FORTY-FOURTH BIENNIAL REPORT 



39 



Miscellaneous Improvements 



The Southern California stream improvement pro- 

 gram, made possible by Wildlife Conservation Board 

 allocations, continued through the biennium. 



A new type rock-masonry, flow-accelerating struc- 

 ture was devised, which is a considerable improvement 

 over the log and rock dams and deflectors tried in 

 1953-54. The chief function of these structures is to 

 create additional pool areas in streams requiring them. 

 A total of 196 devices of this type was constructed 

 on Southern California streams. 



Pool-forming devices were constructed with logs 

 in a one-third mile section in the headwaters of the 

 South Fork of the Mokelumne River, Calaveras 

 Count)', in 1955. Prior to construction, the fish popu- 

 lation was carefully censused with an electric fish 

 shocker. All fish were counted, weighed, and fin 

 clipped for future recognition. The plan is to recensus 

 the stream in future years to determine the influence 

 of these devices on the fish population. 



Experimental Structure 



An experimental structure consisting of two parallel 

 rows of sheet piling anchored to piles was constructed 

 at the outlet of Taylor Creek into Lake Tahoe, El 

 Dorado County, in the summer of 1955. The purpose 

 of the structure was to maintain an open channel for 

 fish migration through the sand bar that forms at the 

 mouth. The structure was a cooperative venture with 

 the County of El Dorado which contributed $660 to- 

 wards the total cost of $3,660. The structure func- 

 tioned perfectly in the fall of 1955 and fish had no 

 difficulty entering Taylor Creek, but the December, 

 1955, floods washed out the upper end of the struc- 

 ture. Efforts were being made at the end of the bien- 

 nium to obtain funds for reconstruction. 



INVESTIGATIONS 



The need for more information about the State's 

 inland fisheries has become increasingly apparent as 

 more and more water use projects are planned and 

 angling pressures continue to mount. 



As in the past biennium, the investigational work 

 generally fell into two groups. Surveys or inventories 

 of local importance, including many water projects 

 studies, were conducted by regional fisheries workers. 

 Basic or long-range research projects were conducted 

 by staff personnel. Close cooperation and frequent 

 contacts bet\\een staff and regional fisheries workers 

 made the work of each group more successful. 



Stream and Lake Surveys 



Initial biological surveys were made of 244 lakes and 

 107 streams. (See Table 11, Appendix.) Rechecks 

 were made of many other waters to determine the 

 success of existing management programs and regula- 

 tions. 



All of the stream and lake improvement activities 

 listed in this report came about as results of stream 

 and lake surveys. 



Creel Censuses 



Creel census work was increased considerably. 

 Table 12, Appendix, lists the 145 streams and lakes 

 on which important information regarding angler use 

 and success were collected. In addition to these, spot 

 censuses were made of many individual waters. 



This work is one of the most important activities 

 carried on by the department. It provides the basis for 

 fish planting allotments, the evaluation of regulations, 

 determining the economic importance of the fishery in 

 relation to other v\ ater uses, and it provides close con- 

 tact betw een the angling public and fisheries workers. 



A few of the waters listed in Table 12 such as 

 Castle Lake in Siskiyou County, Rush Creek in Mono 

 County, and the Lakes Basin area of Plumas and 

 Sierra Counties w ere special test waters where the re- 

 sults of study can be applied to similar waters. 



FISH DISEASE STUDIES 



As fish production has increased, so have the de- 

 mands for fish disease services. During the biennium, 

 virtuall>- all of the eff^ort carried on in fish disease 

 work has been restricted to providing services at state 

 hatcheries. 



During the 1950-52 period the department's disease 

 control program investigated 1 16 cases of diseased fish. 

 Of this number, 51 involved fish at state installations. 

 The remainder of the work involved commercial 

 hatcheries (24 cases) and wild fish (41). 



In 1952-54, the effects of the increased hatchery 

 program began to be felt and fewer fish disease serv- 

 ices were available for commercial and wild fish in- 

 vestigations. With the completion of the hatchery 

 expansion and modernization program in the recent 

 biennium, the pattern of fish disease services shifted 

 almost entirely to hatchery investigations. Of 120 

 cases studied, 112 involved fish at hatcheries. 



Gill Flukes 



Special studies were made of two important trout 

 diseases. The first disease was caused by a gill fluke 

 which is particularly serious at the Darrah Springs 

 Hatchery, and is also important at the Mt. Shasta and 

 Cr\stal Lake Hatcheries. At the present time it appears 

 that snails of the genus Goviohasis act as the inter- 

 mediate hosts for the fluke. 



Some strains of rainbow trout are highly susceptible 

 to this disease and die in considerable numbers; other 

 strains are relatively immune. However, when the gills 

 become heavily parasitized the health of the fish is 

 impaired even though it may not die. An attempt will 

 be made to break the life cycle of this gill worm at 

 the Darrah Springs Hatchery by a partial eradication 



