Feds kill baby salmon
Strong salmon migration diluted by poor management
This fall’s return of chinook salmon was expected to be one of the larger spawning events in recent history. However, the great success of this year’s run, of which hundreds of thousands are believed to have spawned, has been compromised by a management disaster that state biologists believe may have killed up to 40 percent of the eggs produced by the fish.
To conserve water in the reservoir behind Shasta Dam, federal water managers drastically cut the dam’s outflow volume in early November, from more than 6,000 cubic feet per second to 3,750, leaving numerous salmon nests, or redds—each containing thousands of eggs—high and dry.
“We believe hundreds of redds, if not thousands, were lost,” said Doug Killam, an environmental scientist with the California Department of Fish and Wildlife.
The Bureau of Reclamation lowers the outflow through Shasta Dam most years—an action called “dewatering” the river. This helps to build up reservoir volume in Shasta Lake for use the following spring and summer, when Central Valley farmers need the most water for irrigation. However, there wasn’t enough rain this autumn to keep the Sacramento River flowing at full throttle after dewatering began. Thousands of salmon had already spawned, many of them in shallow riffles hardly a foot below the surface. Then, as the river level dropped, many redds full of fertilized eggs were exposed on gravel bars.
Louis Moore, a spokesman with the Bureau of Reclamation, says water must be stored in Shasta Lake to meet the needs of agriculture, industries and municipalities.
“But no one is making an operational decision without regard” for salmon, he said. That a great number of fish was lost “is really unfortunate.”
Killam noted that, even in a dry autumn, dewatering the river shouldn’t necessarily be a disaster for salmon.
“If you believe it’s going to be a dry year, you can lower the flow before the fish start spawning,” he explained. “That way, you’ve set a flow level that’s possible to maintain [for the three months it takes for the eggs to hatch].”
Dewatering is often done in September, just before the fall-run salmon begin arriving at their spawning grounds. But the feds dewatered later this year—well after fall-run salmon were already laying their eggs.
This, ironically, was an effort to avoid exposing the redds of endangered winter-run salmon, which usually spawn in June. But a small number of winter-run fish laid and fertilized their eggs in August. So river levels were held steady to keep the winter-run eggs submerged.
This amounted to a trade-off in which the fall-run redds were sacrificed.
Killam spends many days on the Sacramento River with assistants counting salmon redds, which appear to the eye as oval-shaped patches of disturbed gravel and overturned cobblestones. Redds can even be identified from low-flying airplanes, Killam says.
He estimates that about 20 winter-run redds were spared in the decision that cost such a great percentage of the fall run.
Fishing-industry representatives would like to see federal policies that give more priority to the fall-run fish. John McManus, the executive director of the Golden Gate Salmon Association, a Bay Area conservation group, said he believes the Bureau of Reclamation could have avoided destroying any salmon nests, period.
“They didn’t have to lower the river at all,” he suggested.
The fall run is the core of California’s commercial and recreational salmon fishery, worth an estimated $1.4 billion, according to fishing-industry representatives.
But because the fall-run chinook is not an endangered or threatened species, it is legal for water managers to incidentally destroy the fish if there is no way to avoid doing so. Causing the deaths of winter-run chinook is, by contrast, usually illegal.
“We’d like this to change,” said McManus. “We’d like the feds to be required to plan for the needs of [the fall-run chinook], just like they do for endangered species, for agriculture, for energy.”
Water releases from Shasta Dam are just one of multiple environmental factors that can affect the abundance of Sacramento River salmon. Using the river’s water to irrigate farmland has long been blamed as a reason that chinook-salmon runs have declined from historical highs. The Delta pumps near Stockton that remove this water take about 50 percent of the Sacramento’s volume per year, sending much of it to farms in the San Joaquin Valley. They can kill baby fish by drawing them into the pumps themselves, or indirectly, by diverting them into dead-end sloughs from which the fish never find their way out.
While environmentalists want officials to scale down water exports, the state is looking to ramp up its water diversion and conveyance system. On Monday (Dec. 9), state officials unveiled their Bay Delta Conservation Plan, a proposal to build two enormous tunnels that would boost the capacity to remove the Sacramento River’s water and send it south for municipal and agricultural use. Environmentalists have warned that the BDCP could cause the extinction of salmon, striped bass and sturgeon.
Eight months ago, another mishap in the Sacramento delivered a blow to chinook salmon. Several hundred winter-run adults, at the time migrating upstream to spawn, became trapped in a flooded field in the Sacramento and Delevan national wildlife refuges. The fish grew weak and ill over several weeks in the warm stagnant water before being discovered. Biologists managed to rescue more than 300, said Killam, who was involved in the response effort. Another 300 fish were observed but not captured.
Killam suggested those 600-plus salmon “were just a portion of the fish that were trapped in there.”
Many, if not most, of the rescued fish likely died before they could spawn, he said.
After the driest calendar year in state history and with cloudless skies stretching to the horizon, many of the egg-laden redds in the Sacramento River remain vulnerable. Moreover, the distinct late-fall chinook run is now beginning to spawn in shallow waters that could potentially become exposed by further reductions in the river’s volume.
Moore says the Bureau of Reclamation has the authority to lower the river level down to as little as 3,250 cubic feet per second—an action that he says will occur only if dry conditions persist. Killam and his team have recommended that the agency maintain current flow levels to support the surviving redds.
“But if they decide to drop the flows again, we’ll lose a lot more fish,” he warned.