[env-trinity] Researchers let striped bass off the hook for salmon decline

[Tom Stokely]

http://www.redding.com/lifestyle/outdoors/fishing/researchers-let-striped-bass-off-the-hook-for-salmon-decline-337c261c-1b64-7a21-e053-0100007fbddb-381113951.html


Researchers let striped bass off the hook for salmon decline
By Damon Arthur of the Redding Record SearchlightGetting rid of striped bass would not solve the problem of predator fish feeding on young salmon in the Sacramento River trying to get out to the ocean, according to University of California, Davis, researchers.The proposal to eliminate striped has persisted for years, but it won't work, said Peter Moyle, a professor emeritus at UC Davis. He said there are better ways to ensure young chinook salmon — with one run teetering on the brink of extinction — make it out to the ocean.Get rid of striped bass and another predator will move in and take its place, Moyle said."It's the law of unexpected consequences," Moyle said in a phone interview.Moyle and four other Davis researchers posted a story titled "Understanding predation impacts on Delta native fishes" this week on the California WaterBlog. The blog looks at the effects of predation on salmon and other fish, such as the Delta smelt and longfin smelt living in the Delta and tributary rivers such as the Sacramento.Moyle said in an interview they wrote the blog because the proposal to eradicate the striped bass continues to persist. There are bills in Congress this year that would target non-native predator fish, including striped bass.In 2012 the California Department of Fish and Wildlife recommended tripling the catch limit and reducing the size limit for the bass, but the state Fish and Game Commission rejected the plan.While the striped bass is not native to the Delta or the Sacramento River, they have lived alongside salmon for the past 150 years, enough time for them to adapt to living together, the blog says.The bass live in the ocean, but migrate up rivers to spawn. They once spawned as far north as Red Bluff. But with the removal of the Red Bluff Diversion Dam on the Sacramento River, anglers and others say the stripers have moved north of Red Bluff.Rather than blame the bass for the decline of salmon in California, the report offers several other proposals to increase salmon survival, including habitat improvement and changing the way salmon are raised and released from hatcheries.John McManus, executive director of the Golden Gate Salmon Association, said the biggest problem for little salmon migrating to the ocean is the lack of safe places for the fish to live in.Before people built dams, roads, bridges, canals, pumping plants and channelized the river, there were many smaller side streams, pools and areas shaded by trees and shrubs where little fish could dart into and hide from predators.He likened it to a cottontail rabbit hopping into a thicket of bushes to get away from a fox. But many of the river's safe places have been removed, he said."We have so altered the system that those hiding places are no longer there," he said. Instead, conditions in the river are now more favorable to predators than the prey, he said.Moyle and other Davis researchers also recommend giving fish routes around areas of the river that are "hot spots" for predators.Increasing flows in the Sacramento River and sending water and young salmon through the Yolo Bypass near Sacramento would help the fish get around areas in the river where there are higher numbers of predators, according to the blog.The report also suggests changing fish hatchery release practices so fingerling salmon aren't dumped in large numbers, which attracts predators.Releases should be timed with heavy rain that turns water muddy, providing cover for young fish, the report says.Hatchery fish are raised in concrete troughs and fed "food pellets raining down from above. This does not give the fish much chance to learn how to avoid predators," the report says."It is scarcely surprising that predators take advantage of these naïve and fat-laden prey, gorging themselves," the blog says.Brett Galyean, acting project leader at Coleman National Fish Hatchery near Anderson, said some fish hatcheries have self-feeders that help fish remain wary of predators. They aren't used at Coleman, though.The hatchery annually releases about 12 million fingerling fall-run chinook salmon.This year the hatchery experimented with releasing fish earlier in the year when Battle Creek and the Sacramento River was running higher and the water was muddier from rain.Galyean said they also try to time April releases with storms, but if no storms are in the forecast, the fish have to be released because they get too large and they can't be held indefinitely.Over the past couple decades federal and state officials have been working to meet the goals of the Central Valley Project Improvement Act to double the number of salmon in the Sacramento River.But the act also requires fisheries agencies to double the number of striped bass. That may be changing, though.The same congressional bill that targets removal of striped bass in some California streams also proposes removing salmon from the list of fish whose numbers need to be doubled.
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