CA Delta Water Exports driving fish to extinction
Posted: Mon Feb 16, 2009 2:17 pm
Says National Marine Fisheries Services
http://www.calsport.org/2-13-09b.htm#...(Continued
1. In the Upper Sacramento, high water temperatures have been a major contributor to spawning and egg mortality. The cause relates to too little carry-over water in Lake Shasta to be used in late summer and early fall to support returning fish. Water is over-committed downstream and the impact is complicated by the reductions of diversions from the Trinity River, as directed by the Federal Court. The Trinity must now get at least 40% of its
historical flows, which has reduced cold water diversions into the Sacramento. One study puts the egg loss of Fall Run fish at 10% because of these conditions. High water temperatures also cause major losses of steelhead in the American River.
2. The loss of juveniles between the Upper Sacramento River and the Delta is staggering. Only 20 % of the fish make it to the Delta from Red Bluff. The Red Bluff Dam was cited as one major contributor to these losses. Delayed migration, stress going through the dam and high predator mortality below the dam were cited as primary factors.
3. The Delta also exhibits staggering losses. Indirect losses in the Central Delta were found to be far more significant than losses from direct impingement at the state and federal pumps. With the cross channel gates open at the head of the Delta it was determined that 65% of the juveniles perish as they are drawn into the Delta interior. When the gates are closed, more than 50% survive.
4. At the pumps themselves, only 16.5% of the juveniles survive at the state facility and only 35% survive at the federal pumps. Once fish are pulled into Clifton Court Forebay nearly all of them are lost. The net total loss in the Delta is approximately 60% of the fish entering the system. This number does not include those lost prior to getting to the Delta.
5. Endangered steelhead survival out of the San Joaquin is near zero. Flows and predation are major problems. Much of the complication for the San Joaquin out migrants is the negative flows in Old and Middle River. Fish are unable to move to the North Delta because of these southward moving flows.
Overall, when the Sacramento River survival of 20% is combined with the Delta survival of 40%, only 8% of the smolts make it to the West Delta. It is obvious why the runs have crashed.
The conclusions of these studies are grim. The conclusions are significant alone but when combined with the losses of historic habitat for the salmon, toxicity problems, droughts, climate change, variable ocean conditions and all other stressors, the Central Valley calls out for a complete overhaul. There is no question that several runs are headed to extinction. The endangered Winter Run recovered to 15,000 returning spawners in 1995 but in 2008 dropped back to only about 3,000 fish. At the current levels, the run is not
replenishing itself.
http://www.calsport.org/2-13-09b.htm#...(Continued
1. In the Upper Sacramento, high water temperatures have been a major contributor to spawning and egg mortality. The cause relates to too little carry-over water in Lake Shasta to be used in late summer and early fall to support returning fish. Water is over-committed downstream and the impact is complicated by the reductions of diversions from the Trinity River, as directed by the Federal Court. The Trinity must now get at least 40% of its
historical flows, which has reduced cold water diversions into the Sacramento. One study puts the egg loss of Fall Run fish at 10% because of these conditions. High water temperatures also cause major losses of steelhead in the American River.
2. The loss of juveniles between the Upper Sacramento River and the Delta is staggering. Only 20 % of the fish make it to the Delta from Red Bluff. The Red Bluff Dam was cited as one major contributor to these losses. Delayed migration, stress going through the dam and high predator mortality below the dam were cited as primary factors.
3. The Delta also exhibits staggering losses. Indirect losses in the Central Delta were found to be far more significant than losses from direct impingement at the state and federal pumps. With the cross channel gates open at the head of the Delta it was determined that 65% of the juveniles perish as they are drawn into the Delta interior. When the gates are closed, more than 50% survive.
4. At the pumps themselves, only 16.5% of the juveniles survive at the state facility and only 35% survive at the federal pumps. Once fish are pulled into Clifton Court Forebay nearly all of them are lost. The net total loss in the Delta is approximately 60% of the fish entering the system. This number does not include those lost prior to getting to the Delta.
5. Endangered steelhead survival out of the San Joaquin is near zero. Flows and predation are major problems. Much of the complication for the San Joaquin out migrants is the negative flows in Old and Middle River. Fish are unable to move to the North Delta because of these southward moving flows.
Overall, when the Sacramento River survival of 20% is combined with the Delta survival of 40%, only 8% of the smolts make it to the West Delta. It is obvious why the runs have crashed.
The conclusions of these studies are grim. The conclusions are significant alone but when combined with the losses of historic habitat for the salmon, toxicity problems, droughts, climate change, variable ocean conditions and all other stressors, the Central Valley calls out for a complete overhaul. There is no question that several runs are headed to extinction. The endangered Winter Run recovered to 15,000 returning spawners in 1995 but in 2008 dropped back to only about 3,000 fish. At the current levels, the run is not
replenishing itself.
