STORAGE OF FAT IN MUSCULAR TISSUE OF KING SALMON. 75 



Staining fats for microscopic determination. The particular technique used throughout 

 the series is the Herxheimer method of staining with scarlet red as modified by Bell. 

 This direct histochemical method has been supplemented by histological preparations 

 fixed and sectioned in paraffin and treated with various differential stains. 



Selection of salmon types. — The problem of fat variation in the salmon during the 

 migration is twofold. First, there is variation in any one region of the body at different 

 stages in the migration journey, and second, there is variation in the amount of fat present 

 in different parts of the body at any one time. In order to determine the variations of 

 the first class one must, of course, select typical localities representative of different 

 stages in the journey. For this comparison I have used salmon from the Columbia 

 River Basin, selecting four stations, the first one being at the mouth of the river, 

 working from the town of Ilwaco; the second below the cascades, working at Warrendale; 

 the third at Celilo Rapids and Celilo Falls, working from Seuferts; and the fourth at 

 the spawning grounds on the Clackamas River at Cazadero. 



There is a great variation in type among the individual fish present at any one sta- 

 tion at any given time. It therefore becomes a matter requiring some considerable 

 skill to select consistent types throughout a comparative series. Only after several 

 years of experience can one select these types with some little assurance that he will be 

 following similar salmon through the variations that occur at the different stations or 

 stages in the migration journey. The attempt was made to secure fish just as early in 

 the migration as possible, i. e., the stage at which the feeding ceases and the migration 

 begins. In several years of collecting at Ilwaco at the mouth of the Columbia River, 

 I have found that this very desirable stage can not be had within the fishing limits of 

 the locality; in fact,- the cessation of feeding must begin some considerable time before 

 the fish reach the fishing zone. In order to secure the facts as to the normal fat loading, 

 it was necessary to make a study of the feeding salmon at Monterey, where salmon that 

 are known to reenter the Columbia Basin are caught during the feeding stage. 



Salmon from the four stations on the Columbia mentioned above were collected 

 during the months of August and September, 191 1, 30 salmon in all being studied 

 in detail. The stations were visited in the order in which they are named above. 

 Invaluable aid and cooperation were constantly received from the local fishermen and 

 from the packers at the various stations."^ There is an undoubted seasonal variation 

 in the condition of salmon on the Columbia River, but by a rapid collection of material 

 from station to station the effects of the seasonal variations on the series ought to be 

 reduced to a minimum. The finest salmon at Ilwaco, for example, as regards the amount 

 of fat, are reported by the cannery men to come earlier in the season, though the fact 

 has not yet been determined by scientific methods of measurement. 



As a routine practice, salmon from each station were chosen of only two classes, 

 the choice or best type from the packers' point of view, and the poorest type, as inter- 

 preted by the same standards. Only the choice sizes, ranging in length from 80 to 100 

 centimeters were selected in this series. 



a I am particularly indebted to the P. J. McGowan Co. for aid in securing salmon types, and for numerous material favors in 

 Uie pursuit of the field work at Ilwaco and at Warrendale. The Warren Packing Co. and the Columbia River Packers' Associ- 

 ation granted the use of their receiving house on the Ilwaco Dock for a laboratory at that station. Mr. Frank A. Seufert, of The 

 Dalles, granted an unlimited supply of salmon from his Celilo fish wheels and the Tumwater seining grounds at Cclilo Falls. 

 The Cazadero observations were made at the station of the U. S. Bureau of Fisheries at that point on the Clackamas River, where 

 the hatchery force rendered liberal and invaluable assistance. 



