Migrating Salmon Tackle Nature’s Obstacle Course
Move over American Ninja Warrior — These fit fish have you beat!
By: Julia Pinnix, Visitor Services Manager, Leavenworth Fisheries Complex
April is an exciting month at the hatcheries of Leavenworth Fisheries Complex in Central Washington. This is the time for releasing the young salmon and steelhead we have nurtured for the past twenty months. Every day, regardless of weather or other events, our production staff have cared for these fish. They feed them, clean their tanks and raceways, monitor the water flow and quality, drive off predators, and examine them for signs of health. Now they will release them into the river, hoping for the best as the smolts make their way downstream, into the Columbia River and out to the Pacific Ocean.
It’s a big, complicated world out there. The first challenge hatchery salmon face is the river itself. It’s an unfamiliar environment, with rocks and roots and hungry animals, compared to the quiet of the hatchery. As they adjust to their new environment, the smolts crowd together in schools, drawing the unwanted attention of birds and other predators. To encourage them to move on downstream, Mat Maxey, the manager of Leavenworth National Fish Hatchery (NFH), said they adjusted where the fish are released, piping them into the current so they quickly disperse. The hatchery also changed its timing, beginning releases in the afternoon and running into the evening, letting night cover the downriver migration. Any help we can offer increases the odds of survival for these vulnerable youngsters.
As they enter the Columbia River and move farther downstream, they encounter their first dams. Fish released from Winthrop NFH face nine of these obstacles en route to the Pacific. Smolts may school up near the dams, again making them targets for predatory birds and fish. Dam operators assist the smolts by hazing birds and providing juvenile bypass systems or direct spill to pass them around the turbines. In years when water levels are high, dam operators must carefully monitor the migrating smolts, as too much spill can supersaturate the water with air and cause fish to suffer from the “bends,” with gas bubbles forming in their tissues. The journey down the Columbia River to the ocean is full of danger for our local smolts. This roughly 500-mile journey takes, on average, about a month, and only about half survive.
But the even bigger test looms ahead, which only one in a hundred, if they’re lucky, will pass. Out in the ocean, a myriad of predators await. Fish from our hatcheries make their way up into the north Pacific, a gigantic salmon feeding ground spanning from the Aleutian Islands all the way to the eastern coasts of Japan and Russia. Here the juveniles feed on the rich resources of the sea and grow quickly. When they are released, they are the length of my hand; when they return two years later, they can be the length of my arm or even longer.
Not long after we release smolts from our hatcheries, the first adult fish will be returning. From April until the end of June, spring Chinook power their way upriver 497 miles to Leavenworth and 574 miles to Winthrop. Entiat NFH’s summer Chinook first appear at the hatchery in June and continue coming all the way into October, logging 490 miles. Steelhead from the Winthrop NFH enter the Columbia River in mid-summer (thus their official name “summer steelhead”), head up the Columbia River several hundred miles, then hold over the winter, until they make the final push up the smaller Methow River to spawn the following spring, some 9 or 10 months after entering the fresh water. All of them must navigate through the same dams they encountered on the way down, this time leaping step by step up fish ladders. Fish ladders are a series of small ponds, in essence, each pond a little higher than the last one, curving up and around obstacles to provide a way for fish to pass. Adult salmon and steelhead are highly desirable food for larger predators, from sea lions in the lower Columbia to bears in the upper reaches. Anglers and commercial fishers take a large share.
At Leavenworth, we usually let go 1.2 million smolt. How many fish come home out of the ones we release? About 0.5%, but that can be highly variable. Every year we hope for enough to spawn the next generation: 500 males and 500 females. Some years, there have been more than 13,000 returnees; other years, fewer than 1,000.
As I watch our young fish splash into Icicle Creek from the pipe that conveyed them out of their raceways, I wonder which ones will make it back to us. These tough little survivors are descended from a six million year-old line of successful salmon. I wish for them continued strength and luck.