FORTY-SECOND BIENNIAL REPORT 85 



In the biennium three publications were issued by the statistical unit. 

 Circulars number 25 and 26 present the annual statistics of fresh and 

 canned fishery products, while Fish Bulletin No. 80 presents the com- 

 plete commercial fish catch for the years 1948 and 1949. A historical 

 record and a complete description of current statistical routine is in 

 process of compilation and will be published in a forthcoming bulletin. 



In the preparation of the Fisheries Treaty with Japan this unit 

 supplied an analysis for the yellowfin tuna and skipjack fishery for the 

 guidance of the U. S. representatives. Likewise during the recent tariff 

 hearings concerning the importation of canned and frozen tuna, the 

 statistical unit compiled and supplied the most authoritative statistics 

 on the domestic catch and the importations of tuna into California. 



These changes in equipment, routine and organization within the 

 statistical unit have adequately adapted it to the work of the immediate 

 future. Present policies, with slight additonal reorganization, will 

 continue. An increase in the staff assigned to the analysis of the catch 

 records would increase greatly the value of the statistics. While it will 

 remain the primary function of the unit to make available to the separate 

 biological investigations an analysis of the catch records of these species, 

 no additional work of this nature can be undertaken until projects now 

 in progress have been completed. Current problems requiring immediate 

 action have delayed the analytical work, and prevented us from main- 

 taining a more complete current analysis of the commercial species. 



SCREENS AND LADDERS 



The fish screen and ladder program has been expanding steadily. 

 Two panel trucks equipped as mobile repair shops are working out of 

 the stream improvement headquarters at Elk Grove. All necessary power 

 equipment to do wood or metal work is available at this shop. 



At present, the most successful type of screen appears to be a series 

 of vertical perforated plates set in the stream channel at an angle above 

 the canal heading. These plates are cleaned by parallel vertical bars 

 which move back and forth along the face of the screen. As the water 

 flow passes the face of the screen at an angle, debris dislodged by the 

 wipers passes on down the stream. 



In the past, much friction with the water diverters existed due to the 

 necessity of operating a bypass to permit fish to get from the ditch 

 back to the stream. Wherever we can eliminate the need for a bypass, 

 better relations with the water users are possible. These new screens 

 are prefabricated as far as practicable at the shop, which reduces the 

 amount of field work necessary. This style of screen was developed by 

 Mr. E. Murphey of the department's shop at Yreka. Experimentation is 

 now going on to develop a hydraulic system powered with a water wheel 

 to operate the cleaning mechanism for this type of screen. 



Construction of a large steam-powered electrical generating plant at 

 Antioch by the Pacific Gas and Electric Company brought up a serious 

 problem. The flow of cooling water for this plant was found to be diverting 

 large numbers of small fish out of the river. However, an immediate 

 attack was made on the problem by the Bechtel Corporation acting for 

 the Pacific Gas and Electric Company. A test flume was set up where 

 experiments were run on the small fish of several species. These tests 



