How do we increase salmon runs in 2018 and beyond?

Over the past few months, I wrote posts on the status of specific runs of salmon in rivers throughout the Central Valley. In this post, I describe the overall status of salmon runs and the general actions to take to increase both escapement and fish available for commercial and sport harvest.

It was just over a decade ago that there were nearly one million adult salmon ascending the rivers of the Central Valley (Figure 1). At the same time, there were a millions more Central Valley salmon being harvested each year in sport and commercial fisheries along the coast and rivers of the Central Valley. Improvements in salmon management in the decade of the 1990s by the Central Valley Project Improvement Act, CALFED, and other programs had paid off handsomely with strong runs from 1999 to 2005. New and upgraded hatcheries, along with trucking hatchery smolts to the Bay, significantly increased harvest and escapement to spawning rivers.

Figure 1. Central Valley salmon runs from 1975 to 2016 including fall, late fall, winter, and spring runs. Source of data: CDFW GrandTab.

By 2008-2009, escapement had fallen by over 90% to a mere 70,000 spawners of the four races of salmon.  Fishery harvests were greatly restricted by 2008.  The winter run, the most threatened of the four runs fell from 17,296 to 827 spawners in just five years.  Drier years from 2001-2005, poor ocean conditions in 2004-2005, record-high Delta water diversions, and the 2007-2009 drought were contributing factors in the declines.  Impacts to coastal communities and the fishing industries were severe.

Extraordinary recovery measures included closing fisheries and trucking most of the hatchery smolt production to the Bay or Delta.  Federal salmon biological opinions (2009, 2011) limited winter-spring water-project exports from the Delta.  Hundreds of millions of new dollars were spent on habitat and fish passage improvements in the Valley to increase salmon survival and turn around the declines in runs.  A look at Figure 1 indicates that these efforts proved effective in limiting run declines from the 2012-2015 drought compared to the 1987-1992 and 2007-2009 droughts.

However, the prognosis for the future is again bleak, especially for wild, naturally produced salmon.  The consequences of the 2012-2015 drought  have not fully played out.  Once again, projected runs are low, and harvests are likely to be restricted.  Actions are needed to minimize long-term effects and to help bring about recovery of wild salmon productivity and fisheries in general.

Actions for 2018:

  1. Reduce harvest: Sadly but necessarily, the Pacific Fisheries Management Council and states are likely to take this first step of– restricting the 2018 harvest in the ocean and rivers to protect wild runs.
  2. Improve spawning, rearing, and migrating conditions: Sadly, this past year’s rearing and migrating conditions in the Sacramento River were unnecessarily compromised.   Water temperature at Red Bluff reached above the 56oF prescribed in the biological opinion and Basin Plan.  The higher temperatures resulted from low Shasta Reservoir releases (less than 5000 cfs – Figure 2) despite a virtually full Shasta Reservoir.  The low flow and higher water temperatures likely affected salmon egg incubation, rearing, and emigration-immigration success.  Reservoir releases will be necessary to meet flow and temperature targets in all Central Valley rivers and the Delta.
  3. Limit Delta exports: Delta exports this past spring reached unprecedented highs not seen in recent decades, resulting in high salmon salvage rates at the Delta fish facilities (Figure 3).1 With high water supplies from this past wet water year 2017, there will be high exports again unless there are some constraints.  If anything, winter-spring exports should be reduced to allow salmon to recover.  April-May exports should be reduced, like they were in the 1990’s and 2000’s, to 1500 cfs.

Near term actions over the coming year:

  1. Transport hatchery smolts to Bay: The transport of millions of fall-run smolts from state hatcheries on the Feather, American, and Mokelumne rivers to the Bay provides higher rates of escapement and contributions to the fishery and low rates of straying.  Barge transport to the Bay offers potentially lower rates of predation and straying for federal hatcheries near Redding.
  2. Raise hatchery fry in natural habitats: Recent research indicates that rearing hatchery fry in more natural habitat conditions increases growth rates, survival, and contributions to escapement and fisheries.  Raising hatchery fry in rice fields is one potential approach.
  3. Restore habitats damaged by recent record high flows in salmon spawning and rearing reaches of the Central Valley rivers and floodplains: In nearly every river, habitats were damaged by the winter 2017 floods, requiring extraordinary repairs and maintenance to ready them again to produce salmon.
  4. Take further actions to enhance flows and water temperatures to enhance salmon survival throughout the Central Valley: Actions may include higher base flows, flow pulses, or simply meeting existing target flow and temperature goals.

In conclusion, managers should take immediate actions to minimize the damage to salmon runs from the recent drought and floods, using this past year’s abundant water supply.  They should avoid efforts to exploit the abundant water in storage for small benefits to water supply at the expense of salmon recovery, and should make every effort to use the water in storage for salmon recovery.

Figure 2. Upper Sacramento River flows and water temperatures in May 2017. The target water temperature for Red Bluff is 56oF. Source of data: USBR.

Figure 3. Export rate and young salmon salvage at South Delta federal and state export facilities in May 2017. The target export rate limit for May should be 1500 cfs. Source of data: USBR.

December 2017 – Risks to Salmon

With a potentially record-low rain total for December, the federal and state water projects are cutting reservoir releases but keeping up exports from the Delta, causing great peril to Central Valley salmon.  Figure 1 summarizes Delta conditions as of mid-December.

Figure 1. Major Delta net daily flows (cfs) in mid-December 2017. Map source: USGS. Data sources: USGS and CDEC.

For juvenile winter run, spring run, fall run, and late fall run Chinook salmon migrating down the Sacramento River, the risk is obvious.  With nearly 40% of Sacramento River inflow diverted at Georgiana Slough and another 30% diverted at Threemile Slough, less than half of the Sacramento River’s inflow to the Delta is reaching the Bay.  Of the total Delta inflow, only 45-50% is reaching the Bay.  Nearly all the San Joaquin River Delta inflow is being exported.

Assuming that the young salmon split with the flow, 60% of Sacramento fish are being diverted to the central Delta and near 100% of the San Joaquin fish are lost to the interior Delta.  With winter run and late fall run juvenile salmon from the Sacramento River moving into the Delta during the late November storms (Figure 2), there is a high risk that the diverted fish will be lost in the interior Delta.  Soon, spring run and fall run fry salmon will be moving into the Delta.

Under the conditions in the “Reasonable and Prudent Measures” required by the National Marine Fisheries Service’s Biological Opinion (BO) for the operation of the state and federal water projects, exports should be reduced when “large numbers” of juvenile salmon begin entering the Delta (Figure 3).  The finding that there are “large numbers” is based on monitoring of juvenile salmon at Knights Landing and Sacramento.  Peak catches in the past month were 3-7 per day (Figure 2).  This does not meet the level of 10 per day under which the BO would trigger reducing exports.   However, the trigger dates from a time when the Sacramento River was producing 6 to 10 times more  juvenile winter run salmon.  In the last four years, juvenile production of winter run in the upper Sacramento River near Redding has been at record low levels of 300,000 to 500,000, compared to 3.3 million in 2009 when the BO was published.   “Large numbers” today are understandably smaller than they were eight years ago.

Exports should be reduced immediately until outflow to the Bay increases dramatically.  January BO limits will require Old and Middle River (OMR) flows near the south Delta export pumps to be no more negative than 5000 cfs.  With December OMR flows in excess of -9000 cfs (Figure 4), exports should be reduced now to limit OMR to -5000 cfs or lower per BO Action IV.3 through the remainder of December.


Figure 2. Catch of unmarked older Chinook juveniles (likely winter run and late fall run) at Knights Landing and Sacramento in fall 2017. Data from CDFW and USFWS surveys as reported by

Figure 3. Excerpt from p. 652 of NMFS BO 2009.

Figure 4. OMR flows in south Delta. Source: .

WaterFix USFWS Biological Opinion Conclusions on Delta Smelt

The US Fish and Wildlife Service’s biological opinion (USFWS BO) on the proposed “California WaterFix” (Delta Twin-Tunnels Project or CWF) concludes that the CWF will not jeopardize protected Delta smelt in the Bay-Delta.  In this post, I address the conclusions in the USFWS BO on the potential effects of WaterFix on Delta smelt.  This is another post in a series of posts on the WaterFix.

BO conclusion, p. 252.

Comment: The north Delta diversions (NDD) will increase tidal flows and upstream reverse flows below the NDD intakes. Adult smelt will migrate further upstream on their spawning run on average than they can under existing conditions. Thus, their likelihood of spawning nearer the NDD is greater. There would be more smelt spawners diverted from the Cache Slough area to the Sacramento River upstream of Cache Slough. The only impediment to such upstream movement and to spawning upstream of the project area would be loss to impingement or predation at the NDD diversion intakes. These effects would be significant risks to the population.

BO conclusion, p. 258.

Comment: These analyses did not take into account reduced freshwater inflow into the interior, central, western, and south Delta because of the diversions at the NDD intakes. South Delta exports would remain similar to existing constrained spring exports (~6,000 cfs) and high summer exports (no NDD exports). With less inflow to the lower Delta, the Low Salinity Zone in the lower Sacramento and San Joaquin channels would be expected to be further upstream, and entrainment potential from False River and lower Old River would be greater. Delta outflows would be lower, especially in drier years. Specified summer operations focused on south Delta exports would continue existing high summer risk to smelt and their habitat, especially if more spawning occurs in the lower San Joaquin River channel. Lower freshwater inflow will lead to higher salinities and warmer spring-summer Delta conditions, to the detriment of Delta smelt. Existing high summer impacts to Delta smelt would increase because of the more-upstream springtime distribution of smelt.

BO conclusion, p. 262.

Comment: The removal of a significant portion of freshwater inflow at the proposed NDD will not improve “transport flow function”. OMR effects will intensify with the LSZ further upstream in the lower San Joaquin River channel. The amount of smelt pulled through Three-Mile Slough and the amount transported tidally in the lower San Joaquin River from Antioch to Jersey Point via False River will increase. If OMR will not change in April-May, the primary smelt larval period, then larval impacts will be much worse without the fresh water diverted at the NDD.

BO conclusion, p. 262.

Comment: The 25oC restriction will come much earlier in spring without the freshwater inflow that is removed at the NDD. The change in LSZ position (more upstream) and water temperature (higher) will be generally detrimental to Delta smelt survival.

BO conclusion, p. 263.

Comment: Based on such past commitments and the performance of Reclamation and DWR, this one must also be taken with a grain of salt.” Without a clear understanding of factors affecting Delta smelt, as exemplified in this assessment, it is unlikely that the USFWS could protect Delta smelt under WaterFix operations.

BO conclusion, p. 272.

Comment: Water Year 2017 was the second year since the 2008 BO RPA on Fall Wet Year X2 came into play. In 2011, its application appeared to have positive effects.1 Yet in September 2017, the USFWS approved the provision’s removal. How are we to believe the commitment to employ the RPA in the future?

BO conclusion, p. 274.

Comment: The reduction of freshwater inflow to the Delta below the NDD will move the low salinity zone (LSZ) upstream and contract its size (volume and surface area). This will have serious adverse effects on smelt and their critical habitat.

BO conclusion, p. 274.

Comment: Reduction of freshwater inflow into the Delta can increase Delta water temperatures several degrees, to the detriment of smelt survival. Not only are water temperatures increased by lower net flows, but the LSZ is warmer when it is located further upstream from the Bay and its cooler air temperatures.

BO conclusion, p. 298.

Comment: Recognizing the uncertainty is no excuse for approving the proposed action (PA). There are no guarantees that predicted effects “will likely not be realized” or that future actions will protect smelt. It is more likely that recovery of Delta smelt will be further from reality with WaterFix.