Warming Threatening Cold-Water Fish

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“Here in New York, Trout Unlimited estimates, an average temperature
increase of three degrees will make most of the state “thermally
marginal trout habitat.” The Adirondacks and Catskills will remain
“thermally suitable,” but a large part of the lower Hudson Valley
would be rendered troutless…”
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Daily Gazette article
Thursday, May 22, 2008
http://www.dailygazette.com/

Fly-Fishing: Rising temperatures threat to trout

Will global warming wipe out our trout fishing in New York? A new
report by New York City’s water supply agency suggests that our
favorite trout rivers may well be affected.

Over the next 80 years or so, we can expect more big rainstorms and
more big floods, according to the city’s Department of Environmental
Protection. In the winter, we’ll get less snow and more rain. In
fact, higher elevations will only have half as many days in a year
when the ground is covered with snow.

Because the climate will grad?ually get milder, the growing season
will get longer – more than a month longer, by some estimates.

What’s this got to do with fishing? Big storms and big floods tend to
wreck our fishing – in the short term, by making the water too high
and dirty to fish, and long-term by killing trout and aquatic
insects. Floods do not kill all the trout, of course; if they did,
trout would never have been a viable species. But both trout and the
insects they eat sometimes require years to recover from catastrophic
floods.

Snowpack stores water for the spring, and without plenty of it,
streams and water tables may begin the season low and vulnerable to
heat waves. And there will be more heat waves.

Even the growing season affects trout streams. Plants and trees suck
a lot of water out of the ground when they get their leaves; that’s
water that won’t make its way to the rivers and creeks.

“Warmer temperatures may also lead to impacts on fish life in
watershed streams. Warmer stream water results in lower dissolved
oxygen levels, and dissolved oxygen is a key determinant affecting
fish life,” notes the DEP.

Trout Unlimited, in a report released late last year, says the
southern Appalachian Mountains may lose half their wild brook trout
to global warming; certain spots out west may lose 60 percent of
their wild trout; salmon in the Pacific Northwest will probably
decline in number. A horrendously large swatch of south-central
Pennsylvania, site of some of the nation’s most beloved trout
streams, will become “thermally unsuitable trout habitat.”

Here in New York, Trout Unlimited estimates, an average temperature
increase of three degrees will make most of the state “thermally
marginal trout habitat.” The Adirondacks and Catskills will remain
“thermally suitable,” but a large part of the lower Hudson Valley
would be rendered troutless (except, presumably, in tailwater streams
kept cool by reservoir releases, as in the Croton River watershed.)

But Trout Unlimited also makes the point that the effects of climate
change on trout habitat can be eased by relatively simple,
common-sense measures. Remove dams and culverts that prevent fish
from migrating to more comfortable habitat. Take less water from
streams for irrigation. Restore diverse habitat with things like
boulders and woody debris. Nurture native trout, which adapt better
than hatchery fish or non-native species. Protect springs and
headwaters. Conserve open space. Conserve water. Conserve energy.

And we can, and should, support policymakers and policies that will
help the natural world maintain its character despite the gradual
change in climate – such as the America’s Climate Security Act,
sponsored last fall by Sen. Joseph Lieberman. Along with curbing
greenhouse gas emissions, the act would provide up to $150 billion by
2030 “to enhance sustainability of fish and wildlife in the face of
continuing climate change impacts,” according to TU.

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