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Commentaries and editorials

Managing Salmon Survival

by John McKern
Columbia Basin Bulletin - April 25, 2003

Thanks to CBB for allowing Mr. Masonis and me to continue our discussion of the Columbia River salmon controversy.

If 97 percent of Snake River fall chinook spawned above the Hells Canyon Complex, then 3 percent spawned downstream (probably less than 1 percent in the lower Snake River). With the cool water releases from Dworshak Reservoir and breaching of the lower Snake River dams, spawning may increase in the lower Snake River. However, so long as water coming down from Hells Canyon exceeds 77 degrees F in late summer, it is unlikely that the reproductive potential would come any where near that above the Hells Canyon Complex.

I would certainly support restoring fall chinook, and other salmon and steelhead runs above the Complex. In the late 1980s, I was a member of a steering committee assembled by the U.S. Fish and Wildlife Service to study that exact possibility. Unfortunately, Senator McClure was not re-elected, and funding ended before the study could proceed beyond the reconnaissance level. Nonetheless, the USFWS published some workable alternatives that could have restored fish runs to available habitat.

In the 1970s, I worked on stream rehabilitation projects for the Corps on Pine Creek and Eagle Creek in eastern Oregon. Pine Creek enters the Snake River below Oxbow Dam, and Eagle Creek flows into Brownlee Reservoir. Due to irrigation diversions, both are substantially depleted in the summer, but both have potential for salmon and steelhead production. Unfortunately, other dams blocked many other tributaries before the Hells Canyon Complex was constructed so historic spawning levels could not be reached.

With regard to removal of the lower Snake River dams "substantially reducing mortality associated with passage through the hydropower system," recent research that was not available to the crafters of the Biological Opinion shows that mortality in the hydropower system has been substantially reduced.

University of Idaho studies of adult salmon survival indicate that survival per project is over 97 percent. Travel speed through the reservoirs is faster and energy expenditure is less than in the free-flowing river. NOAA fisheries estimate juvenile spring/summer chinook in-river survival was 0.4 percent in 1977, the worst drought year of record. In 2001, the second worst drought year, survival was 27 percent through the hydropower system. By my math, that is 67.5 times better survival due to improvements at the dams.

In better flow years, in-river survival has been as high as 60 percent within the last 5 years. Add in the fact that 80 to 90 percent of the fish are transported at 98-plus percent survival, and overall survival of Snake River spring/summer chinook often exceeds 90 percent. Breaching the dams would do away with transportation reducing overall survival to a maximum of 75 percent, 15 percent less than it is now.

Mr. Masonis has likened my analysis to the "blind man touching the elephant," and does not consider me to be a scientist due to my "flawed, but nonetheless popular, diagnosis of the problem." Impaired as my scientific ability may be, it seems that even a blind man could see that both adult and juvenile salmon survival through the lower Snake River dams has substantially improved significantly since the 1970s.

Mr. Masonis claims that the dams and reservoirs have degraded water quality and allowed predators to increase. For many years I supervised employees who monitored the water quality, and was involved with the daily reporting of river temperatures related to adult fish passage. Records show that the Snake River reached 83 degrees F near Pasco. After Ice Harbor Dam was completed, the maximum temperature was 77 percent F.

As additional dams were completed, records show that hot water coming out of Hells Canyon and the Clearwater stayed hot as it progressed downstream through the reservoirs. No appreciable warming was caused by the reservoirs. Water temperatures at U.S. Geological Service gages in the Snake River showed temperatures up to 78 degree F and hatchery personnel at Dworshak National Fish Hatchery have reported temperatures above 80 F in the main Clearwater River above the mouth of the North Fork.

Cold-water releases from Dworshak Dam on the North Fork have substantially cooled the lower Clearwater and effects have been recorded all the way down to Ice Harbor Dam. Recent maximum summer temperatures have usually been below 70 degrees F. Since the cold water tends to stay lower than warm water, the cold water releases from Dworshak provide a "cold water refuge" many times (nearly 140 miles) greater than the few deep holes that were present before the dams. I know of no recorded data that shows those "refugia" existed or were used by Snake River salmon in the pre-dam era.

I do know that there is substantial information that shows that fall chinook hold up in the colder (typically 5 to 7 degree F) Columbia River just below the mouth of the Snake River. If recent studies by University of Idaho researchers who have radio-tracked salmon and steelhead use of cold water refugia in the lower Columbia and lower Snake River reservoirs are any indication, it was probably a natural occurrence in most years for fall chinook to hold in the Columbia until the Snake River cooled off enough for them to continue upstream.

In the 1970s, the overriding concern in the region was solving the gas supersaturation problem in the lower Snake and Columbia Rivers. Additional storage reservoirs in the Columbia Basin, installation of additional turbines in the dams to reduce spill, and installation of spillway deflectors to reduce supersaturation, pretty much solved the problem. The states and Environmental Protection Agency established 110 total dissolved gas percent standards that could be met except for short periods in high flow years when spring runoff was higher than the dams could pass without higher gas levels.

Then the fishery agencies decided that mass spill was the best way to get fish downstream. In spite of the research that went into establishing the standards, and the advice of scientists who conducted the research, the fishery managers decided that they could run the river at 120 percent supersaturation. The hydropower managers acquiesced to the demands the National Marine Fisheries Service and spilled to the "gas cap."

While it is true that in this instance the dams degrade water quality, it is ironic that the dam operators have to do this at the demand of the NMFS in an effort to comply with the Biological Opinion that is supposed to be "reasonable and prudent." Some might conclude that the mass spill program reduces system survival by keeping more fish in river at less than 60 percent survival instead of allowing them to be transported at over 98 percent survival.

Perhaps I was not clear in my recommendation for fertilization in the ocean. Most people jump to the conclusion that I mean the whole ocean or a substantial area of the ocean. My point is that if individual salmon stocks migrate to specific areas such as a particular fjord to rear, it may be possible to aid that stock by fertilizing a small area. If, for example, there is a herring fishery in that fjord, it may be that curtailing that localized fishery could substantially increase the survival of that salmon stock. I have fished for chinook in fjords in British Columbia without streams that would support spring chinook. However the spring chinook migrate several miles out of their way to feed in these fjords on their return to their home stream. Perhaps they reared in those areas during part of their juvenile ocean life. With the sophisticated equipment they now have, commercial fishermen can "mine out" the forage base like hearing in a matter of hours.

Many times I have commented on how much further ahead British Columbia researchers are in the knowledge of ocean survival and where juvenile salmon go to rear. I have commented on how smolt-to-adult return rates from un-dammed rivers have plummeted like those from some Columbia River tributaries. A century ago our fishery managers did not recognize that fish runs divided into individual stocks that returned to individual streams to spawn. It took several more decades for them to recognize the need to manage harvest to protect weak stocks. To my way of thinking, not gathering the knowledge of where fish go and how they rear in the ocean, and not managing the whole life history of the fish may be the greatest threat to the threatened and endangered salmon. I have not seen much evidence that our fishery researchers and managers are even interested in furthering this area of knowledge.

John McKern, Fish Passage Solutions, 1444 Lowell Drive, Walla Walla, WA 99362-9331, (509) 525 6283
Managing Salmon Survival
Columbia Basin Bulletin, April 25, 2003

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