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Media Resources :: Newsroom
Salmon Mortality Increases When
Pesticide and Virus Act Together
27 June 2005
Salmon populations are already dwindling because of
pesticides and disease. A new study demonstrates the
synergistic effects of these two stressors—specifically
esfenvalerate (Es) and infectious hematopoietic necrosis
virus (IHNV)—as leading to increased mortality
in juvenile Chinook salmon. The study is published in
the latest issue of Environmental
Toxicology and Chemistry.
At a glance, the decline of the salmon population can
be attributed to such factors as overfishing, pollution,
construction and operation of dams, loss of marshlands
and estuaries, and river-water allocation for cities
and farms. Additionally, the studied virus, IHNV, causes
significant losses of juveniles in hatcheries and trout
farms and is the most important viral pathogen found
among Pacific salmon in the western United States.
To test their hypothesis, the study’s researchers
performed three trials, exposing juvenile Chinook salmon
to sublethal levels of the widely used pesticides Es
and chlorpyrifos (Cp) either alone or concurrently with
IHNV. Among groups exposed to both Es and IHNV, 83%
experienced highly significant mortality, ranging from
20 to 90% at three days post-virus exposure. Cumulatively,
these fish died 2.4 to 7.7 days sooner than fish exposed
to IHNV alone. This trend was not seen in any other
treatment group.
The combined effects of the virus and Es are a red
flag, especially considering the Es concentration used
should not have been lethal. The results of the study,
the researchers said, show the need to rethink acceptable
concentrations of pollutants that are acting as a synergy
with other environmental stressors.
To read the entire study, click here: http://www.allenpress.com/pdf/entc_24_721_1766_1772.pdf
Environmental Toxicology
and Chemistry is a monthly journal of the Society
of Environmental Toxicology and Chemistry (SETAC). For
more information about the Society, visit www.setac.org.
For more information about Environmental
Toxicology and Chemistry, visit http://setac.allenpress.com.
[Synergistic Effects of Esfenvalerate and Infectious
Hematopoietic Necrosis Virus on Juvenile Chinook Salmon
Mortality; Environmental Toxicology and Chemistry],
2005; Vol. 24(7):1766-1772
Contact:
April M. Phillips
T 850 469 1500 x 28
aprilp@setac.org
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