[env-trinity] Global Threats to Trout

[Denise Boggs]

http://flatheadbeacon.com/2018/06/12/local-fish-researcher-urges-global-acti
on


Local Fish Researcher Urges 'Global Action'


Published in 'Science Magazine,' first worldwide assessment sheds light on
plight of trout


By Tristan Scott <http://flatheadbeacon.com/author/tristanscott/>  // Jun
12, 2018 

 

 
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e_school_wide_bank.jpg&w=900&h=600> 

Native westslope cutthroat trout and bull trout stranded in a pool in Ole
Creek in September 2012 due to the low water levels. Courtesy Jonny
Armstrong | USGS


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To anglers across the globe, trout streams are characterized by free-flowing
water that's clear, complex, connected and, most importantly, cold.

Meanwhile, the trout that inhabit the waters, in addition to providing
sustenance and recreation to millions of people, play critical roles in the
health of ecosystems worldwide.

So what's the piscatorial problem?

In the years ahead, the chilly streams that sustain Northwest Montana's
prized native fish - as well as trout habitat worldwide - are predicted to
grow increasingly tepid as a result of rising global temperatures,
threatening the sensitive aquatic species with "global extinction" unless
more conservation studies take place at a local and planetary scale.

That's according to a recent study published in the esteemed research
journal "Science Magazine," whose lead author, Clint Muhlfeld, works an
aquatic geologist for the U.S. Geological Survey's Glacier Park field office
based in Glacier National Park.

The publication offers a lofty platform of scientific prestige that Muhlfeld
hopes will draw broader attention to the plight of native fish and a
multitude of trout species distributed throughout the world's watery
arteries, all of which share something in common - they are especially
sensitive to rising temperatures.

Published in the May 25 issue of "Science," the article, titled "Trout in
Hot Water: A Call for Global Action," marks the first worldwide assessment
of trout species' status. It found that a disproportionately high rate of
trout species (compared to other vertebrates) are now threatened under the
International Union for Conservation of Nature (IUCN) Red List, the world's
most comprehensive inventory of the status of biological species.

Of the 124 recognized species of trout, only 67 percent have been assessed
by the IUCN, Muhlfeld said.

The kicker?

"Alarmingly, 73 percent of these species are currently threatened with
global extinction, and four are now extinct," he wrote in the "Science"
article.

"Trout are like canaries in a coal mine," Muhlfeld said in a recent
interview, speaking by phone from Oslo, Norway, where he is working on a
Fulbright Scholarship. "They are excellent indicators of disturbance,
especially under climate change because of their sensitivity to temperature
and freshwater stream flows."

Native to all continents in the Northern Hemisphere, trout belong to seven
genera (plural of genus), which are distributed across 52 countries. These
cold-water specialists provide recreation and food to millions of people and
play important roles in ecosystem functioning and health.

In an addition to serving as an economic boon - a recent federal analysis of
outdoor recreation found that boating and fishing activities contributed
$38.2 billion to the nation's gross domestic product in 2016 - they are also
excellent markers of an ecosystem's health, Muhlfeld said.

"They are extremely sensitive to human disturbances because they require
cold, clean, complex, and connected habitats for survival and persistence -
all attributes that humans have substantially altered and degraded,"
according to the study. "Despite their importance as societal icons and as
indicators of biodiversity, many of the world's trout species and lineages
are endangered and some require immediate conservation efforts to reverse
their precarious decline."

Muhlfeld, along with a team of researchers, emphasized the need for swift
courses of action to save "one of our most culturally, economically and
ecologically important freshwater fishes."

"Reversing these declines will require progressive conservation efforts to
protect native trout diversity and ameliorate ongoing and future threats at
local and global scales," the study states.

Locally, Muhlfeld pointed to successful efforts by Montana Fish, Wildlife
and Parks, which set out more than a decade ago to preserve and restore the
westslope cutthroat trout fishery in the South Fork Flathead River.

Recognizing the pressure of hybridization with nonnative species like
rainbow trout, the architects behind the South Fork Flathead Cutthroat
Conservation Project began systematically removing nonnative fish and
replacing them with genetically pure westslope cutthroat in 2007.

"Even though this is a global study, it stresses the need for conservation
studies to take place at a local scale," Muhlfeld said. "We know that
hybridization is irreversible, and eliminating those sources that do
long-term damage is a proactive strategy. Dealing with nonnative species
like the South Fork recovery program that FWP implemented is a great example
of that."

Another example takes place in Glacier National Park, historically one of
the last best strongholds for native cutthroat and bull trout. The biggest
problem for these native species is that Glacier's lakes and streams are
brimming with nonnative fish, particularly invasive lake trout, which
radiated out of Flathead Lake and colonized the park's lakes, out-competing
the native residents.

In 2009, biologists with Glacier Park and a USGS team led by Muhlfeld
launched an experimental project on Quartz Lake, located in the park's
remote northwest corner, where lake trout invasion was still in its early
stages of invasion. The aim was to reduce or eliminate lake trout by
gillnetting, a project that required a boat to be helicoptered in and all of
the supplies to be hauled in by biologists and mules.

Muhlfeld and his team first located so-called "Judas fish," captured and
radio-tagged them, then tracked the fish to spawning areas in order to
capture and remove the densest concentrations of spawning lake trout.

The project has shown evidence of success in reducing lake trout, and is
hailed as one of the first successful projects of its kind, standing out as
a leading example that lake trout suppression, once thought to be futile, is
possible.

"Only by addressing threats at their root causes can we accomplish these
conservation goals," Muhlfeld said.

Muhlfeld's co-authors on the study were: Daniel Dauwalter, Ryan P. Kovach,
Jeffrey L Kershner, Jack E. Willians, and John Epifanio.

To learn more about the study, visit science.sciencemag.org
<http://science.sciencemag.org> .

 

 

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