PEOGRESS IN" BIOLOGICAL INQUIEIES, 19 3 593 



Although this fishery Avas slightly more intensive than in 1929, the 

 age composition of the commercial catch reflects the rigid enforce- 

 ment of the regulations and the cooperation of the canners, and 

 indicates that the industry is on a stable basis. The clams varied 

 from 3 to 13 years in age. Over 80 per cent of the clams were older 

 than 6 years, and 86.48 per cent of all clams taken were mature. Of 

 the total number taken 60 per cent had spawned more than once. 



THE COCKLE 



Material collected during the early razor-clam studies included 

 shells of the cockle {Cardhmv corhis) from several localities on the 

 Pacific coast ranging from Tillamook, Oreg., to Port Moller, Alaska. 

 Although the amount of material was relatively small the homo- 

 genity of the samples and the uniformity of clam growth made it 

 excellent material for growth studies and several interesting features 

 have been presented in a report by Dr. F. W. Weymouth, of Stan- 

 ford University, and Seton H. Thompson, temporary assistant. 



(1) The ring method of age determination may be applied to this 

 as w^ell as to others previously studied. 



(2) The growth of Cardiuni is characterized by great regularity 

 as shown by the individual growth curves. 



(3) The type of growth observed in the razor clam is also found 

 in the cockle. In this form the relative growth rate falls throughout 

 postlarval life as first noted by Minot in the guinea pig. The de- 

 cline is orderly and regular and in most cases the growth curve can 

 be accurately fitted from the formula L = Be-'='=-^* based on an ex- 

 ponential rate of decline of the relative growth rate. 



(4) A comj^arison of growth in different localities shows the same 

 relations as observed in the razor clam. The northern forms, in 

 contrast to the southern, show a slower initial but more sustained 

 growth, and reach the greater age and larger size. 



EOGUE m.VER STEELHEAD TAGGING 



During the summer of 1929 a tagging experiment dealing with the 

 steelheads of the Kogue River was initiated in cooperation with the 

 Oregon State Game Commission. This investigation has been under 

 the supervision of J. A. Craig, and the work has as its definite object 

 the solution of the problem of whether or not there are two separate 

 races or self-propagating populations of steelheads in the Eogue 

 River, one of which makes its upstream spawning migration during 

 the summer and early fall and the other during the late fall and 

 winter. 



It seems logical to suppose that if there are two separate popula- 

 tions or races of steelheads in the Rogue River their spawning ac- 

 tivities must be separated either by time or space. In order to dis- 

 cover data relating to the time oi spawning and the extent of the 

 spawning migrations of the steelhead in this stream adult upstream 

 migrants were tagged near the mouth of the river during the sum- 

 mer and early fall of 1929 and the summer and fall of 1930. These 

 fish are also being tagged during the winter of 1930-31. 



