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.
THOMPSON: "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.
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:
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.