CDFW Trucks Salmon Smolts Around Adverse River Conditions

June 17, 2022

The California Department of Fish and Wildlife (CDFW) is nearing the completion of its efforts to transport 19.7 million hatchery-raised fall-run and 960,000 spring-run juvenile Chinook salmon (known as smolts) to the San Pablo Bay, San Francisco Bay and seaside net pens this spring and summer.

CDFW raises the fish at Feather River, Nimbus, Mokelumne and Merced salmon hatcheries and monitors river conditions carefully to estimate the smolts’ chances of successful migration. During times of drought, low flows and elevated water temperatures can be a lethal mixture for the young salmon. This year, conditions are expected to be particularly poor, prompting CDFW to move more than 95 percent of the smolts down river, thus bypassing 50 to 100 miles of hazardous river conditions.

“Three consecutive years of drought have resulted in critically low reservoir water storage, low river flows and poor river conditions overall, which we know decreases the survival of juvenile Chinook salmon as they move downstream toward the Pacific Ocean,” said Jason Julienne, CDFW’s North Central Region hatchery supervisor. “In years like this, when drought conditions are bad and anticipated in-river survival is low, trucking young salmon to downstream release sites has proven to be one of the best ways to increase overall survival of hatchery produced fish to contribute to adult returns in the coming years.”

To increase survival rates, multiple release sites and release methods are used. In some locations, the fish are released directly into the water by specialized fish-hauling tanker trucks. At others, the smolts are released into net pens, which are then towed out to deeper waters before being released. Releases can happen during daylight hours or at night. CDFW fisheries biologists and salmon hatchery managers tailor these methods according to tide conditions, temperatures and the presences of potential predators at each site.

Prior to each release, approximately 25 percent of the smolts have their adipose fin removed and are fitted with a coded wire tag the size of a small pencil lead in its nose. When the fish are caught later, CDFW staff can use the tag information to determine when, where and from which hatchery the fish came. CDFW fish counters check both commercial and sport catch to secure tags and retrieve this information, which helps determine the success rate of each batch of fish released.

“The trucking of these salmon smolts helps ensure both sport and commercial anglers of salmon in the future,” said John McManus, president of the Golden Gate Salmon Association. “CDFW staff has gone above and beyond in their willingness to move the release sites further west, which means we'll see much better survival for those fish released closer to the ocean. This is greatly helping to keep the salmon industry afloat as we suffer through drought.”

The releases began in March and are scheduled to conclude by June 23. One of the last releases will happen over the weekend at Brickyard Cove in Richmond on Sunday, June 19 at 8:45 p.m. The Golden State Salmon Association and the City of Richmond will assist with the release of approximately 200,000 smolts at this site. Media are welcome; please contact Ken Paglia at (916) 825-7120 for details and directions. The city will require attendees to sign a waiver in advance.

And just how many smolts will survive the onslaught of stripers looking for an easy meal?

And just how many smolts will survive the onslaught of stripers looking for an easy meal?

Many??? by swimming???

Not all will make it past the voracious striper. Not all will survive the rockfish either, or the large salmon passing through cal city. Not all will survive the the seals, birds, or even the drive itself. Some will die with the drop into the water, or the waves that meet them there.

But tell me this; why not try? Some (a lot actually) will survive.

Salmon and striper have coexisted for over 150 years. Striper are naturalized, meaning they play an integral role in our ecosystem, and could cause an imbalance if removed, native or not.

Before we dammed rivers beyond recognition and diverted water flows for whatever purpose they have been diverted for- worthy or not, these fish lived together WELL.  6 foot long fish, 100lbs each coexisted with unbelievable numbers about them.

God forbid they try (and succeed) to help

Compared to the traditional release strategies, trucking the smolts most of the way to the ocean has proven a success for overall return rates of adults. As adults, the trucked fish stray more than the fish given more time to imprint on their home river/hatchery. However, I'm not sure there's much genetic integrity (if any) left to preserve in Central Valley Chinook, save for the paltry few native spring- and winter-run versions still clinging to existence in the northern Sac River tribs.

Stripers eat salmon smolts, but they're not a primary player in CV Chinook smolts' demise. Water diversions, habitat simplification, and good ole climate change are the real enemies. It wasn't long ago when both stripers and Chinook runs were doing relatively well in the Central Valley.