April 1951 COMMEHCIAL FISHERIES REVIEW 39 



If funds are appropriated, the expanded research program for maintaining runs 

 of salmon and trout in the Columbia River will attempt to develop general principles 

 which might apply to future dams. Chief among these is the necessity for direction 

 control of fish utilizing both natural and artificial factors, sfuch as current ve- 

 locity and chemicals. Models to test the most effective design of fishways for up- 

 and-downstream migrants are planned. 



Pacific Oceanic Fishery Investigations 



" HUGH M. SMITH " COMPLETES HYDROGRAPHIC AND BIOLOGICAL STUDY CRUISE ( Cruise No. 

 VIII) : In order to continue a hydrograFhic and biological study of that portion of 

 the Pacific Ocean lying between the Hawaiian and Samoan Islands , the Hugh M . Smith 

 completed a 9,000Hnile, 60-day cruise on March 14, This research vessel of the 

 Service's Pacific Oceanic Fishery Investigations on this cruise placed particular 

 emphasis on -the region lying between 1° and 7° N, latitude. The temperature, amount 

 of salt, oxygen, chemical nutrients, and the abundance of plankton life were meas- 

 ured at regular intervals, or stations, at thirteen different levels, ranging frai 

 the surface to about a depth of 3,700 feet — ^104 such stations were successfully 

 completed. 



From information obtained on previous cruises, this particular area (1° to 7° 

 N , latitude) has been found to be a peculiarly rich area in respect to fish life , 

 plankton, and nutrients required to support such life. One purpose of the cruise 

 was to determine whether this zone shifts north or south with the seasons and how 

 this may affect the abundance of tuna vdiich is associated with the rich area. 



In cooperation with the U. S. Weather Bureau, weather observations were made 

 by the ship's staff four times daily. Surface trolling and scouting for tuna were 

 conducted along the route. Fish collections for scientific purpose were made on 

 chosen localities. 



Observations of Tuna Schools at Sea ; A continuous watch was kept for schools 

 of tuna and associated flocks of birds when running during daylight hours. The 

 position and time sighted, behavior of the school, and its identification, vdien 

 possible, were recorded for 54 schools seen en route. Of these, 22 were definitely 

 identified as skipjack schools and one as yellowfin. Such observations, ccmbined 

 with those of other cSruises, are of value as an index to areas of greater or lesser 

 fish abundance. 



Two or three surface lures were trolled almost continuously during daylight 

 hours that the ship was under way. A total of 46O trolling hours yielded relatively 

 few fish (only 25 tuna) and almost all of these were taken close to islands rather 

 than in the open sea. 



« « * * « 



n joKN R. MANNING " INVESTIGATES TUNA SEINING IN PHOENIX-LINE ISLANDS AREA ( Cruise 

 No. V)l An~experimental six-week tuna-fishing cruise was completed on March 2 by 

 the John R. Manning , one of the Service's Pacific Oceanic Fishery Investigations 

 vessels. The vessel, outfitted for purse seining tunas, left Honolulu on January 11, 

 1951. The primary purpose of the cruise was to conduct experimental purse-seining 

 operations around the Phoenix or Line Islands, whichever appeared more premising 

 of results. 



