measured – as salvage at the south Delta pumping plants. It is a variable that can readily be compared to the fall trawl index. But entrainment of larvae and early juveniles (6-25 mm young) is not measured, and thus this part of the “fish’s life cycle” cannot be statistically related to any smelt index.

  • “Neither the volume of water with suitable abiotic attributes nor other factors with indirect effects, including the location of the 2 ppt isohaline in the Delta in the previous fall (“fall X2”), explained delta smelt population trends beyond those accounted for by prey density.” When a variable shows minimal relationship, it cannot be concluded that it has no effect, or compared in strength to another “independent” variable (another potential factor). Fall X2 may only be important in some years, and thus its effect relationship may be non-linear.2 The relationships being studied may also change with time (as indicated in Figure 1). Relationships are also often complicated by factors that act in complex ways. Posts on my own reviews generally support the Fall X2 action for a variety of reasons.3 Thus, the authors’ conclusion or implication that Fall X2 is not important is not reasonable. The prey factor simply takes up more of the variability in the multi-factor statistical analysis, and thus masks the role of Fall X2.

Comments on the Introduction

  • The need for immediate conservation responses is acute, but that need confronts another unfortunate delta smelt reality—perhaps less is known about the habitat of delta smelt, resources essential to its persistence, and the environmental stressors causing its low population numbers than is known about any other listed species.” This statement has no basis and is simply untrue. Delta smelt are one of the most studied fish on Earth.

  • “The life cycle of the tiny estuarine fish takes place in turbid, open waters, making it impossible to observe its behavior and account for many of its vital ecological relationships.” Over the past five decades, there have been numerous studies and volumes of monitoring data on Delta smelt “ecological relationships”. One only has to look at Figure 1. As for behavior, Delta smelt have been raised and observed in labs and hatcheries for over two decades. Two decades ago, I could literally smell them and their prime habitat. I could also tell where they would be by measuring salinity and water temperature.

  • “Several candidate factors have plausible mechanisms of effect on delta smelt numbers, but previous attempts to relate environmental stressors to the decline of this fish were not able to identify the factors responsible for the recent declines in the abundance index to near-extinction levels.” The evidence from the 1987-1992 drought (see Figure 1 for one of many examples) was quite compelling, enough to get the species listed under the Endangered Species Act, first as threatened (1993), then as endangered (2010). All the “plausible factors” could be related to drought conditions that had become worse with ever-increasing effects of water management (increasing exports year after year). Protections instituted in the aftermath of the drought and listing4 included designation of critical habitat (1994) and a recovery plan (1996), as well as multiple federal biological opinions and habitat conservation plans, and state incidental take permits over the next two decades. Recovery programs, including the Central Valley Project Improvement Program (CVPIA) and CALFED Bay-Delta Ecosystem Restoration Program (ERP), focused on Delta smelt recovery. Those efforts led directly to significant progress in 2010-2011; however, weakened protections during the 2012-2015 drought ended the potential for further progress.

  • “No field data have been derived from experimnts that directly relate delta smelt population responses to variation in physical and biotic conditions.” This statement is a gross untruth. The data that support Figure 1 are “field data.” Many of the various monitoring surveys (e.g., Larval Survey, 20-mm survey, Townet Survey) yield indices that show such relationships.

Comments on the Discussion

I could go on in the same -vein through the paper’s introduction, methods, results, and discussion, but I will skip to the paper’s primary conclusions as presented in the discussion section.

  • [E]ntrainment was not a statistically significant factor in survival from fall to fall”. First, entrainment of early smelt life stages into the federal and state south-Delta export facilities is not monitored. Second, monitoring that does help assess entrainment risk shows the inherent risk (Figures 2 and 3). Third, the fall midwater trawl survey includes the fall period of high adult salvage losses that contributed to the population decline, a data feature that compromises the fall-to-fall survival-factor analysis.

  • “Changes in prey density appear to best explain the sharp drop in delta smelt abundance in this century”. First, Delta-smelt prey density is also directly and indirectly related to south Delta exports. Second, an annual index of smelt prey is a very crude way to analyze the effects of prey through the various life stages of smelt or its annual abundance indices.

  • “Density dependence was an important factor affecting survival from fall to summer, summer to fall, and fall to fall.” First, there is little or no evidence that high densities reduce recruitment or survival, at least in the period of record. Historically, available habitat had to limit the population size and recruitment near their highest abundance levels. Second, there is also no evidence that very low population levels lead to higher survival, growth, or abundance (from less crowding and competition). These are the two features that generally contribute to density-dependent population regulation. What the authors term density-dependence is simply the fact that more adults lead to more young, and more young lead to more adults. Water management and use lead to fewer adults and young – density independent population regulation controls population abundance.

  • “This finding indicates that density dependence must be accounted for in analyses directed at identifying factors that are important to the abundance of delta smelt.” This only means that any factors that lead to fewer adults or young damages the population, and that those losses are compounded across life stages. There are no remaining compensatory density-dependent capacity reserves in the population to absorb or counter such added mortality.

  • “There was some indication that average water temperature and calanoid copepod biomass (a general measure of prey density) in April–June were important contributors to survival of delta smelt from fall to summer.” Again, these are factors affected by water management. Delta exports pull warm water and invertebrates into the south Delta. These are density-independent factors.

  • “Furthermore, predation in April–June, representing the combined effects of water clarity and abundance of the predators, inland silversides, largemouth bass, crappie, and sunfish, was important to delta smelt survival from fall to fall.” Again, the effects of predation are increased by the warmer, clearer water pulled into the interior Delta by south Delta exports.

  • “Furthermore, in the case of delta smelt, not only does an effects hierarchy suggest the use of simple linear regression models, but the low sampling errors in abundance relative to process errors indicates that this simple and transparent method of analysis is an appropriate method for identifying environmental factors with direct effects. Therefore, at least for delta smelt and perhaps for other fish for which sampling errors in abundance are relatively low, simple linear regression, as an alternative to more complex life-cycle models, can produce informative results.” Such analyses have been inappropriately used to confuse interpretations of long-term environmental and fish population dynamics data, and to misinform and misdirect environmental resource management and regulatory processes, institutional and public awareness, and the public’s confidence in these societal and cultural institutions.

Summary and Conclusions

Miller et al. (2012), the “scientific” paper referenced in this post, is an example of efforts on the part of state and federal water contractors to point the blame for resource declines on factors other than water operations that overuse and abuse public trust resources. It is important not only in itself, but also because it combines with similar efforts to become part of a body of alternative “science” that is cited by water suppliers and managers in repetition of the narrative that water operations have minimal effect on the Delta smelt’s decline.

I recognize that such efforts may appear in “peer reviewed” journals, and can be sincere efforts to contribute to the understanding of the science underlying resource management. I am simply registering the need for caution and consideration of the source and the content of all analytical and interpretive efforts related to information used by those responsible for protecting our public trust resources.

Figure 1. Delta smelt spawner-recruit relationship. Figure generated by Tom Cannon.

Figure 2. Delta smelt survey catch pattern from mid-June 2012, one of the last surveys with an abundance of larval smelt produced from the strong 2011 brood spawning population. The red lines show the approximate location of the upstream location of X2 (low salinity zone).

Figure 3. Typical dry year spring-summer tidally-filtered (net) or daily-average hydrology for the Delta, showing net flow rates toward south Delta export pumps.