This release can be found in the USGS Newsroom at:
<http://www.usgs.gov/newsroom/article.asp?ID=3190>
http://www.usgs.gov/newsroom/article.asp?ID=3190.
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News Release
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April 30, 2012
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Earbones Accurately Record a Fish's Life Travels
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Studying the earbones of trout can reveal their lifetime movements in a
large river system, according to a study released in the Canadian Journal of
Fisheries and Aquatic Sciences.
Scientists correlated the natural variation in strontium isotopes found in
stream waters against those recorded in otoliths (earbones) of westslope
cutthroat trout to examine fish movements during their lifetime.
This study was the first to show that the use of isotopes in water and
earbones accurately assesses movement of trout wholly within a freshwater
system. The research was conducted by scientists from the U.S. Geological
Survey's Northern Rocky Mountain Science Center, Woods Hole Oceanographic
Institution, Montana State University, and Montana Fish, Wildlife & Parks.
"It worked so well! The values in the water matched those in the otoliths,
which grow like rings in a tree," said Clint Muhlfeld (AFS member, '11),
USGS scientist and lead author of the study. "As fish grow and move into new
environments, the otoliths record that information and we matched that with
stream statistics to reconstruct the entire life cycle of a fish."
The study provides a reliable method that compliments traditional fish
tracking techniques. This research may allow biologists to investigate
non-native species invasions, identify important populations, and quantify
life histories of freshwater fishes in river networks.
"All life is literally a product of its chemical environment, and there is
no more dramatic demonstration of that fact than the ability to retrace the
life history of fish from the variations in the chemicals deposited in their
ear bones as they grow and migrate through space and time," explained USGS
Director Marcia McNutt. "As this technique has already proven its scientific
value in understanding the movement of fish in the marine environment and
those which migrate from freshwater streams to the ocean, it is truly an
achievement that could inspire 'CSI'."
Westslope cutthroat trout are an important native fish species in western
North America where their populations have declined because of factors
including habitat destruction, fragmentation and non-native species. These
fish make extensive migrations among spawning, growth and refuge habitats,
yet conventional tracking techniques have not been able to unravel the
extent of their movements. Knowing exactly what habitat the fish use during
each life stage is an important component to understanding their ecology
and, in turn, more effectively managing this important species.
"This approach could be very useful in understanding life history strategies
and conservation needs of freshwater fishes worldwide," said Muhlfeld.
"Biologists are typically limited to examining movements of fish at
checkpoints throughout their lives or over small periods of time. This
approach allows examination of a fish's entire life with significant
accuracy."
The study provides a reliable method that compliments traditional fish
tracking techniques and may allow biologists to investigate non-native
species invasions, identify important populations, and quantify life
histories of freshwater fishes in river networks. The article, "Estimating
westslope cutthroat trout (Oncorhynchus clarkii lewisi) movements in a river
network using strontium isoscapes," can be viewed
<http://www.nrcresearchpress.com/doi/abs/10.1139/f2012-033> online.
More information about this study can be found on the USGS Northern Rocky
Mountain Science Center <http://nrmsc.usgs.gov/science/invasives> website.
Photos for this release:
Visit: <http://gallery.usgs.gov/tags/NR2012_04_30>
http://gallery.usgs.gov/tags/NR2012_04_30for all available photos.
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