A total of 1,071 Snake River sockeye salmon spawners have completed their journey from the Pacific Ocean to central Idaho’s Sawtooth Valley, making it the second largest return since at least the 1950s.
Idaho Fish and Game biologists have kept a tally at a weir on the Salmon River at Sawtooth Hatchery near Stanley and at a trap on Redfish Lake Creek, a tributary upstream of the hatchery.
Sockeye returns have grown in recent years in large part due to the Snake River Sockeye Salmon Captive Broodstock Program, which was started in 1991 in hopes of preserving the genetic stock of a species approaching extinction. Late in 1991 Snake River sockeye were declared endangered under the Endangered Species Act.
Construction of the Sunbeam Dam on the Salmon River in 1913 blocked upstream fish passage. The dam was partially destroyed in 1934 reopening the upper Salmon River, but no one tried to restore the salmon runs, according to an IDFG fact sheet.
Between 1991 and 1998, only 16 wild sockeye returned to Idaho. All 16 wild fish, along with several hundred Redfish Lake wild juvenile outmigrants, and several residual sockeye salmon adults (fish that spent their entire life cycle in freshwater) were captured and used to develop captive broodstock at the IDFG’s Eagle Fish Hatchery and a NOAA Fisheries Service facility in Washington state.
In 1999 the first anadromous returns from the program, seven in all, were trapped in the Sawtooth Valley. Between 2007, a total 355 hatchery produced adult sockeye salmon returned to Idaho. That included one banner year, 257 in 2000. Over the previous 14 years, only 77 natural-origin sockeye returned.
The 2008 adult return was 650 and was followed by a total of 833 in 2009. The modern-day record came in 2010. That 2010 return is the largest since the 1950s.
The pulse of the sockeye run is measured 400 miles downstream at the lower Snake River’s Lower Granite. It is the eighth and final hydro project the fish pass on their way up the Columbia, Snake and Salmon rivers.
The top sockeye count since Lower Granite was completed in 1975 was 2,201 in 2010. This year’s count is 1,502 with the last two sockeye counted Sept. 3. Most of the fish passed the dam in July. Only 55 have been recorded in August and September.
Of the fish counted at Sawtooth Hatchery and Redfish Lake Creek, most were captured and transported to Eagle Hatchery near Boise for holding and genetic sampling. This week they took a three-hour ride back up to Redfish Lake for release so they can spawn on their own. A portion of the returning fish were trapped and sampled at Redfish Lake Creek and then allowed to proceed to Redfish Lake.
In all 1,519 returned, according to Dan Baker, Eagle Hatchery manager. Some swam there directly (those passed through the Redfish Lake Creek trap. Others included the anadromous fish that were trapped and held at Eagle and still others were captive fish that were reared at Eagle and a NOAA Fisheries facility in eastern Washington.
Through Tuesday a total of 938 adult anadromous sockeye had been accounted for.
Of that total 134 are “natural” fish, meaning they were born in the wild. They are the product of anadromous (fish that have gone to the ocean and back) fish that spawned in Redfish Lake, residual sockeye or from fertilized eggs outplanted in two nearby lakes, Alturas and Pettit.
The vast majority of the return are from migration-ready smolts released two years ago into the Salmon River at Sawtooth Hatchery or into Redfish Lake Creek.
Actual returns have slowed. The Redfish Lake trap was shut down Sept. 9. The Sawtooth Hatchery trapping rate over the past week has been from five to 15 fish.
But on Wednesday biologists held their annual “sockeye roundup,” donning snorkeling equipment to herd stalled fish into the weir near Sawtooth Hatchery. The one day’s haul was 120 more sockeye. Baker said that hatchery officials told him they have seen perhaps as many as 28 fish still in the river so another roundup is planned near month’s end.