8143

• UCREFRP Catalog Number: 8143
• Author: Sousa, R. J., F. P. Meyer and R. A. Schnick.
• Title: Better Fishing Through Management\
• USFW Year: n.d.
• Copyright Material: NO

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Q. How long does it last?
A. How fast rotenone breaks down is affected by
temperature, light, oxygen and alkalinity. Generally,
most treatments are made during summer months. At
80° F, treated water will detoxify naturally in less
than 4 days. As water cools, biological and chemical
processes slow down and the breakdown of rotenone
also slows. At 45° F, the toxicity to fish may last for
33 days. Detoxification may take longer in acid
waters, in very soft water, or in deep stratified bodies
of water. Generally, most lakes treated with rotenone
completely detoxify within 5 weeks of treatment.
Readers are reminded that rotenone is unstable and
will degrade rapidly with exposure to light, heat,
oxygen and alkaline water. In natural waters, other
factors that influence the degradation rate and
therefore redace the toxic effect include the presence
of organic debris, turbidity, lake shape and depth,
dilution by inlets and runoff and the dosage used.
The presence of ice and snow cover may prolong the
toxic effect.
If desired or necessary, a treatment can be ended or
toxicity can be removed by adding oxidizing chemi-
cals, such as potassium permanganate or chlorine, to
accelerate the natural breakdown of rotenone.
0.25
0.2
Z COLD WATER

O ---WARM WATER
Z
X0.15
O

rc I

d 0.1
1
0.05

O
0 10 20 30 40 50 60
TIME IN DAYS
PERSISTENCE OF ROTENONE
IN POND WATER