46 



human activities on the abundance and harvest 

 of these fish. 



Research is directed toward understanding the 

 population structure of each tuna species and to 

 identifying separate unit stocks. Studies will be 

 continued to determine the feeding habits, school- 

 ing behavior, depth and area stratification, spawn- 

 ing, rates of growth, and migrations. It has been 

 amply demonstrated that the distribution and 

 behavior of the timas is intimately related to 

 environmental factors. Research, therefore, will 

 be conducted on the circulation of the ocean, and 

 the distribution of its physical, chemical and bio- 

 logical properties and the relationship of these 

 factors to changes in abimdance, distribiuion, and 

 availability to capture of the timas. 



International Pacific Halibut Commission 



The convention between the United States and 

 Canada for the preservation of the halibut fishery 

 of the North Pacific and Bering Sea was estab- 

 lished to investigate the depletion of the Pacific 



halibut fishery, and to make recommendations 

 for its restoration. 



Joint scientific management by the United States 

 and Canada over the past 35 years has rebuilt 

 the once depleted fishery. However, pressures 

 on the fishery caused by the expanding Japanese 

 and Soviety trawl fisheries in the Gulf of Alaska, 

 can only be mitigated through the use of up-to- 

 date and reliable scientific data showing the 

 exact extent of the halibut resource and the 

 harmful effect of intensive foreign fishing upon it. 



In FY 1967 the Commission will continue its 

 statistical studies to measure the a\ailable supply 

 of halibut on the grounds and to determine the 

 extent of the yields taken from the various 

 stocks. Age composition and growth studies will 

 be made to ascertain the changes that occur within 

 the stocks brought about either by the fishery or 

 by natural forces of the environment. One of the 

 Commission's most valuable research tools, the 

 tagging program, will provide information re- 

 garding intermigration among the various stocks, 

 their seasonal availability, and their natural 

 and fishing mortality rates. 



