field trip!
Little Kenny goes on assignment to see what’s jumpin’ at the Oroville Fish Hatchery. By MaryRose Lovgren
The story of the salmon, like that of Cinderalla, is a classic tale of transformation. From small
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growing up chico magazine
pumpkin-colored egg it morphs into a silvery ocean swimmer, who, when visited by some fairy godmother of a biochemical reaction, rushes to find its mate before time runs out. Lucky for us in Butte County, we have direct access to this ancient love story right in our back yard. The Oroville Salmon Fish Hatchery, a mitigation byproduct from the building of Oroville Dam, is a wonder of modern engineering and foresight. Built with education in mind, it is also a wonderful place to see the process in action. One misty morning last spring
I tracked down Steve Brightwell, of the Department of Fish & Game, for a detailed background on salmon. You can easily imagine the tall Brightwell in the great outdoors-- with his dark brown beard and solid frame-- but right now, we are in the confines of his office, where he obliges my many questions about the salmon circle of life. Salmon, Brightwell begins, are what are called “anadromous” fish: their
life cycle includes time spent in both fresh and salt water. “When they hatch, they imprint on the water supply and there’s something that goes on inside their mind that they remember that supply. They’ll go out into the ocean. After three years, they’ll come back into the bay and they’ll pick up that chemical signature of Feather River water in the bay and they’ll follow it upstream to the Feather River.” But just how, exactly do they remember where to return? “(Scientists)
color change here as well, for the salmon go from the bright silver that they donned in the ocean to the darker olive greens or even reds that you see at the Hatchery. There is one big difference, however-- “once they enter fresh water,” Brightwell warns, “it’s basically a race with death to spawn before they die!” This pivotal journey upriver has one goal in mind: to find the right spot to lay and fertilize the female’s eggs. “When they get ready to spawn, they move up current, and try to get upstream
“Once they enter fresh water,” Brightwell explains, “they undergo physiological changes: they quit eating, they re-absorb their digestive system, and live off that as well as the body fat they’ve stored up. They basically digest their own digestive system.” Ewwww.
know it’s basically sense of smell-- each water has a slightly different chemical makeup. How they can pick that out of all the other ones flowing together, that I don’t know!” In any case, some internal biological trigger is pulled, and a countdown begins. “Once they enter fresh water,” Brightwell explains, “they undergo physiological changes: they quit eating, they re-absorb their digestive system, and live off that as well as the body fat they’ve stored up. They basically digest their own digestive system.” Ewwww. This process might remind you of another great transformation in nature: that of the caterpillar to the butterfly. And like that story, there is a
and into areas where there’s inch and a half-sized gravel, and they lay their eggs in the gravel. They use their fins to blow out any silt that’s in there, and lay their eggs down in the cracks.
Meet Your Tour Guide John Ford seems particularly suited to his work-- with a booming voice and a Mark Twain-like moustache, his imposing presence is tempered with humor and a clear fascination with his job. As tour coordinator for the Oroville Field Division of the Department of Water and Power, Ford provides interpretation on the water project facilities (like the dam), as well as orchestrating all the Hatchery tours. “Most people tend to take for granted the infrastructure that gives us quality of life: water and power. At least in today’s society, most people don’t have a real understanding of how they get water out of the faucet, a light to turn on, or the TV to work. Throughout my career, that’s been really neat to show them a facility like this.” Ford is particularly proud of the foresight that went into the building of the Oroville Dam. “One of the things that they did at that John Ford shows off the Hatchery’s rack time that was ‘out of the box’ was to give the Hatchery and the mitigasystem for incubating eggs. tion effort as much support as they could. I personally look at that as being pretty amazing.” The Hatchery, which is part of the State Water Project facilities, was constructed from 1965-1967, while the fish barrier dam, which redirects the Chinook salmon and Steelhead trout to the Hatchery, was completed in 1962. According to Ford, achieving success for the fish involved three phases. First, the hatchery needed to have a large capacity, as “one hundred years of gold mining and eighty years of logging and building dams in the watershed had taken its toll on fish numbers.” Secondly, a temperature-control system, revolutionary in its design at the time, was needed to provide optimal conditions for the raise of baby fish, or “fry,” as well as to provide hatchery personnel some predictability to monitor that process of hatching eggs and raising fish. Finally, the weirs (small board dams) in place all along the river, which provided a place for irrigation water to pool, had to be removed in order to provide places for spawning. The Thermolito Afterbay was therefore designed to hold and deliver agricultural water separate and off stream of the river channel, relieving the need for these weirs. “Now, you have a large population of fish that spawns naturally in the downstream portion of the river.”
“After they’re fertilized, they cover them back over with gravel to keep the eggs confined and away from predators, but more because the eggs go through a tender stage where if they’re floating free in the current, they’ll bounce into stuff which will kill them.” Spawning salmon may be found from the Hatchery downstream all the way to Gridley-- wherever the conditions, from gravel size to water flow, are just right. Seven out of every ten salmon spawn in the Feather River. The smaller minority who continue upstream are halted by the diversion dam, where these over-achievers may enter the fish ladder that leads them to the Hatchery. In the wild, some will stray and spawn in a different system. “That’s Nature’s way of keeping the genetic diversity there,” as well as ensuring survival of the species, explains
Brightwell. “If something catastrophic happens, such as when Mount St. Helen’s blew, it totally devastated that river system. For about ten years, there were
no fish there, and they started showing back up again from strays that came in from other systems, and now they have a salmon run in that river system again.”