PROGRESS IN BIOLOGICAL iXQUIRIES, 19 32 135 



2. The extent of natural propagation and its contribution toward 

 stream populations. 



3. Mortality of fish of various sizes when planted in the streams 

 from the hatcheries. 



4. Stream environmental studies to determine: (1) Seasonal abun- 

 dance and distribution of fish foods; (2) the amount and kinds of 

 shelter available for both young and adult trout; (3) effects of dams, 

 falls, irrigation ditches, flumes, water wheels, etc.; and (4) chemical 

 conditions such as gases in solution, hydrogen-ion concentration, and 

 pollution. 



For purposes of investigation the waters of the State may roughly 

 be classified in three groups: (1) Southern region, (2) coastal region, 

 and (3) Sierra region. The last-named region can be subdivided into 

 a lower Sien-a region, the waters of which are best adapted to rainbow 

 and brown trout, and a high Sierra region containing waters best 

 suited to golden and eastern brook trout. 



The bulk of the work on streams of the coastal region has been 

 carried on in Scott and Waddell Creeks in Santa Cruz County and 

 to a lesser extent in the Klamath River and Alder and Garcia Creeks 

 north of San Francisco. In the Sierra region the Truckee and 

 Feather Rivers and Blackwood and Taylor Creeks near Lake Tahoe 

 have received considerable attention. Next summer work is to be 

 started on the golden trout of the high Sierras in the Cottonwood 

 Lakes district near Mount Whitney. New studies will also be under- 

 taken in the Merced and Tuolumne Rivers in the lower Sierra region. 

 A knowledge of conditions in the trout waters of the State through- 

 out the year is essential for the development of a scientific stocking 

 policy and as far as possible seasonal studies will be carried on in all 

 these regions. 



Much information has already been obtained from studies of sea-run 

 steelhead trout based on marking experiments w4th young fish and 

 returned spawners and also from periodical samples taken in several 

 coastal streams. In October 40,000 fingerling rainbow trout from 

 two different lots of fish were marked and released into the Truckee 

 River for studies on their migratory habits. The experimental ponds 

 constructed on Hot Creek in Mono County were operated during the 

 summer for the study of growth rates and mortalities of fingerling 

 rainbow trout on natural food. 



Quantitative food samples taken in Sierra streams near Lake Tahoe 

 have shown riffle areas to average approximately 137 pounds of food 

 per acre. Waddell Creek, a coastal stream, was found to produce 

 nearly the same amount giving an average of 132 pounds per acre. 

 The dominant food organisms in all stream bottom samples taken 

 thus far have been caddis larvae and pupae, mayflj^ nymphs, and 

 and aquatic Diptera. The lagoons at the mouths of coastal streams 

 have been found to be exceptionally rich in both amphipod and 

 isopod crustaceans and consequently afl'ord fine feeding grounds for 

 joung trout. 



FISH DISEASES 



Routine investigations have been carried on in connection with 

 several trout diseases whenever there was an opportunity. Although 

 most of the common trout diseases have been studied by various 



