Snake River Sockeye Recovery On Track This Year; 120 Trapped Fish Of Natural Origin
The pulse of the Snake River sockeye salmon recovery effort remains strong this year with a total of 738 sockeye salmon spawners -- so far -- having found their way up 900 miles of the Columbia, Snake and Salmon rivers to central Idaho’s Sawtooth Valley.
All of those fish were trapped either at Sawtooth Hatchery near Stanley or in nearby Redfish Lake Creek by Idaho Department of Fish and Game biologists. Most of the fish were trucked three hours south to Eagle Hatchery near Boise for holding.
But as they did for the first time last year, biologists have released some the fish back into either the creek or Redfish Lake so they could continue their spawning mission.
And the return continues. A total of 23, 32, 28 and 18 sockeye were trapped, respectively, on Monday, Tuesday, Wednesday and Thursday. Eagle Hatchery manager Dan Baker said the final 2011 count could approach 1,000, which would be the second highest total in modern history.
The Snake River sockeye population very nearly winked out when between 1991 and 1998 when only 16 wild sockeye returned to Idaho. In 1991, just a few months before the stock was listed as endangered under the Endangered Species Act, the Snake River Sockeye Salmon Captive Broodstock Program was launched in an attempt to save genetic materials and ward off extinction. Those 16 wild fish, 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 broodstocks 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.
But returns began to pick up in 2008, likely aided by favorable freshwater migrating conditions and a favorable ocean, as well as an emphasis on the rearing and release of migration-ready smolts. The smolt-age fish had proven to produce better adult returns than other release strategies such as the outplanting of fertilized eggs and/or pre-smolts.
The 2008 adult return was 650 and was followed by a total of 833 in 2009 and 1,355 in 2010. That 2010 return is the largest since the 1950s. 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.
The 2011 sockeye return is probably close to running its course. The peak count at Lower Granite Dam was 110 on July 14 but since then the daily totals have been declining with the last double digit total, 10, on Aug. 1. A single fish was counted Tuesday to bring the seasonal total to 1,500.
That’s the second highest total recorded since the dam’s construction was completed in 1975. The highest total was 2,201 in 2010.
The lower Snake River’s Lower Granite, located about 400 river miles downstream from Sawtooth Hatchery, is the eighth and final hydro project the fish hurdle on their way upstream.
The IDFG is holding 457 sockeye spawners at Eagle, where they are evaluated to determine which, genetically, best fit the needs of the broodstock program. About 100 will be used in hatcheries to produce a new generation, Baker said. The rest will be trucked back up to the Sawtooth Valley this month and released into Redfish Lake so they can spawn naturally.
About 300 other returning sockeye were trapped at the Sawtooth Hatchery weir or in Redfish Lake Creek, checked for identifying marks or tags and released. Biologists also took genetic samples from the fish and determined whether the fish were male or female.
Of the fish trapped far, 120 were determined to be of natural origin, produced by anadromous or residual spawners, or originated from outplanted fertilized eggs.
The fish released in September will spawn in October. Their progeny will migrate to the ocean in May 2013. Most of the adults produced from this year's release will return to Idaho in August 2015.
The great majority of the returning sockeye are the result of smolt releases at Sawtooth Hatchery or in Redfish Lake Creek. The smolts were reared at either Sawtooth or Oxbow Hatchery near Cascade Locks, Ore. All are marked with clipped fins or/and identification tags.
The broodstock project cooperators include the IDFG, NOAA Fisheries, Oregon Department of Fish and Wildlife, Shoshone-Bannock Tribes, and the Bonneville Power Administration.
Draft ESA delisting criteria for Snake River sockeye salmon includes the return of 1,000 adults to Redfish Lake, 500 adults to Pettit Lake, and 500 adults to Alturas Lake for two generations. The interim abundance targets must be met without relying on hatchery production, but on natural origin adults.
The IDFG has proposed construction of a sockeye hatchery that would have enough space to rear up to one million smolts. There is currently only enough space available to rear about 200,000 smolts. Increased smolt release should boost adult returns.
From The Columbia Basin Bulletin at www.cbbulletin.com