Record Chinook Salmon, Steelhead Returns Reported on Mokelumne River


A fall Chinook salmon entering the fish ladder at the Mokelumne River Fish Hatchery. Photo by Dan Bacher.

By Dan Bacher | November 18, 2017 | 

For many years after Camanche Dam was built, the Mokelumne River, a major tributary of the San Joaquin River and the Delta, hosted small runs of Chinook salmon.

The historic runs of steelhead after the construction of the dam averaged only 100 fish and no steelhead returned to spawn many years.

But both steelhead and salmon runs have rebounded in recent years, due to a number of factors. In welcome good news for Central Valley salmon populations, the California Department of Fish and Wildlife (CDFW) and the East Bay Municipal Utility District (EBMUD) report record fall spawning returns of Chinook salmon and steelhead to the Mokelumne River, a tributary of the San Joaquin River.

Over a three-hour period Thursday, staff at the Department of Fish and Wildlife’s Mokelumne River Fish Hatchery in Clements spawned and processed one Chinook salmon after another as school children toured the hatchery and photographers and TV cameramen from a variety of media outlets captured the activities.

The river has welcomed over 14,000 salmon to date and is on track to break the record return of 18,000 set in 2011. The hatchery will continue to spawn salmon as they move into the facility through December 18.

For the second year in a row, the hatchery has also counted a record number of steelhead, with more than 350 steelhead having already entered the hatchery in 2017. This follows last year’s record return of 759 adult steelhead to the facility.

No steelhead came back to the hatchery, located on the river right below Camanche Dam, for 10 years from 1976 through 1986. Again in 1998-1999, no adult steelhead returned to the facility.

”There’s a long list of factors responsible for the rebound of salmon and steelhead,” said Will Smith, hatchery manager. “These include good ocean conditions, a change in our juvenile salmon release strategies, a special barging program of salmon downriver, and closing  the Delta Cross Channel gates on weekdays to prevent straying of both Sacramento and Mokelumne River salmon.”  

Another major factor behind the boom in numbers of steelhead is the management of the river as a steelhead fishery. Before the listing of the Central Valley steelhead under the Endangered Species Act (ESA), the Mokelumne was managed as a catchable trout fishery, rather than as a wild steelhead or trout river.

The CDFW used to regularly stock the river with catchable size steelhead in the 10 to 15 inch range, hatched from steelhead eggs obtained from the Mokelumne and Nimbus Fish hatcheries.

Impressive fall returns result from a combination of efforts  

EBMUD officials confirmed the factors mentioned by Smith to explain the record salmon and steelhead runs.

 “The impressive fall returns are a result of combined efforts that have focused on water operations, including managing cold water in Camanche and Pardee reservoirs to attract salmon, releasing pulse flows, Delta Cross Channel gate closures, and using tagging data to evaluate hatchery release strategies,” reported Tracie Morales of EBMUD in a statement.  “Additional innovative measures include transporting juvenile salmon by barge and feeding a specialized diet to assist the freshwater-to-seawater transfer.”

The agency said these fish returns “indicate a healthier river system that supplies water to 1.4 million East Bay customers.”  

The partnership between CDFW and EBMUD is part of a 1998 agreement between the East Bay utility and federal and state agencies to promote healthier conditions and water flows in the Mokelumne River, an agreement that couldn’t have happened without pressure by the California Sportfishing Protection Alliance (CSPA) and the Committee to Save the Mokelumne River.  

“As a water agency that is a vital partner on the Mokelumne River, we’re thrilled to see continuously strong returns,” said EBMUD Manager of Fishery and Wildlife Jose Setka. “For EBMUD, the health of natural ecosystems is critical to our watersheds and a vital part of our mission. This river partnership has enabled management decisions that have improved the survival of salmon and steelhead. By improving habitat, updating hatchery practices, better coordinating Delta operations and continuing scientific studies, the Mokelumne River fish population will be model for recovery.”

Besides hatchery improvements, the construction of new fish passage facilities on the new Woodbridge Dam in the summer of 2006 and the completion of the FERC relicensing process for Camanche Dam in 1999 that provides for increased river flows are responsible for the upswing in the salmon and steelhead runs.

The California Sportfishing Protection Alliance and Committee to Save the Mokelumne River played a key role in securing more water for the river from EBMUD, increasing the allotment from only 13,000 acre feet of water in wet years to 85,000 acre feet of water.

The “Speece Cone” operated by EBUD at Lake Camanche, a device that distributes oxygen to the lower lake waters at the dam, has also boosted the river’s steelhead and resident rainbow fishery. The device, constructed to improve the quality of water released into the fish hatchery and river in order to stop the fish kills that periodically plagued the river, usually operates from August until mid-to-late October. 

Feather River fall salmon numbers soar, but spring run reaches record low

The Mokelumne River is not the only Central Valley river seeing improved runs of salmon and steelhead. CDFW staff at the Feather River Fish Hatchery in Oroville are also seeing a big fall Chinook run this fall.

“We got a whole bunch of fall Chinook salmon this season,” said Anna Kastener, hatchery manager “We’re almost done spawning for the year.”

The hatchery count is 13,800 adults and 7,200 jacks to date this year to date. “We’ve taken over 15,000,000 eggs, including 2,000,000 fish above the mitigation goal that the NorCal Sportsmen’s Association requested,” said Kastener. 

The Feather River Fish Hatchery has released 510 steelhead back into the river since November 1, according to Kastener. The staff won’t begin spawning the steelies until December. 

“By contrast, we saw only 74 steelhead the whole season two years ago,” she noted. 

While the fall run Chinook and steelhead returns to date are very encouraging on both the Mokelumne and Feather rivers, runs of spring run and winter run Chinooks reached record lows this season.

Only 500 spring run Chinook salmon returned to the Feather River Fish Hatchery to spawn this year, “The previous low number was 989 fish in 2010,” said Kastener. “We only have a quarter of the fish eggs that we normally take from the spring run.”  

Sacramento River winter Chinook run is in deep trouble

Only 1,123 adult winter Chinook salmon, once one of the biggest runs of salmon on the Sacramento River and its tributaries, returned to the Sacramento Valley in 2017, according to a report sent to the Pacific Fishery Management Council (PFMC) by the California Department of Fish and Wildlife (CDFW). 

This is the second lowest number of returning adult winter run salmon since modern counting techniques were implemented in 2003, undercut only by the 824 fish that returned in 2011. 

John McManus, Executive Director of the Golden Gate Salmon Association (GGSA), pointed out that in 2014 and 2015, the years these fish were born, state and federal fish agencies reported losses of 95 percent of this and other groups of salmon.

“The losses were caused by water management choices by the federal Bureau of Reclamation during the drought which failed to retain enough cold water for release from Lake Shasta for successful spawning,” said McManus. “Barely adequate cold water supplies existed early in 2014 and again in 2015 when GGSA and others warned the Bureau of Reclamation of the peril facing winter run salmon. The warnings fell on deaf ears. Elevated river temperatures killed most of the salmon eggs incubating in the river.” 

“If we don’t want extinction on our watch, state and federal leaders need to support stronger protections for salmon in the rivers of the Central Valley where most California salmon come from, The low number of winter run salmon that survived the drought to return this year makes crystal clear the need for NMFS to greatly increase temperature protections for these fish in the upper Sacramento Valley where they reproduce,” he concluded.


Groups say Delta Tunnels will kill and harm winter and spring salmon

As spring and winter Chinook populations continue to decline, the state and federal governments continue to forge ahead with the plan to build the Delta Tunnels, considered by opponents to be the most environmentally destructive public works project in California history.  

Four environmental groups on Friday, September 22, filed a lawsuit challenging the Brown administration’s permit to kill endangered salmon and smelt in the proposed Delta Tunnels project. The Center for Biological Diversity, Bay Institute, Natural Resources Defense Council and San Francisco Baykeeper filed the suit in California Superior Court in Sacramento,  represented by the nonprofit environmental law firm Earthjustice.

On July 28, the California Department of Fish and Wildlife (CDFW), issued an “incidental take permit” for the construction and operation of California WaterFix as required under Section 2081(b) of the California Endangered Species Act (CESA).

Representatives of the groups said the agency “improperly authorized” the California Department Water Resources to “kill and harm” state-protected fish species, including Sacramento River winter-run and spring-run chinook salmon, longfin smelt and Delta smelt. 

Summary of factors behind record salmon and steelhead runs at Mokelumne River Fish Hatchery
The strategies for improved returns included:

  • Stronger Pulses - Pulse flows reached higher magnitudes compared to recent years thanks to flood control waters released from Camanche Reservoir. These pulses provide cues for salmon to move up into the river. Additional pulses provided by reoperating Woodbridge Irrigation District Dam extended the period of pulses into November.  
  • Gate Closures – To prevent straying of Sacramento and Mokelumne River salmon, CDFW coordinated closures of the Delta Cross Channel Gates on weekdays and reopened for weekend recreation beginning in September. 
  • Tagging Data – Using Coded Wire Tag data from returning fish, the agencies measured the effectiveness of releasing fish on outgoing tides and limiting releases to no more than two consecutive days from the same location to increase juvenile salmon survival. 
  • Barging - The agencies have transported juvenile salmon from the Mokelumne River by barge and released them in the San Francisco Bay. Barging improves fish survival through the Delta and may also help with imprinting for juvenile salmon to re-trace their way to natal waters.
  • Transfer Diet – Juvenile salmon undergo an incredible physiological change when moving from freshwater to saltwater. To ease the initial stress, a specialized feed containing higher salt levels is fed to the juveniles in the weeks before the release.
  • Habitat Improvement – EBMUD and DFW have spent nearly two decades developing and implementing a plan to improve spawning and rearing habitat in the river below Camanche Dam.  




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