The No-shows are the Hatchery B-run Steelheadby Staff
The Idaho Statesman, October 17, 2003
Biologists are puzzled about why fish aren’t returning from the ocean
LEWISTON -- Thousands of steelhead a day are pouring past Lower Granite Dam west of Clarkston and finning their way to rivers in Idaho, Oregon and Washington.
Anglers are clogging the rivers in similar numbers.
The only no-shows, or more accurately half-shows, are the behemoth hatchery B-run steelhead.
A preseason forecast called for about 26,000 hatchery B-run steelhead to return to the Clearwater and Salmon rivers. So far the number of big steelies counted at Bonneville Dam on the Columbia River has been a disappointment, and the run there is nearly done.
“Overall, we are looking at about half as many hatchery B´s coming back,” says Bill Horton, anadromous fish coordinator for the Idaho Department of Fish and Game at Boise. “They just didn´t come over Bonneville Dam.” An anadromous fish is one that lives part of its adult life in saltwater but that spawns in fresh water.
Bonneville Dam is the first in a series of eight federal dams on the Columbia and Snake rivers that steelhead must pass on their return trip from the ocean. Lower Granite Dam is the last.
A-run steelhead typically spend one year in the ocean and return to the Salmon, Snake, Grand Ronde and Imnaha rivers. B-run steelhead typically spend two years in the ocean and return to the Clearwater River. A small number of B-run steelhead also return to the Salmon River.
Just what happened to the hatchery B´s is a bit of a mystery.
The wild B-run steelhead have returned about as predicted. Last year, a large number of jack B-run steelhead, 400, returned to Dworshak National Fish Hatchery at Ahsahka.
Fisheries managers use the number of jacks, salmon and steelhead that return a year early to predict run sizes. When many jacks return, it normally means many adults will return the following year.
Looking at the spring chinook run provides another clue.
In the spring, biologists expected and saw an excellent run of spring chinook. But their prediction was helped in part to a huge return of chinook that spent three years in the ocean.
These so-called three-salt fish are the hardest to predict and are often considered a bonus. The bonus turned into a blessing this year after the run of chinook that returned after the usual two years failed to materialize to any significance.
The first place to look for the cause is the disastrous out-migration conditions of 2001. That was a record low-water year, which this year´s B-run steelhead and two-salt chinook had to endure on their trip to the sea as youngsters.
Many biologists argue that the volume and velocity of water available to fish when they swim the Snake and Columbia rivers to the sea are among the most important factors to their survival.
Just as important are the foraging conditions in the Pacific Ocean. The ocean took a turn for the better starting about 1998 and is said to play a critical role in the good returns of hatchery salmon and steelhead the past four years.
That is what makes 2001 so interesting.
The ocean was good but the river flows were terrible. The conditions seemingly set up the mother of all empirical experiments.
Is it really the ocean that is responsible for good and bad fish returns? Or do river flows and the system of hydroelectric dams that slow the flow, especially in low-water years, make the difference?
The results of that experiment are nothing if not confounding.
There is still one year of returns left to count, so most fisheries biologists, scientists that they are, want all the evidence before they formulate a conclusion.
Two years ago, fisheries agencies tried to capture and barge as many juvenile fish through the river system as possible. Hatchery steelhead, the hardiest of all fish when it comes to the rigors of barge transportation, have not returned in the numbers expected.
But last year plenty of jacks returned, so they apparently fared well.
Add fall chinook to the mystery.
So far this fall, nearly 10,000 fall chinook have returned past Lower Granite Dam, far above the 10-year average of 3,039. And juvenile fall chinook migrate later in the summer than spring chinook and steelhead.
So back in 2001, young fall chinook on their way to the ocean faced slower, warmer water than steelhead and spring chinook.
And wild B-run steelhead have returned on target, though their numbers remain small. Only about 4,000 are expected.
The return of two-salt spring chinook was dismal, but part of that can be chalked up to the number of juveniles released in 2001. Fewer were produced that year, so fewer returned.
So what gives — ocean or river? It´s one for the ages.
This year´s return gives limited ammo to both those in favor of breaching dams to save fish runs and those who say fish and dams can coexist.
Breachers and supporters of using water to push the young fish can argue warm water moving slowly through the federal hydro system causes more harm to fish than a bountiful ocean can cure.
And dam backers, as well as those who are against using water to help fish, can counter that if the dams or low flows were responsible for the lethargic return of spring chinook and steelhead, they did not for some reason hit fall chinook, wild steelhead and hatchery B-run jacks as hard.
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