Conservation News
Spawners' Comeback
Glen Martin, San Francisco Chronicle 11/27/04
Submitted by Bruce Dau
Spawners' Comeback
Glen Martin, San Francisco Chronicle 11/27/04
Submitted by Bruce Dau
Twenty or 30 years ago, the Napa River was a --well, a stinking open sewer wouldn't be stretching it. "Everyone's septic tanks leached right into the river," said Robert Torres, the vice president of operations for Trinchero Family Estates, a premium winery in St. Helena. "There was brown foam on the water. People dumped their garbage along the banks." The valley's renowned vineyards also contributed to the river's degradation, Torres said. "If people saw a bug, they sprayed it," he said. "Nobody tolerated a weed, and they weren't shy about using fertilizer. All those chemicals and phosphates, and the silt from the bare vineyards ended up in the river."
Such a potent witch's brew took a dire toll on the river's fisheries. Pike minnows and black bass, relatively tolerant of sediment and pollution, hung on. And a few steelhead nosed through the crud to occasionally spawn in the river's tributaries. But chinook salmon, which thrived in the river before the vineyards went in, disappeared, save for a straggler or two from the Sacramento River hatcheries. Last year, however, something remarkable happened. "This river was full of salmon," said Chris Cordano, a St. Helena resident. "I've lived here about 15 years, and I noticed there were more fish coming back a few years ago. But last fall was different -- it was really a banner year. They were jumping over the rocks under the Zinfandel Lane Bridge like popcorn shooting out of a popper."
And the fall-run chinook -- which typically peak in numbers right around Thanksgiving -- are back again in force this year, indicating the returns may be a trend rather than a fluke. "We walked only about 3 miles of the upper river, and we counted around 100 spawners," said Jonathan Koehler, a biologist with the Napa Valley Resource Conservation District, who surveyed the waterway the week before Thanksgiving. Koehler's agency works with local landowners to minimize the environmental impacts of viticulture.
"For a river of this size, that's a sizable return," Koehler said. "Another thing we've found heartening is that these are likely wild fish. Only 2 percent of them have their adipose fins clipped -- at the hatcheries, they clip 15 percent of the fish. Also, these are very big salmon -- up to 35 pounds, meaning they're 4 or 5 years old. Hatchery fish usually return (to spawn) after three years." Torres, a member of the Rutherford Dust Society, a group working to restore 4 1/2 miles of the river's corridor to a natural state, said a concerted effort to improve the Napa Valley's environment is the likely reason for the salmon's return. "Sewage discharges have been stopped," he said, "and the emphasis now is on sustainable farming -- erosion control and minimal pesticide applications. " As he strolled along a portion of the river that flows through Trinchero Estates property, Torres pointed out two female salmon excavating "redds," or nests, in a riffle. "I grew up here, and I fished this river all through high school," some 30 years ago, he said. "We never saw anything like this."
Bill Kier, a Sausalito-based fisheries consultant who specializes in steelhead and salmon, said fall-run chinook salmon are the most "accommodating" of the four distinct runs of chinook salmon that inhabit the San Francisco Bay system. "They're opportunistic, and they can move around, establishing runs where conditions are suitable," Kier said. "When temperatures cool and you have early rains as we did this year, they'll take advantage of it." Kier said fall-run chinook fry emerge from the redds in February and generally leave rivers for estuaries by late spring. The adults die after spawning. "Right now, the greatest concern for them is winter flows," he said. "Too much water, and the redds will be ripped out. Too little, and they'll be left high and dry."
And the salmon face other challenges: most specifically, the long-term viability of the river as habitat. Mike Napolitano, a staffer on the San Francisco Bay Regional Water Quality Control Board, said erosion from vineyards in the mountains surrounding the valley remains a significant problem, as does "channel incision," the increasingly gorgelike quality of the river in the upper valley. Before the vineyards went in, said Napolitano, the river could spread out during winter rains. But now it's straitjacketed by levees, forcing it to cut an ever-deepening canyon. "Instead of a historic configuration of gravel bars and pools, most of the river now is deep pools," Napolitano said. "Without the gravel, the salmon can't spawn." Locals are working to remedy the situation. Some set-back berms have been placed along the main stem of the river to allow it to meander during high flows, and the county now requires the filing of erosion-control plans for all new vineyards. It might also be possible to augment existing spawning areas with additional gravel, Napolitano said.