The steelhead run on the American River is shaping up up to be a relatively good one, though not as big as the record runs in the past when the hatchery reported trapping 3000 to 4000 adult steelhead in a season.
“With four weeks of spawning completed, Nimbus already has counted more than 900 steelhead entering the hatchery – a mix of wild, hatchery-origin and juvenile fish,” according to the California Department of Fish and Wildlife (CDFW) in a statement. “At this same time last year, Nimbus had counted just 300 fish.”
“We are well ahead of what we collected last year,” said Nimbus Fish Hatchery Manager Gary Novak. Nimbus is on track to meet its annual production goal of 430,000 steelhead.”
“The hatchery produces a unique Eel River strain of steelhead that grows significantly larger than the Central Valley stock produced at CDFW’s Feather River and Mokelumne River hatcheries,” the Department wrote.
The CDFW added, “While an adult Central Valley steelhead may reach a maximum size of 7 pounds, an Eel River strain fish can grow to 17 pounds after time in the ocean.”
Actually, steelhead can grow even larger than 17 pounds on the American, just like they can on the Eel River. Several steelhead in the 19-pound to 20-pound class were caught in the 1980s and 1990s on the American, including one weighing exactly 20 pounds that was caught by a client of guide Barry Watson on January 1, 1990.
The largest-ever steelhead/rainbow trout documented on the American was a 25.02 lb. wild fish (weighed on a digital scale) caught below Nimbus Hatchery in February of 2002. The fish may have been a wild rainbow that washed over from Lake Natoma or a steelhead living on the abundant forage below the dam, but since it was considered a wild steelhead under CDFW regulations, the angler had to release it.
And the Feather River Fish Hatchery has reported fish up to 19 pounds in past seasons. I’ve personally seen and photographed steelhead over 12 pounds caught while fishing the Feather River — and significant numbers of steelhead over 8 pounds are caught every year on the Feather.
“In carefully selecting its breeders, Nimbus seeks to perpetuate the Eel River strain by only spawning returning, hatchery-origin fish,” the CDFW continued. “Unlike salmon whose life cycle ends at spawning, steelhead potentially can spawn over multiple years and are returned to the American River almost immediately after spawning at Nimbus.”
The CDFW also wrote that scientific data are collected before the fish are set free – measurements, scales and tissue samples – “to better understand and inform the management of the American River’s steelhead.”
The original run of steelhead on the American River on the American River was apparently larger in size than most other Central Valley stocks before Folsom Dam was built, according to my interviews with one of the few anglers who fished the river below the Nimbus Dam.
The less abundant winter steelhead would average around 7 pounds, while the more abundant spring-run fish that ascended the river and its tributaries from March through June averaged 3 to 6 pounds before the construction of Folsom Dam.
In the spring and summer, fly fishers fishing the North, Middle and South Forks of the American River would catch and release steelhead smolts, along with resident rainbow and brown trout, before Folsom Dam was finished, according to my interview with fishing expert Cliff Clifton, who fished the river in the 1940s.
However, after Nimbus Fish Hatchery was built, the native run of steelhead did not adapt well to the new conditions found on the river during the first few years after the completion of Nimbus and Folsom Dams. Several hundred fish returned each year to the hatchery — the CDFW wanted more fish to return.
The CDFW then brought Eel River-strain steelhead to replace the native strain on the river and those become the predominant strain of steelhead returning to Nimbus.
Those of us who fish the river in the spring from April to June have caught and released wild steelhead that could be the original strain of spring-run steelhead, but no genetic analysis of these particular fish has been ever done.