THIRTY-SIXTH BIENNIAL REPORT 45 



of detailed fishing- and eateh data liave been continued and analyzed 

 regularly. The fishery has maintained a satisfactory increase in catch 

 per unit of gear since the time of the voluntary adoption of larger 

 mesh sizes in the drag nets used in this industry. Tliere luis been an 

 actual gain of over 2,000,000 pounds of fish for the period, 1934-1 !)8!). 

 inclusive, for the same amount of fishing eifort, because of the adjust- 

 ment in the mesh size. This larger catch resulted in a monetary valvn^ 

 of over $100,000. In addition, untold thousands of young fisli have 

 been saved and thus allowed to reach spa^vning as well as market size. 

 In the past two years, several boats operating otter trawls have entered 

 the fishery for ocean bottom species, in competition with the traditional 

 two-boat paranzella net "rigs," which have dominated tliis California 

 industry since its inception in the 1800 's. 



On the investigative trips on the Division's fisheries research ves- 

 sels, collections have been made of material for analyzing the abun- 

 dance of the various age-classes of the flatfish, their mortality rates 

 (due to natural causes and fishing exploitation) ; and in addition, tag- 

 ging operations have been conducted to determine the extent of migra- 

 tions of the various species. Two such trips were made in the course 

 of the biennium on flatfish research work — one in tlie fall of 19;38 along 

 the California coast from San Francisco to Crescent City, and the 

 other in the spring of 1939 in the vicinity of San Francisco and j\Ion- 

 terey. An extended cruise is planned for the early fall of 1940. at 

 which time we hope to do a considerable amount of fish tagging and 

 collecting other additional material. 



Because of the developments in the use of the otter trawl gear by 

 independent boats (not operated by companies as in the case of the 

 paranzella boats, which had voluntarily adopted the use of a larger 

 mesh size in their nets for the protection of the immature fish), it is 

 desirable that legislative recommendations be proposed to provide for 

 a minimum mesh size in the sacks of all drag nets used or in jiossession 

 in the State. 



CENTRAL VALLEY WATER PROJECT STUDY 



Early in 1939, funds were made available to conduct investigations 

 of the effect of the Central Valley Water Project in the Saci-amento 

 and San Joaquin valleys, on the fish life in that region. The water 

 plan of this Project, now under construction by the United States 

 Reclamation Service, is far reaching. The resulting changes have a 

 direct bearing on the fishes in these waters, because of the construction 

 of the Shasta Dam, Friant Dam and the Delta Cross Channel, which 

 will supply additional irrigation water to the San Joaquin River, the 

 Madera Canal and the San Joaquin-Kern Canal. Investigations by the 

 California Division of Fish and Game have been in progress since 1939 

 to determine the effects of these water changes on the population of 

 salmon, striped bass, shad and other species of fish iidiabiting tlie Delta 

 area and the San Joaquin River. (The Sacramento Ifivcr norlli of the 

 Delta area is being investigated by United States Covernmcnt agencies, 

 with the California Division of Fish and Game acting in an advisory 

 capacity.) Final engineering plans for the water changes in the Delta 

 and San Joaquin River are not yet available. However, the knowledge 

 gained through our investigations has now reached a stage wherein 



