5 8i 



FORESTS AND FISH 



PAUL R. NEEDHAM, FRED W. JOHNSON 



Nearly all of our forest waters are 

 trout waters, except those in the 

 warmer localities in the Middle West 

 and South. We do not know the full 

 extent of fishing waters in all our for- 

 ests, but in the national forests alone 

 there are more than 90,000 miles of 

 streams and 1 .5 million acres of ponds 

 and lakes. 



Several factors determine the suit- 

 ability of streams for trout. Size of 

 stream or lake is of little moment; 

 temperature, food, and general aquatic 

 conditions are the items that count. 



Just as our forests and other soil 

 covers developed where soil conditions 

 and climate permitted, fish life that 

 we now know evolved slowly and sur- 

 vived through generations to fit into 

 definite environments with interde- 

 pendent patterns of habitat. It follows, 

 then, that any misuse of these heredi- 

 tary watersheds and the streams drain- 

 ing them will change environmental 

 conditions favorable to trout and other 

 life that is associated with a good for- 

 est cover. 



A multitude of physical, chemical, 

 and biological conditions affect the 

 average trout waters : Oxygen, carbon 

 dioxide, alkalinity of the water, food, 

 shade, floods, ice, droughts, and tem- 

 perature, among others. 



The best trout waters usually range 

 from 65 to 75 F. in the hottest times 

 of the year. Eastern brook trout can 

 stand short periods of exposure to tem- 

 peratures close to 80, and rainbow 

 trout have been taken in water of 85, 

 but these are not good conditions. 

 Brown trout, too, can tolerate tempera- 

 tures higher than 81; in excessively 

 hot periods they work themselves into 

 the gravel bottoms of pools that are 

 cooled by upwelling water. The tem- 

 perature tolerances of salmon and 

 steelhead parallel those of rainbow 

 trout. 



Removal of shade from the margins 



of streams and exposure to the full 

 heat of the sun is the principal reason 

 why the lower reaches of many once 

 excellent trout streams have become 

 too warm for trout under modern con- 

 ditions. Many streams (especially in 

 the Eastern States) that used to pro- 

 duce good eastern brook trout fishing, 

 by reason of high temperatures, have 

 become better suited to brown trout. 

 Leaving the cover strips of streamside 

 vegetation (as now practiced by Fed- 

 eral agencies in logging operations) 

 to shade watercourses of small streams 

 from the full heat of the sun will go 

 far toward preventing excessive stream 

 temperatures, especially in the down- 

 stream reaches at lower elevations. 



THE OXYGEN required by fish is dis- 

 solved in the water and is absorbed 

 through the thin membranes of their 

 gill filaments. In clean, clear, trout 

 streams, oxygen is always present in 

 ample quantities for fish life. 



In polluted waters, however, oxygen 

 is consumed, and carbon dioxide and 

 other gases of decomposition are in- 

 creased in the oxidation and reduction 

 of organic or inorganic wastes. When 

 this condition prevails, destruction of 

 fish life may occur. Under conditions 

 of severe pollution, all aquatic life may 

 be destroyed. Man-caused pollution 

 has rightly been termed our "national 

 shame." 



Natural pollution can also occur. 

 One such is the winterkilling of fish 

 in lakes usually due to gradual reduc- 

 tion of oxygen in water under a layer 

 of ice and snow, coupled with a great 

 increase in carbon dioxide. 



TROUT FOODS are supplied from both 

 land and water. Insects are blown or 

 fall into water from streamside vege- 

 tation. Analyses of stomach contents 

 have indicated that approximately 10 

 percent of the food of trout is supplied 



