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Climate Change Threatens California Salmon

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(Sacramento, CA)
Thursday, October 13, 2011
Not far from Chico California, UC Davis fish biologist Lisa Thompson is perched in a tree on an observation platform overlooking Butte Creek.
THOMPSON: "We're looking at a pretty big group of spring run Chinook salmon. And they have moved into an area over gravels that are a good size for them to spawn and lay their eggs.
And so there are groups of fish milling around trying to decide who they are going to mate with. And that splashing you here is a female flipping on her side and moving her tail and that  movement of the water is sucking the rocks up and she is digging a basin where she can lay her eggs in."
These fish hatched here, spent three years in the ocean and came back thousands of miles, the last hundred up-stream to spawn and die.
THOMPSON: "It's beautiful in a way, and yet it's ugly. I mean they, they look awful some of them. They've got fungus, their all beat up; the males will be all scratched up from fighting one another. Females' tails get worn from swishing against the gravel when they're digging. But it's kind of heroic. I mean, these are the fish that maybe one in a hundred gets to go to the ocean in the first place. And of the ones that get to go to the ocean, one in ten or one in a hundred come back."
Because of all the diversions of water for hydro power and agriculture in California, The last two hundred years have not been kind to these fish. Their dwindling numbers make Butte Creek an incredibly important place.  More than half the spring run Chinook salmon spawning in California do so right here.
1013JR SALMON PICTHOMPSON: "It's hard for me, even as a biologist, to have seen all the data, to look at these fish and to remember there is such a huge problem. The habitat here is still in relatively good shape. There's issues, the way the gravel is placed in this river still carries reminders of the gold mining era. Never the less, the water is clean, it's cool, there's gravel of the right size that the females need to be digging their nests."
But according to the climate change scenarios created by the study, there's a growing threat, stream temperatures are going up.  
Thompson: "Basically, what we found that as you come up to that 20c or 68F, gradually the fish start to die and as you get up to 70, more and more fish are dying and as you get up to about 72, nearly all the fish are not able to handle a weekly average temperature that high."

Under the best case research scenario, by century's  end, the creek's temperatures will climb to levels above 72 degrees, lethal to all salmon.
David Purkey with the Stockholm Environment Institute designed the tool used to take complicated, variable data and turn it into projections for the future of the salmon on Butte creek. That meant a lot of computer time, but he said spending time at the creek was also important. 
PURKEY: "I remember the first time I came up here, it was like wow, what an incredible place. The more we studied it, the more we realized how precarious it was, you know , the harder it was to imagine that it might not continue to be here. But that also motivates trying ways to manage the creek."
At PGE's Centerville Hydro electric plant, about a mile from the salmon pools we visited, as much as eighty-percent of the water in the creek is diverted to generate power.  The diversion raises water temperatures. Right now that isn't especially harmful to salmon. But the research found that in coming decades, during the heat of the summer,   in order to survive the salmon will need the rushing water to stay in the creek.  While the world works grapples with combating climate change, That step could buy the Chinook ten to fifteen years .
Again David Purkey:
PURKEY:  And we need to have policies and rules that are more nuanced, and that are more flexible, so that we can say, maybe there is a heat wave coming on, lets not divert this week, and keep the water in the creek for the fish, as opposed to, just because you can, because your license say you can, divert continuously."
PG&E, which is in the midst of relicensing the Centerville plant, says it has taken many steps on the creek to help the salmon and will monitor stream temperatures.  But would not commit to shutting down the hydroelectric plant during the heat of summer.
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