Record number of steelhead return to spawn during 2017-2018 season at Coleman National Fish Hatchery

More than  10,000 steelhead returned to Coleman National Fish Hatchery during the 2017-2018 season, nearly triple the largest return seen at the hatchery since roughly 3,600 steelhead returned during the 2014-2015 season. Credit: Laura Mahoney/USFWS

Unprecedented numbers attributed to California's back-to-back wet years

By Laura Mahoney
April 17, 2018

Unprecedented. That’s the word to describe the 10,000 steelhead that returned to Coleman National Fish Hatchery during the 2017-2018 season.

While dealing with the large return presented huge challenges for hatchery personnel, anglers will be happy to see the fish released into the Sacramento River after they have been spawned.

A steelhead trout jumps in the holding pond at Coleman National Fish Hatchery. Steelhead are the anadromous, or ocean-going, form of rainbow trout found throughout the Sacramento River system and its tributaries. Credit: Laura Mahoney/USFWS

Steelhead (Oncorhynchus mykiss) are the anadromous, or ocean-going, form of rainbow trout found throughout the Sacramento River system and its tributaries. The fish were listed as threatened under the Endangered Species Act in 1998.

The production of steelhead at the Coleman hatchery serves two purposes; to contribute to the sport fishery in the Sacramento River; and to provide an adequate return of adult fish back to the hatchery for broodstock. The hatchery fulfills both purposes while simultaneously minimizing impacts to naturally occurring populations.

Located on Battle Creek in Northern California, Coleman is the largest federal hatchery in California and was established in 1942 to mitigate habitat loss as a result of the construction of Shasta Dam. In a typical year, a couple hundred fish come back in October, with the number of returns gradually increasing each month through January.

In the past 10 years, the largest return seen at the hatchery was more than 3,600 steelhead during the 2014-2015 season. The hatchery harvests eggs from these returning fish and raises approximately 600,000 steelhead until they’re six to eight inches in length before releasing them back into the Sacramento River in early January.

“Keeping this many fish healthy and fed requires a lot of work from the hatchery staff,” said Ron Stone, a fish production biologist at Coleman National Fish Hatchery. Above, fish culturist Brad Carter moves steelhead out of the holding pond. Credit: Laura Mahoney/USFWS

The October 2017 return, however, was different from a typical year. Hundreds of fish began coming back each week and some weeks even saw returns of over 1,000 fish.

“I think the main reason for all of the steelhead returning has been the back-to-back wet years of 2016 and 2017 in California,” said Brett Galyean, project leader at Coleman. “In particular, the 2016 steelhead release occurred during a week in January that saw several storms sweep through Northern California.”

The high, muddy water of major storm events provide protection from predators as the released fish move downstream. 

A female steelhead that has been spawned is readied for release. Unlike Chinook salmon, adult steelhead that return to Coleman are kept alive after the spawning process. Credit: Laura Mahoney/USFWS

“Keeping this many fish healthy and fed requires a lot of work from the hatchery staff,” said Ron Stone, Coleman production biologist of the early season challenges. “One of the unknowns that we faced with such a large return was not knowing how many fish the facility would be able to hold in the pre-release pond. At one point, we had approximately 10,000 fish in there. We monitored dissolved oxygen levels and everything seemed to be fine.”

Large numbers of fish meant that extra staff were needed during fall Chinook spawning days because the steelhead entered concurrently with the Chinook salmon requiring special care to identify each fish.

Kelts are adult fish that have been spawned and are ready to return to the river or ocean. In early-April, after steelhead have been spawned and reconditioned (or having regained their strength), the adults are released into the Sacramento River system.

They may remain in the river or move into the San Joaquin-Sacramento Delta and out into the ocean.

Extra staff were needed at Coleman National Fish Hatchery during the Chinook spawning season because the steelhead entered the hatchery along with fall-run Chinook. Special care was taken to identify each fish.  Credit: Laura Mahoney/USFWS

Unlike Chinook salmon, adult steelhead that return to Coleman are kept alive during and after the spawning process. Coleman National Fish Hatchery has operated a steelhead kelt program since 2005.

“The kelt program is good for anglers and for the hatchery,” Galyean said. “Keeping the steelhead alive after they are spawned and reconditioning the fish before they are released back into the Sacramento River serves as an additional source of genetic material during the next spawning year and also helps increase the steelhead population numbers.”

Anglers hoping to land a steelhead in the Sacramento River in the spring may find their efforts rewarded if they hook into one of the thousands of fish released from the hatchery.

As for the staff at Coleman, having successfully met the challenges of dealing with such a large return of steelhead, they are now better prepared for similar runs in the future.

"We've implemented new ways to move fish from where they are held in the pre-release pond, new ways of marking fish to identify whether they were early returning or late returning fish, and a more regimented feed program both before and after spawning," Stone said.

 

For more information on the steelhead program visit the Coleman National Fish Hatchery website or call the hatchery Monday through Friday between 8 a.m. to 4 p.m. at (530) 365-8622.


Laura Mahoney is an information and education specialist for Coleman National Fish Hatchery, located near Anderson, California.