Although the number of chinook salmon returning to the Columbia River basin this year far exceeded the 10-year average, Snake River basin returns are continuing to decline for the fifth year in a row.
"The bottom line is that, relative to all the different stocks, we saw some do better than others," said Sharon Kiefer, Idaho Department of Fish and Game anadromous fisheries coordinator. "Unfortunately for Snake River spring and summer chinook, we saw another year of diminishing returns."
Kiefer said 29,586 chinook salmon crossed Lower Granite Dam, the last of eight dams the fish must navigate on their upstream journeys to Idaho, this year. Last year, the number was 32,764. That continues the fifth straight year of ebbing returns to the Snake River system and to Idaho.
Last week, the National Oceanic and Atmospheric Administration Fisheries Service announced that more than 67,000 summer chinook were counted passing Bonneville Dam, the first of the eight dams, between June 16 and July 31, beating the 10-year average for the same time period by 24,000.
Bob Lohn, head of the NOAA Fisheries Northwest Region, said improvements in the swift and safe passage of juvenile salmon through the dams are helping salmon recovery for the long term.
But Kiefer said the majority of the fish referenced by NOAA were not headed to Idaho. Most are genetically independent of Idaho fish and face many different lifecycle challenges.
"They're a totally different life history from our spring and summer chinook," she said. "They came in stronger than forecast. However, that did not translate into a run size improvement in 2006 at Lower Granite Dam over 2005 for our spring and summer chinook."
Kiefer said most of the chinook returning to the Snake River basin are jacks, fish that have spent only two years in the ocean. Because jacks constitute the majority of Idaho's returns, they are used as one of the primary barometers.
"We think we're probably going to see another decline again for next year because migration conditions in 2005, as well as ocean conditions in 2005, were not optimal."
But Fish and Game biologists are hoping to see improvement in 2008 because migration and ocean conditions this year were improved.
"But only time will tell," Kiefer said.
Meanwhile, sockeye salmon returning to the glacial lakes of the Sawtooth Valley are continuing years of abysmal return rates.
"We've trapped three" at the Sawtooth Fish Hatchery south of Stanley, Kiefer said.
The Salmon River basin naturally holds 70 percent of the potential reproductive habitat for salmon in the massive expanse of the Columbia River drainage. Historically, the waters of the Salmon, Middle Fork of the Salmon, South Fork of the Salmon and dozens of tributaries overflowed with anadromous fish—chinook, sockeye and coho salmon, as well as steelhead trout. Idaho's Snake and Clearwater rivers also hold secrets of historically potent runs.
But with dam construction in the middle 20th century, Idaho's once tremendous salmon populations slipped significantly.
The Snake River's coho salmon were declared extinct in 1985. In 1991, Idaho's sockeye salmon were found in need of Endangered Species Act protection and listed as endangered. Chinook salmon were similarly listed as threatened in 1992.
Sockeye, which spawn in lakes, always numbered fewer than chinook, which spawn in rivers, because the number of suitable lakes in Idaho is limited. In the decade of the 1990s, a total of 18 sockeye salmon returned to the Sawtooth Valley. Chinook salmon, which once returned to Idaho in the hundreds of thousands, now return each year numbering in the tens of thousands.
Federal agencies involved with salmon recovery are continuing to look at new ways to improve both juvenile and adult salmon migration and to monitor the effectiveness of measures such as spilling additional water over dams and barging juvenile salmon around them.
Because the benefits of this additional spill are still uncertain, the U.S. Army Corps of Engineers is conducting a number of studies during the spill to determine how best to operate the dams in a manner that aids fish survival.
For example, this summer, under the second consecutive year of court-ordered operations, federal dam operators have spilled additional water at the four Lower Snake River dams, and at McNary Dam on the Columbia River.