to come. ‘Immediately after the 1958 s praying,’ the Department re ported, ‘moribund s uckers
were obs erve d in large numbers in Big Goddard Brook. Thes e fis h exhibited the typical
symptoms of DDT poisoning; they swam erratically, gasped at the s urface, and exhibited
tre mors and s pas ms. In the firs t five days after s praying, 668 dead s uckers were collected from
two blocking nets. Minnows and s uckers were als o killed in large numbe rs in Little Goddard,
Carry, Alder, a nd Blake Broo ks. Fis h were often seen floating passively downstream in a
weakened and moribund c ondition. In s everal ins tances , blind and dying trout we re found
floating passively downstream more than a week after spraying.’
(The fact that DDT may caus e blindnes s in fis h is confirmed by various studies. A Canadian
biologis t who obs erved s praying on northern Vancouver Is land in 1957 reported that cutthroat
trout fingerlings could be picked out of the s treams by hand, for the fis h were moving s luggis hly
and made no attempt to es cape. On examination, they were found to have an opaque white
film covering the eye, indicating that vis ion had bee n impaire d or des troyed. Laboratory s tudies
by the Canadian Department of Fisheries showed that almost all fish [Coho salmon] not actually
killed by expos ure to low concentrations of DDT [3 parts per million] s howed s ymptoms of
blindnes s , with marke d opacity of the lens .) Wherever there are great forests, modern methods
of ins ect control threaten the fis hes inhabiting the s treams in the shelter of the trees. One of
the bes t-known examples of fis h des truction in the United States took place in 1955, as a res ult
of spraying in and near Yellowstone National Park. By the fall of that year, so many dead fish
had been found in the Yellowstone River that s ports men and Montana fis h-and-g a me
administrators became alarmed. About 90 miles of the river were affected. In one 300- yard
length of s horeline, 600 dead fis h were counted, including brown trout, whitefis h, and s uckers.
Strea m ins ects , the natural food of trout, had dis appeared. Forest Service officials declared they
had acted on advice that 1 pound of DDT to the acre was ‘s afe’. But the res ults of the s praying
s hould have been enough to convince anyone that the advice had been far from s ound. A
coope rative s tudy was begun in 1956 by the Montana Fis h and Ga me Department a nd two
federal agencies, the Fish and Wildlife Service and the Forest Service. Spraying in Montana that
year covere d 900,000 acres; 800,000 acres were also treated in 1957. The biologists therefore
had no trouble finding areas for their s tudy. Always , the pattern of death ass umed a
characteristic shape: the smell of DDT over the forests, an oil film on the water s urface, dead
trout along the shoreline. All fish analyzed, whether taken alive or dead, had s tore d DDT in their
tissues. As in eas tern Canada, one of the mos t s erious effects of s praying was the s evere
reducti on of food organis ms. On many s tudy areas aquatic ins ects and other s trea m-bottom
fauna were reduced to a te nth of their normal populations. Once des troye d, populations of
thes e ins ects , s o ess ential to the s urvival of trout, take a long time to rebuild. Even by the end
of the s econd s umme r after s praying, only meager quantities of aquatic ins ects had
reestablished themselves, and on one s tream—formerly rich in bottom fauna—scarcely any
could be found. In this particular s tream, game fis h had been reduced by 80 pe r cent.
The fish do not necessarily die immediately. In fact, delayed mortality may be more extensive
than the immediate kill and, as the Montana biologis ts dis covered, it may go unreported
becaus e it occurs after the fis hing s eas on. Many deaths occurred in the s tudy s treams among
autumn s pawning fis h, including brown trout, brook trout, and whitefis h. This is not s urpris i ng ,
becaus e in time of phys iological s tress the organis m, be it fis h or man, draws on s tored fat for
energy. This expos es it to the full lethal effect of the DDT s tored in the tis s ues.
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