FORTY-THIRD BIENNIAL REPORT 



73 



tagged and released. On one of these cruises mangrove 

 seeds were brought back and planted in Salton Sea, 

 one phase of the plan for developing a sport fishery 

 in this inland body of salt water. 



Two cruises in Central California waters resulted in 

 the development of a mid-depth trawl that can be 

 operated from a single vessel. Shrimp populations in 

 the area were also assessed and this fishery given addi- 

 tional stimulus. One other trip made in connection 

 with the trawl studies extended to the coastal waters 

 of Washington and comprised assessments of bottom 

 fish populations off Central and Northern California 

 and Oregon and Washington. 



Yelloivfiv: Although the work of the Yelloivfin was 

 not as varied as that of the N. B. ScofieUi, this vessel 

 kept equally busy, spending 373 days at sea during the 

 biennium. In the fall of 1952 she made four cruises 

 along the coast of Baja California waters and three in 

 the fall of 1953. On these trips, covering the area be- 

 tween Magdalena Bay, latitude 25 degrees N. and Pt. 

 Reyes, latitude 38 degrees N., a census was taken of 

 the abundance of sardines. Pacific and jack mackerel 

 and anchovies, and of the relative numbers of the year 

 class of sardines resulting from the previous spring 

 spawning, when these fish were about six months old. 



One of the outstanding accomplishments resulting 

 from the work aboard the Yelloivfin has been the de- 

 velopment in the past year of a blanket net for the 

 rapid and efficient collection of fish samples. This net 

 and its successful operation resulted from the ingenu- 

 ity and industry of the vessel crew and illustrates the 

 importance of the contributions that every member 

 of the staff makes to the department's marine research 

 programs. 



Marine Research Cruises 



In addition to the census of fish populations carried 

 out by the Yelloivfin, she made three oceanographic 

 cruises in Southern and Baja California waters collect- 

 ing plankton samples and physical and chemical ocean- 

 ographic data, a part of the cooperative investigations 

 being carried out under the direction of the Marine 

 Research Committee. Five cruises were made in South- 

 ern and Baja California waters during the spring and 

 early summer to study abundance of sardines, jack 

 and Pacific mackerel and anchovies. Two trips were 

 made around the Southern California Channel Islands 

 to determine the condition of abalones in these \\aters. 



Nautilus: Added to the department's research fleet 

 during the biennium was the Nautilus, formerly the 

 Sportfisher II, a standard northern drag boat, to serve 

 as a mother ship for the abalone investigations. The 

 new vessel, purchased in June, 1953, will serve as a 

 base to dry and thaw out divers, for tagging and meas- 

 uring abalones, and as a supply depot. It will be able 

 to work in areas impossible for the 26-foot diving boat 

 Mollusk, and will be available for many other investi- 

 gations when not being used in abalone work. 



Additional gear is being installed on the vessel to 

 broaden its scope and usefulness. Among the installa- 

 tions are radar, enabling crews to take the boat close 

 to shore in bad weather; a sonar "Sea Scanar" show- 

 ing size and depth of underwater obstructions, and 

 schools of fish within 1,600 feet; radio equipment; an 

 anchor winch; and crew facilities. It already is 

 equipped with Loran, a Bendix recording depth finder 

 and two drag winches. 



The Nautilus will be based at Redwood City, clos- 

 est harbor to the Marine Fisheries Branch office at 

 Stanford University. Storage located there consoli- 

 dates equipment formerly kept at four scattered loca- 

 tions. 



FISH SCREENS AND LADDERS 



A coordinated fish screen and ladder program, im- 

 proved in some respects through reorganization and 

 decentralization of the department, resulted in several 

 far-reaching developments. These include new types 

 of screens, devices to prevent trash accumulation, and 

 improvement and remodeling of ladders. Added effi- 

 ciency through decentralization of repair facilities was 

 another major accomplishment. Assistance from the 

 Dingell-Johnson Federal Aid Project F-4-D, on stream 

 and lake improvement, came in the form of repair and 

 remodeling of several existing fish\\ays on coastal 

 waters. 



Under regional organization a new machine shop 

 was established in Red Bluff. Besides servicing screens 

 in Trinity County, the new shop maintained screens 

 and ladders in the southern part of Region I, formerly 

 handled by the Elk Grove shop. This eliminated much 

 travel time for employees of the latter shop in servic- 

 ing distant screens. The Yreka shop continued to han- 

 dle screen and ladder construction and maintenance in 

 the northern portion of the region. 



Transferred to Region II from Marine Fisheries in 

 1953, the Elk Grove shop has been engaged in devel- 

 oping and testing new types of screens as well as in 

 prefabricating conventional perforated plate models. 



Newly designed fish screen for dfversjons, showing automatic gate in 



open position. The gate prevents loss of head in canal when debris has 



accumulated on screen. 



