Predation

“While state and federal wildlife agencies, university researchers, and water users all agree that predation from non-native fishes is a major stressor on salmon populations, we have done nothing to try to directly curb its impact.”

This statement in a recent Fishbio blog post is simply not true.

In 1995, the state removed limits on summer Delta exports that had been in place for decades to protect young striped bass. Stocking of striped bass ended at the beginning of this century. Both actions contributed to record low production of striped bass over the past decade. 1 The Bay-Delta population of striped bass is now greatly depressed. The river population is sustained by the continuing policy of releasing hatchery salmon smolts in the spring at the hatcheries, an unnatural process that simply feeds the river stripers.2

The real problem is spring water management in the Sacramento and San Joaquin rivers that brings unnaturally low flows and warm, clear water that favors the predators. All the salmon runs naturally have juveniles migrating to the Bay in high cold flows from late fall to early spring when predators are inactive and ineffective. But with dams holding the water from winter rains and snows, the rivers lack natural winter flows and spring snowmelt.

Largemouth bass production in the Delta has increased because of habitat changes from water management, droughts, and invasive aquatic plants that have turned the Delta into an “Arkansas lake.” Smallmouth bass production has increased in the rivers with lower, warmer flow conditions from spring through fall.3

The native pikeminnow also benefit from the habitat changes in the rivers and Delta, as well as the abundance of spring hatchery smolts. Huge schools migrate from the Delta into the rivers in spring and summer to spawn. The tailwaters downstream of dams favor pikeminnow. The adults feed on young salmonids and the juveniles compete with juvenile salmonids. Juvenile pikeminnow that return to the Delta feed on smelt.

It is these habitat changes that have resulted in more effective predation on native salmon, steelhead, and smelts. Ignoring the cause won’t solve the problem. Focusing on the predators will not work. The basses and native pikeminnow have prolific reproductive systems. Killing more of them by removing regulations on their harvest or even putting bounties on them (like pikeminnow on the Columbia River) will not solve the root problem – habitat change. And without the predators, what would be left to control all the non-native forage and “trash-fish” that already plague the Delta and rivers?

In the future, if we continue to take more of the river flows and further degrade habitats, there will always be the temptation and the drumbeat to directly remove predators or inhibit their migrations. We can stop salvaging millions of these predators every year at the South Delta export facilities, stop returning all the bass caught in fishing tournaments, and truck all the remaining salmon produced only in hatcheries to the Bay. In the end we will still have abundant predators, an “Arkansas-like lake,” hatchery salmon, and at best novelty populations of endangered wild salmon, steelhead, sturgeon, smelts, complemented by likely newly listed species of native fishes like splittail, blackfish, hitch, etc.

Smallmouth Bass Expansion (Hypothesized)

One of the major salmon predators on the Columbia River is the smallmouth bass. Long protected because of its contribution to a highly popular sport fishery, that protection is now gone because of the predation threat to Columbia River salmon recovery. Smallmouth and walleye are highly regarded game fish, but are not native to the Columbia River. They compete with and prey upon salmon. The Columbia states recognized this and no longer regulate these fisheries. This change will help prevent expansion of these species as global warming provides more favorable conditions for these cool-water non-natives than for the cold-water salmon, sturgeon, and steelhead.

Smallmouth bass have long been present in the Central Valley, especially in the lower Sacramento River and the rim dam reservoirs. Recent changes in the management of water in the lower Sacramento River will accelerate expansion of smallmouth and their preferred habitats over that of global warming alone. Smallmouth have historically been constrained by Basin Plan’s 56°F water temperature limit at Hamilton City (or Red Bluff) and the 68°F limit below Hamilton City to the Delta. However, smallmouth are highly likely to expand their population and range in the lower Sacramento River due to recent changes in flow management strategies that provide lower flows, warmer waters, and less turbidity to nearly 200 miles of the lower Sacramento River.

Ironically, the strategy changes meant to save water and cold-water reservoir supplies for salmon will actually benefit smallmouth, a key predator on salmon. The changes have already benefitted striped bass by enhancing their opportunities for predation. 1 An expansion of the smallmouth population is now likely because of warmer spring water temperatures (Figures 1 and 2) caused by lower river flows in the spring (Figure 3). The more days water temperatures exceed 60°F, the more successful spring breeding and survival of smallmouth will be. 2

Removing fishery protections will not solve the potential population enhancement or predation problems of smallmouth in the Central Valley. It would be a purely symbolic measure because smallmouth are so abundant and widely distributed. It is limitations on their habitat that have held back their expansion and the impact of their predation on salmonids. With the habitat limitations lessening, the smallmouth population will expand and contribute more to the predation problem. The solution is to restore former habitat limitation on smallmouth by sticking to the Basin Plan standards.

For more on smallmouth life history see this excellent YouTube video: https://www.youtube.com/watch?v=hoZ81au_YZg. Note in the video the strategy of smallmouth feeding heavily in the fall on small fish to store energy for the coming winter. Fall is when the winter-run salmon juveniles produced over the summer start their 200-mile downstream journey from the upper river spawning grounds to the Bay. All 200 miles have smallmouth bass.

Figure 1.  Water temperature in Sacramento River at Red Bluff (RM 243) in spring 2016.  Red line depicts Basin Plan limit of 56°F for river at Red Bluff.

Figure 1. Water temperature in Sacramento River at Red Bluff (RM 243) in spring 2016. Red line depicts Basin Plan limit of 56°F for river at Red Bluff.

Figure 2.  Water temperature in Sacramento River at Wilkins Slough (RM 125) in spring 2016.  Red line depicts Basin Plan limit of 68°F for lower river.

Figure 2. Water temperature in Sacramento River at Wilkins Slough (RM 125) in spring 2016. Red line depicts Basin Plan limit of 68°F for lower river.

Figure 3.  Sacramento River daily flow for years 2008 to June 2016.  Red line depicts normal flow of 5000 cfs.  Circles depict the tendencies for lower flows in recent years including spring 2016.

Figure 3. Sacramento River daily flow for years 2008 to June 2016. Red line depicts normal flow of 5000 cfs. Circles depict the tendencies for lower flows in recent years including spring 2016.

My comments on: “SLDMWA Response to Environmentalists’ August 9, 2016 Request to the SWRCB for Even More Water Aimed at Protecting Delta Smelt”

On August 11, Jason Peltier, executive director of the San Luis-Delta Mendota Water Authority, offered comments on a letter from environmental groups to the State Board that requested more water for Delta Smelt. Below, I provide some of Mr. Peltier’s statements, and a response to each:

1. “As environmental special interests request the State Water Resources Control Board expand failed policies on Delta Smelt, Californians are calling on the Board to implement new science-based, common sense approaches to protect the species. It is disheartening to see once credible environmental organizations calling for a “more of the same” approach – one that has so miserably failed for a quarter century – in a misguided attempt to help the imperiled delta smelt.”


Comment: The environmental organizations were proposing what the state has also offered as its new strategy for the Delta Smelt. It is not the old misguided “failed” strategy of diverting more and more water and providing less and less Delta outflow to the Bay. The state’s new strategy derives from some of the same actions suggested in this past April’s science workshop on Delta Smelt held at UC Davis, which Mr. Peltier attended.

2. “[t]he Projects have compensated for Mother Nature’s stinginess with water released from reservoirs, making the Delta far fresher than it would have been naturally.”

Fact: Just the “natural” summer inflow to Shasta Reservoir in the past four years of drought nearly equaled the amount allocated for summer Delta outflow. If you add up all the Central Valley’s “natural” inflow it would far exceed the Delta outflow allotted, even without accounting for use above the rim reservoirs.

3. “This dedication of water for fish from what was stored for drought relief has resulted in unprecedented socio-economic and environmental harms to towns, farms, and numerous species living in the largest wetlands in the West.”

Fact: Most of the water stored is for agriculture and released for agriculture. Mr. Peltier’s organization is simply last in line for stored water and thus gets less water allocated during droughts. In June and July, nearly 30,000 cfs of water was released on average from Central Valley reservoirs, but only 7000-8000 cfs reached the Bay to repel salt intrusion. Because Shasta releases were reduced to protect salmon (not smelt), Mr. Peltier’s organization was unable to receive more than a minimal allocation. Again, this is because its water rights are junior to those of other users, not because of water allocated to smelt (none).

4. “Since the most severe cuts were imposed on the Projects nine years ago, less water has been diverted, and thus more Projects’ water has gone out to the ocean, than at any other time in the past 35 years.”

Fact: Seven of the last nine years were drought years. The only water consistently reaching the ocean in large amounts during those seven years was uncontrolled river flows and reservoir spills during and after sporadic winter storms. The only reservoir water that reached the ocean (Bay) in those seven dry years was the water necessary to hold back salt intrusion into the Delta so Delta diversions and exports remained possible.

5. “Farmers, fishermen, and environmentalists – everyone that truly cares about the status of our imperiled fisheries – should be furious.”

Comment: The fishermen and environmentalists are “furious” because of government mismanagement of the Shasta Reservoir cold water pool that has nearly wiped out the Sacramento salmon runs, and because of the weakening of Delta water quality standards in 2014 and 2015 that allowed excess salt into the Delta and just about exterminated the Delta smelt population.

6. “Decades old state and federal policies have failed and brought delta smelt and salmon to the brink of extinction. The last thing we need is more of the same.”

Comment: Yes, decades-old policies of increasing exports from the Delta has brought near-extinctions. It started with the massive State Water Project that came on line in the 1970’s. Yes, the last thing we need is “more of the same” – increasing exports promised with the WaterFix.

7. “Like delta smelt, we need shelter, we need food, and we need safety from predators, toxics, and invasion. The state and federal regulatory agencies have ignored for far too long the full needs of delta smelt, only willing to do what is easy, and we have all suffered for it.”

Fact: Delta smelt need the cool, brackish, wind-blown turbid waters of Suisun Bay provided when Delta outflow is sufficient to keep the low salinity zone out of the warm, confined channels of the Delta and away from its massive export pumps.

8. “We can continue to ignore decades of sound scientific advice, or we can embark on a bold new initiative, one that is transparent and inclusive of stakeholders working with state and federal agencies to save delta smelt.”

Comment: We have ignored the scientific advice. It has always been there. What “bold new initiative?”

9. “Now is not the time for desperate action, it is the time for thoughtful action.”

Fact: Giving the Delta Smelt 1000 or 2000 cfs in June and July this year – instead of nothing (Delta outflow was allocated to repel salt) – would entail only 3-6% of the water released from reservoirs and 5-10% of Delta inflow. After all, the Delta Reform Act of 2009 mandates that the state must implement the “co-equal” goals of providing a reliable water supply and protecting, restoring and enhancing the Delta ecosystem.

American River Salmon and Steelhead

 Sacrificed and Unprotected

Where are the newspaper articles about the American River “trout?”1 Water supplies and fish are suffering all across the Central Valley, but there is no mention of American River salmon and steelhead being sacrificed so that southern California reservoirs can be filled.

The Santa Clarita Valley Signal reported on August 31, 2016:

“Castaic Lake’s water levels increased due to a rainfall and snowpack in Northern California. Castaic Lake is part of the California State Water Project and is maintained by the California Department of Water Resources as one of the state’s 34 storage facilities. Water collected by the agency is moved around the state to provide drinking and agricultural water to two-thirds of California’s inhabitants. On average, Castaic Lake holds 264,908 acre-feet of water during this time each year. It is currently holding 241,689 acre-feet of water, which is 120,467 acre-feet more than the lake was holding this day in 2015.” 2

Yes, Southern California reservoirs are being filled at the expense of northern California reservoirs (Figure 1). Folsom Reservoir in particular was drained of over half its water over the summer, which has put this year’s steelhead and salmon spawns at great risk, not to mention future water supply and hydroelectric production needed by the Sacramento region.

Figure 1. Reservoir levels in acre-feet of storage from May-August 2016.

Figure 1. Reservoir levels in acre-feet of storage from May-August 2016.

While regional water districts are screaming foul about the declining level of storage in Folsom and San Luis reservoirs, no one seems concerned about the American’s salmon and steelhead. We can understand (but not accept) the sacrifices in the extremes of the 2012-2015 drought (Figure 2), but not in 2016 a normal water year for the American River (Figure 3). Because Reclamation has drawn down Folsom Reservoir too far even in 2016, it lost the ability to use the available cold-water pool to maintain downstream cool river water temperatures (Figure 4). Also because Reclamation drew down the reservoir level, it allowed a provision for extreme conditions to kick in: an allowed increase in the water temperature requirement from 65°F to 68°F at Watt Avenue (Figure 5). That change in the federal biological opinion for operation of Folsom Reservoir (Figure 6) is designed for extraordinary circumstances and should not have occurred in 2016.

Reclamation has also made little progress toward other requirements to fix the Folsom problem (as shown in Figure 7).

After four years of drought and the mismanagement of Folsom Reservoir this summer by Reclamation, we can expect greatly reduced natural production of salmon and steelhead from the American River in the coming years.

For more information on this subject check out: http://www.safca.org/protection/NR_Documents/LARTF_2014_09_ Folsom_TCD_VPD_Ghoring.pdf .

Figure 2. Water temperature in the American River at William Pond Park at the downstream end of the river’s spawning reach in 2015. Red lines depict water temperature objectives set for salmon and steelhead spawning and rearing.

Figure 2. Water temperature in the American River at William Pond Park at the downstream end of the river’s spawning reach in 2015. Red lines depict water temperature objectives set for salmon and steelhead spawning and rearing.

Figure 3. Water temperature in the American River at William Pond Park at the downstream end of the river’s spawning reach in 2016. Red lines depict water temperature objectives set for salmon and steelhead spawning and rearing.

Figure 3. Water temperature in the American River at William Pond Park at the downstream end of the river’s spawning reach in 2016. Red lines depict water temperature objectives set for salmon and steelhead spawning and rearing.

Figure 4. Water temperature of water released from Folsom Reservoir April-August 2016. Red line is maximum temperature objective. Note July 13 attempt to release water from lower colder-water level outlet.

Figure 4. Water temperature of water released from Folsom Reservoir April-August 2016. Red line is maximum temperature objective. Note July 13 attempt to release water from lower colder-water level outlet.

colder-water level outlet. Figure 5. Water temperature in the American River at Watt Avenue in 2016. Green line is normal objective. Red line is relaxed standard for drought years.

Figure 5. Water temperature in the American River at Watt Avenue in 2016. Green line is normal objective. Red line is relaxed standard for drought years.

Figure 6. NMFS Biological Opinion excerpt from p615.

Figure 6. NMFS Biological Opinion excerpt from p615.

Figure 7. NMFS Biological Opinion excerpt from p616.

Figure 7. NMFS Biological Opinion excerpt from p616.

Figure 8

Stanislaus Trout (Steelhead)

An August 18, 2016 article in the Calaveras Enterprise (“Trout population plummets”) and an August 15, 2016 post on the Fishbio blog describe a recent decline in numbers of trout in the lower Stanislaus River. Fishbio pegged the cause of the problem on to four years of drought and to the fact that the Bureau of Reclamation allowed New Melones Reservoir to fall in storage so far as to lose its cold water pool needed for trout production. As reported in the Enterprise, the Oakdale Irrigation District and South San Joaquin Irrigation District issued a statement arguing that “flawed science” in the National Marine Fisheries Service’s 2009 biological opinion issued for the operation of the Central Valley causes federal dam operators to release water in ways that do not benefit steelhead and trout. The Enterprise quotes the Districts as stating: “The current flow standards are destroying the fisheries that they are intending to protect and doing so at the expense of Central Valley agribusiness and urban interests, who also depend upon a healthy and sustainable river.” 

The irrigation districts would prefer that the water released for fish be allocated instead to their constituents. Lost in the discussion is the notion that reducing river flows is not the only way to maintain storage levels in New Melones Reservoir. If the irrigation districts had taken less water over four years of drought, the cold water pool in New Melones could have ended up, in 2015, in much better shape. But the Districts lay the decline of “trout” at the feet of the biological opinion. The fish flow prescriptions biological opinion are not designed for “trout.” They are designed for steelhead migration to the Bay-Delta and ocean. The biological opinion prescribes multi-day spring pulses in flow up to several thousand cubic feet per second to stimulate steelhead (and juvenile salmon) emigration toward the ocean. It states in part:

Objective: To maintain minimum base flows to optimize CV steelhead habitat for all life history stages and to incorporate habitat maintaining geomorphic flows in a flow pattern that will provide migratory cues to smolts and facilitate out-migrant smolt movement on declining limb of pulse. 1

Steelhead need stimulus to migrate. They need the benefits of higher velocities and more turbid water to migrate successfully. Without stimulus, potential steelhead will stay and become resident trout. Mother Nature has given them the inherent knowledge that to go without the flow is to die along the way.

Flow in the Stanislaus River is controlled by operations of New Melones Reservoir (Figure 1). The premise of the article and post is that reservoir drawdown from pulsed flow releases caused the high water temperatures in the lower Stanislaus River that resulted in high trout mortality and the low numbers of trout observed in the snorkel surveys. There is no doubt that low reservoir levels led to warmer water being released into the lower Stanislaus from Goodwin Dam. The information presented in the Fishbio post and report shows clearly that water temperatures were 5 to 10°F higher than normal in the lower Stanislaus, reaching the stressful level of 65°F or even higher downstream of Goodwin Dam at Orange Blossom Bridge (Figure 2). The water temperature criteria prescribed in the biological opinion for the summer at Orange Blossom Bridge is 65°F. The reservoir did fall dangerously low in 2015 (Figure 3).

Figure 1. Map of lower Stanislaus River with USGS gaging stations.

Figure 1. Map of lower Stanislaus River with USGS gaging stations.

Figure 2. Daily average water temperature (°F) in the lower Stanislaus River at Orange Blossom Bridge 2011-2016

Figure 2. Daily average water temperature (°F) in the lower Stanislaus River at Orange Blossom Bridge 2011-2016

Figure 3. New Melones Reservoir storage in acre-feet 2011-2016.

Figure 3. New Melones Reservoir storage in acre-feet 2011-2016.

The Fishbio report relates that water temperature becomes a problem when summer storage falls into the 300-500 thousand ac-ft range.  It would also appear that levels of 500-600 thousand acre-feet, such as those that occurred in summer 2014 and 2016, also lead to elevated water temperatures based on a close look at Figures 2 and 3.

A factor not mentioned by Fishbio is that streamflow in the lower Stanislaus in summer 2015 was lower in 2015, 150-200 cfs, compared to 200 cfs or higher in other summers of the 2011-2016 period (Figure 4).  Such lower flows can also contribute to higher water temperatures.  Lower flows can also affect “trout” survival by significantly reducing rearing space and quality.

A factor that Fishbio did mention was a possible “increase in downstream migration.”  After all, the flow pulses were prescribed to stimulate steelhead smolt emigration.  Flow pulses in combination with higher water temperatures may have stimulated outmigration resulting in lower total numbers.

The main theme of the irrigation districts and Fishbio is that by not providing the pulse flows in spring, it would save up to 100 thousand acre-feet of storage, thus keeping the reservoir higher and water temperatures lower in the river below.  But again, what is missing from the discussion is the effect of reservoir operation on the whole process, and especially on storage.  That effect can be seen in Figures 5a and 5b.  The natural flow regime is highly modified.  The natural winter high flows are retained by the reservoir and released in spring and summer.  Releases to irrigators from storage in 2015 over the April – September irrigation season amounted to approximately four hundred thousand acre-feet (see Figure 3), most of which came from storage carried over from previous years, which made up much of the cold water pool.  This repeated the pattern of previous years, when in fact deliveries to the districts were even higher.  With so little water left in storage by 2015, the districts had no one left to take water from but the fish.

Figure 4. Daily average streamflow (cfs) in the lower Stanislaus River at Orange Blossom Bridge from 2011-2016.

Figure 4. Daily average streamflow (cfs) in the lower Stanislaus River at Orange Blossom Bridge from 2011-2016.

Figure 5. New Melones Reservoir inflow (blue line) and outflow (orange line) in water year 2015 (top) and 2016 (bottom). Note prescribed fall and spring pulse flow releases for salmon and steelhead.

Figure 5. New Melones Reservoir inflow (blue line) and outflow (orange line) in water year 2015 (top) and 2016 (bottom). Note prescribed fall and spring pulse flow releases for salmon and steelhead.