Massive Loss of Endangered Winter Run Salmon
Perhaps half of this years spawning class die in irrigation ditches: survivors
hammered by mismanagement of Shasta cold water reserves
During April, May and early June, large numbers of endangered winter-run Chinook salmon and other species were drawn into channels in the Yolo Bypass and Colusa Basin and died, according to reports by California Department of Fish and Wildlife (CDFW) and National Marine Fisheries Service biologists (NMFS). The total number of stranded fish is unknown but agency biologists said it could be as high as half of this years returning population of winter-run. This tragedy is exacerbated by high temperature stress on spawning winter-run caused by mismanagement of limited cold water pools in Shasta Reservoir this year.
State and federal fish agencies have known and documented for almost two decades that up-migrating endangered and threatened fish on the Sacramento River, including winter-run, spring-run Chinook salmon, steelhead and green sturgeon are drawn into the irrigation and drainage waterways of the Yolo Bypass and Colusa Basin from which there is no exit and are trapped. Excepting sporadic rescue efforts, little has been done to address this longstanding problem.
This is an indefensible failure to protect species hovering on the brink of extinction, said Bill Jennings, executive director of the California Sportfishing Protection Alliance. The fact that our fishery agencies have long been aware of this problem but done little to correct it is appalling and borders on criminal culpability, he said especially, when there are obvious and workable solutions.
Large numbers of salmon were identified in the maze of creeks and canals in the Colusa basin west of the Sacramento River. More than 300 fish were rescued from Hunter, North Fork Logan and Stone Corral Creeks, Colusa Trough and Delevan National Wildlife Refuge and returned to the Sacramento River. Because of their degraded condition, there was concern that these fish would not successfully spawn. Stranded salmon were also observed in other creeks, including Willow and Funks Creeks, the main stem of Logan Creek, Provident Main Canal and the North East Drain but no rescues were attempted. Members of the public reported salmon at other locations but CDFW staff were not able to get around to them.
Its a recurring problem. For example, in 2011, NMFS biologists rescued more than 200 listed green sturgeon, spring-run Chinook salmon and steelhead trout from the Yolo and Sutter bypasses. Many others were not rescued and perished.
Measures to address stranding in the bypass were proposed by the Anadromous Fisheries Restoration Program in 1995, by the CalFed Record of Decision in 2000 and by the NMFS OCAP Biological Opinion in 2009, among others, and all we have is yet another proposal for a band aid solution they hope might be in place by 2017, said Jennings, adding winter-run salmon may be cavorting with passenger pigeons by then.
Winter-run salmon have been hard hit with a double whammy this year. The State Water Resource Control Board recently gave the Bureau of Reclamation permission to move the temperature compliance point for Shasta cold-water releases on the Sacramento River from Red Bluff upstream to Anderson, eliminating 10 miles of the 20 miles of available spawning habitat for winter-run salmon. Beginning in September and October, Spawning fall-run and threatened spring-run salmon will also be hammered by high temperatures. The cold-water pool behind Shasta Dam has been seriously depleted by demands to export water to south-of-Delta farmers. Water exports are averaging more than 17,400 AF daily.
Historically, more than 200,000 adult winter-run salmon returned up the Sacramento to spawn and numbered more than 117,000 as recently as 1969. Shasta Dam eliminated the majority of historical spawning habitat and their numbers plummeted to around 200 fish by 1991. They were listed as endangered in 1994. Adult winter-run salmon numbered 1,533 fish in 2010, increasing slightly to 2,529 in 2012.
Runoff from a million acres of farmland in the west Sacramento Valley drains into the Colusa Basin Drain. Augmented by rainfall, this water either discharges into the Sacramento River at Knights Landing or it flows via the Knights Landing Ridge Cut into the Yolo Bypass and ultimately discharges into Cache Slough and the Delta. Up-migrating fish that are attracted into the Bypass and Colusa Basin are stranded and perish because there is no exit.
CSPAs fisheries consultants believe it is necessary to establish screens or barriers that will prevent up-migrating salmon from entering the Toe Drain and/or Colusa Drain during critical migration periods. During high flow events when Sacramento water is spilling at Fremont Weir into the Yolo Bypass, a conveyance system must be constructed to enable fish to cross Fremont Weir back into the river. At all times, salmonids, sturgeon and steelhead must be prevented from entering Ridge Cut into the Colusa Basin.
Similar problems exist on the eastside of the Sacramento at the Moulton, Colusa and Tisdale weirs in the Sutter-Butte Basin where fish were also reported stranded this year but no rescues were attempted.
Further information on the problem, this years rescue operations and source material on the agencies long-existing awareness of the problem can be found at: www.calsport.org.