On September 21st
one hundred tons of a fish poison will be dumped into Diamond Lake, Ore., and
it is expected that within 24 hours not a gill-breathing creature will have
survived. The target of the operation, the undesirable fish which compete with
the game species for food, will be eradicated along with their sporting
brethren. When the lake is cleared, it will be restocked with game fish only,
and another fisherman's paradise will have been preserved.
Eradication has already been well publicized in the West. The story that hasn't
been told is how the fish poisons work. They have been developed to the point
where they can be applied with a finesse that is amazing.
LETHAL TO THE
Probably the most
modern is Fish-Tox, which contains rotenone—a fish poison which man has known
for centuries. Rotenone is an ingredient of most lake eradicants. Its lethal
qualities are so certain that dosages can be figured to the ounce.
Fish-Tox is a
soluble powder which forms a whitish cloud in the water, then quickly clears.
It has a vertical rate of dispersion of one and a half feet an hour. In other
words, a curtain of death descends in the water at the rate of 18 inches an
hour. Nothing with gills can escape, nothing with lungs will be harmed.
Fish-Tox kills by
constricting the capillaries which carry oxygen from the gills, causing
suffocation. The fish thus killed are perfectly edible. The water is safe for
people to drink.
When the poison
begins to dissolve, minnows are the first to feel it. They shoot out of the
water, dance crazily on the surface, even sail out on the beach. Other fish
have varying degrees of resistance. Walleyed pike die easily; so do bass,
perch, bluegills, crappies and the carp which are so often the reason for the
eradication. Bullheads and catfish last longer, but they only postpone the
inevitable. As the invisible veil of poison sinks, it pins the fish against the
oxygen-thin layer of lower water. When the fish try to shoot up through the
Fish-Tox, it gets them.
Fish poisoning is
not pretty, but the gain to sports fishing is tremendous. A trout lake in
Washington, for example, which yielded only 1,000 fish a year because it was
full of "trash" fish, was cleaned out completely and restocked. Two
years later it was opened and yielded 5,460 half-pound rainbow trout the first
day, and more than 56,000 rainbows during the first year.
In North Dakota,
Storm Creek Reservoir, which formerly provided good fishing for bass and
crappies, was taken over by carp. Eradicated by Fish-Tox and restocked with
bass, pike and blue-gills, it now has excellent sport fishing. A surprise
sideline benefit was noted by a farmer's wife who rejoiced that the lake water
was clear enough to wash clothes in, now that bottom-rooting carp had been
The Bureau of
Reclamation built Jamestown Dam, forming a 20-mile-long lake in the James
River. Silt-laden, shallow and full of "rough" fish, it had never been
considered even a fair sport-fishing river. Before the dam was closed, North
Dakota began the most ambitious eradication project yet attempted. Eighty-six
miles of river, three lakes and countless sloughs that connected with the river
were treated. Fish-Tox was spread from low-flying planes, towed behind
motor-boats in burlap sacks, sprayed with hand pumps into marshy areas. Then
came anxious days of test netting to check the effects of the application. The
poison killed every gill breather in the entire river. Now restocked, the
Jamestown Reservoir will provide sport fishing.