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Debate swirls over striped bass role in rivers’ salmon population

Sampling Salmon on Stanislaus River

Trapping and measurement of juvenile fish helps in assessing how they are doing on rivers heavily used by farms and cities. Work was done near Oakdale, California, on Wednesday, April 6, 2016.
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Trapping and measurement of juvenile fish helps in assessing how they are doing on rivers heavily used by farms and cities. Work was done near Oakdale, California, on Wednesday, April 6, 2016.

The trouble with striped bass started, the story goes, when 132 of the East Coast natives traveled by train to California in 1879.

The fingerlings in the tanks were planted near Martinez and multiplied into a thriving fishery in San Francisco Bay and the Sacramento-San Joaquin Delta.

The stripers did something else: They dined on the native salmon that swim these same waters and the rivers that run into the Delta. Today, the predation issue stands front and center in the debate over how to reverse the salmon decline.

Irrigation districts in Stanislaus and nearby counties are renewing their claim that reducing bass numbers would do much more for salmon than the state’s proposal to boost reservoir releases. They warn of major losses in jobs and income if less water goes to farms and cities. They suggest raising the catch limits for bass, or even no limit at all.

“This is fast and it’s free,” said Doug Demko, whose Oakdale-based consulting firm, Fishbio, has worked with districts seeking a way around the increased-flow demands. He cited a 2012 study that found a 96 percent loss of juvenile salmon on the Tuolumne River downstream of Waterford. He mostly blamed the bass.

Environmental groups disagree. They say predation is one of several stresses on salmon, which also suffer from low flows, warm water, pollution and loss of spawning habitat to dams.

And anglers who love to catch the bass, noted for its fighting spirit on the line, have no use for the idea of a sharply reduced fishery.

“To me, that is the last gasp of the water users to get more water,” said Jim Cox of Antioch, president of the California Striped Bass Association and a retired sport fishing guide. Its 3,000-strong membership includes chapters in Modesto and five other locales in and near the Delta.

Striped bass are native to rivers along most of the Atlantic and Gulf coasts. Like salmon, they spend part of their lives in the ocean. California had a commercial striper fishery until 1935. The sport fishing has continued, but planting of the species ended in 1992.

There is a litany of things that can happen when this region loses a significant amount of surface water.

Herb Smart, Turlock Irrigation District

The predation issue has resurfaced as the districts await a revised state proposal for flows in the lower Stanislaus, Tuolumne, Merced and San Joaquin rivers. The initial plan from the State Water Resources Control Board, released in 2012, would boost river flows to 35 percent of natural, undammed conditions from February through June each year. Fishing and environmental groups have pushed for as much as 60 percent.

These five months are when the districts capture most of the snowmelt and rain runoff that get them through the hot, dry summers. The stored water also generates cheap hydropower during peak demand from air conditoners and industrial plants.

To me, that is the last gasp of the water users to get more water.

Jim Cox, California Striped Bass Association

The districts say the reduced supply would force farmers to increase their well pumping. This would complicate the effort to comply with a 2014 state law that requires sustainable groundwater use within a quarter-century.

“There is a litany of things that can happen when this region loses a significant amount of surface water,” said Herb Smart, water resources analyst for the Turlock Irrigation District, at a meeting last week of the Stanislaus County Agricultural Advisory Committee.

TID and the Modesto Irrigation District get about half of the runoff in the Tuolumne watershed, which averages about 1.9 million acre-feet of water per year. Smart said that under current fish rules, they must release 165,003 acre-feet into the lower river in average years, but that would rise to 641,492 under the state proposal. The releases would go from 94,000 to 353,638 acre-feet in very dry years and from 300,923 to 1,371,656 acre-feet in wet years.

TID and MID are fighting the plan with allies that include the Oakdale and South San Joaquin irrigation districts on the Stanislaus, the Merced Irrigation District on the Merced, and San Francisco, which diverts Tuolumne water to much of the Bay Area.

They have worked without success to get the California Fish and Game Commission to raise the catch limit on striped bass. They support a new bill by Rep. Jeff Denham, R-Turlock, that would do away with a federal mandate to double the striper population in the Delta. Demko testified on the issue at a February hearing of the House Subcommittee on Water, Power and Oceans.

The districts urge other non-flow measures for salmon, including better treatment of city wastewater that flows into the Delta and fish screens on the water intakes for this region’s farmers.

The striped bass fishing group supports limits on the catch to maintain a reproducing population. Cox said the salmon predation claims are overblown and that both species could thrive if water diversions were curtailed.

“It all comes back to how much water is being exported out of the Delta,” he said.

Patrick Koepele, executive director of the Tuolumne River Trust, said salmon could better withstand striped bass if the flows were higher and colder. The San Francisco-based group, which has offices in Modesto and Sonora, urges farmers to redouble their water conservation.

“We think flows should increase quite a bit, and we think that can happen while maintaining a healthy agricultural economy,” Koepele said.

John Holland: 209-578-2385

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